trace.cc revision 32ce2adefb8a3d0eda59a29f5e87c1eb43eef796 
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#include "art_method-inl.h"
23#include "base/casts.h"
24#include "base/stl_util.h"
25#include "base/systrace.h"
26#include "base/time_utils.h"
27#include "base/unix_file/fd_file.h"
28#include "class_linker.h"
29#include "common_throws.h"
30#include "debugger.h"
31#include "dex_file-inl.h"
32#include "gc/scoped_gc_critical_section.h"
33#include "instrumentation.h"
34#include "mirror/class-inl.h"
35#include "mirror/dex_cache-inl.h"
36#include "mirror/object_array-inl.h"
37#include "mirror/object-inl.h"
38#include "os.h"
39#include "scoped_thread_state_change.h"
40#include "ScopedLocalRef.h"
41#include "thread.h"
42#include "thread_list.h"
43#include "utils.h"
44#include "entrypoints/quick/quick_entrypoints.h"
45
46namespace art {
47
48static constexpr size_t TraceActionBits = MinimumBitsToStore(
49    static_cast<size_t>(kTraceMethodActionMask));
50static constexpr uint8_t kOpNewMethod = 1U;
51static constexpr uint8_t kOpNewThread = 2U;
52
53class BuildStackTraceVisitor : public StackVisitor {
54 public:
55  explicit BuildStackTraceVisitor(Thread* thread)
56      : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
57        method_trace_(Trace::AllocStackTrace()) {}
58
59  bool VisitFrame() SHARED_REQUIRES(Locks::mutator_lock_) {
60    ArtMethod* m = GetMethod();
61    // Ignore runtime frames (in particular callee save).
62    if (!m->IsRuntimeMethod()) {
63      method_trace_->push_back(m);
64    }
65    return true;
66  }
67
68  // Returns a stack trace where the topmost frame corresponds with the first element of the vector.
69  std::vector<ArtMethod*>* GetStackTrace() const {
70    return method_trace_;
71  }
72
73 private:
74  std::vector<ArtMethod*>* const method_trace_;
75
76  DISALLOW_COPY_AND_ASSIGN(BuildStackTraceVisitor);
77};
78
79static const char     kTraceTokenChar             = '*';
80static const uint16_t kTraceHeaderLength          = 32;
81static const uint32_t kTraceMagicValue            = 0x574f4c53;
82static const uint16_t kTraceVersionSingleClock    = 2;
83static const uint16_t kTraceVersionDualClock      = 3;
84static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
85static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
86
87TraceClockSource Trace::default_clock_source_ = kDefaultTraceClockSource;
88
89Trace* volatile Trace::the_trace_ = nullptr;
90pthread_t Trace::sampling_pthread_ = 0U;
91std::unique_ptr<std::vector<ArtMethod*>> Trace::temp_stack_trace_;
92
93// The key identifying the tracer to update instrumentation.
94static constexpr const char* kTracerInstrumentationKey = "Tracer";
95
96static TraceAction DecodeTraceAction(uint32_t tmid) {
97  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
98}
99
100ArtMethod* Trace::DecodeTraceMethod(uint32_t tmid) {
101  MutexLock mu(Thread::Current(), *unique_methods_lock_);
102  return unique_methods_[tmid >> TraceActionBits];
103}
104
105uint32_t Trace::EncodeTraceMethod(ArtMethod* method) {
106  MutexLock mu(Thread::Current(), *unique_methods_lock_);
107  uint32_t idx;
108  auto it = art_method_id_map_.find(method);
109  if (it != art_method_id_map_.end()) {
110    idx = it->second;
111  } else {
112    unique_methods_.push_back(method);
113    idx = unique_methods_.size() - 1;
114    art_method_id_map_.emplace(method, idx);
115  }
116  DCHECK_LT(idx, unique_methods_.size());
117  DCHECK_EQ(unique_methods_[idx], method);
118  return idx;
119}
120
121uint32_t Trace::EncodeTraceMethodAndAction(ArtMethod* method, TraceAction action) {
122  uint32_t tmid = (EncodeTraceMethod(method) << TraceActionBits) | action;
123  DCHECK_EQ(method, DecodeTraceMethod(tmid));
124  return tmid;
125}
126
127std::vector<ArtMethod*>* Trace::AllocStackTrace() {
128  return (temp_stack_trace_.get() != nullptr)  ? temp_stack_trace_.release() :
129      new std::vector<ArtMethod*>();
130}
131
132void Trace::FreeStackTrace(std::vector<ArtMethod*>* stack_trace) {
133  stack_trace->clear();
134  temp_stack_trace_.reset(stack_trace);
135}
136
137void Trace::SetDefaultClockSource(TraceClockSource clock_source) {
138#if defined(__linux__)
139  default_clock_source_ = clock_source;
140#else
141  if (clock_source != TraceClockSource::kWall) {
142    LOG(WARNING) << "Ignoring tracing request to use CPU time.";
143  }
144#endif
145}
146
147static uint16_t GetTraceVersion(TraceClockSource clock_source) {
148  return (clock_source == TraceClockSource::kDual) ? kTraceVersionDualClock
149                                                    : kTraceVersionSingleClock;
150}
151
152static uint16_t GetRecordSize(TraceClockSource clock_source) {
153  return (clock_source == TraceClockSource::kDual) ? kTraceRecordSizeDualClock
154                                                    : kTraceRecordSizeSingleClock;
155}
156
157bool Trace::UseThreadCpuClock() {
158  return (clock_source_ == TraceClockSource::kThreadCpu) ||
159      (clock_source_ == TraceClockSource::kDual);
160}
161
162bool Trace::UseWallClock() {
163  return (clock_source_ == TraceClockSource::kWall) ||
164      (clock_source_ == TraceClockSource::kDual);
165}
166
167void Trace::MeasureClockOverhead() {
168  if (UseThreadCpuClock()) {
169    Thread::Current()->GetCpuMicroTime();
170  }
171  if (UseWallClock()) {
172    MicroTime();
173  }
174}
175
176// Compute an average time taken to measure clocks.
177uint32_t Trace::GetClockOverheadNanoSeconds() {
178  Thread* self = Thread::Current();
179  uint64_t start = self->GetCpuMicroTime();
180
181  for (int i = 4000; i > 0; i--) {
182    MeasureClockOverhead();
183    MeasureClockOverhead();
184    MeasureClockOverhead();
185    MeasureClockOverhead();
186    MeasureClockOverhead();
187    MeasureClockOverhead();
188    MeasureClockOverhead();
189    MeasureClockOverhead();
190  }
191
192  uint64_t elapsed_us = self->GetCpuMicroTime() - start;
193  return static_cast<uint32_t>(elapsed_us / 32);
194}
195
196// TODO: put this somewhere with the big-endian equivalent used by JDWP.
197static void Append2LE(uint8_t* buf, uint16_t val) {
198  *buf++ = static_cast<uint8_t>(val);
199  *buf++ = static_cast<uint8_t>(val >> 8);
200}
201
202// TODO: put this somewhere with the big-endian equivalent used by JDWP.
203static void Append4LE(uint8_t* buf, uint32_t val) {
204  *buf++ = static_cast<uint8_t>(val);
205  *buf++ = static_cast<uint8_t>(val >> 8);
206  *buf++ = static_cast<uint8_t>(val >> 16);
207  *buf++ = static_cast<uint8_t>(val >> 24);
208}
209
210// TODO: put this somewhere with the big-endian equivalent used by JDWP.
211static void Append8LE(uint8_t* buf, uint64_t val) {
212  *buf++ = static_cast<uint8_t>(val);
213  *buf++ = static_cast<uint8_t>(val >> 8);
214  *buf++ = static_cast<uint8_t>(val >> 16);
215  *buf++ = static_cast<uint8_t>(val >> 24);
216  *buf++ = static_cast<uint8_t>(val >> 32);
217  *buf++ = static_cast<uint8_t>(val >> 40);
218  *buf++ = static_cast<uint8_t>(val >> 48);
219  *buf++ = static_cast<uint8_t>(val >> 56);
220}
221
222static void GetSample(Thread* thread, void* arg) SHARED_REQUIRES(Locks::mutator_lock_) {
223  BuildStackTraceVisitor build_trace_visitor(thread);
224  build_trace_visitor.WalkStack();
225  std::vector<ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
226  Trace* the_trace = reinterpret_cast<Trace*>(arg);
227  the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
228}
229
230static void ClearThreadStackTraceAndClockBase(Thread* thread, void* arg ATTRIBUTE_UNUSED) {
231  thread->SetTraceClockBase(0);
232  std::vector<ArtMethod*>* stack_trace = thread->GetStackTraceSample();
233  thread->SetStackTraceSample(nullptr);
234  delete stack_trace;
235}
236
237void Trace::CompareAndUpdateStackTrace(Thread* thread,
238                                       std::vector<ArtMethod*>* stack_trace) {
239  CHECK_EQ(pthread_self(), sampling_pthread_);
240  std::vector<ArtMethod*>* old_stack_trace = thread->GetStackTraceSample();
241  // Update the thread's stack trace sample.
242  thread->SetStackTraceSample(stack_trace);
243  // Read timer clocks to use for all events in this trace.
244  uint32_t thread_clock_diff = 0;
245  uint32_t wall_clock_diff = 0;
246  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
247  if (old_stack_trace == nullptr) {
248    // If there's no previous stack trace sample for this thread, log an entry event for all
249    // methods in the trace.
250    for (auto rit = stack_trace->rbegin(); rit != stack_trace->rend(); ++rit) {
251      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
252                          thread_clock_diff, wall_clock_diff);
253    }
254  } else {
255    // If there's a previous stack trace for this thread, diff the traces and emit entry and exit
256    // events accordingly.
257    auto old_rit = old_stack_trace->rbegin();
258    auto rit = stack_trace->rbegin();
259    // Iterate bottom-up over both traces until there's a difference between them.
260    while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
261      old_rit++;
262      rit++;
263    }
264    // Iterate top-down over the old trace until the point where they differ, emitting exit events.
265    for (auto old_it = old_stack_trace->begin(); old_it != old_rit.base(); ++old_it) {
266      LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited,
267                          thread_clock_diff, wall_clock_diff);
268    }
269    // Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
270    for (; rit != stack_trace->rend(); ++rit) {
271      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
272                          thread_clock_diff, wall_clock_diff);
273    }
274    FreeStackTrace(old_stack_trace);
275  }
276}
277
278void* Trace::RunSamplingThread(void* arg) {
279  Runtime* runtime = Runtime::Current();
280  intptr_t interval_us = reinterpret_cast<intptr_t>(arg);
281  CHECK_GE(interval_us, 0);
282  CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
283                                     !runtime->IsAotCompiler()));
284
285  while (true) {
286    usleep(interval_us);
287    ScopedTrace trace("Profile sampling");
288    Thread* self = Thread::Current();
289    Trace* the_trace;
290    {
291      MutexLock mu(self, *Locks::trace_lock_);
292      the_trace = the_trace_;
293      if (the_trace == nullptr) {
294        break;
295      }
296    }
297    {
298      ScopedSuspendAll ssa(__FUNCTION__);
299      MutexLock mu(self, *Locks::thread_list_lock_);
300      runtime->GetThreadList()->ForEach(GetSample, the_trace);
301    }
302  }
303
304  runtime->DetachCurrentThread();
305  return nullptr;
306}
307
308void Trace::Start(const char* trace_filename, int trace_fd, size_t buffer_size, int flags,
309                  TraceOutputMode output_mode, TraceMode trace_mode, int interval_us) {
310  Thread* self = Thread::Current();
311  {
312    MutexLock mu(self, *Locks::trace_lock_);
313    if (the_trace_ != nullptr) {
314      LOG(ERROR) << "Trace already in progress, ignoring this request";
315      return;
316    }
317  }
318
319  // Check interval if sampling is enabled
320  if (trace_mode == TraceMode::kSampling && interval_us <= 0) {
321    LOG(ERROR) << "Invalid sampling interval: " << interval_us;
322    ScopedObjectAccess soa(self);
323    ThrowRuntimeException("Invalid sampling interval: %d", interval_us);
324    return;
325  }
326
327  // Open trace file if not going directly to ddms.
328  std::unique_ptr<File> trace_file;
329  if (output_mode != TraceOutputMode::kDDMS) {
330    if (trace_fd < 0) {
331      trace_file.reset(OS::CreateEmptyFileWriteOnly(trace_filename));
332    } else {
333      trace_file.reset(new File(trace_fd, "tracefile"));
334      trace_file->DisableAutoClose();
335    }
336    if (trace_file.get() == nullptr) {
337      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
338      ScopedObjectAccess soa(self);
339      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
340      return;
341    }
342  }
343
344  Runtime* runtime = Runtime::Current();
345
346  // Enable count of allocs if specified in the flags.
347  bool enable_stats = false;
348
349  // Create Trace object.
350  {
351    // Required since EnableMethodTracing calls ConfigureStubs which visits class linker classes.
352    gc::ScopedGCCriticalSection gcs(self,
353                                    gc::kGcCauseInstrumentation,
354                                    gc::kCollectorTypeInstrumentation);
355    ScopedSuspendAll ssa(__FUNCTION__);
356    MutexLock mu(self, *Locks::trace_lock_);
357    if (the_trace_ != nullptr) {
358      LOG(ERROR) << "Trace already in progress, ignoring this request";
359    } else {
360      enable_stats = (flags && kTraceCountAllocs) != 0;
361      the_trace_ = new Trace(trace_file.release(), trace_filename, buffer_size, flags, output_mode,
362                             trace_mode);
363      if (trace_mode == TraceMode::kSampling) {
364        CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
365                                            reinterpret_cast<void*>(interval_us)),
366                                            "Sampling profiler thread");
367        the_trace_->interval_us_ = interval_us;
368      } else {
369        runtime->GetInstrumentation()->AddListener(the_trace_,
370                                                   instrumentation::Instrumentation::kMethodEntered |
371                                                   instrumentation::Instrumentation::kMethodExited |
372                                                   instrumentation::Instrumentation::kMethodUnwind);
373        // TODO: In full-PIC mode, we don't need to fully deopt.
374        runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
375      }
376    }
377  }
378
379  // Can't call this when holding the mutator lock.
380  if (enable_stats) {
381    runtime->SetStatsEnabled(true);
382  }
383}
384
385void Trace::StopTracing(bool finish_tracing, bool flush_file) {
386  bool stop_alloc_counting = false;
387  Runtime* const runtime = Runtime::Current();
388  Trace* the_trace = nullptr;
389  Thread* const self = Thread::Current();
390  pthread_t sampling_pthread = 0U;
391  {
392    MutexLock mu(self, *Locks::trace_lock_);
393    if (the_trace_ == nullptr) {
394      LOG(ERROR) << "Trace stop requested, but no trace currently running";
395    } else {
396      the_trace = the_trace_;
397      the_trace_ = nullptr;
398      sampling_pthread = sampling_pthread_;
399    }
400  }
401  // Make sure that we join before we delete the trace since we don't want to have
402  // the sampling thread access a stale pointer. This finishes since the sampling thread exits when
403  // the_trace_ is null.
404  if (sampling_pthread != 0U) {
405    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
406    sampling_pthread_ = 0U;
407  }
408
409  {
410    gc::ScopedGCCriticalSection gcs(self,
411                                    gc::kGcCauseInstrumentation,
412                                    gc::kCollectorTypeInstrumentation);
413    ScopedSuspendAll ssa(__FUNCTION__);
414    if (the_trace != nullptr) {
415      stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
416      if (finish_tracing) {
417        the_trace->FinishTracing();
418      }
419
420      if (the_trace->trace_mode_ == TraceMode::kSampling) {
421        MutexLock mu(self, *Locks::thread_list_lock_);
422        runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
423      } else {
424        runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
425        runtime->GetInstrumentation()->RemoveListener(
426            the_trace, instrumentation::Instrumentation::kMethodEntered |
427            instrumentation::Instrumentation::kMethodExited |
428            instrumentation::Instrumentation::kMethodUnwind);
429      }
430      if (the_trace->trace_file_.get() != nullptr) {
431        // Do not try to erase, so flush and close explicitly.
432        if (flush_file) {
433          if (the_trace->trace_file_->Flush() != 0) {
434            PLOG(WARNING) << "Could not flush trace file.";
435          }
436        } else {
437          the_trace->trace_file_->MarkUnchecked();  // Do not trigger guard.
438        }
439        if (the_trace->trace_file_->Close() != 0) {
440          PLOG(ERROR) << "Could not close trace file.";
441        }
442      }
443      delete the_trace;
444    }
445  }
446  if (stop_alloc_counting) {
447    // Can be racy since SetStatsEnabled is not guarded by any locks.
448    runtime->SetStatsEnabled(false);
449  }
450}
451
452void Trace::Abort() {
453  // Do not write anything anymore.
454  StopTracing(false, false);
455}
456
457void Trace::Stop() {
458  // Finish writing.
459  StopTracing(true, true);
460}
461
462void Trace::Shutdown() {
463  if (GetMethodTracingMode() != kTracingInactive) {
464    Stop();
465  }
466}
467
468void Trace::Pause() {
469  bool stop_alloc_counting = false;
470  Runtime* runtime = Runtime::Current();
471  Trace* the_trace = nullptr;
472
473  Thread* const self = Thread::Current();
474  pthread_t sampling_pthread = 0U;
475  {
476    MutexLock mu(self, *Locks::trace_lock_);
477    if (the_trace_ == nullptr) {
478      LOG(ERROR) << "Trace pause requested, but no trace currently running";
479      return;
480    } else {
481      the_trace = the_trace_;
482      sampling_pthread = sampling_pthread_;
483    }
484  }
485
486  if (sampling_pthread != 0U) {
487    {
488      MutexLock mu(self, *Locks::trace_lock_);
489      the_trace_ = nullptr;
490    }
491    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
492    sampling_pthread_ = 0U;
493    {
494      MutexLock mu(self, *Locks::trace_lock_);
495      the_trace_ = the_trace;
496    }
497  }
498
499  if (the_trace != nullptr) {
500    gc::ScopedGCCriticalSection gcs(self,
501                                    gc::kGcCauseInstrumentation,
502                                    gc::kCollectorTypeInstrumentation);
503    ScopedSuspendAll ssa(__FUNCTION__);
504    stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
505
506    if (the_trace->trace_mode_ == TraceMode::kSampling) {
507      MutexLock mu(self, *Locks::thread_list_lock_);
508      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
509    } else {
510      runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
511      runtime->GetInstrumentation()->RemoveListener(
512          the_trace,
513          instrumentation::Instrumentation::kMethodEntered |
514          instrumentation::Instrumentation::kMethodExited |
515          instrumentation::Instrumentation::kMethodUnwind);
516    }
517  }
518
519  if (stop_alloc_counting) {
520    // Can be racy since SetStatsEnabled is not guarded by any locks.
521    Runtime::Current()->SetStatsEnabled(false);
522  }
523}
524
525void Trace::Resume() {
526  Thread* self = Thread::Current();
527  Trace* the_trace;
528  {
529    MutexLock mu(self, *Locks::trace_lock_);
530    if (the_trace_ == nullptr) {
531      LOG(ERROR) << "No trace to resume (or sampling mode), ignoring this request";
532      return;
533    }
534    the_trace = the_trace_;
535  }
536
537  Runtime* runtime = Runtime::Current();
538
539  // Enable count of allocs if specified in the flags.
540  bool enable_stats = (the_trace->flags_ && kTraceCountAllocs) != 0;
541
542  {
543    gc::ScopedGCCriticalSection gcs(self,
544                                    gc::kGcCauseInstrumentation,
545                                    gc::kCollectorTypeInstrumentation);
546    ScopedSuspendAll ssa(__FUNCTION__);
547
548    // Reenable.
549    if (the_trace->trace_mode_ == TraceMode::kSampling) {
550      CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
551          reinterpret_cast<void*>(the_trace->interval_us_)), "Sampling profiler thread");
552    } else {
553      runtime->GetInstrumentation()->AddListener(the_trace,
554                                                 instrumentation::Instrumentation::kMethodEntered |
555                                                 instrumentation::Instrumentation::kMethodExited |
556                                                 instrumentation::Instrumentation::kMethodUnwind);
557      // TODO: In full-PIC mode, we don't need to fully deopt.
558      runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
559    }
560  }
561
562  // Can't call this when holding the mutator lock.
563  if (enable_stats) {
564    runtime->SetStatsEnabled(true);
565  }
566}
567
568TracingMode Trace::GetMethodTracingMode() {
569  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
570  if (the_trace_ == nullptr) {
571    return kTracingInactive;
572  } else {
573    switch (the_trace_->trace_mode_) {
574      case TraceMode::kSampling:
575        return kSampleProfilingActive;
576      case TraceMode::kMethodTracing:
577        return kMethodTracingActive;
578    }
579    LOG(FATAL) << "Unreachable";
580    UNREACHABLE();
581  }
582}
583
584static constexpr size_t kMinBufSize = 18U;  // Trace header is up to 18B.
585
586Trace::Trace(File* trace_file, const char* trace_name, size_t buffer_size, int flags,
587             TraceOutputMode output_mode, TraceMode trace_mode)
588    : trace_file_(trace_file),
589      buf_(new uint8_t[std::max(kMinBufSize, buffer_size)]()),
590      flags_(flags), trace_output_mode_(output_mode), trace_mode_(trace_mode),
591      clock_source_(default_clock_source_),
592      buffer_size_(std::max(kMinBufSize, buffer_size)),
593      start_time_(MicroTime()), clock_overhead_ns_(GetClockOverheadNanoSeconds()), cur_offset_(0),
594      overflow_(false), interval_us_(0), streaming_lock_(nullptr),
595      unique_methods_lock_(new Mutex("unique methods lock", kTracingUniqueMethodsLock)) {
596  uint16_t trace_version = GetTraceVersion(clock_source_);
597  if (output_mode == TraceOutputMode::kStreaming) {
598    trace_version |= 0xF0U;
599  }
600  // Set up the beginning of the trace.
601  memset(buf_.get(), 0, kTraceHeaderLength);
602  Append4LE(buf_.get(), kTraceMagicValue);
603  Append2LE(buf_.get() + 4, trace_version);
604  Append2LE(buf_.get() + 6, kTraceHeaderLength);
605  Append8LE(buf_.get() + 8, start_time_);
606  if (trace_version >= kTraceVersionDualClock) {
607    uint16_t record_size = GetRecordSize(clock_source_);
608    Append2LE(buf_.get() + 16, record_size);
609  }
610  static_assert(18 <= kMinBufSize, "Minimum buffer size not large enough for trace header");
611
612  // Update current offset.
613  cur_offset_.StoreRelaxed(kTraceHeaderLength);
614
615  if (output_mode == TraceOutputMode::kStreaming) {
616    streaming_file_name_ = trace_name;
617    streaming_lock_ = new Mutex("tracing lock", LockLevel::kTracingStreamingLock);
618    seen_threads_.reset(new ThreadIDBitSet());
619  }
620}
621
622Trace::~Trace() {
623  delete streaming_lock_;
624  delete unique_methods_lock_;
625}
626
627static uint64_t ReadBytes(uint8_t* buf, size_t bytes) {
628  uint64_t ret = 0;
629  for (size_t i = 0; i < bytes; ++i) {
630    ret |= static_cast<uint64_t>(buf[i]) << (i * 8);
631  }
632  return ret;
633}
634
635void Trace::DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source) {
636  uint8_t* ptr = buf + kTraceHeaderLength;
637  uint8_t* end = buf + buf_size;
638
639  while (ptr < end) {
640    uint32_t tmid = ReadBytes(ptr + 2, sizeof(tmid));
641    ArtMethod* method = DecodeTraceMethod(tmid);
642    TraceAction action = DecodeTraceAction(tmid);
643    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
644    ptr += GetRecordSize(clock_source);
645  }
646}
647
648static void GetVisitedMethodsFromBitSets(
649    const std::map<const DexFile*, DexIndexBitSet*>& seen_methods,
650    std::set<ArtMethod*>* visited_methods) SHARED_REQUIRES(Locks::mutator_lock_) {
651  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
652  Thread* const self = Thread::Current();
653  for (auto& e : seen_methods) {
654    DexIndexBitSet* bit_set = e.second;
655    // TODO: Visit trace methods as roots.
656    mirror::DexCache* dex_cache = class_linker->FindDexCache(self, *e.first, false);
657    for (uint32_t i = 0; i < bit_set->size(); ++i) {
658      if ((*bit_set)[i]) {
659        visited_methods->insert(dex_cache->GetResolvedMethod(i, sizeof(void*)));
660      }
661    }
662  }
663}
664
665void Trace::FinishTracing() {
666  size_t final_offset = 0;
667
668  std::set<ArtMethod*> visited_methods;
669  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
670    // Write the secondary file with all the method names.
671    GetVisitedMethodsFromBitSets(seen_methods_, &visited_methods);
672
673    // Clean up.
674    STLDeleteValues(&seen_methods_);
675  } else {
676    final_offset = cur_offset_.LoadRelaxed();
677    GetVisitedMethods(final_offset, &visited_methods);
678  }
679
680  // Compute elapsed time.
681  uint64_t elapsed = MicroTime() - start_time_;
682
683  std::ostringstream os;
684
685  os << StringPrintf("%cversion\n", kTraceTokenChar);
686  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
687  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
688  if (UseThreadCpuClock()) {
689    if (UseWallClock()) {
690      os << StringPrintf("clock=dual\n");
691    } else {
692      os << StringPrintf("clock=thread-cpu\n");
693    }
694  } else {
695    os << StringPrintf("clock=wall\n");
696  }
697  os << StringPrintf("elapsed-time-usec=%" PRIu64 "\n", elapsed);
698  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
699    size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
700    os << StringPrintf("num-method-calls=%zd\n", num_records);
701  }
702  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
703  os << StringPrintf("vm=art\n");
704  os << StringPrintf("pid=%d\n", getpid());
705  if ((flags_ & kTraceCountAllocs) != 0) {
706    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
707    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
708    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
709  }
710  os << StringPrintf("%cthreads\n", kTraceTokenChar);
711  DumpThreadList(os);
712  os << StringPrintf("%cmethods\n", kTraceTokenChar);
713  DumpMethodList(os, visited_methods);
714  os << StringPrintf("%cend\n", kTraceTokenChar);
715  std::string header(os.str());
716
717  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
718    File file;
719    if (!file.Open(streaming_file_name_ + ".sec", O_CREAT | O_WRONLY)) {
720      LOG(WARNING) << "Could not open secondary trace file!";
721      return;
722    }
723    if (!file.WriteFully(header.c_str(), header.length())) {
724      file.Erase();
725      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
726      PLOG(ERROR) << detail;
727      ThrowRuntimeException("%s", detail.c_str());
728    }
729    if (file.FlushCloseOrErase() != 0) {
730      PLOG(ERROR) << "Could not write secondary file";
731    }
732  } else {
733    if (trace_file_.get() == nullptr) {
734      iovec iov[2];
735      iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
736      iov[0].iov_len = header.length();
737      iov[1].iov_base = buf_.get();
738      iov[1].iov_len = final_offset;
739      Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
740      const bool kDumpTraceInfo = false;
741      if (kDumpTraceInfo) {
742        LOG(INFO) << "Trace sent:\n" << header;
743        DumpBuf(buf_.get(), final_offset, clock_source_);
744      }
745    } else {
746      if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
747          !trace_file_->WriteFully(buf_.get(), final_offset)) {
748        std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
749        PLOG(ERROR) << detail;
750        ThrowRuntimeException("%s", detail.c_str());
751      }
752    }
753  }
754}
755
756void Trace::DexPcMoved(Thread* thread ATTRIBUTE_UNUSED,
757                       mirror::Object* this_object ATTRIBUTE_UNUSED,
758                       ArtMethod* method,
759                       uint32_t new_dex_pc) {
760  // We're not recorded to listen to this kind of event, so complain.
761  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
762}
763
764void Trace::FieldRead(Thread* thread ATTRIBUTE_UNUSED,
765                      mirror::Object* this_object ATTRIBUTE_UNUSED,
766                      ArtMethod* method,
767                      uint32_t dex_pc,
768                      ArtField* field ATTRIBUTE_UNUSED)
769    SHARED_REQUIRES(Locks::mutator_lock_) {
770  // We're not recorded to listen to this kind of event, so complain.
771  LOG(ERROR) << "Unexpected field read event in tracing " << PrettyMethod(method) << " " << dex_pc;
772}
773
774void Trace::FieldWritten(Thread* thread ATTRIBUTE_UNUSED,
775                         mirror::Object* this_object ATTRIBUTE_UNUSED,
776                         ArtMethod* method,
777                         uint32_t dex_pc,
778                         ArtField* field ATTRIBUTE_UNUSED,
779                         const JValue& field_value ATTRIBUTE_UNUSED)
780    SHARED_REQUIRES(Locks::mutator_lock_) {
781  // We're not recorded to listen to this kind of event, so complain.
782  LOG(ERROR) << "Unexpected field write event in tracing " << PrettyMethod(method) << " " << dex_pc;
783}
784
785void Trace::MethodEntered(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
786                          ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
787  uint32_t thread_clock_diff = 0;
788  uint32_t wall_clock_diff = 0;
789  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
790  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered,
791                      thread_clock_diff, wall_clock_diff);
792}
793
794void Trace::MethodExited(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
795                         ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED,
796                         const JValue& return_value ATTRIBUTE_UNUSED) {
797  uint32_t thread_clock_diff = 0;
798  uint32_t wall_clock_diff = 0;
799  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
800  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited,
801                      thread_clock_diff, wall_clock_diff);
802}
803
804void Trace::MethodUnwind(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
805                         ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
806  uint32_t thread_clock_diff = 0;
807  uint32_t wall_clock_diff = 0;
808  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
809  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind,
810                      thread_clock_diff, wall_clock_diff);
811}
812
813void Trace::ExceptionCaught(Thread* thread ATTRIBUTE_UNUSED,
814                            mirror::Throwable* exception_object ATTRIBUTE_UNUSED)
815    SHARED_REQUIRES(Locks::mutator_lock_) {
816  LOG(ERROR) << "Unexpected exception caught event in tracing";
817}
818
819void Trace::Branch(Thread* /*thread*/, ArtMethod* method,
820                   uint32_t /*dex_pc*/, int32_t /*dex_pc_offset*/)
821      SHARED_REQUIRES(Locks::mutator_lock_) {
822  LOG(ERROR) << "Unexpected branch event in tracing" << PrettyMethod(method);
823}
824
825void Trace::InvokeVirtualOrInterface(Thread*,
826                                     mirror::Object*,
827                                     ArtMethod* method,
828                                     uint32_t dex_pc,
829                                     ArtMethod*) {
830  LOG(ERROR) << "Unexpected invoke event in tracing" << PrettyMethod(method)
831             << " " << dex_pc;
832}
833
834void Trace::ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint32_t* wall_clock_diff) {
835  if (UseThreadCpuClock()) {
836    uint64_t clock_base = thread->GetTraceClockBase();
837    if (UNLIKELY(clock_base == 0)) {
838      // First event, record the base time in the map.
839      uint64_t time = thread->GetCpuMicroTime();
840      thread->SetTraceClockBase(time);
841    } else {
842      *thread_clock_diff = thread->GetCpuMicroTime() - clock_base;
843    }
844  }
845  if (UseWallClock()) {
846    *wall_clock_diff = MicroTime() - start_time_;
847  }
848}
849
850bool Trace::RegisterMethod(ArtMethod* method) {
851  mirror::DexCache* dex_cache = method->GetDexCache();
852  const DexFile* dex_file = dex_cache->GetDexFile();
853  auto* resolved_method = dex_cache->GetResolvedMethod(method->GetDexMethodIndex(), sizeof(void*));
854  if (resolved_method != method) {
855    DCHECK(resolved_method == nullptr);
856    dex_cache->SetResolvedMethod(method->GetDexMethodIndex(), method, sizeof(void*));
857  }
858  if (seen_methods_.find(dex_file) == seen_methods_.end()) {
859    seen_methods_.insert(std::make_pair(dex_file, new DexIndexBitSet()));
860  }
861  DexIndexBitSet* bit_set = seen_methods_.find(dex_file)->second;
862  if (!(*bit_set)[method->GetDexMethodIndex()]) {
863    bit_set->set(method->GetDexMethodIndex());
864    return true;
865  }
866  return false;
867}
868
869bool Trace::RegisterThread(Thread* thread) {
870  pid_t tid = thread->GetTid();
871  CHECK_LT(0U, static_cast<uint32_t>(tid));
872  CHECK_LT(static_cast<uint32_t>(tid), 65536U);
873
874  if (!(*seen_threads_)[tid]) {
875    seen_threads_->set(tid);
876    return true;
877  }
878  return false;
879}
880
881std::string Trace::GetMethodLine(ArtMethod* method) {
882  method = method->GetInterfaceMethodIfProxy(sizeof(void*));
883  return StringPrintf("%p\t%s\t%s\t%s\t%s\n",
884                      reinterpret_cast<void*>((EncodeTraceMethod(method) << TraceActionBits)),
885      PrettyDescriptor(method->GetDeclaringClassDescriptor()).c_str(), method->GetName(),
886      method->GetSignature().ToString().c_str(), method->GetDeclaringClassSourceFile());
887}
888
889void Trace::WriteToBuf(const uint8_t* src, size_t src_size) {
890  int32_t old_offset = cur_offset_.LoadRelaxed();
891  int32_t new_offset = old_offset + static_cast<int32_t>(src_size);
892  if (dchecked_integral_cast<size_t>(new_offset) > buffer_size_) {
893    // Flush buffer.
894    if (!trace_file_->WriteFully(buf_.get(), old_offset)) {
895      PLOG(WARNING) << "Failed streaming a tracing event.";
896    }
897
898    // Check whether the data is too large for the buffer, then write immediately.
899    if (src_size >= buffer_size_) {
900      if (!trace_file_->WriteFully(src, src_size)) {
901        PLOG(WARNING) << "Failed streaming a tracing event.";
902      }
903      cur_offset_.StoreRelease(0);  // Buffer is empty now.
904      return;
905    }
906
907    old_offset = 0;
908    new_offset = static_cast<int32_t>(src_size);
909  }
910  cur_offset_.StoreRelease(new_offset);
911  // Fill in data.
912  memcpy(buf_.get() + old_offset, src, src_size);
913}
914
915void Trace::LogMethodTraceEvent(Thread* thread, ArtMethod* method,
916                                instrumentation::Instrumentation::InstrumentationEvent event,
917                                uint32_t thread_clock_diff, uint32_t wall_clock_diff) {
918  // Advance cur_offset_ atomically.
919  int32_t new_offset;
920  int32_t old_offset = 0;
921
922  // We do a busy loop here trying to acquire the next offset.
923  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
924    do {
925      old_offset = cur_offset_.LoadRelaxed();
926      new_offset = old_offset + GetRecordSize(clock_source_);
927      if (static_cast<size_t>(new_offset) > buffer_size_) {
928        overflow_ = true;
929        return;
930      }
931    } while (!cur_offset_.CompareExchangeWeakSequentiallyConsistent(old_offset, new_offset));
932  }
933
934  TraceAction action = kTraceMethodEnter;
935  switch (event) {
936    case instrumentation::Instrumentation::kMethodEntered:
937      action = kTraceMethodEnter;
938      break;
939    case instrumentation::Instrumentation::kMethodExited:
940      action = kTraceMethodExit;
941      break;
942    case instrumentation::Instrumentation::kMethodUnwind:
943      action = kTraceUnroll;
944      break;
945    default:
946      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
947  }
948
949  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
950
951  // Write data
952  uint8_t* ptr;
953  static constexpr size_t kPacketSize = 14U;  // The maximum size of data in a packet.
954  uint8_t stack_buf[kPacketSize];             // Space to store a packet when in streaming mode.
955  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
956    ptr = stack_buf;
957  } else {
958    ptr = buf_.get() + old_offset;
959  }
960
961  Append2LE(ptr, thread->GetTid());
962  Append4LE(ptr + 2, method_value);
963  ptr += 6;
964
965  if (UseThreadCpuClock()) {
966    Append4LE(ptr, thread_clock_diff);
967    ptr += 4;
968  }
969  if (UseWallClock()) {
970    Append4LE(ptr, wall_clock_diff);
971  }
972  static_assert(kPacketSize == 2 + 4 + 4 + 4, "Packet size incorrect.");
973
974  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
975    MutexLock mu(Thread::Current(), *streaming_lock_);  // To serialize writing.
976    if (RegisterMethod(method)) {
977      // Write a special block with the name.
978      std::string method_line(GetMethodLine(method));
979      uint8_t buf2[5];
980      Append2LE(buf2, 0);
981      buf2[2] = kOpNewMethod;
982      Append2LE(buf2 + 3, static_cast<uint16_t>(method_line.length()));
983      WriteToBuf(buf2, sizeof(buf2));
984      WriteToBuf(reinterpret_cast<const uint8_t*>(method_line.c_str()), method_line.length());
985    }
986    if (RegisterThread(thread)) {
987      // It might be better to postpone this. Threads might not have received names...
988      std::string thread_name;
989      thread->GetThreadName(thread_name);
990      uint8_t buf2[7];
991      Append2LE(buf2, 0);
992      buf2[2] = kOpNewThread;
993      Append2LE(buf2 + 3, static_cast<uint16_t>(thread->GetTid()));
994      Append2LE(buf2 + 5, static_cast<uint16_t>(thread_name.length()));
995      WriteToBuf(buf2, sizeof(buf2));
996      WriteToBuf(reinterpret_cast<const uint8_t*>(thread_name.c_str()), thread_name.length());
997    }
998    WriteToBuf(stack_buf, sizeof(stack_buf));
999  }
1000}
1001
1002void Trace::GetVisitedMethods(size_t buf_size,
1003                              std::set<ArtMethod*>* visited_methods) {
1004  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
1005  uint8_t* end = buf_.get() + buf_size;
1006
1007  while (ptr < end) {
1008    uint32_t tmid = ReadBytes(ptr + 2, sizeof(tmid));
1009    ArtMethod* method = DecodeTraceMethod(tmid);
1010    visited_methods->insert(method);
1011    ptr += GetRecordSize(clock_source_);
1012  }
1013}
1014
1015void Trace::DumpMethodList(std::ostream& os, const std::set<ArtMethod*>& visited_methods) {
1016  for (const auto& method : visited_methods) {
1017    os << GetMethodLine(method);
1018  }
1019}
1020
1021static void DumpThread(Thread* t, void* arg) {
1022  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
1023  std::string name;
1024  t->GetThreadName(name);
1025  os << t->GetTid() << "\t" << name << "\n";
1026}
1027
1028void Trace::DumpThreadList(std::ostream& os) {
1029  Thread* self = Thread::Current();
1030  for (auto it : exited_threads_) {
1031    os << it.first << "\t" << it.second << "\n";
1032  }
1033  Locks::thread_list_lock_->AssertNotHeld(self);
1034  MutexLock mu(self, *Locks::thread_list_lock_);
1035  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
1036}
1037
1038void Trace::StoreExitingThreadInfo(Thread* thread) {
1039  MutexLock mu(thread, *Locks::trace_lock_);
1040  if (the_trace_ != nullptr) {
1041    std::string name;
1042    thread->GetThreadName(name);
1043    // The same thread/tid may be used multiple times. As SafeMap::Put does not allow to override
1044    // a previous mapping, use SafeMap::Overwrite.
1045    the_trace_->exited_threads_.Overwrite(thread->GetTid(), name);
1046  }
1047}
1048
1049Trace::TraceOutputMode Trace::GetOutputMode() {
1050  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1051  CHECK(the_trace_ != nullptr) << "Trace output mode requested, but no trace currently running";
1052  return the_trace_->trace_output_mode_;
1053}
1054
1055Trace::TraceMode Trace::GetMode() {
1056  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1057  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1058  return the_trace_->trace_mode_;
1059}
1060
1061size_t Trace::GetBufferSize() {
1062  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1063  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1064  return the_trace_->buffer_size_;
1065}
1066
1067bool Trace::IsTracingEnabled() {
1068  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1069  return the_trace_ != nullptr;
1070}
1071
1072}  // namespace art
1073