trace.cc revision 542451cc546779f5c67840e105c51205a1b0a8fd 
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/enums.h"
25#include "base/stl_util.h"
26#include "base/systrace.h"
27#include "base/time_utils.h"
28#include "base/unix_file/fd_file.h"
29#include "class_linker.h"
30#include "common_throws.h"
31#include "debugger.h"
32#include "dex_file-inl.h"
33#include "gc/scoped_gc_critical_section.h"
34#include "instrumentation.h"
35#include "mirror/class-inl.h"
36#include "mirror/dex_cache-inl.h"
37#include "mirror/object_array-inl.h"
38#include "mirror/object-inl.h"
39#include "os.h"
40#include "scoped_thread_state_change.h"
41#include "ScopedLocalRef.h"
42#include "thread.h"
43#include "thread_list.h"
44#include "utils.h"
45#include "entrypoints/quick/quick_entrypoints.h"
46
47namespace art {
48
49static constexpr size_t TraceActionBits = MinimumBitsToStore(
50    static_cast<size_t>(kTraceMethodActionMask));
51static constexpr uint8_t kOpNewMethod = 1U;
52static constexpr uint8_t kOpNewThread = 2U;
53
54class BuildStackTraceVisitor : public StackVisitor {
55 public:
56  explicit BuildStackTraceVisitor(Thread* thread)
57      : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
58        method_trace_(Trace::AllocStackTrace()) {}
59
60  bool VisitFrame() SHARED_REQUIRES(Locks::mutator_lock_) {
61    ArtMethod* m = GetMethod();
62    // Ignore runtime frames (in particular callee save).
63    if (!m->IsRuntimeMethod()) {
64      method_trace_->push_back(m);
65    }
66    return true;
67  }
68
69  // Returns a stack trace where the topmost frame corresponds with the first element of the vector.
70  std::vector<ArtMethod*>* GetStackTrace() const {
71    return method_trace_;
72  }
73
74 private:
75  std::vector<ArtMethod*>* const method_trace_;
76
77  DISALLOW_COPY_AND_ASSIGN(BuildStackTraceVisitor);
78};
79
80static const char     kTraceTokenChar             = '*';
81static const uint16_t kTraceHeaderLength          = 32;
82static const uint32_t kTraceMagicValue            = 0x574f4c53;
83static const uint16_t kTraceVersionSingleClock    = 2;
84static const uint16_t kTraceVersionDualClock      = 3;
85static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
86static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
87
88TraceClockSource Trace::default_clock_source_ = kDefaultTraceClockSource;
89
90Trace* volatile Trace::the_trace_ = nullptr;
91pthread_t Trace::sampling_pthread_ = 0U;
92std::unique_ptr<std::vector<ArtMethod*>> Trace::temp_stack_trace_;
93
94// The key identifying the tracer to update instrumentation.
95static constexpr const char* kTracerInstrumentationKey = "Tracer";
96
97static TraceAction DecodeTraceAction(uint32_t tmid) {
98  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
99}
100
101ArtMethod* Trace::DecodeTraceMethod(uint32_t tmid) {
102  MutexLock mu(Thread::Current(), *unique_methods_lock_);
103  return unique_methods_[tmid >> TraceActionBits];
104}
105
106uint32_t Trace::EncodeTraceMethod(ArtMethod* method) {
107  MutexLock mu(Thread::Current(), *unique_methods_lock_);
108  uint32_t idx;
109  auto it = art_method_id_map_.find(method);
110  if (it != art_method_id_map_.end()) {
111    idx = it->second;
112  } else {
113    unique_methods_.push_back(method);
114    idx = unique_methods_.size() - 1;
115    art_method_id_map_.emplace(method, idx);
116  }
117  DCHECK_LT(idx, unique_methods_.size());
118  DCHECK_EQ(unique_methods_[idx], method);
119  return idx;
120}
121
122uint32_t Trace::EncodeTraceMethodAndAction(ArtMethod* method, TraceAction action) {
123  uint32_t tmid = (EncodeTraceMethod(method) << TraceActionBits) | action;
124  DCHECK_EQ(method, DecodeTraceMethod(tmid));
125  return tmid;
126}
127
128std::vector<ArtMethod*>* Trace::AllocStackTrace() {
129  return (temp_stack_trace_.get() != nullptr)  ? temp_stack_trace_.release() :
130      new std::vector<ArtMethod*>();
131}
132
133void Trace::FreeStackTrace(std::vector<ArtMethod*>* stack_trace) {
134  stack_trace->clear();
135  temp_stack_trace_.reset(stack_trace);
136}
137
138void Trace::SetDefaultClockSource(TraceClockSource clock_source) {
139#if defined(__linux__)
140  default_clock_source_ = clock_source;
141#else
142  if (clock_source != TraceClockSource::kWall) {
143    LOG(WARNING) << "Ignoring tracing request to use CPU time.";
144  }
145#endif
146}
147
148static uint16_t GetTraceVersion(TraceClockSource clock_source) {
149  return (clock_source == TraceClockSource::kDual) ? kTraceVersionDualClock
150                                                    : kTraceVersionSingleClock;
151}
152
153static uint16_t GetRecordSize(TraceClockSource clock_source) {
154  return (clock_source == TraceClockSource::kDual) ? kTraceRecordSizeDualClock
155                                                    : kTraceRecordSizeSingleClock;
156}
157
158bool Trace::UseThreadCpuClock() {
159  return (clock_source_ == TraceClockSource::kThreadCpu) ||
160      (clock_source_ == TraceClockSource::kDual);
161}
162
163bool Trace::UseWallClock() {
164  return (clock_source_ == TraceClockSource::kWall) ||
165      (clock_source_ == TraceClockSource::kDual);
166}
167
168void Trace::MeasureClockOverhead() {
169  if (UseThreadCpuClock()) {
170    Thread::Current()->GetCpuMicroTime();
171  }
172  if (UseWallClock()) {
173    MicroTime();
174  }
175}
176
177// Compute an average time taken to measure clocks.
178uint32_t Trace::GetClockOverheadNanoSeconds() {
179  Thread* self = Thread::Current();
180  uint64_t start = self->GetCpuMicroTime();
181
182  for (int i = 4000; i > 0; i--) {
183    MeasureClockOverhead();
184    MeasureClockOverhead();
185    MeasureClockOverhead();
186    MeasureClockOverhead();
187    MeasureClockOverhead();
188    MeasureClockOverhead();
189    MeasureClockOverhead();
190    MeasureClockOverhead();
191  }
192
193  uint64_t elapsed_us = self->GetCpuMicroTime() - start;
194  return static_cast<uint32_t>(elapsed_us / 32);
195}
196
197// TODO: put this somewhere with the big-endian equivalent used by JDWP.
198static void Append2LE(uint8_t* buf, uint16_t val) {
199  *buf++ = static_cast<uint8_t>(val);
200  *buf++ = static_cast<uint8_t>(val >> 8);
201}
202
203// TODO: put this somewhere with the big-endian equivalent used by JDWP.
204static void Append4LE(uint8_t* buf, uint32_t val) {
205  *buf++ = static_cast<uint8_t>(val);
206  *buf++ = static_cast<uint8_t>(val >> 8);
207  *buf++ = static_cast<uint8_t>(val >> 16);
208  *buf++ = static_cast<uint8_t>(val >> 24);
209}
210
211// TODO: put this somewhere with the big-endian equivalent used by JDWP.
212static void Append8LE(uint8_t* buf, uint64_t val) {
213  *buf++ = static_cast<uint8_t>(val);
214  *buf++ = static_cast<uint8_t>(val >> 8);
215  *buf++ = static_cast<uint8_t>(val >> 16);
216  *buf++ = static_cast<uint8_t>(val >> 24);
217  *buf++ = static_cast<uint8_t>(val >> 32);
218  *buf++ = static_cast<uint8_t>(val >> 40);
219  *buf++ = static_cast<uint8_t>(val >> 48);
220  *buf++ = static_cast<uint8_t>(val >> 56);
221}
222
223static void GetSample(Thread* thread, void* arg) SHARED_REQUIRES(Locks::mutator_lock_) {
224  BuildStackTraceVisitor build_trace_visitor(thread);
225  build_trace_visitor.WalkStack();
226  std::vector<ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
227  Trace* the_trace = reinterpret_cast<Trace*>(arg);
228  the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
229}
230
231static void ClearThreadStackTraceAndClockBase(Thread* thread, void* arg ATTRIBUTE_UNUSED) {
232  thread->SetTraceClockBase(0);
233  std::vector<ArtMethod*>* stack_trace = thread->GetStackTraceSample();
234  thread->SetStackTraceSample(nullptr);
235  delete stack_trace;
236}
237
238void Trace::CompareAndUpdateStackTrace(Thread* thread,
239                                       std::vector<ArtMethod*>* stack_trace) {
240  CHECK_EQ(pthread_self(), sampling_pthread_);
241  std::vector<ArtMethod*>* old_stack_trace = thread->GetStackTraceSample();
242  // Update the thread's stack trace sample.
243  thread->SetStackTraceSample(stack_trace);
244  // Read timer clocks to use for all events in this trace.
245  uint32_t thread_clock_diff = 0;
246  uint32_t wall_clock_diff = 0;
247  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
248  if (old_stack_trace == nullptr) {
249    // If there's no previous stack trace sample for this thread, log an entry event for all
250    // methods in the trace.
251    for (auto rit = stack_trace->rbegin(); rit != stack_trace->rend(); ++rit) {
252      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
253                          thread_clock_diff, wall_clock_diff);
254    }
255  } else {
256    // If there's a previous stack trace for this thread, diff the traces and emit entry and exit
257    // events accordingly.
258    auto old_rit = old_stack_trace->rbegin();
259    auto rit = stack_trace->rbegin();
260    // Iterate bottom-up over both traces until there's a difference between them.
261    while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
262      old_rit++;
263      rit++;
264    }
265    // Iterate top-down over the old trace until the point where they differ, emitting exit events.
266    for (auto old_it = old_stack_trace->begin(); old_it != old_rit.base(); ++old_it) {
267      LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited,
268                          thread_clock_diff, wall_clock_diff);
269    }
270    // Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
271    for (; rit != stack_trace->rend(); ++rit) {
272      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
273                          thread_clock_diff, wall_clock_diff);
274    }
275    FreeStackTrace(old_stack_trace);
276  }
277}
278
279void* Trace::RunSamplingThread(void* arg) {
280  Runtime* runtime = Runtime::Current();
281  intptr_t interval_us = reinterpret_cast<intptr_t>(arg);
282  CHECK_GE(interval_us, 0);
283  CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
284                                     !runtime->IsAotCompiler()));
285
286  while (true) {
287    usleep(interval_us);
288    ScopedTrace trace("Profile sampling");
289    Thread* self = Thread::Current();
290    Trace* the_trace;
291    {
292      MutexLock mu(self, *Locks::trace_lock_);
293      the_trace = the_trace_;
294      if (the_trace == nullptr) {
295        break;
296      }
297    }
298    {
299      ScopedSuspendAll ssa(__FUNCTION__);
300      MutexLock mu(self, *Locks::thread_list_lock_);
301      runtime->GetThreadList()->ForEach(GetSample, the_trace);
302    }
303  }
304
305  runtime->DetachCurrentThread();
306  return nullptr;
307}
308
309void Trace::Start(const char* trace_filename, int trace_fd, size_t buffer_size, int flags,
310                  TraceOutputMode output_mode, TraceMode trace_mode, int interval_us) {
311  Thread* self = Thread::Current();
312  {
313    MutexLock mu(self, *Locks::trace_lock_);
314    if (the_trace_ != nullptr) {
315      LOG(ERROR) << "Trace already in progress, ignoring this request";
316      return;
317    }
318  }
319
320  // Check interval if sampling is enabled
321  if (trace_mode == TraceMode::kSampling && interval_us <= 0) {
322    LOG(ERROR) << "Invalid sampling interval: " << interval_us;
323    ScopedObjectAccess soa(self);
324    ThrowRuntimeException("Invalid sampling interval: %d", interval_us);
325    return;
326  }
327
328  // Open trace file if not going directly to ddms.
329  std::unique_ptr<File> trace_file;
330  if (output_mode != TraceOutputMode::kDDMS) {
331    if (trace_fd < 0) {
332      trace_file.reset(OS::CreateEmptyFileWriteOnly(trace_filename));
333    } else {
334      trace_file.reset(new File(trace_fd, "tracefile"));
335      trace_file->DisableAutoClose();
336    }
337    if (trace_file.get() == nullptr) {
338      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
339      ScopedObjectAccess soa(self);
340      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
341      return;
342    }
343  }
344
345  Runtime* runtime = Runtime::Current();
346
347  // Enable count of allocs if specified in the flags.
348  bool enable_stats = false;
349
350  // Create Trace object.
351  {
352    // Required since EnableMethodTracing calls ConfigureStubs which visits class linker classes.
353    gc::ScopedGCCriticalSection gcs(self,
354                                    gc::kGcCauseInstrumentation,
355                                    gc::kCollectorTypeInstrumentation);
356    ScopedSuspendAll ssa(__FUNCTION__);
357    MutexLock mu(self, *Locks::trace_lock_);
358    if (the_trace_ != nullptr) {
359      LOG(ERROR) << "Trace already in progress, ignoring this request";
360    } else {
361      enable_stats = (flags && kTraceCountAllocs) != 0;
362      the_trace_ = new Trace(trace_file.release(), trace_filename, buffer_size, flags, output_mode,
363                             trace_mode);
364      if (trace_mode == TraceMode::kSampling) {
365        CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
366                                            reinterpret_cast<void*>(interval_us)),
367                                            "Sampling profiler thread");
368        the_trace_->interval_us_ = interval_us;
369      } else {
370        runtime->GetInstrumentation()->AddListener(the_trace_,
371                                                   instrumentation::Instrumentation::kMethodEntered |
372                                                   instrumentation::Instrumentation::kMethodExited |
373                                                   instrumentation::Instrumentation::kMethodUnwind);
374        // TODO: In full-PIC mode, we don't need to fully deopt.
375        runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
376      }
377    }
378  }
379
380  // Can't call this when holding the mutator lock.
381  if (enable_stats) {
382    runtime->SetStatsEnabled(true);
383  }
384}
385
386void Trace::StopTracing(bool finish_tracing, bool flush_file) {
387  bool stop_alloc_counting = false;
388  Runtime* const runtime = Runtime::Current();
389  Trace* the_trace = nullptr;
390  Thread* const self = Thread::Current();
391  pthread_t sampling_pthread = 0U;
392  {
393    MutexLock mu(self, *Locks::trace_lock_);
394    if (the_trace_ == nullptr) {
395      LOG(ERROR) << "Trace stop requested, but no trace currently running";
396    } else {
397      the_trace = the_trace_;
398      the_trace_ = nullptr;
399      sampling_pthread = sampling_pthread_;
400    }
401  }
402  // Make sure that we join before we delete the trace since we don't want to have
403  // the sampling thread access a stale pointer. This finishes since the sampling thread exits when
404  // the_trace_ is null.
405  if (sampling_pthread != 0U) {
406    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
407    sampling_pthread_ = 0U;
408  }
409
410  {
411    gc::ScopedGCCriticalSection gcs(self,
412                                    gc::kGcCauseInstrumentation,
413                                    gc::kCollectorTypeInstrumentation);
414    ScopedSuspendAll ssa(__FUNCTION__);
415    if (the_trace != nullptr) {
416      stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
417      if (finish_tracing) {
418        the_trace->FinishTracing();
419      }
420
421      if (the_trace->trace_mode_ == TraceMode::kSampling) {
422        MutexLock mu(self, *Locks::thread_list_lock_);
423        runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
424      } else {
425        runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
426        runtime->GetInstrumentation()->RemoveListener(
427            the_trace, instrumentation::Instrumentation::kMethodEntered |
428            instrumentation::Instrumentation::kMethodExited |
429            instrumentation::Instrumentation::kMethodUnwind);
430      }
431      if (the_trace->trace_file_.get() != nullptr) {
432        // Do not try to erase, so flush and close explicitly.
433        if (flush_file) {
434          if (the_trace->trace_file_->Flush() != 0) {
435            PLOG(WARNING) << "Could not flush trace file.";
436          }
437        } else {
438          the_trace->trace_file_->MarkUnchecked();  // Do not trigger guard.
439        }
440        if (the_trace->trace_file_->Close() != 0) {
441          PLOG(ERROR) << "Could not close trace file.";
442        }
443      }
444      delete the_trace;
445    }
446  }
447  if (stop_alloc_counting) {
448    // Can be racy since SetStatsEnabled is not guarded by any locks.
449    runtime->SetStatsEnabled(false);
450  }
451}
452
453void Trace::Abort() {
454  // Do not write anything anymore.
455  StopTracing(false, false);
456}
457
458void Trace::Stop() {
459  // Finish writing.
460  StopTracing(true, true);
461}
462
463void Trace::Shutdown() {
464  if (GetMethodTracingMode() != kTracingInactive) {
465    Stop();
466  }
467}
468
469void Trace::Pause() {
470  bool stop_alloc_counting = false;
471  Runtime* runtime = Runtime::Current();
472  Trace* the_trace = nullptr;
473
474  Thread* const self = Thread::Current();
475  pthread_t sampling_pthread = 0U;
476  {
477    MutexLock mu(self, *Locks::trace_lock_);
478    if (the_trace_ == nullptr) {
479      LOG(ERROR) << "Trace pause requested, but no trace currently running";
480      return;
481    } else {
482      the_trace = the_trace_;
483      sampling_pthread = sampling_pthread_;
484    }
485  }
486
487  if (sampling_pthread != 0U) {
488    {
489      MutexLock mu(self, *Locks::trace_lock_);
490      the_trace_ = nullptr;
491    }
492    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
493    sampling_pthread_ = 0U;
494    {
495      MutexLock mu(self, *Locks::trace_lock_);
496      the_trace_ = the_trace;
497    }
498  }
499
500  if (the_trace != nullptr) {
501    gc::ScopedGCCriticalSection gcs(self,
502                                    gc::kGcCauseInstrumentation,
503                                    gc::kCollectorTypeInstrumentation);
504    ScopedSuspendAll ssa(__FUNCTION__);
505    stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
506
507    if (the_trace->trace_mode_ == TraceMode::kSampling) {
508      MutexLock mu(self, *Locks::thread_list_lock_);
509      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
510    } else {
511      runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
512      runtime->GetInstrumentation()->RemoveListener(
513          the_trace,
514          instrumentation::Instrumentation::kMethodEntered |
515          instrumentation::Instrumentation::kMethodExited |
516          instrumentation::Instrumentation::kMethodUnwind);
517    }
518  }
519
520  if (stop_alloc_counting) {
521    // Can be racy since SetStatsEnabled is not guarded by any locks.
522    Runtime::Current()->SetStatsEnabled(false);
523  }
524}
525
526void Trace::Resume() {
527  Thread* self = Thread::Current();
528  Trace* the_trace;
529  {
530    MutexLock mu(self, *Locks::trace_lock_);
531    if (the_trace_ == nullptr) {
532      LOG(ERROR) << "No trace to resume (or sampling mode), ignoring this request";
533      return;
534    }
535    the_trace = the_trace_;
536  }
537
538  Runtime* runtime = Runtime::Current();
539
540  // Enable count of allocs if specified in the flags.
541  bool enable_stats = (the_trace->flags_ && kTraceCountAllocs) != 0;
542
543  {
544    gc::ScopedGCCriticalSection gcs(self,
545                                    gc::kGcCauseInstrumentation,
546                                    gc::kCollectorTypeInstrumentation);
547    ScopedSuspendAll ssa(__FUNCTION__);
548
549    // Reenable.
550    if (the_trace->trace_mode_ == TraceMode::kSampling) {
551      CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
552          reinterpret_cast<void*>(the_trace->interval_us_)), "Sampling profiler thread");
553    } else {
554      runtime->GetInstrumentation()->AddListener(the_trace,
555                                                 instrumentation::Instrumentation::kMethodEntered |
556                                                 instrumentation::Instrumentation::kMethodExited |
557                                                 instrumentation::Instrumentation::kMethodUnwind);
558      // TODO: In full-PIC mode, we don't need to fully deopt.
559      runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
560    }
561  }
562
563  // Can't call this when holding the mutator lock.
564  if (enable_stats) {
565    runtime->SetStatsEnabled(true);
566  }
567}
568
569TracingMode Trace::GetMethodTracingMode() {
570  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
571  if (the_trace_ == nullptr) {
572    return kTracingInactive;
573  } else {
574    switch (the_trace_->trace_mode_) {
575      case TraceMode::kSampling:
576        return kSampleProfilingActive;
577      case TraceMode::kMethodTracing:
578        return kMethodTracingActive;
579    }
580    LOG(FATAL) << "Unreachable";
581    UNREACHABLE();
582  }
583}
584
585static constexpr size_t kMinBufSize = 18U;  // Trace header is up to 18B.
586
587Trace::Trace(File* trace_file, const char* trace_name, size_t buffer_size, int flags,
588             TraceOutputMode output_mode, TraceMode trace_mode)
589    : trace_file_(trace_file),
590      buf_(new uint8_t[std::max(kMinBufSize, buffer_size)]()),
591      flags_(flags), trace_output_mode_(output_mode), trace_mode_(trace_mode),
592      clock_source_(default_clock_source_),
593      buffer_size_(std::max(kMinBufSize, buffer_size)),
594      start_time_(MicroTime()), clock_overhead_ns_(GetClockOverheadNanoSeconds()), cur_offset_(0),
595      overflow_(false), interval_us_(0), streaming_lock_(nullptr),
596      unique_methods_lock_(new Mutex("unique methods lock", kTracingUniqueMethodsLock)) {
597  uint16_t trace_version = GetTraceVersion(clock_source_);
598  if (output_mode == TraceOutputMode::kStreaming) {
599    trace_version |= 0xF0U;
600  }
601  // Set up the beginning of the trace.
602  memset(buf_.get(), 0, kTraceHeaderLength);
603  Append4LE(buf_.get(), kTraceMagicValue);
604  Append2LE(buf_.get() + 4, trace_version);
605  Append2LE(buf_.get() + 6, kTraceHeaderLength);
606  Append8LE(buf_.get() + 8, start_time_);
607  if (trace_version >= kTraceVersionDualClock) {
608    uint16_t record_size = GetRecordSize(clock_source_);
609    Append2LE(buf_.get() + 16, record_size);
610  }
611  static_assert(18 <= kMinBufSize, "Minimum buffer size not large enough for trace header");
612
613  // Update current offset.
614  cur_offset_.StoreRelaxed(kTraceHeaderLength);
615
616  if (output_mode == TraceOutputMode::kStreaming) {
617    streaming_file_name_ = trace_name;
618    streaming_lock_ = new Mutex("tracing lock", LockLevel::kTracingStreamingLock);
619    seen_threads_.reset(new ThreadIDBitSet());
620  }
621}
622
623Trace::~Trace() {
624  delete streaming_lock_;
625  delete unique_methods_lock_;
626}
627
628static uint64_t ReadBytes(uint8_t* buf, size_t bytes) {
629  uint64_t ret = 0;
630  for (size_t i = 0; i < bytes; ++i) {
631    ret |= static_cast<uint64_t>(buf[i]) << (i * 8);
632  }
633  return ret;
634}
635
636void Trace::DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source) {
637  uint8_t* ptr = buf + kTraceHeaderLength;
638  uint8_t* end = buf + buf_size;
639
640  while (ptr < end) {
641    uint32_t tmid = ReadBytes(ptr + 2, sizeof(tmid));
642    ArtMethod* method = DecodeTraceMethod(tmid);
643    TraceAction action = DecodeTraceAction(tmid);
644    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
645    ptr += GetRecordSize(clock_source);
646  }
647}
648
649void Trace::FinishTracing() {
650  size_t final_offset = 0;
651
652  std::set<ArtMethod*> visited_methods;
653  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
654    // Clean up.
655    STLDeleteValues(&seen_methods_);
656  } else {
657    final_offset = cur_offset_.LoadRelaxed();
658    GetVisitedMethods(final_offset, &visited_methods);
659  }
660
661  // Compute elapsed time.
662  uint64_t elapsed = MicroTime() - start_time_;
663
664  std::ostringstream os;
665
666  os << StringPrintf("%cversion\n", kTraceTokenChar);
667  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
668  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
669  if (UseThreadCpuClock()) {
670    if (UseWallClock()) {
671      os << StringPrintf("clock=dual\n");
672    } else {
673      os << StringPrintf("clock=thread-cpu\n");
674    }
675  } else {
676    os << StringPrintf("clock=wall\n");
677  }
678  os << StringPrintf("elapsed-time-usec=%" PRIu64 "\n", elapsed);
679  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
680    size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
681    os << StringPrintf("num-method-calls=%zd\n", num_records);
682  }
683  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
684  os << StringPrintf("vm=art\n");
685  os << StringPrintf("pid=%d\n", getpid());
686  if ((flags_ & kTraceCountAllocs) != 0) {
687    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
688    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
689    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
690  }
691  os << StringPrintf("%cthreads\n", kTraceTokenChar);
692  DumpThreadList(os);
693  os << StringPrintf("%cmethods\n", kTraceTokenChar);
694  DumpMethodList(os, visited_methods);
695  os << StringPrintf("%cend\n", kTraceTokenChar);
696  std::string header(os.str());
697
698  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
699    File file(streaming_file_name_ + ".sec", O_CREAT | O_WRONLY, true);
700    if (!file.IsOpened()) {
701      LOG(WARNING) << "Could not open secondary trace file!";
702      return;
703    }
704    if (!file.WriteFully(header.c_str(), header.length())) {
705      file.Erase();
706      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
707      PLOG(ERROR) << detail;
708      ThrowRuntimeException("%s", detail.c_str());
709    }
710    if (file.FlushCloseOrErase() != 0) {
711      PLOG(ERROR) << "Could not write secondary file";
712    }
713  } else {
714    if (trace_file_.get() == nullptr) {
715      iovec iov[2];
716      iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
717      iov[0].iov_len = header.length();
718      iov[1].iov_base = buf_.get();
719      iov[1].iov_len = final_offset;
720      Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
721      const bool kDumpTraceInfo = false;
722      if (kDumpTraceInfo) {
723        LOG(INFO) << "Trace sent:\n" << header;
724        DumpBuf(buf_.get(), final_offset, clock_source_);
725      }
726    } else {
727      if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
728          !trace_file_->WriteFully(buf_.get(), final_offset)) {
729        std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
730        PLOG(ERROR) << detail;
731        ThrowRuntimeException("%s", detail.c_str());
732      }
733    }
734  }
735}
736
737void Trace::DexPcMoved(Thread* thread ATTRIBUTE_UNUSED,
738                       mirror::Object* this_object ATTRIBUTE_UNUSED,
739                       ArtMethod* method,
740                       uint32_t new_dex_pc) {
741  // We're not recorded to listen to this kind of event, so complain.
742  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
743}
744
745void Trace::FieldRead(Thread* thread ATTRIBUTE_UNUSED,
746                      mirror::Object* this_object ATTRIBUTE_UNUSED,
747                      ArtMethod* method,
748                      uint32_t dex_pc,
749                      ArtField* field ATTRIBUTE_UNUSED)
750    SHARED_REQUIRES(Locks::mutator_lock_) {
751  // We're not recorded to listen to this kind of event, so complain.
752  LOG(ERROR) << "Unexpected field read event in tracing " << PrettyMethod(method) << " " << dex_pc;
753}
754
755void Trace::FieldWritten(Thread* thread ATTRIBUTE_UNUSED,
756                         mirror::Object* this_object ATTRIBUTE_UNUSED,
757                         ArtMethod* method,
758                         uint32_t dex_pc,
759                         ArtField* field ATTRIBUTE_UNUSED,
760                         const JValue& field_value ATTRIBUTE_UNUSED)
761    SHARED_REQUIRES(Locks::mutator_lock_) {
762  // We're not recorded to listen to this kind of event, so complain.
763  LOG(ERROR) << "Unexpected field write event in tracing " << PrettyMethod(method) << " " << dex_pc;
764}
765
766void Trace::MethodEntered(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
767                          ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
768  uint32_t thread_clock_diff = 0;
769  uint32_t wall_clock_diff = 0;
770  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
771  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered,
772                      thread_clock_diff, wall_clock_diff);
773}
774
775void Trace::MethodExited(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
776                         ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED,
777                         const JValue& return_value ATTRIBUTE_UNUSED) {
778  uint32_t thread_clock_diff = 0;
779  uint32_t wall_clock_diff = 0;
780  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
781  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited,
782                      thread_clock_diff, wall_clock_diff);
783}
784
785void Trace::MethodUnwind(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::kMethodUnwind,
791                      thread_clock_diff, wall_clock_diff);
792}
793
794void Trace::ExceptionCaught(Thread* thread ATTRIBUTE_UNUSED,
795                            mirror::Throwable* exception_object ATTRIBUTE_UNUSED)
796    SHARED_REQUIRES(Locks::mutator_lock_) {
797  LOG(ERROR) << "Unexpected exception caught event in tracing";
798}
799
800void Trace::Branch(Thread* /*thread*/, ArtMethod* method,
801                   uint32_t /*dex_pc*/, int32_t /*dex_pc_offset*/)
802      SHARED_REQUIRES(Locks::mutator_lock_) {
803  LOG(ERROR) << "Unexpected branch event in tracing" << PrettyMethod(method);
804}
805
806void Trace::InvokeVirtualOrInterface(Thread*,
807                                     mirror::Object*,
808                                     ArtMethod* method,
809                                     uint32_t dex_pc,
810                                     ArtMethod*) {
811  LOG(ERROR) << "Unexpected invoke event in tracing" << PrettyMethod(method)
812             << " " << dex_pc;
813}
814
815void Trace::ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint32_t* wall_clock_diff) {
816  if (UseThreadCpuClock()) {
817    uint64_t clock_base = thread->GetTraceClockBase();
818    if (UNLIKELY(clock_base == 0)) {
819      // First event, record the base time in the map.
820      uint64_t time = thread->GetCpuMicroTime();
821      thread->SetTraceClockBase(time);
822    } else {
823      *thread_clock_diff = thread->GetCpuMicroTime() - clock_base;
824    }
825  }
826  if (UseWallClock()) {
827    *wall_clock_diff = MicroTime() - start_time_;
828  }
829}
830
831bool Trace::RegisterMethod(ArtMethod* method) {
832  mirror::DexCache* dex_cache = method->GetDexCache();
833  const DexFile* dex_file = dex_cache->GetDexFile();
834  if (seen_methods_.find(dex_file) == seen_methods_.end()) {
835    seen_methods_.insert(std::make_pair(dex_file, new DexIndexBitSet()));
836  }
837  DexIndexBitSet* bit_set = seen_methods_.find(dex_file)->second;
838  if (!(*bit_set)[method->GetDexMethodIndex()]) {
839    bit_set->set(method->GetDexMethodIndex());
840    return true;
841  }
842  return false;
843}
844
845bool Trace::RegisterThread(Thread* thread) {
846  pid_t tid = thread->GetTid();
847  CHECK_LT(0U, static_cast<uint32_t>(tid));
848  CHECK_LT(static_cast<uint32_t>(tid), kMaxThreadIdNumber);
849
850  if (!(*seen_threads_)[tid]) {
851    seen_threads_->set(tid);
852    return true;
853  }
854  return false;
855}
856
857std::string Trace::GetMethodLine(ArtMethod* method) {
858  method = method->GetInterfaceMethodIfProxy(kRuntimePointerSize);
859  return StringPrintf("%#x\t%s\t%s\t%s\t%s\n", (EncodeTraceMethod(method) << TraceActionBits),
860      PrettyDescriptor(method->GetDeclaringClassDescriptor()).c_str(), method->GetName(),
861      method->GetSignature().ToString().c_str(), method->GetDeclaringClassSourceFile());
862}
863
864void Trace::WriteToBuf(const uint8_t* src, size_t src_size) {
865  int32_t old_offset = cur_offset_.LoadRelaxed();
866  int32_t new_offset = old_offset + static_cast<int32_t>(src_size);
867  if (dchecked_integral_cast<size_t>(new_offset) > buffer_size_) {
868    // Flush buffer.
869    if (!trace_file_->WriteFully(buf_.get(), old_offset)) {
870      PLOG(WARNING) << "Failed streaming a tracing event.";
871    }
872
873    // Check whether the data is too large for the buffer, then write immediately.
874    if (src_size >= buffer_size_) {
875      if (!trace_file_->WriteFully(src, src_size)) {
876        PLOG(WARNING) << "Failed streaming a tracing event.";
877      }
878      cur_offset_.StoreRelease(0);  // Buffer is empty now.
879      return;
880    }
881
882    old_offset = 0;
883    new_offset = static_cast<int32_t>(src_size);
884  }
885  cur_offset_.StoreRelease(new_offset);
886  // Fill in data.
887  memcpy(buf_.get() + old_offset, src, src_size);
888}
889
890void Trace::LogMethodTraceEvent(Thread* thread, ArtMethod* method,
891                                instrumentation::Instrumentation::InstrumentationEvent event,
892                                uint32_t thread_clock_diff, uint32_t wall_clock_diff) {
893  // Advance cur_offset_ atomically.
894  int32_t new_offset;
895  int32_t old_offset = 0;
896
897  // We do a busy loop here trying to acquire the next offset.
898  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
899    do {
900      old_offset = cur_offset_.LoadRelaxed();
901      new_offset = old_offset + GetRecordSize(clock_source_);
902      if (static_cast<size_t>(new_offset) > buffer_size_) {
903        overflow_ = true;
904        return;
905      }
906    } while (!cur_offset_.CompareExchangeWeakSequentiallyConsistent(old_offset, new_offset));
907  }
908
909  TraceAction action = kTraceMethodEnter;
910  switch (event) {
911    case instrumentation::Instrumentation::kMethodEntered:
912      action = kTraceMethodEnter;
913      break;
914    case instrumentation::Instrumentation::kMethodExited:
915      action = kTraceMethodExit;
916      break;
917    case instrumentation::Instrumentation::kMethodUnwind:
918      action = kTraceUnroll;
919      break;
920    default:
921      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
922  }
923
924  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
925
926  // Write data
927  uint8_t* ptr;
928  static constexpr size_t kPacketSize = 14U;  // The maximum size of data in a packet.
929  uint8_t stack_buf[kPacketSize];             // Space to store a packet when in streaming mode.
930  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
931    ptr = stack_buf;
932  } else {
933    ptr = buf_.get() + old_offset;
934  }
935
936  Append2LE(ptr, thread->GetTid());
937  Append4LE(ptr + 2, method_value);
938  ptr += 6;
939
940  if (UseThreadCpuClock()) {
941    Append4LE(ptr, thread_clock_diff);
942    ptr += 4;
943  }
944  if (UseWallClock()) {
945    Append4LE(ptr, wall_clock_diff);
946  }
947  static_assert(kPacketSize == 2 + 4 + 4 + 4, "Packet size incorrect.");
948
949  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
950    MutexLock mu(Thread::Current(), *streaming_lock_);  // To serialize writing.
951    if (RegisterMethod(method)) {
952      // Write a special block with the name.
953      std::string method_line(GetMethodLine(method));
954      uint8_t buf2[5];
955      Append2LE(buf2, 0);
956      buf2[2] = kOpNewMethod;
957      Append2LE(buf2 + 3, static_cast<uint16_t>(method_line.length()));
958      WriteToBuf(buf2, sizeof(buf2));
959      WriteToBuf(reinterpret_cast<const uint8_t*>(method_line.c_str()), method_line.length());
960    }
961    if (RegisterThread(thread)) {
962      // It might be better to postpone this. Threads might not have received names...
963      std::string thread_name;
964      thread->GetThreadName(thread_name);
965      uint8_t buf2[7];
966      Append2LE(buf2, 0);
967      buf2[2] = kOpNewThread;
968      Append2LE(buf2 + 3, static_cast<uint16_t>(thread->GetTid()));
969      Append2LE(buf2 + 5, static_cast<uint16_t>(thread_name.length()));
970      WriteToBuf(buf2, sizeof(buf2));
971      WriteToBuf(reinterpret_cast<const uint8_t*>(thread_name.c_str()), thread_name.length());
972    }
973    WriteToBuf(stack_buf, sizeof(stack_buf));
974  }
975}
976
977void Trace::GetVisitedMethods(size_t buf_size,
978                              std::set<ArtMethod*>* visited_methods) {
979  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
980  uint8_t* end = buf_.get() + buf_size;
981
982  while (ptr < end) {
983    uint32_t tmid = ReadBytes(ptr + 2, sizeof(tmid));
984    ArtMethod* method = DecodeTraceMethod(tmid);
985    visited_methods->insert(method);
986    ptr += GetRecordSize(clock_source_);
987  }
988}
989
990void Trace::DumpMethodList(std::ostream& os, const std::set<ArtMethod*>& visited_methods) {
991  for (const auto& method : visited_methods) {
992    os << GetMethodLine(method);
993  }
994}
995
996static void DumpThread(Thread* t, void* arg) {
997  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
998  std::string name;
999  t->GetThreadName(name);
1000  os << t->GetTid() << "\t" << name << "\n";
1001}
1002
1003void Trace::DumpThreadList(std::ostream& os) {
1004  Thread* self = Thread::Current();
1005  for (auto it : exited_threads_) {
1006    os << it.first << "\t" << it.second << "\n";
1007  }
1008  Locks::thread_list_lock_->AssertNotHeld(self);
1009  MutexLock mu(self, *Locks::thread_list_lock_);
1010  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
1011}
1012
1013void Trace::StoreExitingThreadInfo(Thread* thread) {
1014  MutexLock mu(thread, *Locks::trace_lock_);
1015  if (the_trace_ != nullptr) {
1016    std::string name;
1017    thread->GetThreadName(name);
1018    // The same thread/tid may be used multiple times. As SafeMap::Put does not allow to override
1019    // a previous mapping, use SafeMap::Overwrite.
1020    the_trace_->exited_threads_.Overwrite(thread->GetTid(), name);
1021  }
1022}
1023
1024Trace::TraceOutputMode Trace::GetOutputMode() {
1025  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1026  CHECK(the_trace_ != nullptr) << "Trace output mode requested, but no trace currently running";
1027  return the_trace_->trace_output_mode_;
1028}
1029
1030Trace::TraceMode Trace::GetMode() {
1031  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1032  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1033  return the_trace_->trace_mode_;
1034}
1035
1036size_t Trace::GetBufferSize() {
1037  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1038  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1039  return the_trace_->buffer_size_;
1040}
1041
1042bool Trace::IsTracingEnabled() {
1043  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1044  return the_trace_ != nullptr;
1045}
1046
1047}  // namespace art
1048