Repo created

TMessagesProj/jni/voip/webrtc/base/trace_event/trace_buffer.h

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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.
+
+#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/trace_event/trace_event.h"
+#include "base/trace_event/trace_event_impl.h"
+
+namespace base {
+
+namespace trace_event {
+
+// TraceBufferChunk is the basic unit of TraceBuffer.
+class BASE_EXPORT TraceBufferChunk {
+ public:
+  explicit TraceBufferChunk(uint32_t seq);
+  ~TraceBufferChunk();
+
+  void Reset(uint32_t new_seq);
+  TraceEvent* AddTraceEvent(size_t* event_index);
+  bool IsFull() const { return next_free_ == kTraceBufferChunkSize; }
+
+  uint32_t seq() const { return seq_; }
+  size_t capacity() const { return kTraceBufferChunkSize; }
+  size_t size() const { return next_free_; }
+
+  TraceEvent* GetEventAt(size_t index) {
+    DCHECK(index < size());
+    return &chunk_[index];
+  }
+  const TraceEvent* GetEventAt(size_t index) const {
+    DCHECK(index < size());
+    return &chunk_[index];
+  }
+
+  void EstimateTraceMemoryOverhead(TraceEventMemoryOverhead* overhead);
+
+  // These values must be kept consistent with the numbers of bits of
+  // chunk_index and event_index fields in TraceEventHandle
+  // (in trace_event_impl.h).
+  static const size_t kMaxChunkIndex = (1u << 26) - 1;
+  static const size_t kTraceBufferChunkSize = 64;
+
+ private:
+  size_t next_free_;
+  std::unique_ptr<TraceEventMemoryOverhead> cached_overhead_estimate_;
+  TraceEvent chunk_[kTraceBufferChunkSize];
+  uint32_t seq_;
+};
+
+// TraceBuffer holds the events as they are collected.
+class BASE_EXPORT TraceBuffer {
+ public:
+  virtual ~TraceBuffer() = default;
+
+  virtual std::unique_ptr<TraceBufferChunk> GetChunk(size_t* index) = 0;
+  virtual void ReturnChunk(size_t index,
+                           std::unique_ptr<TraceBufferChunk> chunk) = 0;
+
+  virtual bool IsFull() const = 0;
+  virtual size_t Size() const = 0;
+  virtual size_t Capacity() const = 0;
+  virtual TraceEvent* GetEventByHandle(TraceEventHandle handle) = 0;
+
+  // For iteration. Each TraceBuffer can only be iterated once.
+  virtual const TraceBufferChunk* NextChunk() = 0;
+
+
+  // Computes an estimate of the size of the buffer, including all the retained
+  // objects.
+  virtual void EstimateTraceMemoryOverhead(
+      TraceEventMemoryOverhead* overhead) = 0;
+
+  static TraceBuffer* CreateTraceBufferRingBuffer(size_t max_chunks);
+  static TraceBuffer* CreateTraceBufferVectorOfSize(size_t max_chunks);
+};
+
+// 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_