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// Copyright 2014 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.
#ifndef COMPONENTS_FEEDBACK_TRACING_MANAGER_H_
#define COMPONENTS_FEEDBACK_TRACING_MANAGER_H_
#include <map>
#include <memory>
#include <string>
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/values.h"
namespace base {
class RefCountedString;
}
// Callback used for getting the output of a trace.
typedef base::Callback<void(scoped_refptr<base::RefCountedString> trace_data)>
TraceDataCallback;
// This class is used to manage performance metrics that can be attached to
// feedback reports. This class is a Singleton that is owned by the preference
// system. It should only be created when it is enabled, and should only be
// accessed elsewhere via Get().
//
// When a performance trace is desired, TracingManager::Get()->RequestTrace()
// should be invoked. The TracingManager will then start preparing a zipped
// version of the performance data. That data can then be requested via
// GetTraceData(). When the data is no longer needed, it should be discarded
// via DiscardTraceData().
class TracingManager {
public:
virtual ~TracingManager();
// Create a TracingManager. Can only be called when none exists.
static std::unique_ptr<TracingManager> Create();
// Get the current TracingManager. Returns NULL if one doesn't exist.
static TracingManager* Get();
// Request a trace ending at the current time. If a trace is already being
// collected, the id for that trace is returned.
int RequestTrace();
// Get the trace data for |id|. On success, true is returned, and the data is
// returned via |callback|. Returns false on failure.
bool GetTraceData(int id, const TraceDataCallback& callback);
// Discard the data for trace |id|.
void DiscardTraceData(int id);
private:
TracingManager();
void StartTracing();
void OnTraceDataCollected(
std::unique_ptr<const base::DictionaryValue> metadata,
base::RefCountedString* data);
// ID of the trace that is being collected.
int current_trace_id_;
// Mapping of trace ID to trace data.
std::map<int, scoped_refptr<base::RefCountedString> > trace_data_;
// Callback for the current trace request.
TraceDataCallback trace_callback_;
base::WeakPtrFactory<TracingManager> weak_ptr_factory_{this};
DISALLOW_COPY_AND_ASSIGN(TracingManager);
};
#endif // COMPONENTS_FEEDBACK_TRACING_MANAGER_H_