1 // Copyright 2015 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include <stddef.h>
6
7 #include "base/trace_event/trace_event.h"
8 #include "base/trace_event/trace_event_impl.h"
9 #include "base/trace_event/trace_log.h"
10 #include "base/trace_event/trace_sampling_thread.h"
11
12 namespace base {
13 namespace trace_event {
14
15 class TraceBucketData {
16 public:
17 TraceBucketData(base::subtle::AtomicWord* bucket,
18 const char* name,
19 TraceSampleCallback callback);
20 ~TraceBucketData();
21
22 TRACE_EVENT_API_ATOMIC_WORD* bucket;
23 const char* bucket_name;
24 TraceSampleCallback callback;
25 };
26
TraceSamplingThread()27 TraceSamplingThread::TraceSamplingThread()
28 : thread_running_(false),
29 waitable_event_for_testing_(WaitableEvent::ResetPolicy::AUTOMATIC,
30 WaitableEvent::InitialState::NOT_SIGNALED) {}
31
~TraceSamplingThread()32 TraceSamplingThread::~TraceSamplingThread() {}
33
ThreadMain()34 void TraceSamplingThread::ThreadMain() {
35 PlatformThread::SetName("Sampling Thread");
36 thread_running_ = true;
37 const int kSamplingFrequencyMicroseconds = 1000;
38 while (!cancellation_flag_.IsSet()) {
39 PlatformThread::Sleep(
40 TimeDelta::FromMicroseconds(kSamplingFrequencyMicroseconds));
41 GetSamples();
42 waitable_event_for_testing_.Signal();
43 }
44 }
45
46 // static
DefaultSamplingCallback(TraceBucketData * bucket_data)47 void TraceSamplingThread::DefaultSamplingCallback(
48 TraceBucketData* bucket_data) {
49 TRACE_EVENT_API_ATOMIC_WORD category_and_name =
50 TRACE_EVENT_API_ATOMIC_LOAD(*bucket_data->bucket);
51 if (!category_and_name)
52 return;
53 const char* const combined =
54 reinterpret_cast<const char* const>(category_and_name);
55 const char* category_group;
56 const char* name;
57 ExtractCategoryAndName(combined, &category_group, &name);
58 TRACE_EVENT_API_ADD_TRACE_EVENT(
59 TRACE_EVENT_PHASE_SAMPLE,
60 TraceLog::GetCategoryGroupEnabled(category_group), name,
61 trace_event_internal::kGlobalScope, trace_event_internal::kNoId, 0,
62 NULL, NULL, NULL, NULL, 0);
63 }
64
GetSamples()65 void TraceSamplingThread::GetSamples() {
66 for (size_t i = 0; i < sample_buckets_.size(); ++i) {
67 TraceBucketData* bucket_data = &sample_buckets_[i];
68 bucket_data->callback.Run(bucket_data);
69 }
70 }
71
RegisterSampleBucket(TRACE_EVENT_API_ATOMIC_WORD * bucket,const char * const name,TraceSampleCallback callback)72 void TraceSamplingThread::RegisterSampleBucket(
73 TRACE_EVENT_API_ATOMIC_WORD* bucket,
74 const char* const name,
75 TraceSampleCallback callback) {
76 // Access to sample_buckets_ doesn't cause races with the sampling thread
77 // that uses the sample_buckets_, because it is guaranteed that
78 // RegisterSampleBucket is called before the sampling thread is created.
79 DCHECK(!thread_running_);
80 sample_buckets_.push_back(TraceBucketData(bucket, name, callback));
81 }
82
83 // static
ExtractCategoryAndName(const char * combined,const char ** category,const char ** name)84 void TraceSamplingThread::ExtractCategoryAndName(const char* combined,
85 const char** category,
86 const char** name) {
87 *category = combined;
88 *name = &combined[strlen(combined) + 1];
89 }
90
Stop()91 void TraceSamplingThread::Stop() {
92 cancellation_flag_.Set();
93 }
94
WaitSamplingEventForTesting()95 void TraceSamplingThread::WaitSamplingEventForTesting() {
96 waitable_event_for_testing_.Wait();
97 }
98
TraceBucketData(base::subtle::AtomicWord * bucket,const char * name,TraceSampleCallback callback)99 TraceBucketData::TraceBucketData(base::subtle::AtomicWord* bucket,
100 const char* name,
101 TraceSampleCallback callback)
102 : bucket(bucket), bucket_name(name), callback(callback) {}
103
~TraceBucketData()104 TraceBucketData::~TraceBucketData() {}
105
106 } // namespace trace_event
107 } // namespace base
108