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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "reference_table.h"
#include "base/mutex.h"
#include "indirect_reference_table.h"
#include "mirror/array.h"
#include "mirror/array-inl.h"
#include "mirror/class.h"
#include "mirror/class-inl.h"
#include "mirror/object-inl.h"
#include "mirror/string-inl.h"
#include "runtime-inl.h"
#include "thread.h"
#include "utils.h"
namespace art {
ReferenceTable::ReferenceTable(const char* name, size_t initial_size, size_t max_size)
: name_(name), max_size_(max_size) {
CHECK_LE(initial_size, max_size);
entries_.reserve(initial_size);
}
ReferenceTable::~ReferenceTable() {
}
void ReferenceTable::Add(mirror::Object* obj) {
DCHECK(obj != nullptr);
VerifyObject(obj);
if (entries_.size() >= max_size_) {
LOG(FATAL) << "ReferenceTable '" << name_ << "' "
<< "overflowed (" << max_size_ << " entries)";
}
entries_.push_back(GcRoot<mirror::Object>(obj));
}
void ReferenceTable::Remove(mirror::Object* obj) {
// We iterate backwards on the assumption that references are LIFO.
for (int i = entries_.size() - 1; i >= 0; --i) {
mirror::Object* entry = entries_[i].Read();
if (entry == obj) {
entries_.erase(entries_.begin() + i);
return;
}
}
}
// If "obj" is an array, return the number of elements in the array.
// Otherwise, return zero.
static size_t GetElementCount(mirror::Object* obj) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// We assume the special cleared value isn't an array in the if statement below.
DCHECK(!Runtime::Current()->GetClearedJniWeakGlobal()->IsArrayInstance());
if (obj == nullptr || !obj->IsArrayInstance()) {
return 0;
}
return obj->AsArray()->GetLength();
}
// Log an object with some additional info.
//
// Pass in the number of elements in the array (or 0 if this is not an
// array object), and the number of additional objects that are identical
// or equivalent to the original.
static void DumpSummaryLine(std::ostream& os, mirror::Object* obj, size_t element_count,
int identical, int equiv)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
if (obj == nullptr) {
os << " null reference (count=" << equiv << ")\n";
return;
}
if (Runtime::Current()->IsClearedJniWeakGlobal(obj)) {
os << " cleared jweak (count=" << equiv << ")\n";
return;
}
std::string className(PrettyTypeOf(obj));
if (obj->IsClass()) {
// We're summarizing multiple instances, so using the exemplar
// Class' type parameter here would be misleading.
className = "java.lang.Class";
}
if (element_count != 0) {
StringAppendF(&className, " (%zd elements)", element_count);
}
size_t total = identical + equiv + 1;
std::string msg(StringPrintf("%5zd of %s", total, className.c_str()));
if (identical + equiv != 0) {
StringAppendF(&msg, " (%d unique instances)", equiv + 1);
}
os << " " << msg << "\n";
}
size_t ReferenceTable::Size() const {
return entries_.size();
}
void ReferenceTable::Dump(std::ostream& os) {
os << name_ << " reference table dump:\n";
Dump(os, entries_);
}
void ReferenceTable::Dump(std::ostream& os, Table& entries) {
// Compare GC roots, first by class, then size, then address.
struct GcRootComparator {
bool operator()(GcRoot<mirror::Object> root1, GcRoot<mirror::Object> root2) const
// TODO: enable analysis when analysis can work with the STL.
NO_THREAD_SAFETY_ANALYSIS {
Locks::mutator_lock_->AssertSharedHeld(Thread::Current());
// These GC roots are already forwarded in ReferenceTable::Dump. We sort by class since there
// are no suspend points which can happen during the sorting process. This works since
// we are guaranteed that the addresses of obj1, obj2, obj1->GetClass, obj2->GetClass wont
// change during the sorting process. The classes are forwarded by ref->GetClass().
mirror::Object* obj1 = root1.Read<kWithoutReadBarrier>();
mirror::Object* obj2 = root2.Read<kWithoutReadBarrier>();
DCHECK(obj1 != nullptr);
DCHECK(obj2 != nullptr);
Runtime* runtime = Runtime::Current();
DCHECK(!runtime->IsClearedJniWeakGlobal(obj1));
DCHECK(!runtime->IsClearedJniWeakGlobal(obj2));
// Sort by class...
if (obj1->GetClass() != obj2->GetClass()) {
return obj1->GetClass() < obj2->GetClass();
}
// ...then by size...
const size_t size1 = obj1->SizeOf();
const size_t size2 = obj2->SizeOf();
if (size1 != size2) {
return size1 < size2;
}
// ...and finally by address.
return obj1 < obj2;
}
};
if (entries.empty()) {
os << " (empty)\n";
return;
}
// Dump the most recent N entries.
const size_t kLast = 10;
size_t count = entries.size();
int first = count - kLast;
if (first < 0) {
first = 0;
}
os << " Last " << (count - first) << " entries (of " << count << "):\n";
Runtime* runtime = Runtime::Current();
for (int idx = count - 1; idx >= first; --idx) {
mirror::Object* ref = entries[idx].Read();
if (ref == nullptr) {
continue;
}
if (runtime->IsClearedJniWeakGlobal(ref)) {
os << StringPrintf(" %5d: cleared jweak\n", idx);
continue;
}
if (ref->GetClass() == nullptr) {
// should only be possible right after a plain dvmMalloc().
size_t size = ref->SizeOf();
os << StringPrintf(" %5d: %p (raw) (%zd bytes)\n", idx, ref, size);
continue;
}
std::string className(PrettyTypeOf(ref));
std::string extras;
size_t element_count = GetElementCount(ref);
if (element_count != 0) {
StringAppendF(&extras, " (%zd elements)", element_count);
} else if (ref->GetClass()->IsStringClass()) {
mirror::String* s = ref->AsString();
std::string utf8(s->ToModifiedUtf8());
if (s->GetLength() <= 16) {
StringAppendF(&extras, " \"%s\"", utf8.c_str());
} else {
StringAppendF(&extras, " \"%.16s... (%d chars)", utf8.c_str(), s->GetLength());
}
}
os << StringPrintf(" %5d: ", idx) << ref << " " << className << extras << "\n";
}
// Make a copy of the table and sort it, only adding non null and not cleared elements.
Table sorted_entries;
for (GcRoot<mirror::Object>& root : entries) {
if (!root.IsNull() && !runtime->IsClearedJniWeakGlobal(root.Read())) {
sorted_entries.push_back(root);
}
}
if (sorted_entries.empty()) {
return;
}
std::sort(sorted_entries.begin(), sorted_entries.end(), GcRootComparator());
// Dump a summary of the whole table.
os << " Summary:\n";
size_t equiv = 0;
size_t identical = 0;
mirror::Object* prev = nullptr;
for (GcRoot<mirror::Object>& root : sorted_entries) {
mirror::Object* current = root.Read<kWithoutReadBarrier>();
if (prev != nullptr) {
const size_t element_count = GetElementCount(prev);
if (current == prev) {
// Same reference, added more than once.
++identical;
} else if (current->GetClass() == prev->GetClass() &&
GetElementCount(current) == element_count) {
// Same class / element count, different object.
++equiv;
} else {
// Different class.
DumpSummaryLine(os, prev, element_count, identical, equiv);
equiv = 0;
identical = 0;
}
}
prev = current;
}
// Handle the last entry.
DumpSummaryLine(os, prev, GetElementCount(prev), identical, equiv);
}
void ReferenceTable::VisitRoots(RootVisitor* visitor, const RootInfo& root_info) {
BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(visitor, root_info);
for (GcRoot<mirror::Object>& root : entries_) {
buffered_visitor.VisitRoot(root);
}
}
} // namespace art