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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TRACE_EVENT_AUTO_OPEN_CLOSE_EVENT_H_
#define BASE_TRACE_EVENT_AUTO_OPEN_CLOSE_EVENT_H_
#include "base/check.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
namespace base {
namespace trace_event {
// Class for tracing events that support "auto-opening" and "auto-closing".
// "auto-opening" = if the trace event is started (call Begin() before
// tracing is started,the trace event will be opened, with the start time
// being the time that the trace event was actually started.
// "auto-closing" = if the trace event is started but not ended by the time
// tracing ends, then the trace event will be automatically closed at the
// end of tracing.
// |category| must be known at compile-time in order to be used in trace macros.
// Hence, it's passed as a class templace argument.
template <const char* category>
class AutoOpenCloseEvent : public TraceLog::AsyncEnabledStateObserver {
public:
enum Type { kAsync };
// As in the rest of the tracing macros, the const char* arguments here
// must be pointers to indefinitely lived strings (e.g. hard-coded string
// literals are okay, but not strings created by c_str())
AutoOpenCloseEvent(Type type, const char* event_name)
: event_name_(event_name) {
base::trace_event::TraceLog::GetInstance()->AddAsyncEnabledStateObserver(
weak_factory_.GetWeakPtr());
}
AutoOpenCloseEvent(const AutoOpenCloseEvent&) = delete;
AutoOpenCloseEvent& operator=(const AutoOpenCloseEvent&) = delete;
~AutoOpenCloseEvent() override {
DCHECK(thread_checker_.CalledOnValidThread());
base::trace_event::TraceLog::GetInstance()->RemoveAsyncEnabledStateObserver(
this);
}
void Begin() {
DCHECK(thread_checker_.CalledOnValidThread());
start_time_ = TRACE_TIME_TICKS_NOW();
TRACE_EVENT_ASYNC_BEGIN_WITH_TIMESTAMP0(
category, event_name_, static_cast<void*>(this), start_time_);
}
void End() {
DCHECK(thread_checker_.CalledOnValidThread());
TRACE_EVENT_ASYNC_END0(category, event_name_, static_cast<void*>(this));
start_time_ = base::TimeTicks();
}
// AsyncEnabledStateObserver implementation
void OnTraceLogEnabled() override {
DCHECK(thread_checker_.CalledOnValidThread());
if (!start_time_.is_null()) {
TRACE_EVENT_ASYNC_BEGIN_WITH_TIMESTAMP0(
category, event_name_, static_cast<void*>(this), start_time_);
}
}
void OnTraceLogDisabled() override {}
private:
const char* const event_name_;
base::TimeTicks start_time_;
base::ThreadChecker thread_checker_;
WeakPtrFactory<AutoOpenCloseEvent> weak_factory_{this};
};
} // namespace trace_event
} // namespace base
#endif // BASE_TRACE_EVENT_AUTO_OPEN_CLOSE_EVENT_H_
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