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// Copyright 2015 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_TRACE_BUFFER_H_
#define BASE_TRACE_EVENT_TRACE_BUFFER_H_
#include <stddef.h>
#include <stdint.h>
#include "base/base_export.h"
#include "base/check.h"
#include "base/functional/callback.h"
namespace base {
namespace trace_event {
// TraceResultBuffer collects and converts trace fragments returned by TraceLog
// to JSON output.
class BASE_EXPORT TraceResultBuffer {
public:
using OutputCallback = base::RepeatingCallback<void(const std::string&)>;
// If you don't need to stream JSON chunks out efficiently, and just want to
// get a complete JSON string after calling Finish, use this struct to collect
// JSON trace output.
struct BASE_EXPORT SimpleOutput {
OutputCallback GetCallback();
void Append(const std::string& json_string);
// Do what you want with the json_output_ string after calling
// TraceResultBuffer::Finish.
std::string json_output;
};
TraceResultBuffer();
~TraceResultBuffer();
// Set callback. The callback will be called during Start with the initial
// JSON output and during AddFragment and Finish with following JSON output
// chunks. The callback target must live past the last calls to
// TraceResultBuffer::Start/AddFragment/Finish.
void SetOutputCallback(OutputCallback json_chunk_callback);
// Start JSON output. This resets all internal state, so you can reuse
// the TraceResultBuffer by calling Start.
void Start();
// Call AddFragment 0 or more times to add trace fragments from TraceLog.
void AddFragment(const std::string& trace_fragment);
// When all fragments have been added, call Finish to complete the JSON
// formatted output.
void Finish();
private:
OutputCallback output_callback_;
bool append_comma_;
};
} // namespace trace_event
} // namespace base
#endif // BASE_TRACE_EVENT_TRACE_BUFFER_H_
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