mojo/services/tracing/trace_data_sink.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "mojo/services/tracing/trace_data_sink.h"
   6
   7 #include "base/logging.h"
   8 #include "mojo/common/data_pipe_utils.h"
   9
  10 using mojo::common::BlockingCopyFromString;
  11
  12 namespace tracing {
  13 namespace {
  14
  15 const char kStart[] = "{\"traceEvents\":[";
  16 const char kEnd[] = "]}";
  17
  18 }  // namespace
  19
  20 TraceDataSink::TraceDataSink(mojo::ScopedDataPipeProducerHandle pipe)
  21     : pipe_(pipe.Pass()), empty_(true) {
  22   BlockingCopyFromString(kStart, pipe_);
  23 }
  24
  25 TraceDataSink::~TraceDataSink() {
  26   if (pipe_.is_valid())
  27     Flush();
  28   DCHECK(!pipe_.is_valid());
  29 }
  30
  31 void TraceDataSink::AddChunk(const std::string& json) {
  32   if (!empty_)
  33     BlockingCopyFromString(",", pipe_);
  34   empty_ = false;
  35   BlockingCopyFromString(json, pipe_);
  36 }
  37
  38 void TraceDataSink::Flush() {
  39   BlockingCopyFromString(kEnd, pipe_);
  40   pipe_.reset();
  41 }
  42
  43 }  // namespace tracing