Mojo: WebSocket interface now reuses the DataPipe for subsequent sends or

mojo/services/public/cpp/network/web_socket_read_queue.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/public/cpp/network/web_socket_read_queue.h"
+
+#include "base/bind.h"
+
+namespace mojo {
+
+struct WebSocketReadQueue::Operation {
+  uint32_t num_bytes_;
+  base::Callback<void(const char*)> callback_;
+};
+
+WebSocketReadQueue::WebSocketReadQueue(DataPipeConsumerHandle handle)
+    : handle_(handle), is_waiting_(false) {
+}
+
+WebSocketReadQueue::~WebSocketReadQueue() {
+}
+
+void WebSocketReadQueue::Read(uint32_t num_bytes,
+                              base::Callback<void(const char*)> callback) {
+  Operation* op = new Operation;
+  op->num_bytes_ = num_bytes;
+  op->callback_ = callback;
+  queue_.push_back(op);
+
+  if (!is_waiting_)
+    TryToRead();
+}
+
+void WebSocketReadQueue::TryToRead() {
+  Operation* op = queue_[0];
+  const void* buffer = NULL;
+  uint32_t bytes_read = op->num_bytes_;
+  MojoResult result = BeginReadDataRaw(
+      handle_, &buffer, &bytes_read, MOJO_READ_DATA_FLAG_ALL_OR_NONE);
+  if (result == MOJO_RESULT_SHOULD_WAIT) {
+    EndReadDataRaw(handle_, bytes_read);
+    Wait();
+    return;
+  }
+
+  // Ensure |op| is deleted, whether or not |this| goes away.
+  scoped_ptr<Operation> op_deleter(op);
+  queue_.weak_erase(queue_.begin());
+  if (result != MOJO_RESULT_OK)
+    return;
+  DataPipeConsumerHandle handle = handle_;
+  op->callback_.Run(static_cast<const char*>(buffer));  // may delete |this|
+  EndReadDataRaw(handle, bytes_read);
+}
+
+void WebSocketReadQueue::Wait() {
+  is_waiting_ = true;
+  handle_watcher_.Start(
+      handle_,
+      MOJO_HANDLE_SIGNAL_READABLE,
+      MOJO_DEADLINE_INDEFINITE,
+      base::Bind(&WebSocketReadQueue::OnHandleReady, base::Unretained(this)));
+}
+
+void WebSocketReadQueue::OnHandleReady(MojoResult result) {
+  is_waiting_ = false;
+  TryToRead();
+}
+
+}  // namespace mojo