trace.cc revision c5d824a20c225763761a6dff43294b229ff35469 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "trace.h"
18
19#include <sys/uio.h>
20
21#include "base/stl_util.h"
22#include "base/unix_file/fd_file.h"
23#include "class_linker.h"
24#include "common_throws.h"
25#include "debugger.h"
26#include "dex_file-inl.h"
27#include "instrumentation.h"
28#include "mirror/art_method-inl.h"
29#include "mirror/class-inl.h"
30#include "mirror/dex_cache.h"
31#include "mirror/object_array-inl.h"
32#include "mirror/object-inl.h"
33#include "os.h"
34#include "scoped_thread_state_change.h"
35#include "ScopedLocalRef.h"
36#include "thread.h"
37#include "thread_list.h"
38#if !defined(ART_USE_PORTABLE_COMPILER)
39#include "entrypoints/quick/quick_entrypoints.h"
40#endif
41
42namespace art {
43
44// File format:
45//     header
46//     record 0
47//     record 1
48//     ...
49//
50// Header format:
51//     u4  magic ('SLOW')
52//     u2  version
53//     u2  offset to data
54//     u8  start date/time in usec
55//     u2  record size in bytes (version >= 2 only)
56//     ... padding to 32 bytes
57//
58// Record format v1:
59//     u1  thread ID
60//     u4  method ID | method action
61//     u4  time delta since start, in usec
62//
63// Record format v2:
64//     u2  thread ID
65//     u4  method ID | method action
66//     u4  time delta since start, in usec
67//
68// Record format v3:
69//     u2  thread ID
70//     u4  method ID | method action
71//     u4  time delta since start, in usec
72//     u4  wall time since start, in usec (when clock == "dual" only)
73//
74// 32 bits of microseconds is 70 minutes.
75//
76// All values are stored in little-endian order.
77
78enum TraceAction {
79    kTraceMethodEnter = 0x00,       // method entry
80    kTraceMethodExit = 0x01,        // method exit
81    kTraceUnroll = 0x02,            // method exited by exception unrolling
82    // 0x03 currently unused
83    kTraceMethodActionMask = 0x03,  // two bits
84};
85
86class BuildStackTraceVisitor : public StackVisitor {
87 public:
88  explicit BuildStackTraceVisitor(Thread* thread) : StackVisitor(thread, NULL),
89      method_trace_(Trace::AllocStackTrace()) {}
90
91  bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
92    mirror::ArtMethod* m = GetMethod();
93    // Ignore runtime frames (in particular callee save).
94    if (!m->IsRuntimeMethod()) {
95      method_trace_->push_back(m);
96    }
97    return true;
98  }
99
100  // Returns a stack trace where the topmost frame corresponds with the first element of the vector.
101  std::vector<mirror::ArtMethod*>* GetStackTrace() const {
102    return method_trace_;
103  }
104
105 private:
106  std::vector<mirror::ArtMethod*>* const method_trace_;
107};
108
109static const char     kTraceTokenChar             = '*';
110static const uint16_t kTraceHeaderLength          = 32;
111static const uint32_t kTraceMagicValue            = 0x574f4c53;
112static const uint16_t kTraceVersionSingleClock    = 2;
113static const uint16_t kTraceVersionDualClock      = 3;
114static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
115static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
116
117TraceClockSource Trace::default_clock_source_ = kDefaultTraceClockSource;
118
119Trace* volatile Trace::the_trace_ = NULL;
120pthread_t Trace::sampling_pthread_ = 0U;
121std::unique_ptr<std::vector<mirror::ArtMethod*>> Trace::temp_stack_trace_;
122
123static mirror::ArtMethod* DecodeTraceMethodId(uint32_t tmid) {
124  return reinterpret_cast<mirror::ArtMethod*>(tmid & ~kTraceMethodActionMask);
125}
126
127static TraceAction DecodeTraceAction(uint32_t tmid) {
128  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
129}
130
131static uint32_t EncodeTraceMethodAndAction(mirror::ArtMethod* method,
132                                           TraceAction action) {
133  uint32_t tmid = PointerToLowMemUInt32(method) | action;
134  DCHECK_EQ(method, DecodeTraceMethodId(tmid));
135  return tmid;
136}
137
138std::vector<mirror::ArtMethod*>* Trace::AllocStackTrace() {
139  if (temp_stack_trace_.get() != NULL) {
140    return temp_stack_trace_.release();
141  } else {
142    return new std::vector<mirror::ArtMethod*>();
143  }
144}
145
146void Trace::FreeStackTrace(std::vector<mirror::ArtMethod*>* stack_trace) {
147  stack_trace->clear();
148  temp_stack_trace_.reset(stack_trace);
149}
150
151void Trace::SetDefaultClockSource(TraceClockSource clock_source) {
152#if defined(HAVE_POSIX_CLOCKS)
153  default_clock_source_ = clock_source;
154#else
155  if (clock_source != kTraceClockSourceWall) {
156    LOG(WARNING) << "Ignoring tracing request to use CPU time.";
157  }
158#endif
159}
160
161static uint16_t GetTraceVersion(TraceClockSource clock_source) {
162  return (clock_source == kTraceClockSourceDual) ? kTraceVersionDualClock
163                                                    : kTraceVersionSingleClock;
164}
165
166static uint16_t GetRecordSize(TraceClockSource clock_source) {
167  return (clock_source == kTraceClockSourceDual) ? kTraceRecordSizeDualClock
168                                                    : kTraceRecordSizeSingleClock;
169}
170
171bool Trace::UseThreadCpuClock() {
172  return (clock_source_ == kTraceClockSourceThreadCpu) ||
173      (clock_source_ == kTraceClockSourceDual);
174}
175
176bool Trace::UseWallClock() {
177  return (clock_source_ == kTraceClockSourceWall) ||
178      (clock_source_ == kTraceClockSourceDual);
179}
180
181void Trace::MeasureClockOverhead() {
182  if (UseThreadCpuClock()) {
183    Thread::Current()->GetCpuMicroTime();
184  }
185  if (UseWallClock()) {
186    MicroTime();
187  }
188}
189
190// Compute an average time taken to measure clocks.
191uint32_t Trace::GetClockOverheadNanoSeconds() {
192  Thread* self = Thread::Current();
193  uint64_t start = self->GetCpuMicroTime();
194
195  for (int i = 4000; i > 0; i--) {
196    MeasureClockOverhead();
197    MeasureClockOverhead();
198    MeasureClockOverhead();
199    MeasureClockOverhead();
200    MeasureClockOverhead();
201    MeasureClockOverhead();
202    MeasureClockOverhead();
203    MeasureClockOverhead();
204  }
205
206  uint64_t elapsed_us = self->GetCpuMicroTime() - start;
207  return static_cast<uint32_t>(elapsed_us / 32);
208}
209
210// TODO: put this somewhere with the big-endian equivalent used by JDWP.
211static void Append2LE(uint8_t* buf, uint16_t val) {
212  *buf++ = static_cast<uint8_t>(val);
213  *buf++ = static_cast<uint8_t>(val >> 8);
214}
215
216// TODO: put this somewhere with the big-endian equivalent used by JDWP.
217static void Append4LE(uint8_t* buf, uint32_t val) {
218  *buf++ = static_cast<uint8_t>(val);
219  *buf++ = static_cast<uint8_t>(val >> 8);
220  *buf++ = static_cast<uint8_t>(val >> 16);
221  *buf++ = static_cast<uint8_t>(val >> 24);
222}
223
224// TODO: put this somewhere with the big-endian equivalent used by JDWP.
225static void Append8LE(uint8_t* buf, uint64_t val) {
226  *buf++ = static_cast<uint8_t>(val);
227  *buf++ = static_cast<uint8_t>(val >> 8);
228  *buf++ = static_cast<uint8_t>(val >> 16);
229  *buf++ = static_cast<uint8_t>(val >> 24);
230  *buf++ = static_cast<uint8_t>(val >> 32);
231  *buf++ = static_cast<uint8_t>(val >> 40);
232  *buf++ = static_cast<uint8_t>(val >> 48);
233  *buf++ = static_cast<uint8_t>(val >> 56);
234}
235
236static void GetSample(Thread* thread, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
237  BuildStackTraceVisitor build_trace_visitor(thread);
238  build_trace_visitor.WalkStack();
239  std::vector<mirror::ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
240  Trace* the_trace = reinterpret_cast<Trace*>(arg);
241  the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
242}
243
244static void ClearThreadStackTraceAndClockBase(Thread* thread, void* arg) {
245  thread->SetTraceClockBase(0);
246  std::vector<mirror::ArtMethod*>* stack_trace = thread->GetStackTraceSample();
247  thread->SetStackTraceSample(NULL);
248  delete stack_trace;
249}
250
251void Trace::CompareAndUpdateStackTrace(Thread* thread,
252                                       std::vector<mirror::ArtMethod*>* stack_trace) {
253  CHECK_EQ(pthread_self(), sampling_pthread_);
254  std::vector<mirror::ArtMethod*>* old_stack_trace = thread->GetStackTraceSample();
255  // Update the thread's stack trace sample.
256  thread->SetStackTraceSample(stack_trace);
257  // Read timer clocks to use for all events in this trace.
258  uint32_t thread_clock_diff = 0;
259  uint32_t wall_clock_diff = 0;
260  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
261  if (old_stack_trace == NULL) {
262    // If there's no previous stack trace sample for this thread, log an entry event for all
263    // methods in the trace.
264    for (std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
265         rit != stack_trace->rend(); ++rit) {
266      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
267                          thread_clock_diff, wall_clock_diff);
268    }
269  } else {
270    // If there's a previous stack trace for this thread, diff the traces and emit entry and exit
271    // events accordingly.
272    std::vector<mirror::ArtMethod*>::reverse_iterator old_rit = old_stack_trace->rbegin();
273    std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
274    // Iterate bottom-up over both traces until there's a difference between them.
275    while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
276      old_rit++;
277      rit++;
278    }
279    // Iterate top-down over the old trace until the point where they differ, emitting exit events.
280    for (std::vector<mirror::ArtMethod*>::iterator old_it = old_stack_trace->begin();
281         old_it != old_rit.base(); ++old_it) {
282      LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited,
283                          thread_clock_diff, wall_clock_diff);
284    }
285    // Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
286    for (; rit != stack_trace->rend(); ++rit) {
287      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
288                          thread_clock_diff, wall_clock_diff);
289    }
290    FreeStackTrace(old_stack_trace);
291  }
292}
293
294void* Trace::RunSamplingThread(void* arg) {
295  Runtime* runtime = Runtime::Current();
296  intptr_t interval_us = reinterpret_cast<intptr_t>(arg);
297  CHECK_GE(interval_us, 0);
298  CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
299                                     !runtime->IsCompiler()));
300
301  while (true) {
302    usleep(interval_us);
303    ATRACE_BEGIN("Profile sampling");
304    Thread* self = Thread::Current();
305    Trace* the_trace;
306    {
307      MutexLock mu(self, *Locks::trace_lock_);
308      the_trace = the_trace_;
309      if (the_trace == NULL) {
310        break;
311      }
312    }
313
314    runtime->GetThreadList()->SuspendAll();
315    {
316      MutexLock mu(self, *Locks::thread_list_lock_);
317      runtime->GetThreadList()->ForEach(GetSample, the_trace);
318    }
319    runtime->GetThreadList()->ResumeAll();
320    ATRACE_END();
321  }
322
323  runtime->DetachCurrentThread();
324  return NULL;
325}
326
327void Trace::Start(const char* trace_filename, int trace_fd, int buffer_size, int flags,
328                  bool direct_to_ddms, bool sampling_enabled, int interval_us) {
329  Thread* self = Thread::Current();
330  {
331    MutexLock mu(self, *Locks::trace_lock_);
332    if (the_trace_ != NULL) {
333      LOG(ERROR) << "Trace already in progress, ignoring this request";
334      return;
335    }
336  }
337  Runtime* runtime = Runtime::Current();
338  runtime->GetThreadList()->SuspendAll();
339
340  // Open trace file if not going directly to ddms.
341  std::unique_ptr<File> trace_file;
342  if (!direct_to_ddms) {
343    if (trace_fd < 0) {
344      trace_file.reset(OS::CreateEmptyFile(trace_filename));
345    } else {
346      trace_file.reset(new File(trace_fd, "tracefile"));
347      trace_file->DisableAutoClose();
348    }
349    if (trace_file.get() == NULL) {
350      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
351      runtime->GetThreadList()->ResumeAll();
352      ScopedObjectAccess soa(self);
353      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
354      return;
355    }
356  }
357
358  // Create Trace object.
359  {
360    MutexLock mu(self, *Locks::trace_lock_);
361    if (the_trace_ != NULL) {
362      LOG(ERROR) << "Trace already in progress, ignoring this request";
363    } else {
364      the_trace_ = new Trace(trace_file.release(), buffer_size, flags, sampling_enabled);
365
366      // Enable count of allocs if specified in the flags.
367      if ((flags && kTraceCountAllocs) != 0) {
368        runtime->SetStatsEnabled(true);
369      }
370
371
372
373      if (sampling_enabled) {
374        CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, NULL, &RunSamplingThread,
375                                            reinterpret_cast<void*>(interval_us)),
376                                            "Sampling profiler thread");
377      } else {
378        runtime->GetInstrumentation()->AddListener(the_trace_,
379                                                   instrumentation::Instrumentation::kMethodEntered |
380                                                   instrumentation::Instrumentation::kMethodExited |
381                                                   instrumentation::Instrumentation::kMethodUnwind);
382        runtime->GetInstrumentation()->EnableMethodTracing();
383      }
384    }
385  }
386  runtime->GetThreadList()->ResumeAll();
387}
388
389void Trace::Stop() {
390  Runtime* runtime = Runtime::Current();
391  runtime->GetThreadList()->SuspendAll();
392  Trace* the_trace = NULL;
393  pthread_t sampling_pthread = 0U;
394  {
395    MutexLock mu(Thread::Current(), *Locks::trace_lock_);
396    if (the_trace_ == NULL) {
397      LOG(ERROR) << "Trace stop requested, but no trace currently running";
398    } else {
399      the_trace = the_trace_;
400      the_trace_ = NULL;
401      sampling_pthread = sampling_pthread_;
402      sampling_pthread_ = 0U;
403    }
404  }
405  if (the_trace != NULL) {
406    the_trace->FinishTracing();
407
408    if (the_trace->sampling_enabled_) {
409      MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
410      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, NULL);
411    } else {
412      runtime->GetInstrumentation()->DisableMethodTracing();
413      runtime->GetInstrumentation()->RemoveListener(the_trace,
414                                                    instrumentation::Instrumentation::kMethodEntered |
415                                                    instrumentation::Instrumentation::kMethodExited |
416                                                    instrumentation::Instrumentation::kMethodUnwind);
417    }
418    delete the_trace;
419  }
420  runtime->GetThreadList()->ResumeAll();
421
422  if (sampling_pthread != 0U) {
423    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, NULL), "sampling thread shutdown");
424  }
425}
426
427void Trace::Shutdown() {
428  if (GetMethodTracingMode() != kTracingInactive) {
429    Stop();
430  }
431}
432
433TracingMode Trace::GetMethodTracingMode() {
434  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
435  if (the_trace_ == NULL) {
436    return kTracingInactive;
437  } else if (the_trace_->sampling_enabled_) {
438    return kSampleProfilingActive;
439  } else {
440    return kMethodTracingActive;
441  }
442}
443
444Trace::Trace(File* trace_file, int buffer_size, int flags, bool sampling_enabled)
445    : trace_file_(trace_file), buf_(new uint8_t[buffer_size]()), flags_(flags),
446      sampling_enabled_(sampling_enabled), clock_source_(default_clock_source_),
447      buffer_size_(buffer_size), start_time_(MicroTime()),
448      clock_overhead_ns_(GetClockOverheadNanoSeconds()), cur_offset_(0), overflow_(false) {
449  // Set up the beginning of the trace.
450  uint16_t trace_version = GetTraceVersion(clock_source_);
451  memset(buf_.get(), 0, kTraceHeaderLength);
452  Append4LE(buf_.get(), kTraceMagicValue);
453  Append2LE(buf_.get() + 4, trace_version);
454  Append2LE(buf_.get() + 6, kTraceHeaderLength);
455  Append8LE(buf_.get() + 8, start_time_);
456  if (trace_version >= kTraceVersionDualClock) {
457    uint16_t record_size = GetRecordSize(clock_source_);
458    Append2LE(buf_.get() + 16, record_size);
459  }
460
461  // Update current offset.
462  cur_offset_.StoreRelaxed(kTraceHeaderLength);
463}
464
465static void DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source)
466    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
467  uint8_t* ptr = buf + kTraceHeaderLength;
468  uint8_t* end = buf + buf_size;
469
470  while (ptr < end) {
471    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
472    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
473    TraceAction action = DecodeTraceAction(tmid);
474    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
475    ptr += GetRecordSize(clock_source);
476  }
477}
478
479void Trace::FinishTracing() {
480  // Compute elapsed time.
481  uint64_t elapsed = MicroTime() - start_time_;
482
483  size_t final_offset = cur_offset_.LoadRelaxed();
484
485  if ((flags_ & kTraceCountAllocs) != 0) {
486    Runtime::Current()->SetStatsEnabled(false);
487  }
488
489  std::set<mirror::ArtMethod*> visited_methods;
490  GetVisitedMethods(final_offset, &visited_methods);
491
492  std::ostringstream os;
493
494  os << StringPrintf("%cversion\n", kTraceTokenChar);
495  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
496  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
497  if (UseThreadCpuClock()) {
498    if (UseWallClock()) {
499      os << StringPrintf("clock=dual\n");
500    } else {
501      os << StringPrintf("clock=thread-cpu\n");
502    }
503  } else {
504    os << StringPrintf("clock=wall\n");
505  }
506  os << StringPrintf("elapsed-time-usec=%" PRIu64 "\n", elapsed);
507  size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
508  os << StringPrintf("num-method-calls=%zd\n", num_records);
509  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
510  os << StringPrintf("vm=art\n");
511  if ((flags_ & kTraceCountAllocs) != 0) {
512    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
513    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
514    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
515  }
516  os << StringPrintf("%cthreads\n", kTraceTokenChar);
517  DumpThreadList(os);
518  os << StringPrintf("%cmethods\n", kTraceTokenChar);
519  DumpMethodList(os, visited_methods);
520  os << StringPrintf("%cend\n", kTraceTokenChar);
521
522  std::string header(os.str());
523  if (trace_file_.get() == NULL) {
524    iovec iov[2];
525    iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
526    iov[0].iov_len = header.length();
527    iov[1].iov_base = buf_.get();
528    iov[1].iov_len = final_offset;
529    Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
530    const bool kDumpTraceInfo = false;
531    if (kDumpTraceInfo) {
532      LOG(INFO) << "Trace sent:\n" << header;
533      DumpBuf(buf_.get(), final_offset, clock_source_);
534    }
535  } else {
536    if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
537        !trace_file_->WriteFully(buf_.get(), final_offset)) {
538      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
539      PLOG(ERROR) << detail;
540      ThrowRuntimeException("%s", detail.c_str());
541    }
542  }
543}
544
545void Trace::DexPcMoved(Thread* thread, mirror::Object* this_object,
546                       mirror::ArtMethod* method, uint32_t new_dex_pc) {
547  // We're not recorded to listen to this kind of event, so complain.
548  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
549};
550
551void Trace::FieldRead(Thread* /*thread*/, mirror::Object* this_object,
552                       mirror::ArtMethod* method, uint32_t dex_pc, mirror::ArtField* field)
553    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
554  // We're not recorded to listen to this kind of event, so complain.
555  LOG(ERROR) << "Unexpected field read event in tracing " << PrettyMethod(method) << " " << dex_pc;
556}
557
558void Trace::FieldWritten(Thread* /*thread*/, mirror::Object* this_object,
559                          mirror::ArtMethod* method, uint32_t dex_pc, mirror::ArtField* field,
560                          const JValue& field_value)
561    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
562  // We're not recorded to listen to this kind of event, so complain.
563  LOG(ERROR) << "Unexpected field write event in tracing " << PrettyMethod(method) << " " << dex_pc;
564}
565
566void Trace::MethodEntered(Thread* thread, mirror::Object* this_object,
567                          mirror::ArtMethod* method, uint32_t dex_pc) {
568  uint32_t thread_clock_diff = 0;
569  uint32_t wall_clock_diff = 0;
570  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
571  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered,
572                      thread_clock_diff, wall_clock_diff);
573}
574
575void Trace::MethodExited(Thread* thread, mirror::Object* this_object,
576                         mirror::ArtMethod* method, uint32_t dex_pc,
577                         const JValue& return_value) {
578  UNUSED(return_value);
579  uint32_t thread_clock_diff = 0;
580  uint32_t wall_clock_diff = 0;
581  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
582  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited,
583                      thread_clock_diff, wall_clock_diff);
584}
585
586void Trace::MethodUnwind(Thread* thread, mirror::Object* this_object,
587                         mirror::ArtMethod* method, uint32_t dex_pc) {
588  uint32_t thread_clock_diff = 0;
589  uint32_t wall_clock_diff = 0;
590  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
591  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind,
592                      thread_clock_diff, wall_clock_diff);
593}
594
595void Trace::ExceptionCaught(Thread* thread, const ThrowLocation& throw_location,
596                            mirror::ArtMethod* catch_method, uint32_t catch_dex_pc,
597                            mirror::Throwable* exception_object)
598    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
599  LOG(ERROR) << "Unexpected exception caught event in tracing";
600}
601
602void Trace::ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint32_t* wall_clock_diff) {
603  if (UseThreadCpuClock()) {
604    uint64_t clock_base = thread->GetTraceClockBase();
605    if (UNLIKELY(clock_base == 0)) {
606      // First event, record the base time in the map.
607      uint64_t time = thread->GetCpuMicroTime();
608      thread->SetTraceClockBase(time);
609    } else {
610      *thread_clock_diff = thread->GetCpuMicroTime() - clock_base;
611    }
612  }
613  if (UseWallClock()) {
614    *wall_clock_diff = MicroTime() - start_time_;
615  }
616}
617
618void Trace::LogMethodTraceEvent(Thread* thread, mirror::ArtMethod* method,
619                                instrumentation::Instrumentation::InstrumentationEvent event,
620                                uint32_t thread_clock_diff, uint32_t wall_clock_diff) {
621  // Advance cur_offset_ atomically.
622  int32_t new_offset;
623  int32_t old_offset;
624  do {
625    old_offset = cur_offset_.LoadRelaxed();
626    new_offset = old_offset + GetRecordSize(clock_source_);
627    if (new_offset > buffer_size_) {
628      overflow_ = true;
629      return;
630    }
631  } while (!cur_offset_.CompareExchangeWeakSequentiallyConsistent(old_offset, new_offset));
632
633  TraceAction action = kTraceMethodEnter;
634  switch (event) {
635    case instrumentation::Instrumentation::kMethodEntered:
636      action = kTraceMethodEnter;
637      break;
638    case instrumentation::Instrumentation::kMethodExited:
639      action = kTraceMethodExit;
640      break;
641    case instrumentation::Instrumentation::kMethodUnwind:
642      action = kTraceUnroll;
643      break;
644    default:
645      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
646  }
647
648  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
649
650  // Write data
651  uint8_t* ptr = buf_.get() + old_offset;
652  Append2LE(ptr, thread->GetTid());
653  Append4LE(ptr + 2, method_value);
654  ptr += 6;
655
656  if (UseThreadCpuClock()) {
657    Append4LE(ptr, thread_clock_diff);
658    ptr += 4;
659  }
660  if (UseWallClock()) {
661    Append4LE(ptr, wall_clock_diff);
662  }
663}
664
665void Trace::GetVisitedMethods(size_t buf_size,
666                              std::set<mirror::ArtMethod*>* visited_methods) {
667  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
668  uint8_t* end = buf_.get() + buf_size;
669
670  while (ptr < end) {
671    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
672    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
673    visited_methods->insert(method);
674    ptr += GetRecordSize(clock_source_);
675  }
676}
677
678void Trace::DumpMethodList(std::ostream& os, const std::set<mirror::ArtMethod*>& visited_methods) {
679  for (const auto& method : visited_methods) {
680    os << StringPrintf("%p\t%s\t%s\t%s\t%s\n", method,
681        PrettyDescriptor(method->GetDeclaringClassDescriptor()).c_str(), method->GetName(),
682        method->GetSignature().ToString().c_str(), method->GetDeclaringClassSourceFile());
683  }
684}
685
686static void DumpThread(Thread* t, void* arg) {
687  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
688  std::string name;
689  t->GetThreadName(name);
690  os << t->GetTid() << "\t" << name << "\n";
691}
692
693void Trace::DumpThreadList(std::ostream& os) {
694  Thread* self = Thread::Current();
695  Locks::thread_list_lock_->AssertNotHeld(self);
696  MutexLock mu(self, *Locks::thread_list_lock_);
697  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
698}
699
700}  // namespace art
701