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/*
* Copyright (C) 2011 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 "trace.h"
#include <sys/uio.h>
#include "base/stl_util.h"
#include "base/unix_file/fd_file.h"
#include "class_linker.h"
#include "common_throws.h"
#include "debugger.h"
#include "dex_file-inl.h"
#include "instrumentation.h"
#include "mirror/art_method-inl.h"
#include "mirror/class-inl.h"
#include "mirror/dex_cache.h"
#include "mirror/object_array-inl.h"
#include "mirror/object-inl.h"
#include "object_utils.h"
#include "os.h"
#include "scoped_thread_state_change.h"
#include "ScopedLocalRef.h"
#include "thread.h"
#include "thread_list.h"
#if !defined(ART_USE_PORTABLE_COMPILER)
#include "entrypoints/quick/quick_entrypoints.h"
#endif
namespace art {
// File format:
// header
// record 0
// record 1
// ...
//
// Header format:
// u4 magic ('SLOW')
// u2 version
// u2 offset to data
// u8 start date/time in usec
// u2 record size in bytes (version >= 2 only)
// ... padding to 32 bytes
//
// Record format v1:
// u1 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
//
// Record format v2:
// u2 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
//
// Record format v3:
// u2 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
// u4 wall time since start, in usec (when clock == "dual" only)
//
// 32 bits of microseconds is 70 minutes.
//
// All values are stored in little-endian order.
enum TraceAction {
kTraceMethodEnter = 0x00, // method entry
kTraceMethodExit = 0x01, // method exit
kTraceUnroll = 0x02, // method exited by exception unrolling
// 0x03 currently unused
kTraceMethodActionMask = 0x03, // two bits
};
class BuildStackTraceVisitor : public StackVisitor {
public:
explicit BuildStackTraceVisitor(Thread* thread) : StackVisitor(thread, NULL),
method_trace_(new std::vector<mirror::ArtMethod*>) {}
bool VisitFrame() {
mirror::ArtMethod* m = GetMethod();
// Ignore runtime frames (in particular callee save).
if (!m->IsRuntimeMethod()) {
method_trace_->push_back(m);
}
return true;
}
// Returns a stack trace where the topmost frame corresponds with the first element of the vector.
std::vector<mirror::ArtMethod*>* GetStackTrace() const {
return method_trace_;
}
private:
std::vector<mirror::ArtMethod*>* const method_trace_;
};
static const char kTraceTokenChar = '*';
static const uint16_t kTraceHeaderLength = 32;
static const uint32_t kTraceMagicValue = 0x574f4c53;
static const uint16_t kTraceVersionSingleClock = 2;
static const uint16_t kTraceVersionDualClock = 3;
static const uint16_t kTraceRecordSizeSingleClock = 10; // using v2
static const uint16_t kTraceRecordSizeDualClock = 14; // using v3 with two timestamps
#if defined(HAVE_POSIX_CLOCKS)
ProfilerClockSource Trace::default_clock_source_ = kProfilerClockSourceDual;
#else
ProfilerClockSource Trace::default_clock_source_ = kProfilerClockSourceWall;
#endif
Trace* volatile Trace::the_trace_ = NULL;
// TODO: Add way to enable sampling and set interval through gui.
bool Trace::sampling_enabled_ = true;
uint32_t Trace::sampling_interval_us_ = 10000;
pthread_t Trace::sampling_pthread_ = 0U;
static mirror::ArtMethod* DecodeTraceMethodId(uint32_t tmid) {
return reinterpret_cast<mirror::ArtMethod*>(tmid & ~kTraceMethodActionMask);
}
static TraceAction DecodeTraceAction(uint32_t tmid) {
return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
}
static uint32_t EncodeTraceMethodAndAction(const mirror::ArtMethod* method,
TraceAction action) {
uint32_t tmid = reinterpret_cast<uint32_t>(method) | action;
DCHECK_EQ(method, DecodeTraceMethodId(tmid));
return tmid;
}
void Trace::SetDefaultClockSource(ProfilerClockSource clock_source) {
#if defined(HAVE_POSIX_CLOCKS)
default_clock_source_ = clock_source;
#else
if (clock_source != kProfilerClockSourceWall) {
LOG(WARNING) << "Ignoring tracing request to use ";
}
#endif
}
static uint16_t GetTraceVersion(ProfilerClockSource clock_source) {
return (clock_source == kProfilerClockSourceDual) ? kTraceVersionDualClock
: kTraceVersionSingleClock;
}
static uint16_t GetRecordSize(ProfilerClockSource clock_source) {
return (clock_source == kProfilerClockSourceDual) ? kTraceRecordSizeDualClock
: kTraceRecordSizeSingleClock;
}
bool Trace::UseThreadCpuClock() {
return (clock_source_ == kProfilerClockSourceThreadCpu) ||
(clock_source_ == kProfilerClockSourceDual);
}
bool Trace::UseWallClock() {
return (clock_source_ == kProfilerClockSourceWall) ||
(clock_source_ == kProfilerClockSourceDual);
}
static void MeasureClockOverhead(Trace* trace) {
if (trace->UseThreadCpuClock()) {
Thread::Current()->GetCpuMicroTime();
}
if (trace->UseWallClock()) {
MicroTime();
}
}
static uint32_t GetClockOverhead(Trace* trace) {
Thread* self = Thread::Current();
uint64_t start = self->GetCpuMicroTime();
for (int i = 4000; i > 0; i--) {
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
MeasureClockOverhead(trace);
}
uint64_t elapsed = self->GetCpuMicroTime() - start;
return uint32_t (elapsed / 32);
}
// TODO: put this somewhere with the big-endian equivalent used by JDWP.
static void Append2LE(uint8_t* buf, uint16_t val) {
*buf++ = (uint8_t) val;
*buf++ = (uint8_t) (val >> 8);
}
// TODO: put this somewhere with the big-endian equivalent used by JDWP.
static void Append4LE(uint8_t* buf, uint32_t val) {
*buf++ = (uint8_t) val;
*buf++ = (uint8_t) (val >> 8);
*buf++ = (uint8_t) (val >> 16);
*buf++ = (uint8_t) (val >> 24);
}
// TODO: put this somewhere with the big-endian equivalent used by JDWP.
static void Append8LE(uint8_t* buf, uint64_t val) {
*buf++ = (uint8_t) val;
*buf++ = (uint8_t) (val >> 8);
*buf++ = (uint8_t) (val >> 16);
*buf++ = (uint8_t) (val >> 24);
*buf++ = (uint8_t) (val >> 32);
*buf++ = (uint8_t) (val >> 40);
*buf++ = (uint8_t) (val >> 48);
*buf++ = (uint8_t) (val >> 56);
}
static void GetSample(Thread* thread, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
BuildStackTraceVisitor build_trace_visitor(thread);
build_trace_visitor.WalkStack();
std::vector<mirror::ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
Trace* the_trace = reinterpret_cast<Trace*>(arg);
the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
}
void Trace::CompareAndUpdateStackTrace(Thread* thread,
std::vector<mirror::ArtMethod*>* stack_trace) {
CHECK_EQ(pthread_self(), sampling_pthread_);
SafeMap<Thread*, std::vector<mirror::ArtMethod*>*>::iterator map_it = thread_stack_trace_map_.find(thread);
if (map_it == thread_stack_trace_map_.end()) {
// If there's no existing stack trace in the map for this thread, log an entry event for all
// methods in the trace.
thread_stack_trace_map_.Put(thread, stack_trace);
for (std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
rit != stack_trace->rend(); ++rit) {
LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered);
}
} else {
// If there's a previous stack trace for this thread, diff the traces and emit entry and exit
// events accordingly.
std::vector<mirror::ArtMethod*>* old_stack_trace = map_it->second;
thread_stack_trace_map_.Overwrite(thread, stack_trace);
std::vector<mirror::ArtMethod*>::reverse_iterator old_rit = old_stack_trace->rbegin();
std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
// Iterate bottom-up over both traces until there's a difference between them.
while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
old_rit++;
rit++;
}
// Iterate top-down over the old trace until the point where they differ, emitting exit events.
for (std::vector<mirror::ArtMethod*>::iterator old_it = old_stack_trace->begin();
old_it != old_rit.base(); ++old_it) {
LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited);
}
// Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
for (; rit != stack_trace->rend(); ++rit) {
LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered);
}
delete old_stack_trace;
}
}
void* Trace::RunSamplingThread(void* arg) {
Runtime* runtime = Runtime::Current();
CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
!runtime->IsCompiler()));
while (true) {
usleep(sampling_interval_us_);
Thread* self = Thread::Current();
Trace* the_trace;
{
MutexLock mu(self, *Locks::trace_lock_);
the_trace = the_trace_;
if (the_trace == NULL) {
break;
}
}
runtime->GetThreadList()->SuspendAll();
{
MutexLock mu(self, *Locks::thread_list_lock_);
runtime->GetThreadList()->ForEach(GetSample, the_trace);
}
runtime->GetThreadList()->ResumeAll();
}
runtime->DetachCurrentThread();
return NULL;
}
void Trace::Start(const char* trace_filename, int trace_fd, int buffer_size, int flags,
bool direct_to_ddms) {
Thread* self = Thread::Current();
{
MutexLock mu(self, *Locks::trace_lock_);
if (the_trace_ != NULL) {
LOG(ERROR) << "Trace already in progress, ignoring this request";
return;
}
}
Runtime* runtime = Runtime::Current();
runtime->GetThreadList()->SuspendAll();
// Open trace file if not going directly to ddms.
UniquePtr<File> trace_file;
if (!direct_to_ddms) {
if (trace_fd < 0) {
trace_file.reset(OS::CreateEmptyFile(trace_filename));
} else {
trace_file.reset(new File(trace_fd, "tracefile"));
trace_file->DisableAutoClose();
}
if (trace_file.get() == NULL) {
PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
runtime->GetThreadList()->ResumeAll();
ScopedObjectAccess soa(self);
ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
return;
}
}
// Create Trace object.
{
MutexLock mu(self, *Locks::trace_lock_);
if (the_trace_ != NULL) {
LOG(ERROR) << "Trace already in progress, ignoring this request";
} else {
the_trace_ = new Trace(trace_file.release(), buffer_size, flags);
// Enable count of allocs if specified in the flags.
if ((flags && kTraceCountAllocs) != 0) {
runtime->SetStatsEnabled(true);
}
if (sampling_enabled_) {
CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, NULL, &RunSamplingThread, NULL),
"Sampling profiler thread");
} else {
runtime->GetInstrumentation()->AddListener(the_trace_,
instrumentation::Instrumentation::kMethodEntered |
instrumentation::Instrumentation::kMethodExited |
instrumentation::Instrumentation::kMethodUnwind);
}
}
}
runtime->GetThreadList()->ResumeAll();
}
void Trace::Stop() {
Runtime* runtime = Runtime::Current();
runtime->GetThreadList()->SuspendAll();
Trace* the_trace = NULL;
pthread_t sampling_pthread = 0U;
{
MutexLock mu(Thread::Current(), *Locks::trace_lock_);
if (the_trace_ == NULL) {
LOG(ERROR) << "Trace stop requested, but no trace currently running";
} else {
the_trace = the_trace_;
the_trace_ = NULL;
sampling_pthread = sampling_pthread_;
sampling_pthread_ = 0U;
}
}
if (the_trace != NULL) {
the_trace->FinishTracing();
if (!sampling_enabled_) {
runtime->GetInstrumentation()->RemoveListener(the_trace,
instrumentation::Instrumentation::kMethodEntered |
instrumentation::Instrumentation::kMethodExited |
instrumentation::Instrumentation::kMethodUnwind);
}
delete the_trace;
}
runtime->GetThreadList()->ResumeAll();
if (sampling_enabled_ && sampling_pthread != 0U) {
CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, NULL), "sampling thread shutdown");
}
}
void Trace::Shutdown() {
if (IsMethodTracingActive()) {
Stop();
}
}
bool Trace::IsMethodTracingActive() {
MutexLock mu(Thread::Current(), *Locks::trace_lock_);
return the_trace_ != NULL;
}
Trace::Trace(File* trace_file, int buffer_size, int flags)
: trace_file_(trace_file), buf_(new uint8_t[buffer_size]()), flags_(flags),
clock_source_(default_clock_source_), buffer_size_(buffer_size), start_time_(MicroTime()),
cur_offset_(0), overflow_(false) {
// Set up the beginning of the trace.
uint16_t trace_version = GetTraceVersion(clock_source_);
memset(buf_.get(), 0, kTraceHeaderLength);
Append4LE(buf_.get(), kTraceMagicValue);
Append2LE(buf_.get() + 4, trace_version);
Append2LE(buf_.get() + 6, kTraceHeaderLength);
Append8LE(buf_.get() + 8, start_time_);
if (trace_version >= kTraceVersionDualClock) {
uint16_t record_size = GetRecordSize(clock_source_);
Append2LE(buf_.get() + 16, record_size);
}
// Update current offset.
cur_offset_ = kTraceHeaderLength;
}
Trace::~Trace() {
CHECK_EQ(sampling_pthread_, static_cast<pthread_t>(0U));
STLDeleteValues(&thread_stack_trace_map_);
}
static void DumpBuf(uint8_t* buf, size_t buf_size, ProfilerClockSource clock_source)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
uint8_t* ptr = buf + kTraceHeaderLength;
uint8_t* end = buf + buf_size;
while (ptr < end) {
uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
TraceAction action = DecodeTraceAction(tmid);
LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
ptr += GetRecordSize(clock_source);
}
}
void Trace::FinishTracing() {
// Compute elapsed time.
uint64_t elapsed = MicroTime() - start_time_;
size_t final_offset = cur_offset_;
uint32_t clock_overhead = GetClockOverhead(this);
if ((flags_ & kTraceCountAllocs) != 0) {
Runtime::Current()->SetStatsEnabled(false);
}
std::set<mirror::ArtMethod*> visited_methods;
GetVisitedMethods(final_offset, &visited_methods);
std::ostringstream os;
os << StringPrintf("%cversion\n", kTraceTokenChar);
os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
if (UseThreadCpuClock()) {
if (UseWallClock()) {
os << StringPrintf("clock=dual\n");
} else {
os << StringPrintf("clock=thread-cpu\n");
}
} else {
os << StringPrintf("clock=wall\n");
}
os << StringPrintf("elapsed-time-usec=%llu\n", elapsed);
size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
os << StringPrintf("num-method-calls=%zd\n", num_records);
os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead);
os << StringPrintf("vm=art\n");
if ((flags_ & kTraceCountAllocs) != 0) {
os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
}
os << StringPrintf("%cthreads\n", kTraceTokenChar);
DumpThreadList(os);
os << StringPrintf("%cmethods\n", kTraceTokenChar);
DumpMethodList(os, visited_methods);
os << StringPrintf("%cend\n", kTraceTokenChar);
std::string header(os.str());
if (trace_file_.get() == NULL) {
iovec iov[2];
iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
iov[0].iov_len = header.length();
iov[1].iov_base = buf_.get();
iov[1].iov_len = final_offset;
Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
const bool kDumpTraceInfo = false;
if (kDumpTraceInfo) {
LOG(INFO) << "Trace sent:\n" << header;
DumpBuf(buf_.get(), final_offset, clock_source_);
}
} else {
if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
!trace_file_->WriteFully(buf_.get(), final_offset)) {
std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
PLOG(ERROR) << detail;
ThrowRuntimeException("%s", detail.c_str());
}
}
}
void Trace::DexPcMoved(Thread* thread, mirror::Object* this_object,
const mirror::ArtMethod* method, uint32_t new_dex_pc) {
// We're not recorded to listen to this kind of event, so complain.
LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
};
void Trace::MethodEntered(Thread* thread, mirror::Object* this_object,
const mirror::ArtMethod* method, uint32_t dex_pc) {
LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered);
}
void Trace::MethodExited(Thread* thread, mirror::Object* this_object,
const mirror::ArtMethod* method, uint32_t dex_pc,
const JValue& return_value) {
UNUSED(return_value);
LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited);
}
void Trace::MethodUnwind(Thread* thread, const mirror::ArtMethod* method, uint32_t dex_pc) {
LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind);
}
void Trace::ExceptionCaught(Thread* thread, const ThrowLocation& throw_location,
mirror::ArtMethod* catch_method, uint32_t catch_dex_pc,
mirror::Throwable* exception_object)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
LOG(ERROR) << "Unexpected exception caught event in tracing";
}
void Trace::LogMethodTraceEvent(Thread* thread, const mirror::ArtMethod* method,
instrumentation::Instrumentation::InstrumentationEvent event) {
// Advance cur_offset_ atomically.
int32_t new_offset;
int32_t old_offset;
do {
old_offset = cur_offset_;
new_offset = old_offset + GetRecordSize(clock_source_);
if (new_offset > buffer_size_) {
overflow_ = true;
return;
}
} while (android_atomic_release_cas(old_offset, new_offset, &cur_offset_) != 0);
TraceAction action = kTraceMethodEnter;
switch (event) {
case instrumentation::Instrumentation::kMethodEntered:
action = kTraceMethodEnter;
break;
case instrumentation::Instrumentation::kMethodExited:
action = kTraceMethodExit;
break;
case instrumentation::Instrumentation::kMethodUnwind:
action = kTraceUnroll;
break;
default:
UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
}
uint32_t method_value = EncodeTraceMethodAndAction(method, action);
// Write data
uint8_t* ptr = buf_.get() + old_offset;
Append2LE(ptr, thread->GetTid());
Append4LE(ptr + 2, method_value);
ptr += 6;
if (UseThreadCpuClock()) {
// TODO: this isn't vaguely thread safe.
SafeMap<Thread*, uint64_t>::iterator it = thread_clock_base_map_.find(thread);
uint32_t thread_clock_diff = 0;
if (UNLIKELY(it == thread_clock_base_map_.end())) {
// First event, the diff is 0, record the base time in the map.
uint64_t time = thread->GetCpuMicroTime();
thread_clock_base_map_.Put(thread, time);
} else {
uint64_t thread_clock_base = it->second;
thread_clock_diff = thread->GetCpuMicroTime() - thread_clock_base;
}
Append4LE(ptr, thread_clock_diff);
ptr += 4;
}
if (UseWallClock()) {
uint32_t wall_clock_diff = MicroTime() - start_time_;
Append4LE(ptr, wall_clock_diff);
}
}
void Trace::GetVisitedMethods(size_t buf_size,
std::set<mirror::ArtMethod*>* visited_methods) {
uint8_t* ptr = buf_.get() + kTraceHeaderLength;
uint8_t* end = buf_.get() + buf_size;
while (ptr < end) {
uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
visited_methods->insert(method);
ptr += GetRecordSize(clock_source_);
}
}
void Trace::DumpMethodList(std::ostream& os, const std::set<mirror::ArtMethod*>& visited_methods) {
MethodHelper mh;
for (const auto& method : visited_methods) {
mh.ChangeMethod(method);
os << StringPrintf("%p\t%s\t%s\t%s\t%s\n", method,
PrettyDescriptor(mh.GetDeclaringClassDescriptor()).c_str(), mh.GetName(),
mh.GetSignature().c_str(), mh.GetDeclaringClassSourceFile());
}
}
static void DumpThread(Thread* t, void* arg) {
std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
std::string name;
t->GetThreadName(name);
os << t->GetTid() << "\t" << name << "\n";
}
void Trace::DumpThreadList(std::ostream& os) {
Thread* self = Thread::Current();
Locks::thread_list_lock_->AssertNotHeld(self);
MutexLock mu(self, *Locks::thread_list_lock_);
Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
}
} // namespace art