trace.cc revision 834b394ee759ed31c5371d8093d7cd8cd90014a8 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "trace.h"
18
19#include <sys/uio.h>
20
21#include "base/unix_file/fd_file.h"
22#include "class_linker.h"
23#include "common_throws.h"
24#include "debugger.h"
25#include "dex_file-inl.h"
26#include "instrumentation.h"
27#include "mirror/abstract_method-inl.h"
28#include "mirror/class-inl.h"
29#include "mirror/dex_cache.h"
30#include "mirror/object_array-inl.h"
31#include "mirror/object-inl.h"
32#include "object_utils.h"
33#include "os.h"
34#include "scoped_thread_state_change.h"
35#include "thread.h"
36#include "thread_list.h"
37#if !defined(ART_USE_PORTABLE_COMPILER)
38#include "entrypoints/quick/quick_entrypoints.h"
39#endif
40
41namespace art {
42
43// File format:
44//     header
45//     record 0
46//     record 1
47//     ...
48//
49// Header format:
50//     u4  magic ('SLOW')
51//     u2  version
52//     u2  offset to data
53//     u8  start date/time in usec
54//     u2  record size in bytes (version >= 2 only)
55//     ... padding to 32 bytes
56//
57// Record format v1:
58//     u1  thread ID
59//     u4  method ID | method action
60//     u4  time delta since start, in usec
61//
62// Record format v2:
63//     u2  thread ID
64//     u4  method ID | method action
65//     u4  time delta since start, in usec
66//
67// Record format v3:
68//     u2  thread ID
69//     u4  method ID | method action
70//     u4  time delta since start, in usec
71//     u4  wall time since start, in usec (when clock == "dual" only)
72//
73// 32 bits of microseconds is 70 minutes.
74//
75// All values are stored in little-endian order.
76
77enum TraceAction {
78    kTraceMethodEnter = 0x00,       // method entry
79    kTraceMethodExit = 0x01,        // method exit
80    kTraceUnroll = 0x02,            // method exited by exception unrolling
81    // 0x03 currently unused
82    kTraceMethodActionMask = 0x03,  // two bits
83};
84
85static const char     kTraceTokenChar             = '*';
86static const uint16_t kTraceHeaderLength          = 32;
87static const uint32_t kTraceMagicValue            = 0x574f4c53;
88static const uint16_t kTraceVersionSingleClock    = 2;
89static const uint16_t kTraceVersionDualClock      = 3;
90static const uint16_t kTraceRecordSizeSingleClock = 10;  // using v2
91static const uint16_t kTraceRecordSizeDualClock   = 14;  // using v3 with two timestamps
92
93#if defined(HAVE_POSIX_CLOCKS)
94ProfilerClockSource Trace::default_clock_source_ = kProfilerClockSourceDual;
95#else
96ProfilerClockSource Trace::default_clock_source_ = kProfilerClockSourceWall;
97#endif
98
99Trace* Trace::the_trace_ = NULL;
100
101static mirror::AbstractMethod* DecodeTraceMethodId(uint32_t tmid) {
102  return reinterpret_cast<mirror::AbstractMethod*>(tmid & ~kTraceMethodActionMask);
103}
104
105static TraceAction DecodeTraceAction(uint32_t tmid) {
106  return static_cast<TraceAction>(tmid & kTraceMethodActionMask);
107}
108
109static uint32_t EncodeTraceMethodAndAction(const mirror::AbstractMethod* method,
110                                           TraceAction action) {
111  uint32_t tmid = reinterpret_cast<uint32_t>(method) | action;
112  DCHECK_EQ(method, DecodeTraceMethodId(tmid));
113  return tmid;
114}
115
116void Trace::SetDefaultClockSource(ProfilerClockSource clock_source) {
117#if defined(HAVE_POSIX_CLOCKS)
118  default_clock_source_ = clock_source;
119#else
120  if (clock_source != kProfilerClockSourceWall) {
121    LOG(WARNING) << "Ignoring tracing request to use ";
122  }
123#endif
124}
125
126static uint16_t GetTraceVersion(ProfilerClockSource clock_source) {
127  return (clock_source == kProfilerClockSourceDual) ? kTraceVersionDualClock
128                                                    : kTraceVersionSingleClock;
129}
130
131static uint16_t GetRecordSize(ProfilerClockSource clock_source) {
132  return (clock_source == kProfilerClockSourceDual) ? kTraceRecordSizeDualClock
133                                                    : kTraceRecordSizeSingleClock;
134}
135
136bool Trace::UseThreadCpuClock() {
137  return (clock_source_ == kProfilerClockSourceThreadCpu) ||
138      (clock_source_ == kProfilerClockSourceDual);
139}
140
141bool Trace::UseWallClock() {
142  return (clock_source_ == kProfilerClockSourceWall) ||
143      (clock_source_ == kProfilerClockSourceDual);
144}
145
146static void MeasureClockOverhead(Trace* trace) {
147  if (trace->UseThreadCpuClock()) {
148    ThreadCpuMicroTime();
149  }
150  if (trace->UseWallClock()) {
151    MicroTime();
152  }
153}
154
155static uint32_t GetClockOverhead(Trace* trace) {
156  uint64_t start = ThreadCpuMicroTime();
157
158  for (int i = 4000; i > 0; i--) {
159    MeasureClockOverhead(trace);
160    MeasureClockOverhead(trace);
161    MeasureClockOverhead(trace);
162    MeasureClockOverhead(trace);
163    MeasureClockOverhead(trace);
164    MeasureClockOverhead(trace);
165    MeasureClockOverhead(trace);
166    MeasureClockOverhead(trace);
167  }
168
169  uint64_t elapsed = ThreadCpuMicroTime() - start;
170  return uint32_t (elapsed / 32);
171}
172
173// TODO: put this somewhere with the big-endian equivalent used by JDWP.
174static void Append2LE(uint8_t* buf, uint16_t val) {
175  *buf++ = (uint8_t) val;
176  *buf++ = (uint8_t) (val >> 8);
177}
178
179// TODO: put this somewhere with the big-endian equivalent used by JDWP.
180static void Append4LE(uint8_t* buf, uint32_t val) {
181  *buf++ = (uint8_t) val;
182  *buf++ = (uint8_t) (val >> 8);
183  *buf++ = (uint8_t) (val >> 16);
184  *buf++ = (uint8_t) (val >> 24);
185}
186
187// TODO: put this somewhere with the big-endian equivalent used by JDWP.
188static void Append8LE(uint8_t* buf, uint64_t val) {
189  *buf++ = (uint8_t) val;
190  *buf++ = (uint8_t) (val >> 8);
191  *buf++ = (uint8_t) (val >> 16);
192  *buf++ = (uint8_t) (val >> 24);
193  *buf++ = (uint8_t) (val >> 32);
194  *buf++ = (uint8_t) (val >> 40);
195  *buf++ = (uint8_t) (val >> 48);
196  *buf++ = (uint8_t) (val >> 56);
197}
198
199void Trace::Start(const char* trace_filename, int trace_fd, int buffer_size, int flags,
200                  bool direct_to_ddms) {
201  Thread* self = Thread::Current();
202  {
203    MutexLock mu(self, *Locks::trace_lock_);
204    if (the_trace_ != NULL) {
205      LOG(ERROR) << "Trace already in progress, ignoring this request";
206      return;
207    }
208  }
209  Runtime* runtime = Runtime::Current();
210  runtime->GetThreadList()->SuspendAll();
211
212  // Open trace file if not going directly to ddms.
213  UniquePtr<File> trace_file;
214  if (!direct_to_ddms) {
215    if (trace_fd < 0) {
216      trace_file.reset(OS::OpenFile(trace_filename, true));
217    } else {
218      trace_file.reset(new File(trace_fd, "tracefile"));
219      trace_file->DisableAutoClose();
220    }
221    if (trace_file.get() == NULL) {
222      PLOG(ERROR) << "Unable to open trace file '" << trace_filename << "'";
223      runtime->GetThreadList()->ResumeAll();
224      ScopedObjectAccess soa(self);
225      ThrowRuntimeException("Unable to open trace file '%s'", trace_filename);
226      return;
227    }
228  }
229
230  // Create Trace object.
231  {
232    MutexLock mu(self, *Locks::trace_lock_);
233    if (the_trace_ != NULL) {
234      LOG(ERROR) << "Trace already in progress, ignoring this request";
235    } else {
236      the_trace_ = new Trace(trace_file.release(), buffer_size, flags);
237
238      // Enable count of allocs if specified in the flags.
239      if ((flags && kTraceCountAllocs) != 0) {
240        runtime->SetStatsEnabled(true);
241      }
242
243      runtime->GetInstrumentation()->AddListener(the_trace_,
244                                                 instrumentation::Instrumentation::kMethodEntered |
245                                                 instrumentation::Instrumentation::kMethodExited |
246                                                 instrumentation::Instrumentation::kMethodUnwind);
247    }
248  }
249  runtime->GetThreadList()->ResumeAll();
250}
251
252void Trace::Stop() {
253  Runtime* runtime = Runtime::Current();
254  runtime->GetThreadList()->SuspendAll();
255  Trace* the_trace = NULL;
256  {
257    MutexLock mu(Thread::Current(), *Locks::trace_lock_);
258    if (the_trace_ == NULL) {
259      LOG(ERROR) << "Trace stop requested, but no trace currently running";
260    } else {
261      the_trace = the_trace_;
262      the_trace_ = NULL;
263    }
264  }
265  if (the_trace != NULL) {
266    the_trace->FinishTracing();
267    runtime->GetInstrumentation()->RemoveListener(the_trace,
268                                                  instrumentation::Instrumentation::kMethodEntered |
269                                                  instrumentation::Instrumentation::kMethodExited |
270                                                  instrumentation::Instrumentation::kMethodUnwind);
271    delete the_trace;
272  }
273  runtime->GetThreadList()->ResumeAll();
274}
275
276void Trace::Shutdown() {
277  if (IsMethodTracingActive()) {
278    Stop();
279  }
280}
281
282bool Trace::IsMethodTracingActive() {
283  MutexLock mu(Thread::Current(), *Locks::trace_lock_);
284  return the_trace_ != NULL;
285}
286
287Trace::Trace(File* trace_file, int buffer_size, int flags)
288    : trace_file_(trace_file), buf_(new uint8_t[buffer_size]()), flags_(flags),
289      clock_source_(default_clock_source_), buffer_size_(buffer_size), start_time_(MicroTime()),
290      cur_offset_(0),  overflow_(false) {
291  // Set up the beginning of the trace.
292  uint16_t trace_version = GetTraceVersion(clock_source_);
293  memset(buf_.get(), 0, kTraceHeaderLength);
294  Append4LE(buf_.get(), kTraceMagicValue);
295  Append2LE(buf_.get() + 4, trace_version);
296  Append2LE(buf_.get() + 6, kTraceHeaderLength);
297  Append8LE(buf_.get() + 8, start_time_);
298  if (trace_version >= kTraceVersionDualClock) {
299    uint16_t record_size = GetRecordSize(clock_source_);
300    Append2LE(buf_.get() + 16, record_size);
301  }
302
303  // Update current offset.
304  cur_offset_ = kTraceHeaderLength;
305}
306
307static void DumpBuf(uint8_t* buf, size_t buf_size, ProfilerClockSource clock_source)
308    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
309  uint8_t* ptr = buf + kTraceHeaderLength;
310  uint8_t* end = buf + buf_size;
311
312  while (ptr < end) {
313    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
314    mirror::AbstractMethod* method = DecodeTraceMethodId(tmid);
315    TraceAction action = DecodeTraceAction(tmid);
316    LOG(INFO) << PrettyMethod(method) << " " << static_cast<int>(action);
317    ptr += GetRecordSize(clock_source);
318  }
319}
320
321void Trace::FinishTracing() {
322  // Compute elapsed time.
323  uint64_t elapsed = MicroTime() - start_time_;
324
325  size_t final_offset = cur_offset_;
326  uint32_t clock_overhead = GetClockOverhead(this);
327
328  if ((flags_ & kTraceCountAllocs) != 0) {
329    Runtime::Current()->SetStatsEnabled(false);
330  }
331
332  std::set<mirror::AbstractMethod*> visited_methods;
333  GetVisitedMethods(final_offset, &visited_methods);
334
335  std::ostringstream os;
336
337  os << StringPrintf("%cversion\n", kTraceTokenChar);
338  os << StringPrintf("%d\n", GetTraceVersion(clock_source_));
339  os << StringPrintf("data-file-overflow=%s\n", overflow_ ? "true" : "false");
340  if (UseThreadCpuClock()) {
341    if (UseWallClock()) {
342      os << StringPrintf("clock=dual\n");
343    } else {
344      os << StringPrintf("clock=thread-cpu\n");
345    }
346  } else {
347    os << StringPrintf("clock=wall\n");
348  }
349  os << StringPrintf("elapsed-time-usec=%llu\n", elapsed);
350  size_t num_records = (final_offset - kTraceHeaderLength) / GetRecordSize(clock_source_);
351  os << StringPrintf("num-method-calls=%zd\n", num_records);
352  os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead);
353  os << StringPrintf("vm=art\n");
354  if ((flags_ & kTraceCountAllocs) != 0) {
355    os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
356    os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));
357    os << StringPrintf("gc-count=%d\n", Runtime::Current()->GetStat(KIND_GC_INVOCATIONS));
358  }
359  os << StringPrintf("%cthreads\n", kTraceTokenChar);
360  DumpThreadList(os);
361  os << StringPrintf("%cmethods\n", kTraceTokenChar);
362  DumpMethodList(os, visited_methods);
363  os << StringPrintf("%cend\n", kTraceTokenChar);
364
365  std::string header(os.str());
366  if (trace_file_.get() == NULL) {
367    iovec iov[2];
368    iov[0].iov_base = reinterpret_cast<void*>(const_cast<char*>(header.c_str()));
369    iov[0].iov_len = header.length();
370    iov[1].iov_base = buf_.get();
371    iov[1].iov_len = final_offset;
372    Dbg::DdmSendChunkV(CHUNK_TYPE("MPSE"), iov, 2);
373    const bool kDumpTraceInfo = false;
374    if (kDumpTraceInfo) {
375      LOG(INFO) << "Trace sent:\n" << header;
376      DumpBuf(buf_.get(), final_offset, clock_source_);
377    }
378  } else {
379    if (!trace_file_->WriteFully(header.c_str(), header.length()) ||
380        !trace_file_->WriteFully(buf_.get(), final_offset)) {
381      std::string detail(StringPrintf("Trace data write failed: %s", strerror(errno)));
382      PLOG(ERROR) << detail;
383      ThrowRuntimeException("%s", detail.c_str());
384    }
385  }
386}
387
388void Trace::DexPcMoved(Thread* thread, mirror::Object* this_object,
389                       const mirror::AbstractMethod* method, uint32_t new_dex_pc) {
390  // We're not recorded to listen to this kind of event, so complain.
391  LOG(ERROR) << "Unexpected dex PC event in tracing " << PrettyMethod(method) << " " << new_dex_pc;
392};
393
394void Trace::MethodEntered(Thread* thread, mirror::Object* this_object,
395                          const mirror::AbstractMethod* method, uint32_t dex_pc) {
396  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodEntered);
397}
398
399void Trace::MethodExited(Thread* thread, mirror::Object* this_object,
400                         const mirror::AbstractMethod* method, uint32_t dex_pc,
401                         const JValue& return_value) {
402  UNUSED(return_value);
403  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodExited);
404}
405
406void Trace::MethodUnwind(Thread* thread, const mirror::AbstractMethod* method, uint32_t dex_pc) {
407  LogMethodTraceEvent(thread, method, instrumentation::Instrumentation::kMethodUnwind);
408}
409
410void Trace::ExceptionCaught(Thread* thread, const ThrowLocation& throw_location,
411                            mirror::AbstractMethod* catch_method, uint32_t catch_dex_pc,
412                            mirror::Throwable* exception_object)
413    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
414  LOG(ERROR) << "Unexpected exception caught event in tracing";
415}
416
417void Trace::LogMethodTraceEvent(Thread* thread, const mirror::AbstractMethod* method,
418                                instrumentation::Instrumentation::InstrumentationEvent event) {
419  // Advance cur_offset_ atomically.
420  int32_t new_offset;
421  int32_t old_offset;
422  do {
423    old_offset = cur_offset_;
424    new_offset = old_offset + GetRecordSize(clock_source_);
425    if (new_offset > buffer_size_) {
426      overflow_ = true;
427      return;
428    }
429  } while (android_atomic_release_cas(old_offset, new_offset, &cur_offset_) != 0);
430
431  TraceAction action = kTraceMethodEnter;
432  switch (event) {
433    case instrumentation::Instrumentation::kMethodEntered:
434      action = kTraceMethodEnter;
435      break;
436    case instrumentation::Instrumentation::kMethodExited:
437      action = kTraceMethodExit;
438      break;
439    case instrumentation::Instrumentation::kMethodUnwind:
440      action = kTraceUnroll;
441      break;
442    default:
443      UNIMPLEMENTED(FATAL) << "Unexpected event: " << event;
444  }
445
446  uint32_t method_value = EncodeTraceMethodAndAction(method, action);
447
448  // Write data
449  uint8_t* ptr = buf_.get() + old_offset;
450  Append2LE(ptr, thread->GetTid());
451  Append4LE(ptr + 2, method_value);
452  ptr += 6;
453
454  if (UseThreadCpuClock()) {
455    // TODO: this isn't vaguely thread safe.
456    SafeMap<Thread*, uint64_t>::iterator it = thread_clock_base_map_.find(thread);
457    uint32_t thread_clock_diff = 0;
458    if (UNLIKELY(it == thread_clock_base_map_.end())) {
459      // First event, the diff is 0, record the base time in the map.
460      uint64_t time = ThreadCpuMicroTime();
461      thread_clock_base_map_.Put(thread, time);
462    } else {
463      uint64_t thread_clock_base = it->second;
464      thread_clock_diff = ThreadCpuMicroTime() - thread_clock_base;
465    }
466    Append4LE(ptr, thread_clock_diff);
467    ptr += 4;
468  }
469  if (UseWallClock()) {
470    uint32_t wall_clock_diff = MicroTime() - start_time_;
471    Append4LE(ptr, wall_clock_diff);
472  }
473}
474
475void Trace::GetVisitedMethods(size_t buf_size,
476                              std::set<mirror::AbstractMethod*>* visited_methods) {
477  uint8_t* ptr = buf_.get() + kTraceHeaderLength;
478  uint8_t* end = buf_.get() + buf_size;
479
480  while (ptr < end) {
481    uint32_t tmid = ptr[2] | (ptr[3] << 8) | (ptr[4] << 16) | (ptr[5] << 24);
482    mirror::AbstractMethod* method = DecodeTraceMethodId(tmid);
483    visited_methods->insert(method);
484    ptr += GetRecordSize(clock_source_);
485  }
486}
487
488void Trace::DumpMethodList(std::ostream& os,
489                           const std::set<mirror::AbstractMethod*>& visited_methods) {
490  typedef std::set<mirror::AbstractMethod*>::const_iterator It;  // TODO: C++0x auto
491  MethodHelper mh;
492  for (It it = visited_methods.begin(); it != visited_methods.end(); ++it) {
493    mirror::AbstractMethod* method = *it;
494    mh.ChangeMethod(method);
495    os << StringPrintf("%p\t%s\t%s\t%s\t%s\n", method,
496        PrettyDescriptor(mh.GetDeclaringClassDescriptor()).c_str(), mh.GetName(),
497        mh.GetSignature().c_str(), mh.GetDeclaringClassSourceFile());
498  }
499}
500
501static void DumpThread(Thread* t, void* arg) {
502  std::ostream& os = *reinterpret_cast<std::ostream*>(arg);
503  std::string name;
504  t->GetThreadName(name);
505  os << t->GetTid() << "\t" << name << "\n";
506}
507
508void Trace::DumpThreadList(std::ostream& os) {
509  Thread* self = Thread::Current();
510  Locks::thread_list_lock_->AssertNotHeld(self);
511  MutexLock mu(self, *Locks::thread_list_lock_);
512  Runtime::Current()->GetThreadList()->ForEach(DumpThread, &os);
513}
514
515}  // namespace art
516