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android / platform / external / jetbrains / jdk8u_hotspot / a482fc01a461b60a024295f544eaa063285fee2d / . / src / share / vm / prims / jvmtiTagMap.cpp
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/*
* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "jvmtifiles/jvmtiEnv.hpp"
#include "oops/instanceMirrorKlass.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/oop.inline2.hpp"
#include "prims/jvmtiEventController.hpp"
#include "prims/jvmtiEventController.inline.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/jvmtiImpl.hpp"
#include "prims/jvmtiTagMap.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/jniHandles.hpp"
#include "runtime/mutex.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/reflectionUtils.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vm_operations.hpp"
#include "services/serviceUtil.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_ALL_GCS
#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
#endif // INCLUDE_ALL_GCS
// JvmtiTagHashmapEntry
//
// Each entry encapsulates a reference to the tagged object
// and the tag value. In addition an entry includes a next pointer which
// is used to chain entries together.
class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
private:
friend class JvmtiTagMap;
oop _object; // tagged object
jlong _tag; // the tag
JvmtiTagHashmapEntry* _next; // next on the list
inline void init(oop object, jlong tag) {
_object = object;
_tag = tag;
_next = NULL;
}
// constructor
JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); }
public:
// accessor methods
inline oop object() const { return _object; }
inline oop* object_addr() { return &_object; }
inline jlong tag() const { return _tag; }
inline void set_tag(jlong tag) {
assert(tag != 0, "can't be zero");
_tag = tag;
}
inline JvmtiTagHashmapEntry* next() const { return _next; }
inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
};
// JvmtiTagHashmap
//
// A hashmap is essentially a table of pointers to entries. Entries
// are hashed to a location, or position in the table, and then
// chained from that location. The "key" for hashing is address of
// the object, or oop. The "value" is the tag value.
//
// A hashmap maintains a count of the number entries in the hashmap
// and resizes if the number of entries exceeds a given threshold.
// The threshold is specified as a percentage of the size - for
// example a threshold of 0.75 will trigger the hashmap to resize
// if the number of entries is >75% of table size.
//
// A hashmap provides functions for adding, removing, and finding
// entries. It also provides a function to iterate over all entries
// in the hashmap.
class JvmtiTagHashmap : public CHeapObj<mtInternal> {
private:
friend class JvmtiTagMap;
enum {
small_trace_threshold = 10000, // threshold for tracing
medium_trace_threshold = 100000,
large_trace_threshold = 1000000,
initial_trace_threshold = small_trace_threshold
};
static int _sizes[]; // array of possible hashmap sizes
int _size; // actual size of the table
int _size_index; // index into size table
int _entry_count; // number of entries in the hashmap
float _load_factor; // load factor as a % of the size
int _resize_threshold; // computed threshold to trigger resizing.
bool _resizing_enabled; // indicates if hashmap can resize
int _trace_threshold; // threshold for trace messages
JvmtiTagHashmapEntry** _table; // the table of entries.
// private accessors
int resize_threshold() const { return _resize_threshold; }
int trace_threshold() const { return _trace_threshold; }
// initialize the hashmap
void init(int size_index=0, float load_factor=4.0f) {
int initial_size = _sizes[size_index];
_size_index = size_index;
_size = initial_size;
_entry_count = 0;
if (TraceJVMTIObjectTagging) {
_trace_threshold = initial_trace_threshold;
} else {
_trace_threshold = -1;
}
_load_factor = load_factor;
_resize_threshold = (int)(_load_factor * _size);
_resizing_enabled = true;
size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
if (_table == NULL) {
vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
"unable to allocate initial hashtable for jvmti object tags");
}
for (int i=0; i<initial_size; i++) {
_table[i] = NULL;
}
}
// hash a given key (oop) with the specified size
static unsigned int hash(oop key, int size) {
// shift right to get better distribution (as these bits will be zero
// with aligned addresses)
unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
#ifdef _LP64
return (addr >> 3) % size;
#else
return (addr >> 2) % size;
#endif
}
// hash a given key (oop)
unsigned int hash(oop key) {
return hash(key, _size);
}
// resize the hashmap - allocates a large table and re-hashes
// all entries into the new table.
void resize() {
int new_size_index = _size_index+1;
int new_size = _sizes[new_size_index];
if (new_size < 0) {
// hashmap already at maximum capacity
return;
}
// allocate new table
size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
if (new_table == NULL) {
warning("unable to allocate larger hashtable for jvmti object tags");
set_resizing_enabled(false);
return;
}
// initialize new table
int i;
for (i=0; i<new_size; i++) {
new_table[i] = NULL;
}
// rehash all entries into the new table
for (i=0; i<_size; i++) {
JvmtiTagHashmapEntry* entry = _table[i];
while (entry != NULL) {
JvmtiTagHashmapEntry* next = entry->next();
oop key = entry->object();
assert(key != NULL, "jni weak reference cleared!!");
unsigned int h = hash(key, new_size);
JvmtiTagHashmapEntry* anchor = new_table[h];
if (anchor == NULL) {
new_table[h] = entry;
entry->set_next(NULL);
} else {
entry->set_next(anchor);
new_table[h] = entry;
}
entry = next;
}
}
// free old table and update settings.
os::free((void*)_table);
_table = new_table;
_size_index = new_size_index;
_size = new_size;
// compute new resize threshold
_resize_threshold = (int)(_load_factor * _size);
}
// internal remove function - remove an entry at a given position in the
// table.
inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
assert(pos >= 0 && pos < _size, "out of range");
if (prev == NULL) {
_table[pos] = entry->next();
} else {
prev->set_next(entry->next());
}
assert(_entry_count > 0, "checking");
_entry_count--;
}
// resizing switch
bool is_resizing_enabled() const { return _resizing_enabled; }
void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
// debugging
void print_memory_usage();
void compute_next_trace_threshold();
public:
// create a JvmtiTagHashmap of a preferred size and optionally a load factor.
// The preferred size is rounded down to an actual size.
JvmtiTagHashmap(int size, float load_factor=0.0f) {
int i=0;
while (_sizes[i] < size) {
if (_sizes[i] < 0) {
assert(i > 0, "sanity check");
i--;
break;
}
i++;
}
// if a load factor is specified then use it, otherwise use default
if (load_factor > 0.01f) {
init(i, load_factor);
} else {
init(i);
}
}
// create a JvmtiTagHashmap with default settings
JvmtiTagHashmap() {
init();
}
// release table when JvmtiTagHashmap destroyed
~JvmtiTagHashmap() {
if (_table != NULL) {
os::free((void*)_table);
_table = NULL;
}
}
// accessors
int size() const { return _size; }
JvmtiTagHashmapEntry** table() const { return _table; }
int entry_count() const { return _entry_count; }
// find an entry in the hashmap, returns NULL if not found.
inline JvmtiTagHashmapEntry* find(oop key) {
unsigned int h = hash(key);
JvmtiTagHashmapEntry* entry = _table[h];
while (entry != NULL) {
if (entry->object() == key) {
return entry;
}
entry = entry->next();
}
return NULL;
}
// add a new entry to hashmap
inline void add(oop key, JvmtiTagHashmapEntry* entry) {
assert(key != NULL, "checking");
assert(find(key) == NULL, "duplicate detected");
unsigned int h = hash(key);
JvmtiTagHashmapEntry* anchor = _table[h];
if (anchor == NULL) {
_table[h] = entry;
entry->set_next(NULL);
} else {
entry->set_next(anchor);
_table[h] = entry;
}
_entry_count++;
if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
assert(TraceJVMTIObjectTagging, "should only get here when tracing");
print_memory_usage();
compute_next_trace_threshold();
}
// if the number of entries exceed the threshold then resize
if (entry_count() > resize_threshold() && is_resizing_enabled()) {
resize();
}
}
// remove an entry with the given key.
inline JvmtiTagHashmapEntry* remove(oop key) {
unsigned int h = hash(key);
JvmtiTagHashmapEntry* entry = _table[h];
JvmtiTagHashmapEntry* prev = NULL;
while (entry != NULL) {
if (key == entry->object()) {
break;
}
prev = entry;
entry = entry->next();
}
if (entry != NULL) {
remove(prev, h, entry);
}
return entry;
}
// iterate over all entries in the hashmap
void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
};
// possible hashmap sizes - odd primes that roughly double in size.
// To avoid excessive resizing the odd primes from 4801-76831 and
// 76831-307261 have been removed. The list must be terminated by -1.
int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
// A supporting class for iterating over all entries in Hashmap
class JvmtiTagHashmapEntryClosure {
public:
virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
};
// iterate over all entries in the hashmap
void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
for (int i=0; i<_size; i++) {
JvmtiTagHashmapEntry* entry = _table[i];
JvmtiTagHashmapEntry* prev = NULL;
while (entry != NULL) {
// obtain the next entry before invoking do_entry - this is
// necessary because do_entry may remove the entry from the
// hashmap.
JvmtiTagHashmapEntry* next = entry->next();
closure->do_entry(entry);
entry = next;
}
}
}
// debugging
void JvmtiTagHashmap::print_memory_usage() {
intptr_t p = (intptr_t)this;
tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
// table + entries in KB
int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
entry_count(), hashmap_usage, weak_globals_usage);
}
// compute threshold for the next trace message
void JvmtiTagHashmap::compute_next_trace_threshold() {
if (trace_threshold() < medium_trace_threshold) {
_trace_threshold += small_trace_threshold;
} else {
if (trace_threshold() < large_trace_threshold) {
_trace_threshold += medium_trace_threshold;
} else {
_trace_threshold += large_trace_threshold;
}
}
}
// create a JvmtiTagMap
JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
_env(env),
_lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
_free_entries(NULL),
_free_entries_count(0)
{
assert(JvmtiThreadState_lock->is_locked(), "sanity check");
assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
_hashmap = new JvmtiTagHashmap();
// finally add us to the environment
((JvmtiEnvBase *)env)->set_tag_map(this);
}
// destroy a JvmtiTagMap
JvmtiTagMap::~JvmtiTagMap() {
// no lock acquired as we assume the enclosing environment is
// also being destroryed.
((JvmtiEnvBase *)_env)->set_tag_map(NULL);
JvmtiTagHashmapEntry** table = _hashmap->table();
for (int j = 0; j < _hashmap->size(); j++) {
JvmtiTagHashmapEntry* entry = table[j];
while (entry != NULL) {
JvmtiTagHashmapEntry* next = entry->next();
delete entry;
entry = next;
}
}
// finally destroy the hashmap
delete _hashmap;
_hashmap = NULL;
// remove any entries on the free list
JvmtiTagHashmapEntry* entry = _free_entries;
while (entry != NULL) {
JvmtiTagHashmapEntry* next = entry->next();
delete entry;
entry = next;
}
_free_entries = NULL;
}
// create a hashmap entry
// - if there's an entry on the (per-environment) free list then this
// is returned. Otherwise an new entry is allocated.
JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
JvmtiTagHashmapEntry* entry;
if (_free_entries == NULL) {
entry = new JvmtiTagHashmapEntry(ref, tag);
} else {
assert(_free_entries_count > 0, "mismatched _free_entries_count");
_free_entries_count--;
entry = _free_entries;
_free_entries = entry->next();
entry->init(ref, tag);
}
return entry;
}
// destroy an entry by returning it to the free list
void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
// limit the size of the free list
if (_free_entries_count >= max_free_entries) {
delete entry;
} else {
entry->set_next(_free_entries);
_free_entries = entry;
_free_entries_count++;
}
}
// returns the tag map for the given environments. If the tag map
// doesn't exist then it is created.
JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
if (tag_map == NULL) {
MutexLocker mu(JvmtiThreadState_lock);
tag_map = ((JvmtiEnvBase*)env)->tag_map();
if (tag_map == NULL) {
tag_map = new JvmtiTagMap(env);
}
} else {
CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
}
return tag_map;
}
// iterate over all entries in the tag map.
void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
hashmap()->entry_iterate(closure);
}
// returns true if the hashmaps are empty
bool JvmtiTagMap::is_empty() {
assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
return hashmap()->entry_count() == 0;
}
// Return the tag value for an object, or 0 if the object is
// not tagged
//
static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
if (entry == NULL) {
return 0;
} else {
return entry->tag();
}
}
// A CallbackWrapper is a support class for querying and tagging an object
// around a callback to a profiler. The constructor does pre-callback
// work to get the tag value, klass tag value, ... and the destructor
// does the post-callback work of tagging or untagging the object.
//
// {
// CallbackWrapper wrapper(tag_map, o);
//
// (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
//
// } // wrapper goes out of scope here which results in the destructor
// checking to see if the object has been tagged, untagged, or the
// tag value has changed.
//
class CallbackWrapper : public StackObj {
private:
JvmtiTagMap* _tag_map;
JvmtiTagHashmap* _hashmap;
JvmtiTagHashmapEntry* _entry;
oop _o;
jlong _obj_size;
jlong _obj_tag;
jlong _klass_tag;
protected:
JvmtiTagMap* tag_map() const { return _tag_map; }
// invoked post-callback to tag, untag, or update the tag of an object
void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
JvmtiTagHashmapEntry* entry, jlong obj_tag);
public:
CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
"MT unsafe or must be VM thread");
// object to tag
_o = o;
// object size
_obj_size = (jlong)_o->size() * wordSize;
// record the context
_tag_map = tag_map;
_hashmap = tag_map->hashmap();
_entry = _hashmap->find(_o);
// get object tag
_obj_tag = (_entry == NULL) ? 0 : _entry->tag();
// get the class and the class's tag value
assert(SystemDictionary::Class_klass()->oop_is_instanceMirror(), "Is not?");
_klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
}
~CallbackWrapper() {
post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
}
inline jlong* obj_tag_p() { return &_obj_tag; }
inline jlong obj_size() const { return _obj_size; }
inline jlong obj_tag() const { return _obj_tag; }
inline jlong klass_tag() const { return _klass_tag; }
};
// callback post-callback to tag, untag, or update the tag of an object
void inline CallbackWrapper::post_callback_tag_update(oop o,
JvmtiTagHashmap* hashmap,
JvmtiTagHashmapEntry* entry,
jlong obj_tag) {
if (entry == NULL) {
if (obj_tag != 0) {
// callback has tagged the object
assert(Thread::current()->is_VM_thread(), "must be VMThread");
entry = tag_map()->create_entry(o, obj_tag);
hashmap->add(o, entry);
}
} else {
// object was previously tagged - the callback may have untagged
// the object or changed the tag value
if (obj_tag == 0) {
JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
assert(entry_removed == entry, "checking");
tag_map()->destroy_entry(entry);
} else {
if (obj_tag != entry->tag()) {
entry->set_tag(obj_tag);
}
}
}
}
// An extended CallbackWrapper used when reporting an object reference
// to the agent.
//
// {
// TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
//
// (*callback)(wrapper.klass_tag(),
// wrapper.obj_size(),
// wrapper.obj_tag_p()
// wrapper.referrer_tag_p(), ...)
//
// } // wrapper goes out of scope here which results in the destructor
// checking to see if the referrer object has been tagged, untagged,
// or the tag value has changed.
//
class TwoOopCallbackWrapper : public CallbackWrapper {
private:
bool _is_reference_to_self;
JvmtiTagHashmap* _referrer_hashmap;
JvmtiTagHashmapEntry* _referrer_entry;
oop _referrer;
jlong _referrer_obj_tag;
jlong _referrer_klass_tag;
jlong* _referrer_tag_p;
bool is_reference_to_self() const { return _is_reference_to_self; }
public:
TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
CallbackWrapper(tag_map, o)
{
// self reference needs to be handled in a special way
_is_reference_to_self = (referrer == o);
if (_is_reference_to_self) {
_referrer_klass_tag = klass_tag();
_referrer_tag_p = obj_tag_p();
} else {
_referrer = referrer;
// record the context
_referrer_hashmap = tag_map->hashmap();
_referrer_entry = _referrer_hashmap->find(_referrer);
// get object tag
_referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
_referrer_tag_p = &_referrer_obj_tag;
// get referrer class tag.
_referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
}
}
~TwoOopCallbackWrapper() {
if (!is_reference_to_self()){
post_callback_tag_update(_referrer,
_referrer_hashmap,
_referrer_entry,
_referrer_obj_tag);
}
}
// address of referrer tag
// (for a self reference this will return the same thing as obj_tag_p())
inline jlong* referrer_tag_p() { return _referrer_tag_p; }
// referrer's class tag
inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
};
// tag an object
//
// This function is performance critical. If many threads attempt to tag objects
// around the same time then it's possible that the Mutex associated with the
// tag map will be a hot lock.
void JvmtiTagMap::set_tag(jobject object, jlong tag) {
MutexLocker ml(lock());
// resolve the object
oop o = JNIHandles::resolve_non_null(object);
// see if the object is already tagged
JvmtiTagHashmap* hashmap = _hashmap;
JvmtiTagHashmapEntry* entry = hashmap->find(o);
// if the object is not already tagged then we tag it
if (entry == NULL) {
if (tag != 0) {
entry = create_entry(o, tag);
hashmap->add(o, entry);
} else {
// no-op
}
} else {
// if the object is already tagged then we either update
// the tag (if a new tag value has been provided)
// or remove the object if the new tag value is 0.
if (tag == 0) {
hashmap->remove(o);
destroy_entry(entry);
} else {
entry->set_tag(tag);
}
}
}
// get the tag for an object
jlong JvmtiTagMap::get_tag(jobject object) {
MutexLocker ml(lock());
// resolve the object
oop o = JNIHandles::resolve_non_null(object);
return tag_for(this, o);
}
// Helper class used to describe the static or instance fields of a class.
// For each field it holds the field index (as defined by the JVMTI specification),
// the field type, and the offset.
class ClassFieldDescriptor: public CHeapObj<mtInternal> {
private:
int _field_index;
int _field_offset;
char _field_type;
public:
ClassFieldDescriptor(int index, char type, int offset) :
_field_index(index), _field_type(type), _field_offset(offset) {
}
int field_index() const { return _field_index; }
char field_type() const { return _field_type; }
int field_offset() const { return _field_offset; }
};
class ClassFieldMap: public CHeapObj<mtInternal> {
private:
enum {
initial_field_count = 5
};
// list of field descriptors
GrowableArray<ClassFieldDescriptor*>* _fields;
// constructor
ClassFieldMap();
// add a field
void add(int index, char type, int offset);
// returns the field count for the given class
static int compute_field_count(instanceKlassHandle ikh);
public:
~ClassFieldMap();
// access
int field_count() { return _fields->length(); }
ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
// functions to create maps of static or instance fields
static ClassFieldMap* create_map_of_static_fields(Klass* k);
static ClassFieldMap* create_map_of_instance_fields(oop obj);
};
ClassFieldMap::ClassFieldMap() {
_fields = new (ResourceObj::C_HEAP, mtInternal)
GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
}
ClassFieldMap::~ClassFieldMap() {
for (int i=0; i<_fields->length(); i++) {
delete _fields->at(i);
}
delete _fields;
}
void ClassFieldMap::add(int index, char type, int offset) {
ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
_fields->append(field);
}
// Returns a heap allocated ClassFieldMap to describe the static fields
// of the given class.
//
ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
HandleMark hm;
instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
// create the field map
ClassFieldMap* field_map = new ClassFieldMap();
FilteredFieldStream f(ikh, false, false);
int max_field_index = f.field_count()-1;
int index = 0;
for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
// ignore instance fields
if (!fld.access_flags().is_static()) {
continue;
}
field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
}
return field_map;
}
// Returns a heap allocated ClassFieldMap to describe the instance fields
// of the given class. All instance fields are included (this means public
// and private fields declared in superclasses and superinterfaces too).
//
ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
HandleMark hm;
instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
// create the field map
ClassFieldMap* field_map = new ClassFieldMap();
FilteredFieldStream f(ikh, false, false);
int max_field_index = f.field_count()-1;
int index = 0;
for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
// ignore static fields
if (fld.access_flags().is_static()) {
continue;
}
field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
}
return field_map;
}
// Helper class used to cache a ClassFileMap for the instance fields of
// a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
// heap iteration and avoid creating a field map for each object in the heap
// (only need to create the map when the first instance of a class is encountered).
//
class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
private:
enum {
initial_class_count = 200
};
ClassFieldMap* _field_map;
ClassFieldMap* field_map() const { return _field_map; }
JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
~JvmtiCachedClassFieldMap();
static GrowableArray<InstanceKlass*>* _class_list;
static void add_to_class_list(InstanceKlass* ik);
public:
// returns the field map for a given object (returning map cached
// by InstanceKlass if possible
static ClassFieldMap* get_map_of_instance_fields(oop obj);
// removes the field map from all instanceKlasses - should be
// called before VM operation completes
static void clear_cache();
// returns the number of ClassFieldMap cached by instanceKlasses
static int cached_field_map_count();
};
GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
_field_map = field_map;
}
JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
if (_field_map != NULL) {
delete _field_map;
}
}
// Marker class to ensure that the class file map cache is only used in a defined
// scope.
class ClassFieldMapCacheMark : public StackObj {
private:
static bool _is_active;
public:
ClassFieldMapCacheMark() {
assert(Thread::current()->is_VM_thread(), "must be VMThread");
assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
_is_active = true;
}
~ClassFieldMapCacheMark() {
JvmtiCachedClassFieldMap::clear_cache();
_is_active = false;
}
static bool is_active() { return _is_active; }
};
bool ClassFieldMapCacheMark::_is_active;
// record that the given InstanceKlass is caching a field map
void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
if (_class_list == NULL) {
_class_list = new (ResourceObj::C_HEAP, mtInternal)
GrowableArray<InstanceKlass*>(initial_class_count, true);
}
_class_list->push(ik);
}
// returns the instance field map for the given object
// (returns field map cached by the InstanceKlass if possible)
ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
assert(Thread::current()->is_VM_thread(), "must be VMThread");
assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
Klass* k = obj->klass();
InstanceKlass* ik = InstanceKlass::cast(k);
// return cached map if possible
JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
if (cached_map != NULL) {
assert(cached_map->field_map() != NULL, "missing field list");
return cached_map->field_map();
} else {
ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
cached_map = new JvmtiCachedClassFieldMap(field_map);
ik->set_jvmti_cached_class_field_map(cached_map);
add_to_class_list(ik);
return field_map;
}
}
// remove the fields maps cached from all instanceKlasses
void JvmtiCachedClassFieldMap::clear_cache() {
assert(Thread::current()->is_VM_thread(), "must be VMThread");
if (_class_list != NULL) {
for (int i = 0; i < _class_list->length(); i++) {
InstanceKlass* ik = _class_list->at(i);
JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
assert(cached_map != NULL, "should not be NULL");
ik->set_jvmti_cached_class_field_map(NULL);
delete cached_map; // deletes the encapsulated field map
}
delete _class_list;
_class_list = NULL;
}
}
// returns the number of ClassFieldMap cached by instanceKlasses
int JvmtiCachedClassFieldMap::cached_field_map_count() {
return (_class_list == NULL) ? 0 : _class_list->length();
}
// helper function to indicate if an object is filtered by its tag or class tag
static inline bool is_filtered_by_heap_filter(jlong obj_tag,
jlong klass_tag,
int heap_filter) {
// apply the heap filter
if (obj_tag != 0) {
// filter out tagged objects
if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
} else {
// filter out untagged objects
if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
}
if (klass_tag != 0) {
// filter out objects with tagged classes
if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
} else {
// filter out objects with untagged classes.
if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
}
return false;
}
// helper function to indicate if an object is filtered by a klass filter
static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
if (!klass_filter.is_null()) {
if (obj->klass() != klass_filter()) {
return true;
}
}
return false;
}
// helper function to tell if a field is a primitive field or not
static inline bool is_primitive_field_type(char type) {
return (type != 'L' && type != '[');
}
// helper function to copy the value from location addr to jvalue.
static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
switch (value_type) {
case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
default: ShouldNotReachHere();
}
}
// helper function to invoke string primitive value callback
// returns visit control flags
static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
CallbackWrapper* wrapper,
oop str,
void* user_data)
{
assert(str->klass() == SystemDictionary::String_klass(), "not a string");
typeArrayOop s_value = java_lang_String::value(str);
// JDK-6584008: the value field may be null if a String instance is
// partially constructed.
if (s_value == NULL) {
return 0;
}
// get the string value and length
// (string value may be offset from the base)
int s_len = java_lang_String::length(str);
int s_offset = java_lang_String::offset(str);
jchar* value;
if (s_len > 0) {
value = s_value->char_at_addr(s_offset);
} else {
value = (jchar*) s_value->base(T_CHAR);
}
// invoke the callback
return (*cb)(wrapper->klass_tag(),
wrapper->obj_size(),
wrapper->obj_tag_p(),
value,
(jint)s_len,
user_data);
}
// helper function to invoke string primitive value callback
// returns visit control flags
static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
CallbackWrapper* wrapper,
oop obj,
void* user_data)
{
assert(obj->is_typeArray(), "not a primitive array");
// get base address of first element
typeArrayOop array = typeArrayOop(obj);
BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
void* elements = array->base(type);
// jvmtiPrimitiveType is defined so this mapping is always correct
jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
return (*cb)(wrapper->klass_tag(),
wrapper->obj_size(),
wrapper->obj_tag_p(),
(jint)array->length(),
elem_type,
elements,
user_data);
}
// helper function to invoke the primitive field callback for all static fields
// of a given class
static jint invoke_primitive_field_callback_for_static_fields
(CallbackWrapper* wrapper,
oop obj,
jvmtiPrimitiveFieldCallback cb,
void* user_data)
{
// for static fields only the index will be set
static jvmtiHeapReferenceInfo reference_info = { 0 };
assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
if (java_lang_Class::is_primitive(obj)) {
return 0;
}
Klass* klass = java_lang_Class::as_Klass(obj);
// ignore classes for object and type arrays
if (!klass->oop_is_instance()) {
return 0;
}
// ignore classes which aren't linked yet
InstanceKlass* ik = InstanceKlass::cast(klass);
if (!ik->is_linked()) {
return 0;
}
// get the field map
ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
// invoke the callback for each static primitive field
for (int i=0; i<field_map->field_count(); i++) {
ClassFieldDescriptor* field = field_map->field_at(i);
// ignore non-primitive fields
char type = field->field_type();
if (!is_primitive_field_type(type)) {
continue;
}
// one-to-one mapping
jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
// get offset and field value
int offset = field->field_offset();
address addr = (address)klass->java_mirror() + offset;
jvalue value;
copy_to_jvalue(&value, addr, value_type);
// field index
reference_info.field.index = field->field_index();
// invoke the callback
jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
&reference_info,
wrapper->klass_tag(),
wrapper->obj_tag_p(),
value,
value_type,
user_data);
if (res & JVMTI_VISIT_ABORT) {
delete field_map;
return res;
}
}
delete field_map;
return 0;
}
// helper function to invoke the primitive field callback for all instance fields
// of a given object
static jint invoke_primitive_field_callback_for_instance_fields(
CallbackWrapper* wrapper,
oop obj,
jvmtiPrimitiveFieldCallback cb,
void* user_data)
{
// for instance fields only the index will be set
static jvmtiHeapReferenceInfo reference_info = { 0 };
// get the map of the instance fields
ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
// invoke the callback for each instance primitive field
for (int i=0; i<fields->field_count(); i++) {
ClassFieldDescriptor* field = fields->field_at(i);
// ignore non-primitive fields
char type = field->field_type();
if (!is_primitive_field_type(type)) {
continue;
}
// one-to-one mapping
jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
// get offset and field value
int offset = field->field_offset();
address addr = (address)obj + offset;
jvalue value;
copy_to_jvalue(&value, addr, value_type);
// field index
reference_info.field.index = field->field_index();
// invoke the callback
jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
&reference_info,
wrapper->klass_tag(),
wrapper->obj_tag_p(),
value,
value_type,
user_data);
if (res & JVMTI_VISIT_ABORT) {
return res;
}
}
return 0;
}
// VM operation to iterate over all objects in the heap (both reachable
// and unreachable)
class VM_HeapIterateOperation: public VM_Operation {
private:
ObjectClosure* _blk;
public:
VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
VMOp_Type type() const { return VMOp_HeapIterateOperation; }
void doit() {
// allows class files maps to be cached during iteration
ClassFieldMapCacheMark cm;
// make sure that heap is parsable (fills TLABs with filler objects)
Universe::heap()->ensure_parsability(false); // no need to retire TLABs
// Verify heap before iteration - if the heap gets corrupted then
// JVMTI's IterateOverHeap will crash.
if (VerifyBeforeIteration) {
Universe::verify();
}
// do the iteration
// If this operation encounters a bad object when using CMS,
// consider using safe_object_iterate() which avoids perm gen
// objects that may contain bad references.
Universe::heap()->object_iterate(_blk);
}
};
// An ObjectClosure used to support the deprecated IterateOverHeap and
// IterateOverInstancesOfClass functions
class IterateOverHeapObjectClosure: public ObjectClosure {
private:
JvmtiTagMap* _tag_map;
KlassHandle _klass;
jvmtiHeapObjectFilter _object_filter;
jvmtiHeapObjectCallback _heap_object_callback;
const void* _user_data;
// accessors
JvmtiTagMap* tag_map() const { return _tag_map; }
jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
KlassHandle klass() const { return _klass; }
const void* user_data() const { return _user_data; }
// indicates if iteration has been aborted
bool _iteration_aborted;
bool is_iteration_aborted() const { return _iteration_aborted; }
void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
public:
IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
KlassHandle klass,
jvmtiHeapObjectFilter object_filter,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data) :
_tag_map(tag_map),
_klass(klass),
_object_filter(object_filter),
_heap_object_callback(heap_object_callback),
_user_data(user_data),
_iteration_aborted(false)
{
}
void do_object(oop o);
};
// invoked for each object in the heap
void IterateOverHeapObjectClosure::do_object(oop o) {
// check if iteration has been halted
if (is_iteration_aborted()) return;
// ignore any objects that aren't visible to profiler
if (!ServiceUtil::visible_oop(o)) return;
// instanceof check when filtering by klass
if (!klass().is_null() && !o->is_a(klass()())) {
return;
}
// prepare for the calllback
CallbackWrapper wrapper(tag_map(), o);
// if the object is tagged and we're only interested in untagged objects
// then don't invoke the callback. Similiarly, if the object is untagged
// and we're only interested in tagged objects we skip the callback.
if (wrapper.obj_tag() != 0) {
if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
} else {
if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
}
// invoke the agent's callback
jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
(void*)user_data());
if (control == JVMTI_ITERATION_ABORT) {
set_iteration_aborted(true);
}
}
// An ObjectClosure used to support the IterateThroughHeap function
class IterateThroughHeapObjectClosure: public ObjectClosure {
private:
JvmtiTagMap* _tag_map;
KlassHandle _klass;
int _heap_filter;
const jvmtiHeapCallbacks* _callbacks;
const void* _user_data;
// accessor functions
JvmtiTagMap* tag_map() const { return _tag_map; }
int heap_filter() const { return _heap_filter; }
const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
KlassHandle klass() const { return _klass; }
const void* user_data() const { return _user_data; }
// indicates if the iteration has been aborted
bool _iteration_aborted;
bool is_iteration_aborted() const { return _iteration_aborted; }
// used to check the visit control flags. If the abort flag is set
// then we set the iteration aborted flag so that the iteration completes
// without processing any further objects
bool check_flags_for_abort(jint flags) {
bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
if (is_abort) {
_iteration_aborted = true;
}
return is_abort;
}
public:
IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
KlassHandle klass,
int heap_filter,
const jvmtiHeapCallbacks* heap_callbacks,
const void* user_data) :
_tag_map(tag_map),
_klass(klass),
_heap_filter(heap_filter),
_callbacks(heap_callbacks),
_user_data(user_data),
_iteration_aborted(false)
{
}
void do_object(oop o);
};
// invoked for each object in the heap
void IterateThroughHeapObjectClosure::do_object(oop obj) {
// check if iteration has been halted
if (is_iteration_aborted()) return;
// ignore any objects that aren't visible to profiler
if (!ServiceUtil::visible_oop(obj)) return;
// apply class filter
if (is_filtered_by_klass_filter(obj, klass())) return;
// prepare for callback
CallbackWrapper wrapper(tag_map(), obj);
// check if filtered by the heap filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
return;
}
// for arrays we need the length, otherwise -1
bool is_array = obj->is_array();
int len = is_array ? arrayOop(obj)->length() : -1;
// invoke the object callback (if callback is provided)
if (callbacks()->heap_iteration_callback != NULL) {
jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
jint res = (*cb)(wrapper.klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
(jint)len,
(void*)user_data());
if (check_flags_for_abort(res)) return;
}
// for objects and classes we report primitive fields if callback provided
if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
jint res;
jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
if (obj->klass() == SystemDictionary::Class_klass()) {
res = invoke_primitive_field_callback_for_static_fields(&wrapper,
obj,
cb,
(void*)user_data());
} else {
res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
obj,
cb,
(void*)user_data());
}
if (check_flags_for_abort(res)) return;
}
// string callback
if (!is_array &&
callbacks()->string_primitive_value_callback != NULL &&
obj->klass() == SystemDictionary::String_klass()) {
jint res = invoke_string_value_callback(
callbacks()->string_primitive_value_callback,
&wrapper,
obj,
(void*)user_data() );
if (check_flags_for_abort(res)) return;
}
// array callback
if (is_array &&
callbacks()->array_primitive_value_callback != NULL &&
obj->is_typeArray()) {
jint res = invoke_array_primitive_value_callback(
callbacks()->array_primitive_value_callback,
&wrapper,
obj,
(void*)user_data() );
if (check_flags_for_abort(res)) return;
}
};
// Deprecated function to iterate over all objects in the heap
void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
KlassHandle klass,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data)
{
MutexLocker ml(Heap_lock);
IterateOverHeapObjectClosure blk(this,
klass,
object_filter,
heap_object_callback,
user_data);
VM_HeapIterateOperation op(&blk);
VMThread::execute(&op);
}
// Iterates over all objects in the heap
void JvmtiTagMap::iterate_through_heap(jint heap_filter,
KlassHandle klass,
const jvmtiHeapCallbacks* callbacks,
const void* user_data)
{
MutexLocker ml(Heap_lock);
IterateThroughHeapObjectClosure blk(this,
klass,
heap_filter,
callbacks,
user_data);
VM_HeapIterateOperation op(&blk);
VMThread::execute(&op);
}
// support class for get_objects_with_tags
class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
private:
JvmtiEnv* _env;
jlong* _tags;
jint _tag_count;
GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
GrowableArray<uint64_t>* _tag_results; // collected tags
public:
TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
_env = env;
_tags = (jlong*)tags;
_tag_count = tag_count;
_object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
_tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
}
~TagObjectCollector() {
delete _object_results;
delete _tag_results;
}
// for each tagged object check if the tag value matches
// - if it matches then we create a JNI local reference to the object
// and record the reference and tag value.
//
void do_entry(JvmtiTagHashmapEntry* entry) {
for (int i=0; i<_tag_count; i++) {
if (_tags[i] == entry->tag()) {
oop o = entry->object();
assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
jobject ref = JNIHandles::make_local(JavaThread::current(), o);
_object_results->append(ref);
_tag_results->append((uint64_t)entry->tag());
}
}
}
// return the results from the collection
//
jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
jvmtiError error;
int count = _object_results->length();
assert(count >= 0, "sanity check");
// if object_result_ptr is not NULL then allocate the result and copy
// in the object references.
if (object_result_ptr != NULL) {
error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
if (error != JVMTI_ERROR_NONE) {
return error;
}
for (int i=0; i<count; i++) {
(*object_result_ptr)[i] = _object_results->at(i);
}
}
// if tag_result_ptr is not NULL then allocate the result and copy
// in the tag values.
if (tag_result_ptr != NULL) {
error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
if (error != JVMTI_ERROR_NONE) {
if (object_result_ptr != NULL) {
_env->Deallocate((unsigned char*)object_result_ptr);
}
return error;
}
for (int i=0; i<count; i++) {
(*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
}
}
*count_ptr = count;
return JVMTI_ERROR_NONE;
}
};
// return the list of objects with the specified tags
jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
TagObjectCollector collector(env(), tags, count);
{
// iterate over all tagged objects
MutexLocker ml(lock());
entry_iterate(&collector);
}
return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
}
// ObjectMarker is used to support the marking objects when walking the
// heap.
//
// This implementation uses the existing mark bits in an object for
// marking. Objects that are marked must later have their headers restored.
// As most objects are unlocked and don't have their identity hash computed
// we don't have to save their headers. Instead we save the headers that
// are "interesting". Later when the headers are restored this implementation
// restores all headers to their initial value and then restores the few
// objects that had interesting headers.
//
// Future work: This implementation currently uses growable arrays to save
// the oop and header of interesting objects. As an optimization we could
// use the same technique as the GC and make use of the unused area
// between top() and end().
//
// An ObjectClosure used to restore the mark bits of an object
class RestoreMarksClosure : public ObjectClosure {
public:
void do_object(oop o) {
if (o != NULL) {
markOop mark = o->mark();
if (mark->is_marked()) {
o->init_mark();
}
}
}
};
// ObjectMarker provides the mark and visited functions
class ObjectMarker : AllStatic {
private:
// saved headers
static GrowableArray<oop>* _saved_oop_stack;
static GrowableArray<markOop>* _saved_mark_stack;
static bool _needs_reset; // do we need to reset mark bits?
public:
static void init(); // initialize
static void done(); // clean-up
static inline void mark(oop o); // mark an object
static inline bool visited(oop o); // check if object has been visited
static inline bool needs_reset() { return _needs_reset; }
static inline void set_needs_reset(bool v) { _needs_reset = v; }
};
GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
// initialize ObjectMarker - prepares for object marking
void ObjectMarker::init() {
assert(Thread::current()->is_VM_thread(), "must be VMThread");
// prepare heap for iteration
Universe::heap()->ensure_parsability(false); // no need to retire TLABs
// create stacks for interesting headers
_saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
_saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
if (UseBiasedLocking) {
BiasedLocking::preserve_marks();
}
}
// Object marking is done so restore object headers
void ObjectMarker::done() {
// iterate over all objects and restore the mark bits to
// their initial value
RestoreMarksClosure blk;
if (needs_reset()) {
Universe::heap()->object_iterate(&blk);
} else {
// We don't need to reset mark bits on this call, but reset the
// flag to the default for the next call.
set_needs_reset(true);
}
// now restore the interesting headers
for (int i = 0; i < _saved_oop_stack->length(); i++) {
oop o = _saved_oop_stack->at(i);
markOop mark = _saved_mark_stack->at(i);
o->set_mark(mark);
}
if (UseBiasedLocking) {
BiasedLocking::restore_marks();
}
// free the stacks
delete _saved_oop_stack;
delete _saved_mark_stack;
}
// mark an object
inline void ObjectMarker::mark(oop o) {
assert(Universe::heap()->is_in(o), "sanity check");
assert(!o->mark()->is_marked(), "should only mark an object once");
// object's mark word
markOop mark = o->mark();
if (mark->must_be_preserved(o)) {
_saved_mark_stack->push(mark);
_saved_oop_stack->push(o);
}
// mark the object
o->set_mark(markOopDesc::prototype()->set_marked());
}
// return true if object is marked
inline bool ObjectMarker::visited(oop o) {
return o->mark()->is_marked();
}
// Stack allocated class to help ensure that ObjectMarker is used
// correctly. Constructor initializes ObjectMarker, destructor calls
// ObjectMarker's done() function to restore object headers.
class ObjectMarkerController : public StackObj {
public:
ObjectMarkerController() {
ObjectMarker::init();
}
~ObjectMarkerController() {
ObjectMarker::done();
}
};
// helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
// (not performance critical as only used for roots)
static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
switch (kind) {
case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
}
}
// Base class for all heap walk contexts. The base class maintains a flag
// to indicate if the context is valid or not.
class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
private:
bool _valid;
public:
HeapWalkContext(bool valid) { _valid = valid; }
void invalidate() { _valid = false; }
bool is_valid() const { return _valid; }
};
// A basic heap walk context for the deprecated heap walking functions.
// The context for a basic heap walk are the callbacks and fields used by
// the referrer caching scheme.
class BasicHeapWalkContext: public HeapWalkContext {
private:
jvmtiHeapRootCallback _heap_root_callback;
jvmtiStackReferenceCallback _stack_ref_callback;
jvmtiObjectReferenceCallback _object_ref_callback;
// used for caching
oop _last_referrer;
jlong _last_referrer_tag;
public:
BasicHeapWalkContext() : HeapWalkContext(false) { }
BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
jvmtiStackReferenceCallback stack_ref_callback,
jvmtiObjectReferenceCallback object_ref_callback) :
HeapWalkContext(true),
_heap_root_callback(heap_root_callback),
_stack_ref_callback(stack_ref_callback),
_object_ref_callback(object_ref_callback),
_last_referrer(NULL),
_last_referrer_tag(0) {
}
// accessors
jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
oop last_referrer() const { return _last_referrer; }
void set_last_referrer(oop referrer) { _last_referrer = referrer; }
jlong last_referrer_tag() const { return _last_referrer_tag; }
void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
};
// The advanced heap walk context for the FollowReferences functions.
// The context is the callbacks, and the fields used for filtering.
class AdvancedHeapWalkContext: public HeapWalkContext {
private:
jint _heap_filter;
KlassHandle _klass_filter;
const jvmtiHeapCallbacks* _heap_callbacks;
public:
AdvancedHeapWalkContext() : HeapWalkContext(false) { }
AdvancedHeapWalkContext(jint heap_filter,
KlassHandle klass_filter,
const jvmtiHeapCallbacks* heap_callbacks) :
HeapWalkContext(true),
_heap_filter(heap_filter),
_klass_filter(klass_filter),
_heap_callbacks(heap_callbacks) {
}
// accessors
jint heap_filter() const { return _heap_filter; }
KlassHandle klass_filter() const { return _klass_filter; }
const jvmtiHeapReferenceCallback heap_reference_callback() const {
return _heap_callbacks->heap_reference_callback;
};
const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
return _heap_callbacks->primitive_field_callback;
}
const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
return _heap_callbacks->array_primitive_value_callback;
}
const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
return _heap_callbacks->string_primitive_value_callback;
}
};
// The CallbackInvoker is a class with static functions that the heap walk can call
// into to invoke callbacks. It works in one of two modes. The "basic" mode is
// used for the deprecated IterateOverReachableObjects functions. The "advanced"
// mode is for the newer FollowReferences function which supports a lot of
// additional callbacks.
class CallbackInvoker : AllStatic {
private:
// heap walk styles
enum { basic, advanced };
static int _heap_walk_type;
static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
// context for basic style heap walk
static BasicHeapWalkContext _basic_context;
static BasicHeapWalkContext* basic_context() {
assert(_basic_context.is_valid(), "invalid");
return &_basic_context;
}
// context for advanced style heap walk
static AdvancedHeapWalkContext _advanced_context;
static AdvancedHeapWalkContext* advanced_context() {
assert(_advanced_context.is_valid(), "invalid");
return &_advanced_context;
}
// context needed for all heap walks
static JvmtiTagMap* _tag_map;
static const void* _user_data;
static GrowableArray<oop>* _visit_stack;
// accessors
static JvmtiTagMap* tag_map() { return _tag_map; }
static const void* user_data() { return _user_data; }
static GrowableArray<oop>* visit_stack() { return _visit_stack; }
// if the object hasn't been visited then push it onto the visit stack
// so that it will be visited later
static inline bool check_for_visit(oop obj) {
if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
return true;
}
// invoke basic style callbacks
static inline bool invoke_basic_heap_root_callback
(jvmtiHeapRootKind root_kind, oop obj);
static inline bool invoke_basic_stack_ref_callback
(jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
int slot, oop obj);
static inline bool invoke_basic_object_reference_callback
(jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
// invoke advanced style callbacks
static inline bool invoke_advanced_heap_root_callback
(jvmtiHeapReferenceKind ref_kind, oop obj);
static inline bool invoke_advanced_stack_ref_callback
(jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
jmethodID method, jlocation bci, jint slot, oop obj);
static inline bool invoke_advanced_object_reference_callback
(jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
// used to report the value of primitive fields
static inline bool report_primitive_field
(jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
public:
// initialize for basic mode
static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
GrowableArray<oop>* visit_stack,
const void* user_data,
BasicHeapWalkContext context);
// initialize for advanced mode
static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
GrowableArray<oop>* visit_stack,
const void* user_data,
AdvancedHeapWalkContext context);
// functions to report roots
static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
jmethodID m, oop o);
static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
jmethodID method, jlocation bci, jint slot, oop o);
// functions to report references
static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
static inline bool report_class_reference(oop referrer, oop referree);
static inline bool report_class_loader_reference(oop referrer, oop referree);
static inline bool report_signers_reference(oop referrer, oop referree);
static inline bool report_protection_domain_reference(oop referrer, oop referree);
static inline bool report_superclass_reference(oop referrer, oop referree);
static inline bool report_interface_reference(oop referrer, oop referree);
static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
static inline bool report_field_reference(oop referrer, oop referree, jint slot);
static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
static inline bool report_primitive_array_values(oop array);
static inline bool report_string_value(oop str);
static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
};
// statics
int CallbackInvoker::_heap_walk_type;
BasicHeapWalkContext CallbackInvoker::_basic_context;
AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
JvmtiTagMap* CallbackInvoker::_tag_map;
const void* CallbackInvoker::_user_data;
GrowableArray<oop>* CallbackInvoker::_visit_stack;
// initialize for basic heap walk (IterateOverReachableObjects et al)
void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
GrowableArray<oop>* visit_stack,
const void* user_data,
BasicHeapWalkContext context) {
_tag_map = tag_map;
_visit_stack = visit_stack;
_user_data = user_data;
_basic_context = context;
_advanced_context.invalidate(); // will trigger assertion if used
_heap_walk_type = basic;
}
// initialize for advanced heap walk (FollowReferences)
void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
GrowableArray<oop>* visit_stack,
const void* user_data,
AdvancedHeapWalkContext context) {
_tag_map = tag_map;
_visit_stack = visit_stack;
_user_data = user_data;
_advanced_context = context;
_basic_context.invalidate(); // will trigger assertion if used
_heap_walk_type = advanced;
}
// invoke basic style heap root callback
inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
assert(ServiceUtil::visible_oop(obj), "checking");
// if we heap roots should be reported
jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
if (cb == NULL) {
return check_for_visit(obj);
}
CallbackWrapper wrapper(tag_map(), obj);
jvmtiIterationControl control = (*cb)(root_kind,
wrapper.klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
(void*)user_data());
// push root to visit stack when following references
if (control == JVMTI_ITERATION_CONTINUE &&
basic_context()->object_ref_callback() != NULL) {
visit_stack()->push(obj);
}
return control != JVMTI_ITERATION_ABORT;
}
// invoke basic style stack ref callback
inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
jlong thread_tag,
jint depth,
jmethodID method,
jint slot,
oop obj) {
assert(ServiceUtil::visible_oop(obj), "checking");
// if we stack refs should be reported
jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
if (cb == NULL) {
return check_for_visit(obj);
}
CallbackWrapper wrapper(tag_map(), obj);
jvmtiIterationControl control = (*cb)(root_kind,
wrapper.klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
thread_tag,
depth,
method,
slot,
(void*)user_data());
// push root to visit stack when following references
if (control == JVMTI_ITERATION_CONTINUE &&
basic_context()->object_ref_callback() != NULL) {
visit_stack()->push(obj);
}
return control != JVMTI_ITERATION_ABORT;
}
// invoke basic style object reference callback
inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
oop referrer,
oop referree,
jint index) {
assert(ServiceUtil::visible_oop(referrer), "checking");
assert(ServiceUtil::visible_oop(referree), "checking");
BasicHeapWalkContext* context = basic_context();
// callback requires the referrer's tag. If it's the same referrer
// as the last call then we use the cached value.
jlong referrer_tag;
if (referrer == context->last_referrer()) {
referrer_tag = context->last_referrer_tag();
} else {
referrer_tag = tag_for(tag_map(), referrer);
}
// do the callback
CallbackWrapper wrapper(tag_map(), referree);
jvmtiObjectReferenceCallback cb = context->object_ref_callback();
jvmtiIterationControl control = (*cb)(ref_kind,
wrapper.klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
referrer_tag,
index,
(void*)user_data());
// record referrer and referrer tag. For self-references record the
// tag value from the callback as this might differ from referrer_tag.
context->set_last_referrer(referrer);
if (referrer == referree) {
context->set_last_referrer_tag(*wrapper.obj_tag_p());
} else {
context->set_last_referrer_tag(referrer_tag);
}
if (control == JVMTI_ITERATION_CONTINUE) {
return check_for_visit(referree);
} else {
return control != JVMTI_ITERATION_ABORT;
}
}
// invoke advanced style heap root callback
inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
oop obj) {
assert(ServiceUtil::visible_oop(obj), "checking");
AdvancedHeapWalkContext* context = advanced_context();
// check that callback is provided
jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
if (cb == NULL) {
return check_for_visit(obj);
}
// apply class filter
if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
return check_for_visit(obj);
}
// setup the callback wrapper
CallbackWrapper wrapper(tag_map(), obj);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return check_for_visit(obj);
}
// for arrays we need the length, otherwise -1
jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
// invoke the callback
jint res = (*cb)(ref_kind,
NULL, // referrer info
wrapper.klass_tag(),
0, // referrer_class_tag is 0 for heap root
wrapper.obj_size(),
wrapper.obj_tag_p(),
NULL, // referrer_tag_p
len,
(void*)user_data());
if (res & JVMTI_VISIT_ABORT) {
return false;// referrer class tag
}
if (res & JVMTI_VISIT_OBJECTS) {
check_for_visit(obj);
}
return true;
}
// report a reference from a thread stack to an object
inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
jlong thread_tag,
jlong tid,
int depth,
jmethodID method,
jlocation bci,
jint slot,
oop obj) {
assert(ServiceUtil::visible_oop(obj), "checking");
AdvancedHeapWalkContext* context = advanced_context();
// check that callback is provider
jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
if (cb == NULL) {
return check_for_visit(obj);
}
// apply class filter
if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
return check_for_visit(obj);
}
// setup the callback wrapper
CallbackWrapper wrapper(tag_map(), obj);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return check_for_visit(obj);
}
// setup the referrer info
jvmtiHeapReferenceInfo reference_info;
reference_info.stack_local.thread_tag = thread_tag;
reference_info.stack_local.thread_id = tid;
reference_info.stack_local.depth = depth;
reference_info.stack_local.method = method;
reference_info.stack_local.location = bci;
reference_info.stack_local.slot = slot;
// for arrays we need the length, otherwise -1
jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
// call into the agent
int res = (*cb)(ref_kind,
&reference_info,
wrapper.klass_tag(),
0, // referrer_class_tag is 0 for heap root (stack)
wrapper.obj_size(),
wrapper.obj_tag_p(),
NULL, // referrer_tag is 0 for root
len,
(void*)user_data());
if (res & JVMTI_VISIT_ABORT) {
return false;
}
if (res & JVMTI_VISIT_OBJECTS) {
check_for_visit(obj);
}
return true;
}
// This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
// only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
#define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
| (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
| (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
| (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
| (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
| (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
// invoke the object reference callback to report a reference
inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
oop referrer,
oop obj,
jint index)
{
// field index is only valid field in reference_info
static jvmtiHeapReferenceInfo reference_info = { 0 };
assert(ServiceUtil::visible_oop(referrer), "checking");
assert(ServiceUtil::visible_oop(obj), "checking");
AdvancedHeapWalkContext* context = advanced_context();
// check that callback is provider
jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
if (cb == NULL) {
return check_for_visit(obj);
}
// apply class filter
if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
return check_for_visit(obj);
}
// setup the callback wrapper
TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return check_for_visit(obj);
}
// field index is only valid field in reference_info
reference_info.field.index = index;
// for arrays we need the length, otherwise -1
jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
// invoke the callback
int res = (*cb)(ref_kind,
(REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
wrapper.klass_tag(),
wrapper.referrer_klass_tag(),
wrapper.obj_size(),
wrapper.obj_tag_p(),
wrapper.referrer_tag_p(),
len,
(void*)user_data());
if (res & JVMTI_VISIT_ABORT) {
return false;
}
if (res & JVMTI_VISIT_OBJECTS) {
check_for_visit(obj);
}
return true;
}
// report a "simple root"
inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
assert(ServiceUtil::visible_oop(obj), "checking");
if (is_basic_heap_walk()) {
// map to old style root kind
jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
return invoke_basic_heap_root_callback(root_kind, obj);
} else {
assert(is_advanced_heap_walk(), "wrong heap walk type");
return invoke_advanced_heap_root_callback(kind, obj);
}
}
// invoke the primitive array values
inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
assert(obj->is_typeArray(), "not a primitive array");
AdvancedHeapWalkContext* context = advanced_context();
assert(context->array_primitive_value_callback() != NULL, "no callback");
// apply class filter
if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
return true;
}
CallbackWrapper wrapper(tag_map(), obj);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return true;
}
// invoke the callback
int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
&wrapper,
obj,
(void*)user_data());
return (!(res & JVMTI_VISIT_ABORT));
}
// invoke the string value callback
inline bool CallbackInvoker::report_string_value(oop str) {
assert(str->klass() == SystemDictionary::String_klass(), "not a string");
AdvancedHeapWalkContext* context = advanced_context();
assert(context->string_primitive_value_callback() != NULL, "no callback");
// apply class filter
if (is_filtered_by_klass_filter(str, context->klass_filter())) {
return true;
}
CallbackWrapper wrapper(tag_map(), str);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return true;
}
// invoke the callback
int res = invoke_string_value_callback(context->string_primitive_value_callback(),
&wrapper,
str,
(void*)user_data());
return (!(res & JVMTI_VISIT_ABORT));
}
// invoke the primitive field callback
inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
oop obj,
jint index,
address addr,
char type)
{
// for primitive fields only the index will be set
static jvmtiHeapReferenceInfo reference_info = { 0 };
AdvancedHeapWalkContext* context = advanced_context();
assert(context->primitive_field_callback() != NULL, "no callback");
// apply class filter
if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
return true;
}
CallbackWrapper wrapper(tag_map(), obj);
// apply tag filter
if (is_filtered_by_heap_filter(wrapper.obj_tag(),
wrapper.klass_tag(),
context->heap_filter())) {
return true;
}
// the field index in the referrer
reference_info.field.index = index;
// map the type
jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
// setup the jvalue
jvalue value;
copy_to_jvalue(&value, addr, value_type);
jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
int res = (*cb)(ref_kind,
&reference_info,
wrapper.klass_tag(),
wrapper.obj_tag_p(),
value,
value_type,
(void*)user_data());
return (!(res & JVMTI_VISIT_ABORT));
}
// instance field
inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
jint index,
address value,
char type) {
return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
obj,
index,
value,
type);
}
// static field
inline bool CallbackInvoker::report_primitive_static_field(oop obj,
jint index,
address value,
char type) {
return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
obj,
index,
value,
type);
}
// report a JNI local (root object) to the profiler
inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
if (is_basic_heap_walk()) {
return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
thread_tag,
depth,
m,
-1,
obj);
} else {
return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
thread_tag, tid,
depth,
m,
(jlocation)-1,
-1,
obj);
}
}
// report a local (stack reference, root object)
inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
jlong tid,
jint depth,
jmethodID method,
jlocation bci,
jint slot,
oop obj) {
if (is_basic_heap_walk()) {
return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
thread_tag,
depth,
method,
slot,
obj);
} else {
return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
thread_tag,
tid,
depth,
method,
bci,
slot,
obj);
}
}
// report an object referencing a class.
inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
}
}
// report a class referencing its class loader.
inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
}
}
// report a class referencing its signers.
inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
}
}
// report a class referencing its protection domain..
inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
}
}
// report a class referencing its superclass.
inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
// Send this to be consistent with past implementation
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
}
}
// report a class referencing one of its interfaces.
inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
}
}
// report a class referencing one of its static fields.
inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
}
}
// report an array referencing an element object
inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
}
}
// report an object referencing an instance field object
inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
}
}
// report an array referencing an element object
inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
if (is_basic_heap_walk()) {
return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
} else {
return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
}
}
// A supporting closure used to process simple roots
class SimpleRootsClosure : public OopClosure {
private:
jvmtiHeapReferenceKind _kind;
bool _continue;
jvmtiHeapReferenceKind root_kind() { return _kind; }
public:
void set_kind(jvmtiHeapReferenceKind kind) {
_kind = kind;
_continue = true;
}
inline bool stopped() {
return !_continue;
}
void do_oop(oop* obj_p) {
// iteration has terminated
if (stopped()) {
return;
}
// ignore null or deleted handles
oop o = *obj_p;
if (o == NULL || o == JNIHandles::deleted_handle()) {
return;
}
assert(Universe::heap()->is_in_reserved(o), "should be impossible");
jvmtiHeapReferenceKind kind = root_kind();
if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
// SystemDictionary::always_strong_oops_do reports the application
// class loader as a root. We want this root to be reported as
// a root kind of "OTHER" rather than "SYSTEM_CLASS".
if (!o->is_instanceMirror()) {
kind = JVMTI_HEAP_REFERENCE_OTHER;
}
}
// some objects are ignored - in the case of simple
// roots it's mostly Symbol*s that we are skipping
// here.
if (!ServiceUtil::visible_oop(o)) {
return;
}
// invoke the callback
_continue = CallbackInvoker::report_simple_root(kind, o);
}
virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
};
// A supporting closure used to process JNI locals
class JNILocalRootsClosure : public OopClosure {
private:
jlong _thread_tag;
jlong _tid;
jint _depth;
jmethodID _method;
bool _continue;
public:
void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
_thread_tag = thread_tag;
_tid = tid;
_depth = depth;
_method = method;
_continue = true;
}
inline bool stopped() {
return !_continue;
}
void do_oop(oop* obj_p) {
// iteration has terminated
if (stopped()) {
return;
}
// ignore null or deleted handles
oop o = *obj_p;
if (o == NULL || o == JNIHandles::deleted_handle()) {
return;
}
if (!ServiceUtil::visible_oop(o)) {
return;
}
// invoke the callback
_continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
}
virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
};
// A VM operation to iterate over objects that are reachable from
// a set of roots or an initial object.
//
// For VM_HeapWalkOperation the set of roots used is :-
//
// - All JNI global references
// - All inflated monitors
// - All classes loaded by the boot class loader (or all classes
// in the event that class unloading is disabled)
// - All java threads
// - For each java thread then all locals and JNI local references
// on the thread's execution stack
// - All visible/explainable objects from Universes::oops_do
//
class VM_HeapWalkOperation: public VM_Operation {
private:
enum {
initial_visit_stack_size = 4000
};
bool _is_advanced_heap_walk; // indicates FollowReferences
JvmtiTagMap* _tag_map;
Handle _initial_object;
GrowableArray<oop>* _visit_stack; // the visit stack
bool _collecting_heap_roots; // are we collecting roots
bool _following_object_refs; // are we following object references
bool _reporting_primitive_fields; // optional reporting
bool _reporting_primitive_array_values;
bool _reporting_string_values;
GrowableArray<oop>* create_visit_stack() {
return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
}
// accessors
bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
JvmtiTagMap* tag_map() const { return _tag_map; }
Handle initial_object() const { return _initial_object; }
bool is_following_references() const { return _following_object_refs; }
bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
bool is_reporting_string_values() const { return _reporting_string_values; }
GrowableArray<oop>* visit_stack() const { return _visit_stack; }
// iterate over the various object types
inline bool iterate_over_array(oop o);
inline bool iterate_over_type_array(oop o);
inline bool iterate_over_class(oop o);
inline bool iterate_over_object(oop o);
// root collection
inline bool collect_simple_roots();
inline bool collect_stack_roots();
inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
// visit an object
inline bool visit(oop o);
public:
VM_HeapWalkOperation(JvmtiTagMap* tag_map,
Handle initial_object,
BasicHeapWalkContext callbacks,
const void* user_data);
VM_HeapWalkOperation(JvmtiTagMap* tag_map,
Handle initial_object,
AdvancedHeapWalkContext callbacks,
const void* user_data);
~VM_HeapWalkOperation();
VMOp_Type type() const { return VMOp_HeapWalkOperation; }
void doit();
};
VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
Handle initial_object,
BasicHeapWalkContext callbacks,
const void* user_data) {
_is_advanced_heap_walk = false;
_tag_map = tag_map;
_initial_object = initial_object;
_following_object_refs = (callbacks.object_ref_callback() != NULL);
_reporting_primitive_fields = false;
_reporting_primitive_array_values = false;
_reporting_string_values = false;
_visit_stack = create_visit_stack();
CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
}
VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
Handle initial_object,
AdvancedHeapWalkContext callbacks,
const void* user_data) {
_is_advanced_heap_walk = true;
_tag_map = tag_map;
_initial_object = initial_object;
_following_object_refs = true;
_reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
_reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
_reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
_visit_stack = create_visit_stack();
CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
}
VM_HeapWalkOperation::~VM_HeapWalkOperation() {
if (_following_object_refs) {
assert(_visit_stack != NULL, "checking");
delete _visit_stack;
_visit_stack = NULL;
}
}
// an array references its class and has a reference to
// each element in the array
inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
objArrayOop array = objArrayOop(o);
// array reference to its class
oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
if (!CallbackInvoker::report_class_reference(o, mirror)) {
return false;
}
// iterate over the array and report each reference to a
// non-null element
for (int index=0; index<array->length(); index++) {
oop elem = array->obj_at(index);
if (elem == NULL) {
continue;
}
// report the array reference o[index] = elem
if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
return false;
}
}
return true;
}
// a type array references its class
inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
Klass* k = o->klass();
oop mirror = k->java_mirror();
if (!CallbackInvoker::report_class_reference(o, mirror)) {
return false;
}
// report the array contents if required
if (is_reporting_primitive_array_values()) {
if (!CallbackInvoker::report_primitive_array_values(o)) {
return false;
}
}
return true;
}
// verify that a static oop field is in range
static inline bool verify_static_oop(InstanceKlass* ik,
oop mirror, int offset) {
address obj_p = (address)mirror + offset;
address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
assert(end >= start, "sanity check");
if (obj_p >= start && obj_p < end) {
return true;
} else {
return false;
}
}
// a class references its super class, interfaces, class loader, ...
// and finally its static fields
inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
int i;
Klass* klass = java_lang_Class::as_Klass(java_class);
if (klass->oop_is_instance()) {
InstanceKlass* ik = InstanceKlass::cast(klass);
// ignore the class if it's has been initialized yet
if (!ik->is_linked()) {
return true;
}
// get the java mirror
oop mirror = klass->java_mirror();
// super (only if something more interesting than java.lang.Object)
Klass* java_super = ik->java_super();
if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
oop super = java_super->java_mirror();
if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
return false;
}
}
// class loader
oop cl = ik->class_loader();
if (cl != NULL) {
if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
return false;
}
}
// protection domain
oop pd = ik->protection_domain();
if (pd != NULL) {
if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
return false;
}
}
// signers
oop signers = ik->signers();
if (signers != NULL) {
if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
return false;
}
}
// references from the constant pool
{
ConstantPool* pool = ik->constants();
for (int i = 1; i < pool->length(); i++) {
constantTag tag = pool->tag_at(i).value();
if (tag.is_string() || tag.is_klass()) {
oop entry;
if (tag.is_string()) {
entry = pool->resolved_string_at(i);
// If the entry is non-null it is resolved.
if (entry == NULL) continue;
} else {
entry = pool->resolved_klass_at(i)->java_mirror();
}
if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
return false;
}
}
}
}
// interfaces
// (These will already have been reported as references from the constant pool
// but are specified by IterateOverReachableObjects and must be reported).
Array<Klass*>* interfaces = ik->local_interfaces();
for (i = 0; i < interfaces->length(); i++) {
oop interf = ((Klass*)interfaces->at(i))->java_mirror();
if (interf == NULL) {
continue;
}
if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
return false;
}
}
// iterate over the static fields
ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
for (i=0; i<field_map->field_count(); i++) {
ClassFieldDescriptor* field = field_map->field_at(i);
char type = field->field_type();
if (!is_primitive_field_type(type)) {
oop fld_o = mirror->obj_field(field->field_offset());
assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
if (fld_o != NULL) {
int slot = field->field_index();
if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
delete field_map;
return false;
}
}
} else {
if (is_reporting_primitive_fields()) {
address addr = (address)mirror + field->field_offset();
int slot = field->field_index();
if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
delete field_map;
return false;
}
}
}
}
delete field_map;
return true;
}
return true;
}
// an object references a class and its instance fields
// (static fields are ignored here as we report these as
// references from the class).
inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
// reference to the class
if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
return false;
}
// iterate over instance fields
ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
for (int i=0; i<field_map->field_count(); i++) {
ClassFieldDescriptor* field = field_map->field_at(i);
char type = field->field_type();
if (!is_primitive_field_type(type)) {
oop fld_o = o->obj_field(field->field_offset());
// ignore any objects that aren't visible to profiler
if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
"have references to Klass* anymore");
int slot = field->field_index();
if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
return false;
}
}
} else {
if (is_reporting_primitive_fields()) {
// primitive instance field
address addr = (address)o + field->field_offset();
int slot = field->field_index();
if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
return false;
}
}
}
}
// if the object is a java.lang.String
if (is_reporting_string_values() &&
o->klass() == SystemDictionary::String_klass()) {
if (!CallbackInvoker::report_string_value(o)) {
return false;
}
}
return true;
}
// Collects all simple (non-stack) roots except for threads;
// threads are handled in collect_stack_roots() as an optimization.
// if there's a heap root callback provided then the callback is
// invoked for each simple root.
// if an object reference callback is provided then all simple
// roots are pushed onto the marking stack so that they can be
// processed later
//
inline bool VM_HeapWalkOperation::collect_simple_roots() {
SimpleRootsClosure blk;
// JNI globals
blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
JNIHandles::oops_do(&blk);
if (blk.stopped()) {
return false;
}
// Preloaded classes and loader from the system dictionary
blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
SystemDictionary::always_strong_oops_do(&blk);
KlassToOopClosure klass_blk(&blk);
ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false);
if (blk.stopped()) {
return false;
}
// Inflated monitors
blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
ObjectSynchronizer::oops_do(&blk);
if (blk.stopped()) {
return false;
}
// threads are now handled in collect_stack_roots()
// Other kinds of roots maintained by HotSpot
// Many of these won't be visible but others (such as instances of important
// exceptions) will be visible.
blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
Universe::oops_do(&blk);
// If there are any non-perm roots in the code cache, visit them.
blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
return true;
}
// Walk the stack of a given thread and find all references (locals
// and JNI calls) and report these as stack references
inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
JNILocalRootsClosure* blk)
{
oop threadObj = java_thread->threadObj();
assert(threadObj != NULL, "sanity check");
// only need to get the thread's tag once per thread
jlong thread_tag = tag_for(_tag_map, threadObj);
// also need the thread id
jlong tid = java_lang_Thread::thread_id(threadObj);
if (java_thread->has_last_Java_frame()) {
// vframes are resource allocated
Thread* current_thread = Thread::current();
ResourceMark rm(current_thread);
HandleMark hm(current_thread);
RegisterMap reg_map(java_thread);
frame f = java_thread->last_frame();
vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
bool is_top_frame = true;
int depth = 0;
frame* last_entry_frame = NULL;
while (vf != NULL) {
if (vf->is_java_frame()) {
// java frame (interpreted, compiled, ...)
javaVFrame *jvf = javaVFrame::cast(vf);
// the jmethodID
jmethodID method = jvf->method()->jmethod_id();
if (!(jvf->method()->is_native())) {
jlocation bci = (jlocation)jvf->bci();
StackValueCollection* locals = jvf->locals();
for (int slot=0; slot<locals->size(); slot++) {
if (locals->at(slot)->type() == T_OBJECT) {
oop o = locals->obj_at(slot)();
if (o == NULL) {
continue;
}
// stack reference
if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
bci, slot, o)) {
return false;
}
}
}
} else {
blk->set_context(thread_tag, tid, depth, method);
if (is_top_frame) {
// JNI locals for the top frame.
java_thread->active_handles()->oops_do(blk);
} else {
if (last_entry_frame != NULL) {
// JNI locals for the entry frame
assert(last_entry_frame->is_entry_frame(), "checking");
last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
}
}
}
last_entry_frame = NULL;
depth++;
} else {
// externalVFrame - for an entry frame then we report the JNI locals
// when we find the corresponding javaVFrame
frame* fr = vf->frame_pointer();
assert(fr != NULL, "sanity check");
if (fr->is_entry_frame()) {
last_entry_frame = fr;
}
}
vf = vf->sender();
is_top_frame = false;
}
} else {
// no last java frame but there may be JNI locals
blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
java_thread->active_handles()->oops_do(blk);
}
return true;
}
// Collects the simple roots for all threads and collects all
// stack roots - for each thread it walks the execution
// stack to find all references and local JNI refs.
inline bool VM_HeapWalkOperation::collect_stack_roots() {
JNILocalRootsClosure blk;
for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
oop threadObj = thread->threadObj();
if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
// Collect the simple root for this thread before we
// collect its stack roots
if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
threadObj)) {
return false;
}
if (!collect_stack_roots(thread, &blk)) {
return false;
}
}
}
return true;
}
// visit an object
// first mark the object as visited
// second get all the outbound references from this object (in other words, all
// the objects referenced by this object).
//
bool VM_HeapWalkOperation::visit(oop o) {
// mark object as visited
assert(!ObjectMarker::visited(o), "can't visit same object more than once");
ObjectMarker::mark(o);
// instance
if (o->is_instance()) {
if (o->klass() == SystemDictionary::Class_klass()) {
if (!java_lang_Class::is_primitive(o)) {
// a java.lang.Class
return iterate_over_class(o);
}
} else {
return iterate_over_object(o);
}
}
// object array
if (o->is_objArray()) {
return iterate_over_array(o);
}
// type array
if (o->is_typeArray()) {
return iterate_over_type_array(o);
}
return true;
}
void VM_HeapWalkOperation::doit() {
ResourceMark rm;
ObjectMarkerController marker;
ClassFieldMapCacheMark cm;
assert(visit_stack()->is_empty(), "visit stack must be empty");
// the heap walk starts with an initial object or the heap roots
if (initial_object().is_null()) {
// If either collect_stack_roots() or collect_simple_roots()
// returns false at this point, then there are no mark bits
// to reset.
ObjectMarker::set_needs_reset(false);
// Calling collect_stack_roots() before collect_simple_roots()
// can result in a big performance boost for an agent that is
// focused on analyzing references in the thread stacks.
if (!collect_stack_roots()) return;
if (!collect_simple_roots()) return;
// no early return so enable heap traversal to reset the mark bits
ObjectMarker::set_needs_reset(true);
} else {
visit_stack()->push(initial_object()());
}
// object references required
if (is_following_references()) {
// visit each object until all reachable objects have been
// visited or the callback asked to terminate the iteration.
while (!visit_stack()->is_empty()) {
oop o = visit_stack()->pop();
if (!ObjectMarker::visited(o)) {
if (!visit(o)) {
break;
}
}
}
}
}
// iterate over all objects that are reachable from a set of roots
void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
jvmtiStackReferenceCallback stack_ref_callback,
jvmtiObjectReferenceCallback object_ref_callback,
const void* user_data) {
MutexLocker ml(Heap_lock);
BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
VM_HeapWalkOperation op(this, Handle(), context, user_data);
VMThread::execute(&op);
}
// iterate over all objects that are reachable from a given object
void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
jvmtiObjectReferenceCallback object_ref_callback,
const void* user_data) {
oop obj = JNIHandles::resolve(object);
Handle initial_object(Thread::current(), obj);
MutexLocker ml(Heap_lock);
BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
VM_HeapWalkOperation op(this, initial_object, context, user_data);
VMThread::execute(&op);
}
// follow references from an initial object or the GC roots
void JvmtiTagMap::follow_references(jint heap_filter,
KlassHandle klass,
jobject object,
const jvmtiHeapCallbacks* callbacks,
const void* user_data)
{
oop obj = JNIHandles::resolve(object);
Handle initial_object(Thread::current(), obj);
MutexLocker ml(Heap_lock);
AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
VM_HeapWalkOperation op(this, initial_object, context, user_data);
VMThread::execute(&op);
}
void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
// No locks during VM bring-up (0 threads) and no safepoints after main
// thread creation and before VMThread creation (1 thread); initial GC
// verification can happen in that window which gets to here.
assert(Threads::number_of_threads() <= 1 ||
SafepointSynchronize::is_at_safepoint(),
"must be executed at a safepoint");
if (JvmtiEnv::environments_might_exist()) {
JvmtiEnvIterator it;
for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
JvmtiTagMap* tag_map = env->tag_map();
if (tag_map != NULL && !tag_map->is_empty()) {
tag_map->do_weak_oops(is_alive, f);
}
}
}
}
void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
// does this environment have the OBJECT_FREE event enabled
bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
// counters used for trace message
int freed = 0;
int moved = 0;
JvmtiTagHashmap* hashmap = this->hashmap();
// reenable sizing (if disabled)
hashmap->set_resizing_enabled(true);
// if the hashmap is empty then we can skip it
if (hashmap->_entry_count == 0) {
return;
}
// now iterate through each entry in the table
JvmtiTagHashmapEntry** table = hashmap->table();
int size = hashmap->size();
JvmtiTagHashmapEntry* delayed_add = NULL;
for (int pos = 0; pos < size; ++pos) {
JvmtiTagHashmapEntry* entry = table[pos];
JvmtiTagHashmapEntry* prev = NULL;
while (entry != NULL) {
JvmtiTagHashmapEntry* next = entry->next();
oop* obj = entry->object_addr();
// has object been GC'ed
if (!is_alive->do_object_b(entry->object())) {
// grab the tag
jlong tag = entry->tag();
guarantee(tag != 0, "checking");
// remove GC'ed entry from hashmap and return the
// entry to the free list
hashmap->remove(prev, pos, entry);
destroy_entry(entry);
// post the event to the profiler
if (post_object_free) {
JvmtiExport::post_object_free(env(), tag);
}
++freed;
} else {
f->do_oop(entry->object_addr());
oop new_oop = entry->object();
// if the object has moved then re-hash it and move its
// entry to its new location.
unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
if (new_pos != (unsigned int)pos) {
if (prev == NULL) {
table[pos] = next;
} else {
prev->set_next(next);
}
if (new_pos < (unsigned int)pos) {
entry->set_next(table[new_pos]);
table[new_pos] = entry;
} else {
// Delay adding this entry to it's new position as we'd end up
// hitting it again during this iteration.
entry->set_next(delayed_add);
delayed_add = entry;
}
moved++;
} else {
// object didn't move
prev = entry;
}
}
entry = next;
}
}
// Re-add all the entries which were kept aside
while (delayed_add != NULL) {
JvmtiTagHashmapEntry* next = delayed_add->next();
unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
delayed_add->set_next(table[pos]);
table[pos] = delayed_add;
delayed_add = next;
}
// stats
if (TraceJVMTIObjectTagging) {
int post_total = hashmap->_entry_count;
int pre_total = post_total + freed;
tty->print_cr("(%d->%d, %d freed, %d total moves)",
pre_total, post_total, freed, moved);
}
}