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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include "base/trace_event/trace_event.h"
#include "base/trace_event/trace_event_impl.h"
#include "base/trace_event/trace_log.h"
#include "base/trace_event/trace_sampling_thread.h"
namespace base {
namespace trace_event {
class TraceBucketData {
public:
TraceBucketData(base::subtle::AtomicWord* bucket,
const char* name,
TraceSampleCallback callback);
~TraceBucketData();
TRACE_EVENT_API_ATOMIC_WORD* bucket;
const char* bucket_name;
TraceSampleCallback callback;
};
TraceSamplingThread::TraceSamplingThread()
: thread_running_(false),
waitable_event_for_testing_(WaitableEvent::ResetPolicy::AUTOMATIC,
WaitableEvent::InitialState::NOT_SIGNALED) {}
TraceSamplingThread::~TraceSamplingThread() {}
void TraceSamplingThread::ThreadMain() {
PlatformThread::SetName("Sampling Thread");
thread_running_ = true;
const int kSamplingFrequencyMicroseconds = 1000;
while (!cancellation_flag_.IsSet()) {
PlatformThread::Sleep(
TimeDelta::FromMicroseconds(kSamplingFrequencyMicroseconds));
GetSamples();
waitable_event_for_testing_.Signal();
}
}
// static
void TraceSamplingThread::DefaultSamplingCallback(
TraceBucketData* bucket_data) {
TRACE_EVENT_API_ATOMIC_WORD category_and_name =
TRACE_EVENT_API_ATOMIC_LOAD(*bucket_data->bucket);
if (!category_and_name)
return;
const char* const combined =
reinterpret_cast<const char* const>(category_and_name);
const char* category_group;
const char* name;
ExtractCategoryAndName(combined, &category_group, &name);
TRACE_EVENT_API_ADD_TRACE_EVENT(
TRACE_EVENT_PHASE_SAMPLE,
TraceLog::GetCategoryGroupEnabled(category_group), name,
trace_event_internal::kGlobalScope, trace_event_internal::kNoId, 0,
NULL, NULL, NULL, NULL, 0);
}
void TraceSamplingThread::GetSamples() {
for (size_t i = 0; i < sample_buckets_.size(); ++i) {
TraceBucketData* bucket_data = &sample_buckets_[i];
bucket_data->callback.Run(bucket_data);
}
}
void TraceSamplingThread::RegisterSampleBucket(
TRACE_EVENT_API_ATOMIC_WORD* bucket,
const char* const name,
TraceSampleCallback callback) {
// Access to sample_buckets_ doesn't cause races with the sampling thread
// that uses the sample_buckets_, because it is guaranteed that
// RegisterSampleBucket is called before the sampling thread is created.
DCHECK(!thread_running_);
sample_buckets_.push_back(TraceBucketData(bucket, name, callback));
}
// static
void TraceSamplingThread::ExtractCategoryAndName(const char* combined,
const char** category,
const char** name) {
*category = combined;
*name = &combined[strlen(combined) + 1];
}
void TraceSamplingThread::Stop() {
cancellation_flag_.Set();
}
void TraceSamplingThread::WaitSamplingEventForTesting() {
waitable_event_for_testing_.Wait();
}
TraceBucketData::TraceBucketData(base::subtle::AtomicWord* bucket,
const char* name,
TraceSampleCallback callback)
: bucket(bucket), bucket_name(name), callback(callback) {}
TraceBucketData::~TraceBucketData() {}
} // namespace trace_event
} // namespace base
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