trace.cc revision 41b175aba41c9365a1c53b8a1afbd17129c87c14 
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/casts.h"
26#include "base/stl_util.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 "instrumentation.h"
34#include "mirror/art_method-inl.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
49// File format:
50//     header
51//     record 0
52//     record 1
53//     ...
54//
55// Header format:
56//     u4  magic ('SLOW')
57//     u2  version
58//     u2  offset to data
59//     u8  start date/time in usec
60//     u2  record size in bytes (version >= 2 only)
61//     ... padding to 32 bytes
62//
63// Record format v1:
64//     u1  thread ID
65//     u4  method ID | method action
66//     u4  time delta since start, in usec
67//
68// Record format v2:
69//     u2  thread ID
70//     u4  method ID | method action
71//     u4  time delta since start, in usec
72//
73// Record format v3:
74//     u2  thread ID
75//     u4  method ID | method action
76//     u4  time delta since start, in usec
77//     u4  wall time since start, in usec (when clock == "dual" only)
78//
79// 32 bits of microseconds is 70 minutes.
80//
81// All values are stored in little-endian order.
82
83enum TraceAction {
84    kTraceMethodEnter = 0x00,       // method entry
85    kTraceMethodExit = 0x01,        // method exit
86    kTraceUnroll = 0x02,            // method exited by exception unrolling
87    // 0x03 currently unused
88    kTraceMethodActionMask = 0x03,  // two bits
89};
90
91static constexpr uint8_t kOpNewMethod = 1U;
92static constexpr uint8_t kOpNewThread = 2U;
93
94class BuildStackTraceVisitor : public StackVisitor {
95 public:
96  explicit BuildStackTraceVisitor(Thread* thread)
97      : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
98        method_trace_(Trace::AllocStackTrace()) {}
99
100  bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
101    mirror::ArtMethod* m = GetMethod();
102    // Ignore runtime frames (in particular callee save).
103    if (!m->IsRuntimeMethod()) {
104      method_trace_->push_back(m);
105    }
106    return true;
107  }
108
109  // Returns a stack trace where the topmost frame corresponds with the first element of the vector.
110  std::vector<mirror::ArtMethod*>* GetStackTrace() const {
111    return method_trace_;
112  }
113
114 private:
115  std::vector<mirror::ArtMethod*>* const method_trace_;
116};
117
118static const char     kTraceTokenChar             = '*';
119static const uint16_t kTraceHeaderLength          = 32;
120static const uint32_t kTraceMagicValue            = 0x574f4c53;
121static const uint16_t kTraceVersionSingleClock    = 2;
122static const uint16_t kTraceVersionDualClock      = 3;
123static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
124static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
125
126TraceClockSource Trace::default_clock_source_ = kDefaultTraceClockSource;
127
128Trace* volatile Trace::the_trace_ = nullptr;
129pthread_t Trace::sampling_pthread_ = 0U;
130std::unique_ptr<std::vector<mirror::ArtMethod*>> Trace::temp_stack_trace_;
131
132// The key identifying the tracer to update instrumentation.
133static constexpr const char* kTracerInstrumentationKey = "Tracer";
134
135static mirror::ArtMethod* DecodeTraceMethodId(uint32_t tmid) {
136  return reinterpret_cast<mirror::ArtMethod*>(tmid & ~kTraceMethodActionMask);
137}
138
139static TraceAction DecodeTraceAction(uint32_t tmid) {
140  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
141}
142
143static uint32_t EncodeTraceMethodAndAction(mirror::ArtMethod* method,
144                                           TraceAction action) {
145  uint32_t tmid = PointerToLowMemUInt32(method) | action;
146  DCHECK_EQ(method, DecodeTraceMethodId(tmid));
147  return tmid;
148}
149
150std::vector<mirror::ArtMethod*>* Trace::AllocStackTrace() {
151  if (temp_stack_trace_.get() != nullptr) {
152    return temp_stack_trace_.release();
153  } else {
154    return new std::vector<mirror::ArtMethod*>();
155  }
156}
157
158void Trace::FreeStackTrace(std::vector<mirror::ArtMethod*>* stack_trace) {
159  stack_trace->clear();
160  temp_stack_trace_.reset(stack_trace);
161}
162
163void Trace::SetDefaultClockSource(TraceClockSource clock_source) {
164#if defined(__linux__)
165  default_clock_source_ = clock_source;
166#else
167  if (clock_source != TraceClockSource::kWall) {
168    LOG(WARNING) << "Ignoring tracing request to use CPU time.";
169  }
170#endif
171}
172
173static uint16_t GetTraceVersion(TraceClockSource clock_source) {
174  return (clock_source == TraceClockSource::kDual) ? kTraceVersionDualClock
175                                                    : kTraceVersionSingleClock;
176}
177
178static uint16_t GetRecordSize(TraceClockSource clock_source) {
179  return (clock_source == TraceClockSource::kDual) ? kTraceRecordSizeDualClock
180                                                    : kTraceRecordSizeSingleClock;
181}
182
183bool Trace::UseThreadCpuClock() {
184  return (clock_source_ == TraceClockSource::kThreadCpu) ||
185      (clock_source_ == TraceClockSource::kDual);
186}
187
188bool Trace::UseWallClock() {
189  return (clock_source_ == TraceClockSource::kWall) ||
190      (clock_source_ == TraceClockSource::kDual);
191}
192
193void Trace::MeasureClockOverhead() {
194  if (UseThreadCpuClock()) {
195    Thread::Current()->GetCpuMicroTime();
196  }
197  if (UseWallClock()) {
198    MicroTime();
199  }
200}
201
202// Compute an average time taken to measure clocks.
203uint32_t Trace::GetClockOverheadNanoSeconds() {
204  Thread* self = Thread::Current();
205  uint64_t start = self->GetCpuMicroTime();
206
207  for (int i = 4000; i > 0; i--) {
208    MeasureClockOverhead();
209    MeasureClockOverhead();
210    MeasureClockOverhead();
211    MeasureClockOverhead();
212    MeasureClockOverhead();
213    MeasureClockOverhead();
214    MeasureClockOverhead();
215    MeasureClockOverhead();
216  }
217
218  uint64_t elapsed_us = self->GetCpuMicroTime() - start;
219  return static_cast<uint32_t>(elapsed_us / 32);
220}
221
222// TODO: put this somewhere with the big-endian equivalent used by JDWP.
223static void Append2LE(uint8_t* buf, uint16_t val) {
224  *buf++ = static_cast<uint8_t>(val);
225  *buf++ = static_cast<uint8_t>(val >> 8);
226}
227
228// TODO: put this somewhere with the big-endian equivalent used by JDWP.
229static void Append4LE(uint8_t* buf, uint32_t val) {
230  *buf++ = static_cast<uint8_t>(val);
231  *buf++ = static_cast<uint8_t>(val >> 8);
232  *buf++ = static_cast<uint8_t>(val >> 16);
233  *buf++ = static_cast<uint8_t>(val >> 24);
234}
235
236// TODO: put this somewhere with the big-endian equivalent used by JDWP.
237static void Append8LE(uint8_t* buf, uint64_t val) {
238  *buf++ = static_cast<uint8_t>(val);
239  *buf++ = static_cast<uint8_t>(val >> 8);
240  *buf++ = static_cast<uint8_t>(val >> 16);
241  *buf++ = static_cast<uint8_t>(val >> 24);
242  *buf++ = static_cast<uint8_t>(val >> 32);
243  *buf++ = static_cast<uint8_t>(val >> 40);
244  *buf++ = static_cast<uint8_t>(val >> 48);
245  *buf++ = static_cast<uint8_t>(val >> 56);
246}
247
248static void GetSample(Thread* thread, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
249  BuildStackTraceVisitor build_trace_visitor(thread);
250  build_trace_visitor.WalkStack();
251  std::vector<mirror::ArtMethod*>* stack_trace = build_trace_visitor.GetStackTrace();
252  Trace* the_trace = reinterpret_cast<Trace*>(arg);
253  the_trace->CompareAndUpdateStackTrace(thread, stack_trace);
254}
255
256static void ClearThreadStackTraceAndClockBase(Thread* thread, void* arg ATTRIBUTE_UNUSED) {
257  thread->SetTraceClockBase(0);
258  std::vector<mirror::ArtMethod*>* stack_trace = thread->GetStackTraceSample();
259  thread->SetStackTraceSample(nullptr);
260  delete stack_trace;
261}
262
263void Trace::CompareAndUpdateStackTrace(Thread* thread,
264                                       std::vector<mirror::ArtMethod*>* stack_trace) {
265  CHECK_EQ(pthread_self(), sampling_pthread_);
266  std::vector<mirror::ArtMethod*>* old_stack_trace = thread->GetStackTraceSample();
267  // Update the thread's stack trace sample.
268  thread->SetStackTraceSample(stack_trace);
269  // Read timer clocks to use for all events in this trace.
270  uint32_t thread_clock_diff = 0;
271  uint32_t wall_clock_diff = 0;
272  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
273  if (old_stack_trace == nullptr) {
274    // If there's no previous stack trace sample for this thread, log an entry event for all
275    // methods in the trace.
276    for (std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
277         rit != stack_trace->rend(); ++rit) {
278      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
279                          thread_clock_diff, wall_clock_diff);
280    }
281  } else {
282    // If there's a previous stack trace for this thread, diff the traces and emit entry and exit
283    // events accordingly.
284    std::vector<mirror::ArtMethod*>::reverse_iterator old_rit = old_stack_trace->rbegin();
285    std::vector<mirror::ArtMethod*>::reverse_iterator rit = stack_trace->rbegin();
286    // Iterate bottom-up over both traces until there's a difference between them.
287    while (old_rit != old_stack_trace->rend() && rit != stack_trace->rend() && *old_rit == *rit) {
288      old_rit++;
289      rit++;
290    }
291    // Iterate top-down over the old trace until the point where they differ, emitting exit events.
292    for (std::vector<mirror::ArtMethod*>::iterator old_it = old_stack_trace->begin();
293         old_it != old_rit.base(); ++old_it) {
294      LogMethodTraceEvent(thread, *old_it, instrumentation::Instrumentation::kMethodExited,
295                          thread_clock_diff, wall_clock_diff);
296    }
297    // Iterate bottom-up over the new trace from the point where they differ, emitting entry events.
298    for (; rit != stack_trace->rend(); ++rit) {
299      LogMethodTraceEvent(thread, *rit, instrumentation::Instrumentation::kMethodEntered,
300                          thread_clock_diff, wall_clock_diff);
301    }
302    FreeStackTrace(old_stack_trace);
303  }
304}
305
306void* Trace::RunSamplingThread(void* arg) {
307  Runtime* runtime = Runtime::Current();
308  intptr_t interval_us = reinterpret_cast<intptr_t>(arg);
309  CHECK_GE(interval_us, 0);
310  CHECK(runtime->AttachCurrentThread("Sampling Profiler", true, runtime->GetSystemThreadGroup(),
311                                     !runtime->IsAotCompiler()));
312
313  while (true) {
314    usleep(interval_us);
315    ATRACE_BEGIN("Profile sampling");
316    Thread* self = Thread::Current();
317    Trace* the_trace;
318    {
319      MutexLock mu(self, *Locks::trace_lock_);
320      the_trace = the_trace_;
321      if (the_trace == nullptr) {
322        break;
323      }
324    }
325
326    runtime->GetThreadList()->SuspendAll(__FUNCTION__);
327    {
328      MutexLock mu(self, *Locks::thread_list_lock_);
329      runtime->GetThreadList()->ForEach(GetSample, the_trace);
330    }
331    runtime->GetThreadList()->ResumeAll();
332    ATRACE_END();
333  }
334
335  runtime->DetachCurrentThread();
336  return nullptr;
337}
338
339void Trace::Start(const char* trace_filename, int trace_fd, size_t buffer_size, int flags,
340                  TraceOutputMode output_mode, TraceMode trace_mode, int interval_us) {
341  Thread* self = Thread::Current();
342  {
343    MutexLock mu(self, *Locks::trace_lock_);
344    if (the_trace_ != nullptr) {
345      LOG(ERROR) << "Trace already in progress, ignoring this request";
346      return;
347    }
348  }
349
350  // Check interval if sampling is enabled
351  if (trace_mode == TraceMode::kSampling && interval_us <= 0) {
352    LOG(ERROR) << "Invalid sampling interval: " << interval_us;
353    ScopedObjectAccess soa(self);
354    ThrowRuntimeException("Invalid sampling interval: %d", interval_us);
355    return;
356  }
357
358  // Open trace file if not going directly to ddms.
359  std::unique_ptr<File> trace_file;
360  if (output_mode != TraceOutputMode::kDDMS) {
361    if (trace_fd < 0) {
362      trace_file.reset(OS::CreateEmptyFile(trace_filename));
363    } else {
364      trace_file.reset(new File(trace_fd, "tracefile"));
365      trace_file->DisableAutoClose();
366    }
367    if (trace_file.get() == nullptr) {
368      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
369      ScopedObjectAccess soa(self);
370      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
371      return;
372    }
373  }
374
375  Runtime* runtime = Runtime::Current();
376
377  // Enable count of allocs if specified in the flags.
378  bool enable_stats = false;
379
380  runtime->GetThreadList()->SuspendAll(__FUNCTION__);
381
382  // Create Trace object.
383  {
384    MutexLock mu(self, *Locks::trace_lock_);
385    if (the_trace_ != nullptr) {
386      LOG(ERROR) << "Trace already in progress, ignoring this request";
387    } else {
388      enable_stats = (flags && kTraceCountAllocs) != 0;
389      the_trace_ = new Trace(trace_file.release(), trace_filename, buffer_size, flags, output_mode,
390                             trace_mode);
391      if (trace_mode == TraceMode::kSampling) {
392        CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
393                                            reinterpret_cast<void*>(interval_us)),
394                                            "Sampling profiler thread");
395        the_trace_->interval_us_ = interval_us;
396      } else {
397        runtime->GetInstrumentation()->AddListener(the_trace_,
398                                                   instrumentation::Instrumentation::kMethodEntered |
399                                                   instrumentation::Instrumentation::kMethodExited |
400                                                   instrumentation::Instrumentation::kMethodUnwind);
401        // TODO: In full-PIC mode, we don't need to fully deopt.
402        runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
403      }
404    }
405  }
406
407  runtime->GetThreadList()->ResumeAll();
408
409  // Can't call this when holding the mutator lock.
410  if (enable_stats) {
411    runtime->SetStatsEnabled(true);
412  }
413}
414
415void Trace::StopTracing(bool finish_tracing, bool flush_file) {
416  bool stop_alloc_counting = false;
417  Runtime* const runtime = Runtime::Current();
418  Trace* the_trace = nullptr;
419  pthread_t sampling_pthread = 0U;
420  {
421    MutexLock mu(Thread::Current(), *Locks::trace_lock_);
422    if (the_trace_ == nullptr) {
423      LOG(ERROR) << "Trace stop requested, but no trace currently running";
424    } else {
425      the_trace = the_trace_;
426      the_trace_ = nullptr;
427      sampling_pthread = sampling_pthread_;
428    }
429  }
430  // Make sure that we join before we delete the trace since we don't want to have
431  // the sampling thread access a stale pointer. This finishes since the sampling thread exits when
432  // the_trace_ is null.
433  if (sampling_pthread != 0U) {
434    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
435    sampling_pthread_ = 0U;
436  }
437  runtime->GetThreadList()->SuspendAll(__FUNCTION__);
438
439  if (the_trace != nullptr) {
440    stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
441    if (finish_tracing) {
442      the_trace->FinishTracing();
443    }
444
445    if (the_trace->trace_mode_ == TraceMode::kSampling) {
446      MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
447      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
448    } else {
449      runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
450      runtime->GetInstrumentation()->RemoveListener(
451          the_trace, instrumentation::Instrumentation::kMethodEntered |
452          instrumentation::Instrumentation::kMethodExited |
453          instrumentation::Instrumentation::kMethodUnwind);
454    }
455    if (the_trace->trace_file_.get() != nullptr) {
456      // Do not try to erase, so flush and close explicitly.
457      if (flush_file) {
458        if (the_trace->trace_file_->Flush() != 0) {
459          PLOG(ERROR) << "Could not flush trace file.";
460        }
461      } else {
462        the_trace->trace_file_->MarkUnchecked();  // Do not trigger guard.
463      }
464      if (the_trace->trace_file_->Close() != 0) {
465        PLOG(ERROR) << "Could not close trace file.";
466      }
467    }
468    delete the_trace;
469  }
470  runtime->GetThreadList()->ResumeAll();
471  if (stop_alloc_counting) {
472    // Can be racy since SetStatsEnabled is not guarded by any locks.
473    runtime->SetStatsEnabled(false);
474  }
475}
476
477void Trace::Abort() {
478  // Do not write anything anymore.
479  StopTracing(false, false);
480}
481
482void Trace::Stop() {
483  // Finish writing.
484  StopTracing(true, true);
485}
486
487void Trace::Shutdown() {
488  if (GetMethodTracingMode() != kTracingInactive) {
489    Stop();
490  }
491}
492
493void Trace::Pause() {
494  bool stop_alloc_counting = false;
495  Runtime* runtime = Runtime::Current();
496  Trace* the_trace = nullptr;
497
498  pthread_t sampling_pthread = 0U;
499  {
500    MutexLock mu(Thread::Current(), *Locks::trace_lock_);
501    if (the_trace_ == nullptr) {
502      LOG(ERROR) << "Trace pause requested, but no trace currently running";
503      return;
504    } else {
505      the_trace = the_trace_;
506      sampling_pthread = sampling_pthread_;
507    }
508  }
509
510  if (sampling_pthread != 0U) {
511    {
512      MutexLock mu(Thread::Current(), *Locks::trace_lock_);
513      the_trace_ = nullptr;
514    }
515    CHECK_PTHREAD_CALL(pthread_join, (sampling_pthread, nullptr), "sampling thread shutdown");
516    sampling_pthread_ = 0U;
517    {
518      MutexLock mu(Thread::Current(), *Locks::trace_lock_);
519      the_trace_ = the_trace;
520    }
521  }
522
523  if (the_trace != nullptr) {
524    runtime->GetThreadList()->SuspendAll(__FUNCTION__);
525    stop_alloc_counting = (the_trace->flags_ & Trace::kTraceCountAllocs) != 0;
526
527    if (the_trace->trace_mode_ == TraceMode::kSampling) {
528      MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
529      runtime->GetThreadList()->ForEach(ClearThreadStackTraceAndClockBase, nullptr);
530    } else {
531      runtime->GetInstrumentation()->DisableMethodTracing(kTracerInstrumentationKey);
532      runtime->GetInstrumentation()->RemoveListener(the_trace,
533                                                    instrumentation::Instrumentation::kMethodEntered |
534                                                    instrumentation::Instrumentation::kMethodExited |
535                                                    instrumentation::Instrumentation::kMethodUnwind);
536    }
537    runtime->GetThreadList()->ResumeAll();
538  }
539
540  if (stop_alloc_counting) {
541    // Can be racy since SetStatsEnabled is not guarded by any locks.
542    Runtime::Current()->SetStatsEnabled(false);
543  }
544}
545
546void Trace::Resume() {
547  Thread* self = Thread::Current();
548  Trace* the_trace;
549  {
550    MutexLock mu(self, *Locks::trace_lock_);
551    if (the_trace_ == nullptr) {
552      LOG(ERROR) << "No trace to resume (or sampling mode), ignoring this request";
553      return;
554    }
555    the_trace = the_trace_;
556  }
557
558  Runtime* runtime = Runtime::Current();
559
560  // Enable count of allocs if specified in the flags.
561  bool enable_stats = (the_trace->flags_ && kTraceCountAllocs) != 0;
562
563  runtime->GetThreadList()->SuspendAll(__FUNCTION__);
564
565  // Reenable.
566  if (the_trace->trace_mode_ == TraceMode::kSampling) {
567    CHECK_PTHREAD_CALL(pthread_create, (&sampling_pthread_, nullptr, &RunSamplingThread,
568        reinterpret_cast<void*>(the_trace->interval_us_)), "Sampling profiler thread");
569  } else {
570    runtime->GetInstrumentation()->AddListener(the_trace,
571                                               instrumentation::Instrumentation::kMethodEntered |
572                                               instrumentation::Instrumentation::kMethodExited |
573                                               instrumentation::Instrumentation::kMethodUnwind);
574    // TODO: In full-PIC mode, we don't need to fully deopt.
575    runtime->GetInstrumentation()->EnableMethodTracing(kTracerInstrumentationKey);
576  }
577
578  runtime->GetThreadList()->ResumeAll();
579
580  // Can't call this when holding the mutator lock.
581  if (enable_stats) {
582    runtime->SetStatsEnabled(true);
583  }
584}
585
586TracingMode Trace::GetMethodTracingMode() {
587  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
588  if (the_trace_ == nullptr) {
589    return kTracingInactive;
590  } else {
591    switch (the_trace_->trace_mode_) {
592      case TraceMode::kSampling:
593        return kSampleProfilingActive;
594      case TraceMode::kMethodTracing:
595        return kMethodTracingActive;
596    }
597    LOG(FATAL) << "Unreachable";
598    UNREACHABLE();
599  }
600}
601
602static constexpr size_t kMinBufSize = 18U;  // Trace header is up to 18B.
603
604Trace::Trace(File* trace_file, const char* trace_name, size_t buffer_size, int flags,
605             TraceOutputMode output_mode, TraceMode trace_mode)
606    : trace_file_(trace_file),
607      buf_(new uint8_t[std::max(kMinBufSize, buffer_size)]()),
608      flags_(flags), trace_output_mode_(output_mode), trace_mode_(trace_mode),
609      clock_source_(default_clock_source_),
610      buffer_size_(std::max(kMinBufSize, buffer_size)),
611      start_time_(MicroTime()), clock_overhead_ns_(GetClockOverheadNanoSeconds()), cur_offset_(0),
612      overflow_(false), interval_us_(0), streaming_lock_(nullptr) {
613  uint16_t trace_version = GetTraceVersion(clock_source_);
614  if (output_mode == TraceOutputMode::kStreaming) {
615    trace_version |= 0xF0U;
616  }
617  // Set up the beginning of the trace.
618  memset(buf_.get(), 0, kTraceHeaderLength);
619  Append4LE(buf_.get(), kTraceMagicValue);
620  Append2LE(buf_.get() + 4, trace_version);
621  Append2LE(buf_.get() + 6, kTraceHeaderLength);
622  Append8LE(buf_.get() + 8, start_time_);
623  if (trace_version >= kTraceVersionDualClock) {
624    uint16_t record_size = GetRecordSize(clock_source_);
625    Append2LE(buf_.get() + 16, record_size);
626  }
627  static_assert(18 <= kMinBufSize, "Minimum buffer size not large enough for trace header");
628
629  // Update current offset.
630  cur_offset_.StoreRelaxed(kTraceHeaderLength);
631
632  if (output_mode == TraceOutputMode::kStreaming) {
633    streaming_file_name_ = trace_name;
634    streaming_lock_ = new Mutex("tracing lock");
635    seen_threads_.reset(new ThreadIDBitSet());
636  }
637}
638
639Trace::~Trace() {
640  delete streaming_lock_;
641}
642
643static void DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source)
644    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
645  uint8_t* ptr = buf + kTraceHeaderLength;
646  uint8_t* end = buf + buf_size;
647
648  while (ptr < end) {
649    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
650    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
651    TraceAction action = DecodeTraceAction(tmid);
652    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
653    ptr += GetRecordSize(clock_source);
654  }
655}
656
657static void GetVisitedMethodsFromBitSets(
658    const std::map<mirror::DexCache*, DexIndexBitSet*>& seen_methods,
659    std::set<mirror::ArtMethod*>* visited_methods) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
660  for (auto& e : seen_methods) {
661    DexIndexBitSet* bit_set = e.second;
662    for (uint32_t i = 0; i < bit_set->size(); ++i) {
663      if ((*bit_set)[i]) {
664        visited_methods->insert(e.first->GetResolvedMethod(i));
665      }
666    }
667  }
668}
669
670void Trace::FinishTracing() {
671  size_t final_offset = 0;
672
673  std::set<mirror::ArtMethod*> visited_methods;
674  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
675    // Write the secondary file with all the method names.
676    GetVisitedMethodsFromBitSets(seen_methods_, &visited_methods);
677
678    // Clean up.
679    for (auto& e : seen_methods_) {
680      delete e.second;
681    }
682  } else {
683    final_offset = cur_offset_.LoadRelaxed();
684    GetVisitedMethods(final_offset, &visited_methods);
685  }
686
687  // Compute elapsed time.
688  uint64_t elapsed = MicroTime() - start_time_;
689
690  std::ostringstream os;
691
692  os << StringPrintf("%cversion\n", kTraceTokenChar);
693  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
694  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
695  if (UseThreadCpuClock()) {
696    if (UseWallClock()) {
697      os << StringPrintf("clock=dual\n");
698    } else {
699      os << StringPrintf("clock=thread-cpu\n");
700    }
701  } else {
702    os << StringPrintf("clock=wall\n");
703  }
704  os << StringPrintf("elapsed-time-usec=%" PRIu64 "\n", elapsed);
705  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
706    size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
707    os << StringPrintf("num-method-calls=%zd\n", num_records);
708  }
709  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
710  os << StringPrintf("vm=art\n");
711  os << StringPrintf("pid=%d\n", getpid());
712  if ((flags_ & kTraceCountAllocs) != 0) {
713    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
714    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
715    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
716  }
717  os << StringPrintf("%cthreads\n", kTraceTokenChar);
718  DumpThreadList(os);
719  os << StringPrintf("%cmethods\n", kTraceTokenChar);
720  DumpMethodList(os, visited_methods);
721  os << StringPrintf("%cend\n", kTraceTokenChar);
722  std::string header(os.str());
723
724  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
725    File file;
726    if (!file.Open(streaming_file_name_ + ".sec", O_CREAT | O_WRONLY)) {
727      LOG(WARNING) << "Could not open secondary trace file!";
728      return;
729    }
730    if (!file.WriteFully(header.c_str(), header.length())) {
731      file.Erase();
732      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
733      PLOG(ERROR) << detail;
734      ThrowRuntimeException("%s", detail.c_str());
735    }
736    if (file.FlushCloseOrErase() != 0) {
737      PLOG(ERROR) << "Could not write secondary file";
738    }
739  } else {
740    if (trace_file_.get() == nullptr) {
741      iovec iov[2];
742      iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
743      iov[0].iov_len = header.length();
744      iov[1].iov_base = buf_.get();
745      iov[1].iov_len = final_offset;
746      Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
747      const bool kDumpTraceInfo = false;
748      if (kDumpTraceInfo) {
749        LOG(INFO) << "Trace sent:\n" << header;
750        DumpBuf(buf_.get(), final_offset, clock_source_);
751      }
752    } else {
753      if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
754          !trace_file_->WriteFully(buf_.get(), final_offset)) {
755        std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
756        PLOG(ERROR) << detail;
757        ThrowRuntimeException("%s", detail.c_str());
758      }
759    }
760  }
761}
762
763void Trace::DexPcMoved(Thread* thread, mirror::Object* this_object,
764                       mirror::ArtMethod* method, uint32_t new_dex_pc) {
765  UNUSED(thread, this_object, method, new_dex_pc);
766  // We're not recorded to listen to this kind of event, so complain.
767  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
768}
769
770void Trace::FieldRead(Thread* thread, mirror::Object* this_object,
771                       mirror::ArtMethod* method, uint32_t dex_pc, ArtField* field)
772    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
773  UNUSED(thread, this_object, method, dex_pc, field);
774  // We're not recorded to listen to this kind of event, so complain.
775  LOG(ERROR) << "Unexpected field read event in tracing " << PrettyMethod(method) << " " << dex_pc;
776}
777
778void Trace::FieldWritten(Thread* thread, mirror::Object* this_object,
779                          mirror::ArtMethod* method, uint32_t dex_pc, ArtField* field,
780                          const JValue& field_value)
781    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
782  UNUSED(thread, this_object, method, dex_pc, field, field_value);
783  // We're not recorded to listen to this kind of event, so complain.
784  LOG(ERROR) << "Unexpected field write event in tracing " << PrettyMethod(method) << " " << dex_pc;
785}
786
787void Trace::MethodEntered(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
788                          mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
789  uint32_t thread_clock_diff = 0;
790  uint32_t wall_clock_diff = 0;
791  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
792  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered,
793                      thread_clock_diff, wall_clock_diff);
794}
795
796void Trace::MethodExited(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
797                         mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED,
798                         const JValue& return_value ATTRIBUTE_UNUSED) {
799  uint32_t thread_clock_diff = 0;
800  uint32_t wall_clock_diff = 0;
801  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
802  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited,
803                      thread_clock_diff, wall_clock_diff);
804}
805
806void Trace::MethodUnwind(Thread* thread, mirror::Object* this_object ATTRIBUTE_UNUSED,
807                         mirror::ArtMethod* method, uint32_t dex_pc ATTRIBUTE_UNUSED) {
808  uint32_t thread_clock_diff = 0;
809  uint32_t wall_clock_diff = 0;
810  ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);
811  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind,
812                      thread_clock_diff, wall_clock_diff);
813}
814
815void Trace::ExceptionCaught(Thread* thread, mirror::Throwable* exception_object)
816    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
817  UNUSED(thread, exception_object);
818  LOG(ERROR) << "Unexpected exception caught event in tracing";
819}
820
821void Trace::BackwardBranch(Thread* /*thread*/, mirror::ArtMethod* method,
822                           int32_t /*dex_pc_offset*/)
823      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
824  LOG(ERROR) << "Unexpected backward branch event in tracing" << PrettyMethod(method);
825}
826
827void Trace::ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint32_t* wall_clock_diff) {
828  if (UseThreadCpuClock()) {
829    uint64_t clock_base = thread->GetTraceClockBase();
830    if (UNLIKELY(clock_base == 0)) {
831      // First event, record the base time in the map.
832      uint64_t time = thread->GetCpuMicroTime();
833      thread->SetTraceClockBase(time);
834    } else {
835      *thread_clock_diff = thread->GetCpuMicroTime() - clock_base;
836    }
837  }
838  if (UseWallClock()) {
839    *wall_clock_diff = MicroTime() - start_time_;
840  }
841}
842
843bool Trace::RegisterMethod(mirror::ArtMethod* method) {
844  mirror::DexCache* dex_cache = method->GetDexCache();
845  if (dex_cache->GetResolvedMethod(method->GetDexMethodIndex()) != method) {
846    DCHECK(dex_cache->GetResolvedMethod(method->GetDexMethodIndex()) == nullptr);
847    dex_cache->SetResolvedMethod(method->GetDexMethodIndex(), method);
848  }
849  if (seen_methods_.find(dex_cache) == seen_methods_.end()) {
850    seen_methods_.insert(std::make_pair(dex_cache, new DexIndexBitSet()));
851  }
852  DexIndexBitSet* bit_set = seen_methods_.find(dex_cache)->second;
853  if (!(*bit_set)[method->GetDexMethodIndex()]) {
854    bit_set->set(method->GetDexMethodIndex());
855    return true;
856  }
857  return false;
858}
859
860bool Trace::RegisterThread(Thread* thread) {
861  pid_t tid = thread->GetTid();
862  CHECK_LT(0U, static_cast<uint32_t>(tid));
863  CHECK_LT(static_cast<uint32_t>(tid), 65536U);
864
865  if (!(*seen_threads_)[tid]) {
866    seen_threads_->set(tid);
867    return true;
868  }
869  return false;
870}
871
872static std::string GetMethodLine(mirror::ArtMethod* method)
873    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
874  return StringPrintf("%p\t%s\t%s\t%s\t%s\n", method,
875      PrettyDescriptor(method->GetDeclaringClassDescriptor()).c_str(), method->GetName(),
876      method->GetSignature().ToString().c_str(), method->GetDeclaringClassSourceFile());
877}
878
879void Trace::WriteToBuf(const uint8_t* src, size_t src_size) {
880  int32_t old_offset = cur_offset_.LoadRelaxed();
881  int32_t new_offset = old_offset + static_cast<int32_t>(src_size);
882  if (dchecked_integral_cast<size_t>(new_offset) > buffer_size_) {
883    // Flush buffer.
884    if (!trace_file_->WriteFully(buf_.get(), old_offset)) {
885      PLOG(WARNING) << "Failed streaming a tracing event.";
886    }
887
888    // Check whether the data is too large for the buffer, then write immediately.
889    if (src_size >= buffer_size_) {
890      if (!trace_file_->WriteFully(src, src_size)) {
891        PLOG(WARNING) << "Failed streaming a tracing event.";
892      }
893      cur_offset_.StoreRelease(0);  // Buffer is empty now.
894      return;
895    }
896
897    old_offset = 0;
898    new_offset = static_cast<int32_t>(src_size);
899  }
900  cur_offset_.StoreRelease(new_offset);
901  // Fill in data.
902  memcpy(buf_.get() + old_offset, src, src_size);
903}
904
905void Trace::LogMethodTraceEvent(Thread* thread, mirror::ArtMethod* method,
906                                instrumentation::Instrumentation::InstrumentationEvent event,
907                                uint32_t thread_clock_diff, uint32_t wall_clock_diff) {
908  // Advance cur_offset_ atomically.
909  int32_t new_offset;
910  int32_t old_offset = 0;
911
912  // We do a busy loop here trying to acquire the next offset.
913  if (trace_output_mode_ != TraceOutputMode::kStreaming) {
914    do {
915      old_offset = cur_offset_.LoadRelaxed();
916      new_offset = old_offset + GetRecordSize(clock_source_);
917      if (static_cast<size_t>(new_offset) > buffer_size_) {
918        overflow_ = true;
919        return;
920      }
921    } while (!cur_offset_.CompareExchangeWeakSequentiallyConsistent(old_offset, new_offset));
922  }
923
924  TraceAction action = kTraceMethodEnter;
925  switch (event) {
926    case instrumentation::Instrumentation::kMethodEntered:
927      action = kTraceMethodEnter;
928      break;
929    case instrumentation::Instrumentation::kMethodExited:
930      action = kTraceMethodExit;
931      break;
932    case instrumentation::Instrumentation::kMethodUnwind:
933      action = kTraceUnroll;
934      break;
935    default:
936      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
937  }
938
939  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
940
941  // Write data
942  uint8_t* ptr;
943  static constexpr size_t kPacketSize = 14U;  // The maximum size of data in a packet.
944  uint8_t stack_buf[kPacketSize];             // Space to store a packet when in streaming mode.
945  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
946    ptr = stack_buf;
947  } else {
948    ptr = buf_.get() + old_offset;
949  }
950
951  Append2LE(ptr, thread->GetTid());
952  Append4LE(ptr + 2, method_value);
953  ptr += 6;
954
955  if (UseThreadCpuClock()) {
956    Append4LE(ptr, thread_clock_diff);
957    ptr += 4;
958  }
959  if (UseWallClock()) {
960    Append4LE(ptr, wall_clock_diff);
961  }
962  static_assert(kPacketSize == 2 + 4 + 4 + 4, "Packet size incorrect.");
963
964  if (trace_output_mode_ == TraceOutputMode::kStreaming) {
965    MutexLock mu(Thread::Current(), *streaming_lock_);  // To serialize writing.
966    if (RegisterMethod(method)) {
967      // Write a special block with the name.
968      std::string method_line(GetMethodLine(method));
969      uint8_t buf2[5];
970      Append2LE(buf2, 0);
971      buf2[2] = kOpNewMethod;
972      Append2LE(buf2 + 3, static_cast<uint16_t>(method_line.length()));
973      WriteToBuf(buf2, sizeof(buf2));
974      WriteToBuf(reinterpret_cast<const uint8_t*>(method_line.c_str()), method_line.length());
975    }
976    if (RegisterThread(thread)) {
977      // It might be better to postpone this. Threads might not have received names...
978      std::string thread_name;
979      thread->GetThreadName(thread_name);
980      uint8_t buf2[7];
981      Append2LE(buf2, 0);
982      buf2[2] = kOpNewThread;
983      Append2LE(buf2 + 3, static_cast<uint16_t>(thread->GetTid()));
984      Append2LE(buf2 + 5, static_cast<uint16_t>(thread_name.length()));
985      WriteToBuf(buf2, sizeof(buf2));
986      WriteToBuf(reinterpret_cast<const uint8_t*>(thread_name.c_str()), thread_name.length());
987    }
988    WriteToBuf(stack_buf, sizeof(stack_buf));
989  }
990}
991
992void Trace::GetVisitedMethods(size_t buf_size,
993                              std::set<mirror::ArtMethod*>* visited_methods) {
994  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
995  uint8_t* end = buf_.get() + buf_size;
996
997  while (ptr < end) {
998    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
999    mirror::ArtMethod* method = DecodeTraceMethodId(tmid);
1000    visited_methods->insert(method);
1001    ptr += GetRecordSize(clock_source_);
1002  }
1003}
1004
1005void Trace::DumpMethodList(std::ostream& os, const std::set<mirror::ArtMethod*>& visited_methods) {
1006  for (const auto& method : visited_methods) {
1007    os << GetMethodLine(method);
1008  }
1009}
1010
1011static void DumpThread(Thread* t, void* arg) {
1012  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
1013  std::string name;
1014  t->GetThreadName(name);
1015  os << t->GetTid() << "\t" << name << "\n";
1016}
1017
1018void Trace::DumpThreadList(std::ostream& os) {
1019  Thread* self = Thread::Current();
1020  for (auto it : exited_threads_) {
1021    os << it.first << "\t" << it.second << "\n";
1022  }
1023  Locks::thread_list_lock_->AssertNotHeld(self);
1024  MutexLock mu(self, *Locks::thread_list_lock_);
1025  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
1026}
1027
1028void Trace::StoreExitingThreadInfo(Thread* thread) {
1029  MutexLock mu(thread, *Locks::trace_lock_);
1030  if (the_trace_ != nullptr) {
1031    std::string name;
1032    thread->GetThreadName(name);
1033    // The same thread/tid may be used multiple times. As SafeMap::Put does not allow to override
1034    // a previous mapping, use SafeMap::Overwrite.
1035    the_trace_->exited_threads_.Overwrite(thread->GetTid(), name);
1036  }
1037}
1038
1039Trace::TraceOutputMode Trace::GetOutputMode() {
1040  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1041  CHECK(the_trace_ != nullptr) << "Trace output mode requested, but no trace currently running";
1042  return the_trace_->trace_output_mode_;
1043}
1044
1045Trace::TraceMode Trace::GetMode() {
1046  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1047  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1048  return the_trace_->trace_mode_;
1049}
1050
1051size_t Trace::GetBufferSize() {
1052  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
1053  CHECK(the_trace_ != nullptr) << "Trace mode requested, but no trace currently running";
1054  return the_trace_->buffer_size_;
1055}
1056
1057}  // namespace art
1058