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mojo/services/tracing/trace_data_sink.cc

+// 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.
+
+#include "mojo/services/tracing/trace_data_sink.h"
+
+#include "base/logging.h"
+#include "mojo/common/data_pipe_utils.h"
+
+using mojo::common::BlockingCopyFromString;
+
+namespace tracing {
+namespace {
+
+const char kStart[] = "{\"traceEvents\":[";
+const char kEnd[] = "]}";
+
+}  // namespace
+
+TraceDataSink::TraceDataSink(mojo::ScopedDataPipeProducerHandle pipe)
+    : pipe_(pipe.Pass()), empty_(true) {
+  BlockingCopyFromString(kStart, pipe_);
+}
+
+TraceDataSink::~TraceDataSink() {
+  if (pipe_.is_valid())
+    Flush();
+  DCHECK(!pipe_.is_valid());
+}
+
+void TraceDataSink::AddChunk(const std::string& json) {
+  if (!empty_)
+    BlockingCopyFromString(",", pipe_);
+  empty_ = false;
+  BlockingCopyFromString(json, pipe_);
+}
+
+void TraceDataSink::Flush() {
+  BlockingCopyFromString(kEnd, pipe_);
+  pipe_.reset();
+}
+
+}  // namespace tracing