trace.cc revision 0624a27b9a2951bfcf23321a714543e137836904 
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#include <unistd.h>
21
22#define ATRACE_TAG ATRACE_TAG_DALVIK
23#include "cutils/trace.h"
24
25#include "base/stl_util.h"
26#include "base/unix_file/fd_file.h"
27#include "class_linker.h"
28#include "common_throws.h"
29#include "debugger.h"
30#include "dex_file-inl.h"
31#include "instrumentation.h"
32#include "mirror/art_method-inl.h"
33#include "mirror/class-inl.h"
34#include "mirror/dex_cache.h"
35#include "mirror/object_array-inl.h"
36#include "mirror/object-inl.h"
37#include "os.h"
38#include "scoped_thread_state_change.h"
39#include "ScopedLocalRef.h"
40#include "thread.h"
41#include "thread_list.h"
42#include "entrypoints/quick/quick_entrypoints.h"
43
44namespace art {
45
46// File format:
47//     header
48//     record 0
49//     record 1
50//     ...
51//
52// Header format:
53//     u4  magic ('SLOW')
54//     u2  version
55//     u2  offset to data
56//     u8  start date/time in usec
57//     u2  record size in bytes (version >= 2 only)
58//     ... padding to 32 bytes
59//
60// Record format v1:
61//     u1  thread ID
62//     u4  method ID | method action
63//     u4  time delta since start, in usec
64//
65// Record format v2:
66//     u2  thread ID
67//     u4  method ID | method action
68//     u4  time delta since start, in usec
69//
70// Record format v3:
71//     u2  thread ID
72//     u4  method ID | method action
73//     u4  time delta since start, in usec
74//     u4  wall time since start, in usec (when clock == "dual" only)
75//
76// 32 bits of microseconds is 70 minutes.
77//
78// All values are stored in little-endian order.
79
80enum TraceAction {
81    kTraceMethodEnter = 0x00,       // method entry
82    kTraceMethodExit = 0x01,        // method exit
83    kTraceUnroll = 0x02,            // method exited by exception unrolling
84    // 0x03 currently unused
85    kTraceMethodActionMask = 0x03,  // two bits
86};
87
88class BuildStackTraceVisitor : public StackVisitor {
89 public:
90  explicit BuildStackTraceVisitor(Thread* thread) : StackVisitor(thread, NULL),
91      method_trace_(Trace::AllocStackTrace()) {}
92
93  bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
94    mirror::ArtMethod* m = GetMethod();
95    // Ignore runtime frames (in particular callee save).
96    if (!m->IsRuntimeMethod()) {
97      method_trace_->push_back(m);
98    }
99    return true;
100  }
101
102  // Returns a stack trace where the topmost frame corresponds with the first element of the vector.
103  std::vector<mirror::ArtMethod*>* GetStackTrace() const {
104    return method_trace_;
105  }
106
107 private:
108  std::vector<mirror::ArtMethod*>* const method_trace_;
109};
110
111static const char     kTraceTokenChar             = '*';
112static const uint16_t kTraceHeaderLength          = 32;
113static const uint32_t kTraceMagicValue            = 0x574f4c53;
114static const uint16_t kTraceVersionSingleClock    = 2;
115static const uint16_t kTraceVersionDualClock      = 3;
116static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
117static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
118
119TraceClockSource Trace::default_clock_source_ = kDefaultTraceClockSource;
120
121Trace* volatile Trace::the_trace_ = NULL;
122pthread_t Trace::sampling_pthread_ = 0U;
123std::unique_ptr<std::vector<mirror::ArtMethod*>> Trace::temp_stack_trace_;
124
125static mirror::ArtMethod* DecodeTraceMethodId(uint32_t tmid) {
126  return reinterpret_cast<mirror::ArtMethod*>(tmid & ~kTraceMethodActionMask);
127}
128
129static TraceAction DecodeTraceAction(uint32_t tmid) {
130  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
131}
132
133static uint32_t EncodeTraceMethodAndAction(mirror::ArtMethod* method,
134                                           TraceAction action) {
135  uint32_t tmid = PointerToLowMemUInt32(method) | action;
136  DCHECK_EQ(method, DecodeTraceMethodId(tmid));
137  return tmid;
138}
139
140std::vector<mirror::ArtMethod*>* Trace::AllocStackTrace() {
141  if (temp_stack_trace_.get() != NULL) {
142    return temp_stack_trace_.release();
143  } else {
144    return new std::vector<mirror::ArtMethod*>();
145  }
146}
147
148void Trace::FreeStackTrace(std::vector<mirror::ArtMethod*>* stack_trace) {
149  stack_trace->clear();
150  temp_stack_trace_.reset(stack_trace);
151}
152
153void Trace::SetDefaultClockSource(TraceClockSource clock_source) {
154#if defined(__linux__)
155  default_clock_source_ = clock_source;
156#else
157  if (clock_source != TraceClockSource::kWall) {
158    LOG(WARNING) << "Ignoring tracing request to use CPU time.";
159  }
160#endif
161}
162
163static uint16_t GetTraceVersion(TraceClockSource clock_source) {
164  return (clock_source == TraceClockSource::kDual) ? kTraceVersionDualClock
165                                                    : kTraceVersionSingleClock;
166}
167
168static uint16_t GetRecordSize(TraceClockSource clock_source) {
169  return (clock_source == TraceClockSource::kDual) ? kTraceRecordSizeDualClock
170                                                    : kTraceRecordSizeSingleClock;
171}
172
173bool Trace::UseThreadCpuClock() {
174  return (clock_source_ == TraceClockSource::kThreadCpu) ||
175      (clock_source_ == TraceClockSource::kDual);
176}
177
178bool Trace::UseWallClock() {
179  return (clock_source_ == TraceClockSource::kWall) ||
180      (clock_source_ == TraceClockSource::kDual);
181}
182
183void Trace::MeasureClockOverhead() {
184  if (UseThreadCpuClock()) {
185    Thread::Current()->GetCpuMicroTime();
186  }
187  if (UseWallClock()) {
188    MicroTime();
189  }
190}
191
192// Compute an average time taken to measure clocks.
193uint32_t Trace::GetClockOverheadNanoSeconds() {
194  Thread* self = Thread::Current();
195  uint64_t start = self->GetCpuMicroTime();
196
197  for (int i = 4000; i > 0; i--) {
198    MeasureClockOverhead();
199    MeasureClockOverhead();
200    MeasureClockOverhead();
201    MeasureClockOverhead();
202    MeasureClockOverhead();
203    MeasureClockOverhead();
204    MeasureClockOverhead();
205    MeasureClockOverhead();
206  }
207
208  uint64_t elapsed_us = self->GetCpuMicroTime() - start;
209  return static_cast<uint32_t>(elapsed_us / 32);
210}
211
212// TODO: put this somewhere with the big-endian equivalent used by JDWP.
213static void Append2LE(uint8_t* buf, uint16_t val) {
214  *buf++ = static_cast<uint8_t>(val);
215  *buf++ = static_cast<uint8_t>(val >> 8);
216}
217
218// TODO: put this somewhere with the big-endian equivalent used by JDWP.
219static void Append4LE(uint8_t* buf, uint32_t val) {
220  *buf++ = static_cast<uint8_t>(val);
221  *buf++ = static_cast<uint8_t>(val >> 8);
222  *buf++ = static_cast<uint8_t>(val >> 16);
223  *buf++ = static_cast<uint8_t>(val >> 24);
224}
225
226// TODO: put this somewhere with the big-endian equivalent used by JDWP.
227static void Append8LE(uint8_t* buf, uint64_t val) {
228  *buf++ = static_cast<uint8_t>(val);
229  *buf++ = static_cast<uint8_t>(val >> 8);
230  *buf++ = static_cast<uint8_t>(val >> 16);
231  *buf++ = static_cast<uint8_t>(val >> 24);
232  *buf++ = static_cast<uint8_t>(val >> 32);
233  *buf++ = static_cast<uint8_t>(val >> 40);
234  *buf++ = static_cast<uint8_t>(val >> 48);
235  *buf++ = static_cast<uint8_t>(val >> 56);
236}
237
238static void GetSample(Thread* thread, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
239  BuildStackTraceVisitor build_trace_visitor(thread);
240  build_trace_visitor.WalkStack();
241  std::vector<mirror::ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
242  Trace* the_trace = reinterpret_cast<Trace*>(arg);
243  the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
244}
245
246static void ClearThreadStackTraceAndClockBase(Thread* thread ATTRIBUTE_UNUSED,
247                                              void* arg ATTRIBUTE_UNUSED) {
248  thread->SetTraceClockBase(0);
249  std::vector<mirror::ArtMethod*>* stack_trace = thread->GetStackTraceSample();
250  thread->SetStackTraceSample(NULL);
251  delete stack_trace;
252}
253
254void Trace::CompareAndUpdateStackTrace(Thread* thread,
255                                       std::vector<mirror::ArtMethod*>* stack_trace) {
256  CHECK_EQ(pthread_self(), sampling_pthread_);
257  std::vector<mirror::ArtMethod*>* old_stack_trace = thread->GetStackTraceSample();
258  // Update the thread's stack trace sample.
259  thread->SetStackTraceSample(stack_trace);
260  // Read timer clocks to use for all events in this trace.
261  uint32_t thread_clock_diff = 0;
262  uint32_t wall_clock_diff = 0;
263  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
264  if (old_stack_trace == NULL) {
265    // If there's no previous stack trace sample for this thread, log an entry event for all
266    // methods in the trace.
267    for (std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
268         rit != stack_trace->rend(); ++rit) {
269      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
270                          thread_clock_diff, wall_clock_diff);
271    }
272  } else {
273    // If there's a previous stack trace for this thread, diff the traces and emit entry and exit
274    // events accordingly.
275    std::vector<mirror::ArtMethod*>::reverse_iterator old_rit = old_stack_trace->rbegin();
276    std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
277    // Iterate bottom-up over both traces until there's a difference between them.
278    while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
279      old_rit++;
280      rit++;
281    }
282    // Iterate top-down over the old trace until the point where they differ, emitting exit events.
283    for (std::vector<mirror::ArtMethod*>::iterator old_it = old_stack_trace->begin();
284         old_it != old_rit.base(); ++old_it) {
285      LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited,
286                          thread_clock_diff, wall_clock_diff);
287    }
288    // Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
289    for (; rit != stack_trace->rend(); ++rit) {
290      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
291                          thread_clock_diff, wall_clock_diff);
292    }
293    FreeStackTrace(old_stack_trace);
294  }
295}
296
297void* Trace::RunSamplingThread(void* arg) {
298  Runtime* runtime = Runtime::Current();
299  intptr_t interval_us = reinterpret_cast<intptr_t>(arg);
300  CHECK_GE(interval_us, 0);
301  CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
302                                     !runtime->IsAotCompiler()));
303
304  while (true) {
305    usleep(interval_us);
306    ATRACE_BEGIN("Profile sampling");
307    Thread* self = Thread::Current();
308    Trace* the_trace;
309    {
310      MutexLock mu(self, *Locks::trace_lock_);
311      the_trace = the_trace_;
312      if (the_trace == NULL) {
313        break;
314      }
315    }
316
317    runtime->GetThreadList()->SuspendAll(__FUNCTION__);
318    {
319      MutexLock mu(self, *Locks::thread_list_lock_);
320      runtime->GetThreadList()->ForEach(GetSample, the_trace);
321    }
322    runtime->GetThreadList()->ResumeAll();
323    ATRACE_END();
324  }
325
326  runtime->DetachCurrentThread();
327  return NULL;
328}
329
330void Trace::Start(const char* trace_filename, int trace_fd, int buffer_size, int flags,
331                  bool direct_to_ddms, bool sampling_enabled, int interval_us) {
332  Thread* self = Thread::Current();
333  {
334    MutexLock mu(self, *Locks::trace_lock_);
335    if (the_trace_ != NULL) {
336      LOG(ERROR) << "Trace already in progress, ignoring this request";
337      return;
338    }
339  }
340
341  // Check interval if sampling is enabled
342  if (sampling_enabled && interval_us <= 0) {
343    LOG(ERROR) << "Invalid sampling interval: " << interval_us;
344    ScopedObjectAccess soa(self);
345    ThrowRuntimeException("Invalid sampling interval: %d", interval_us);
346    return;
347  }
348
349  // Open trace file if not going directly to ddms.
350  std::unique_ptr<File> trace_file;
351  if (!direct_to_ddms) {
352    if (trace_fd < 0) {
353      trace_file.reset(OS::CreateEmptyFile(trace_filename));
354    } else {
355      trace_file.reset(new File(trace_fd, "tracefile"));
356      trace_file->DisableAutoClose();
357    }
358    if (trace_file.get() == NULL) {
359      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
360      ScopedObjectAccess soa(self);
361      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
362      return;
363    }
364  }
365
366  Runtime* runtime = Runtime::Current();
367
368  // Enable count of allocs if specified in the flags.
369  bool enable_stats = false;
370
371  runtime->GetThreadList()->SuspendAll(__FUNCTION__);
372
373  // Create Trace object.
374  {
375    MutexLock mu(self, *Locks::trace_lock_);
376    if (the_trace_ != NULL) {
377      LOG(ERROR) << "Trace already in progress, ignoring this request";
378    } else {
379      enable_stats = (flags && kTraceCountAllocs) != 0;
380      the_trace_ = new Trace(trace_file.release(), buffer_size, flags, sampling_enabled);
381      if (sampling_enabled) {
382        CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, NULL, &RunSamplingThread,
383                                            reinterpret_cast<void*>(interval_us)),
384                                            "Sampling profiler thread");
385      } else {
386        runtime->GetInstrumentation()->AddListener(the_trace_,
387                                                   instrumentation::Instrumentation::kMethodEntered |
388                                                   instrumentation::Instrumentation::kMethodExited |
389                                                   instrumentation::Instrumentation::kMethodUnwind);
390        runtime->GetInstrumentation()->EnableMethodTracing();
391      }
392    }
393  }
394
395  runtime->GetThreadList()->ResumeAll();
396
397  // Can't call this when holding the mutator lock.
398  if (enable_stats) {
399    runtime->SetStatsEnabled(true);
400  }
401}
402
403void Trace::Stop() {
404  bool stop_alloc_counting = false;
405  Runtime* const runtime = Runtime::Current();
406  Trace* the_trace = nullptr;
407  pthread_t sampling_pthread = 0U;
408  {
409    MutexLock mu(Thread::Current(), *Locks::trace_lock_);
410    if (the_trace_ == NULL) {
411      LOG(ERROR) << "Trace stop requested, but no trace currently running";
412    } else {
413      the_trace = the_trace_;
414      the_trace_ = NULL;
415      sampling_pthread = sampling_pthread_;
416    }
417  }
418  // Make sure that we join before we delete the trace since we don't want to have
419  // the sampling thread access a stale pointer. This finishes since the sampling thread exits when
420  // the_trace_ is null.
421  if (sampling_pthread != 0U) {
422    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, NULL), "sampling thread shutdown");
423    sampling_pthread_ = 0U;
424  }
425  runtime->GetThreadList()->SuspendAll(__FUNCTION__);
426  if (the_trace != nullptr) {
427    stop_alloc_counting = (the_trace->flags_ & kTraceCountAllocs) != 0;
428    the_trace->FinishTracing();
429
430    if (the_trace->sampling_enabled_) {
431      MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
432      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
433    } else {
434      runtime->GetInstrumentation()->DisableMethodTracing();
435      runtime->GetInstrumentation()->RemoveListener(
436          the_trace, instrumentation::Instrumentation::kMethodEntered |
437          instrumentation::Instrumentation::kMethodExited |
438          instrumentation::Instrumentation::kMethodUnwind);
439    }
440    if (the_trace->trace_file_.get() != nullptr) {
441      // Do not try to erase, so flush and close explicitly.
442      if (the_trace->trace_file_->Flush() != 0) {
443        PLOG(ERROR) << "Could not flush trace file.";
444      }
445      if (the_trace->trace_file_->Close() != 0) {
446        PLOG(ERROR) << "Could not close trace file.";
447      }
448    }
449    delete the_trace;
450  }
451  runtime->GetThreadList()->ResumeAll();
452  if (stop_alloc_counting) {
453    // Can be racy since SetStatsEnabled is not guarded by any locks.
454    runtime->SetStatsEnabled(false);
455  }
456}
457
458void Trace::Shutdown() {
459  if (GetMethodTracingMode() != kTracingInactive) {
460    Stop();
461  }
462}
463
464TracingMode Trace::GetMethodTracingMode() {
465  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
466  if (the_trace_ == NULL) {
467    return kTracingInactive;
468  } else if (the_trace_->sampling_enabled_) {
469    return kSampleProfilingActive;
470  } else {
471    return kMethodTracingActive;
472  }
473}
474
475Trace::Trace(File* trace_file, int buffer_size, int flags, bool sampling_enabled)
476    : trace_file_(trace_file), buf_(new uint8_t[buffer_size]()), flags_(flags),
477      sampling_enabled_(sampling_enabled), clock_source_(default_clock_source_),
478      buffer_size_(buffer_size), start_time_(MicroTime()),
479      clock_overhead_ns_(GetClockOverheadNanoSeconds()), cur_offset_(0), overflow_(false) {
480  // Set up the beginning of the trace.
481  uint16_t trace_version = GetTraceVersion(clock_source_);
482  memset(buf_.get(), 0, kTraceHeaderLength);
483  Append4LE(buf_.get(), kTraceMagicValue);
484  Append2LE(buf_.get() + 4, trace_version);
485  Append2LE(buf_.get() + 6, kTraceHeaderLength);
486  Append8LE(buf_.get() + 8, start_time_);
487  if (trace_version >= kTraceVersionDualClock) {
488    uint16_t record_size = GetRecordSize(clock_source_);
489    Append2LE(buf_.get() + 16, record_size);
490  }
491
492  // Update current offset.
493  cur_offset_.StoreRelaxed(kTraceHeaderLength);
494}
495
496static void DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source)
497    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
498  uint8_t* ptr = buf + kTraceHeaderLength;
499  uint8_t* end = buf + buf_size;
500
501  while (ptr < end) {
502    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
503    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
504    TraceAction action = DecodeTraceAction(tmid);
505    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
506    ptr += GetRecordSize(clock_source);
507  }
508}
509
510void Trace::FinishTracing() {
511  // Compute elapsed time.
512  uint64_t elapsed = MicroTime() - start_time_;
513
514  size_t final_offset = cur_offset_.LoadRelaxed();
515
516  std::set<mirror::ArtMethod*> visited_methods;
517  GetVisitedMethods(final_offset, &visited_methods);
518
519  std::ostringstream os;
520
521  os << StringPrintf("%cversion\n", kTraceTokenChar);
522  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
523  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
524  if (UseThreadCpuClock()) {
525    if (UseWallClock()) {
526      os << StringPrintf("clock=dual\n");
527    } else {
528      os << StringPrintf("clock=thread-cpu\n");
529    }
530  } else {
531    os << StringPrintf("clock=wall\n");
532  }
533  os << StringPrintf("elapsed-time-usec=%" PRIu64 "\n", elapsed);
534  size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
535  os << StringPrintf("num-method-calls=%zd\n", num_records);
536  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
537  os << StringPrintf("vm=art\n");
538  os << StringPrintf("pid=%d\n", getpid());
539  if ((flags_ & kTraceCountAllocs) != 0) {
540    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
541    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
542    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
543  }
544  os << StringPrintf("%cthreads\n", kTraceTokenChar);
545  DumpThreadList(os);
546  os << StringPrintf("%cmethods\n", kTraceTokenChar);
547  DumpMethodList(os, visited_methods);
548  os << StringPrintf("%cend\n", kTraceTokenChar);
549
550  std::string header(os.str());
551  if (trace_file_.get() == NULL) {
552    iovec iov[2];
553    iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
554    iov[0].iov_len = header.length();
555    iov[1].iov_base = buf_.get();
556    iov[1].iov_len = final_offset;
557    Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
558    const bool kDumpTraceInfo = false;
559    if (kDumpTraceInfo) {
560      LOG(INFO) << "Trace sent:\n" << header;
561      DumpBuf(buf_.get(), final_offset, clock_source_);
562    }
563  } else {
564    if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
565        !trace_file_->WriteFully(buf_.get(), final_offset)) {
566      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
567      PLOG(ERROR) << detail;
568      ThrowRuntimeException("%s", detail.c_str());
569    }
570  }
571}
572
573void Trace::DexPcMoved(Thread* thread, mirror::Object* this_object,
574                       mirror::ArtMethod* method, uint32_t new_dex_pc) {
575  UNUSED(thread, this_object, method, new_dex_pc);
576  // We're not recorded to listen to this kind of event, so complain.
577  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
578}
579
580void Trace::FieldRead(Thread* thread, mirror::Object* this_object,
581                       mirror::ArtMethod* method, uint32_t dex_pc, mirror::ArtField* field)
582    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
583  UNUSED(thread, this_object, method, dex_pc, field);
584  // We're not recorded to listen to this kind of event, so complain.
585  LOG(ERROR) << "Unexpected field read event in tracing " << PrettyMethod(method) << " " << dex_pc;
586}
587
588void Trace::FieldWritten(Thread* thread, mirror::Object* this_object,
589                          mirror::ArtMethod* method, uint32_t dex_pc, mirror::ArtField* field,
590                          const JValue& field_value)
591    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
592  UNUSED(thread, this_object, method, dex_pc, field, field_value);
593  // We're not recorded to listen to this kind of event, so complain.
594  LOG(ERROR) << "Unexpected field write event in tracing " << PrettyMethod(method) << " " << dex_pc;
595}
596
597void Trace::MethodEntered(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
598                          mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
599  uint32_t thread_clock_diff = 0;
600  uint32_t wall_clock_diff = 0;
601  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
602  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered,
603                      thread_clock_diff, wall_clock_diff);
604}
605
606void Trace::MethodExited(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
607                         mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED,
608                         const JValue& return_value ATTRIBUTE_UNUSED) {
609  uint32_t thread_clock_diff = 0;
610  uint32_t wall_clock_diff = 0;
611  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
612  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited,
613                      thread_clock_diff, wall_clock_diff);
614}
615
616void Trace::MethodUnwind(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
617                         mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
618  uint32_t thread_clock_diff = 0;
619  uint32_t wall_clock_diff = 0;
620  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
621  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind,
622                      thread_clock_diff, wall_clock_diff);
623}
624
625void Trace::ExceptionCaught(Thread* thread, mirror::Throwable* exception_object)
626    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
627  UNUSED(thread, exception_object);
628  LOG(ERROR) << "Unexpected exception caught event in tracing";
629}
630
631void Trace::BackwardBranch(Thread* /*thread*/, mirror::ArtMethod* method,
632                           int32_t /*dex_pc_offset*/)
633      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
634  LOG(ERROR) << "Unexpected backward branch event in tracing" << PrettyMethod(method);
635}
636
637void Trace::ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint32_t* wall_clock_diff) {
638  if (UseThreadCpuClock()) {
639    uint64_t clock_base = thread->GetTraceClockBase();
640    if (UNLIKELY(clock_base == 0)) {
641      // First event, record the base time in the map.
642      uint64_t time = thread->GetCpuMicroTime();
643      thread->SetTraceClockBase(time);
644    } else {
645      *thread_clock_diff = thread->GetCpuMicroTime() - clock_base;
646    }
647  }
648  if (UseWallClock()) {
649    *wall_clock_diff = MicroTime() - start_time_;
650  }
651}
652
653void Trace::LogMethodTraceEvent(Thread* thread, mirror::ArtMethod* method,
654                                instrumentation::Instrumentation::InstrumentationEvent event,
655                                uint32_t thread_clock_diff, uint32_t wall_clock_diff) {
656  // Advance cur_offset_ atomically.
657  int32_t new_offset;
658  int32_t old_offset;
659  do {
660    old_offset = cur_offset_.LoadRelaxed();
661    new_offset = old_offset + GetRecordSize(clock_source_);
662    if (new_offset > buffer_size_) {
663      overflow_ = true;
664      return;
665    }
666  } while (!cur_offset_.CompareExchangeWeakSequentiallyConsistent(old_offset, new_offset));
667
668  TraceAction action = kTraceMethodEnter;
669  switch (event) {
670    case instrumentation::Instrumentation::kMethodEntered:
671      action = kTraceMethodEnter;
672      break;
673    case instrumentation::Instrumentation::kMethodExited:
674      action = kTraceMethodExit;
675      break;
676    case instrumentation::Instrumentation::kMethodUnwind:
677      action = kTraceUnroll;
678      break;
679    default:
680      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
681  }
682
683  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
684
685  // Write data
686  uint8_t* ptr = buf_.get() + old_offset;
687  Append2LE(ptr, thread->GetTid());
688  Append4LE(ptr + 2, method_value);
689  ptr += 6;
690
691  if (UseThreadCpuClock()) {
692    Append4LE(ptr, thread_clock_diff);
693    ptr += 4;
694  }
695  if (UseWallClock()) {
696    Append4LE(ptr, wall_clock_diff);
697  }
698}
699
700void Trace::GetVisitedMethods(size_t buf_size,
701                              std::set<mirror::ArtMethod*>* visited_methods) {
702  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
703  uint8_t* end = buf_.get() + buf_size;
704
705  while (ptr < end) {
706    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
707    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
708    visited_methods->insert(method);
709    ptr += GetRecordSize(clock_source_);
710  }
711}
712
713void Trace::DumpMethodList(std::ostream& os, const std::set<mirror::ArtMethod*>& visited_methods) {
714  for (const auto& method : visited_methods) {
715    os << StringPrintf("%p\t%s\t%s\t%s\t%s\n", method,
716        PrettyDescriptor(method->GetDeclaringClassDescriptor()).c_str(), method->GetName(),
717        method->GetSignature().ToString().c_str(), method->GetDeclaringClassSourceFile());
718  }
719}
720
721static void DumpThread(Thread* t, void* arg) {
722  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
723  std::string name;
724  t->GetThreadName(name);
725  os << t->GetTid() << "\t" << name << "\n";
726}
727
728void Trace::DumpThreadList(std::ostream& os) {
729  Thread* self = Thread::Current();
730  for (auto it : exited_threads_) {
731    os << it.first << "\t" << it.second << "\n";
732  }
733  Locks::thread_list_lock_->AssertNotHeld(self);
734  MutexLock mu(self, *Locks::thread_list_lock_);
735  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
736}
737
738void Trace::StoreExitingThreadInfo(Thread* thread) {
739  MutexLock mu(thread, *Locks::trace_lock_);
740  if (the_trace_ != nullptr) {
741    std::string name;
742    thread->GetThreadName(name);
743    // The same thread/tid may be used multiple times. As SafeMap::Put does not allow to override
744    // a previous mapping, use SafeMap::Overwrite.
745    the_trace_->exited_threads_.Overwrite(thread->GetTid(), name);
746  }
747}
748
749}  // namespace art
750