Refactor the socket API to remove onEvent callback in socket.create() function.

chrome/browser/extensions/api/socket/tcp_socket.cc

Index: chrome/browser/extensions/api/socket/tcp_socket.cc
diff --git a/chrome/browser/extensions/api/socket/tcp_socket.cc b/chrome/browser/extensions/api/socket/tcp_socket.cc
index cde2685a043646dd2e390ba2928748919a77fd6d..11c6941b9f0246bd26d7696db683dde536336dee 100644
--- a/chrome/browser/extensions/api/socket/tcp_socket.cc
+++ b/chrome/browser/extensions/api/socket/tcp_socket.cc
@@ -38,23 +38,37 @@ TCPSocket::~TCPSocket() {
   }
 }
 
-int TCPSocket::Connect(const std::string& address, int port) {
-  if (is_connected_)
-    return net::ERR_CONNECTION_FAILED;
-
-  net::AddressList address_list;
-  if (!StringAndPortToAddressList(address, port, &address_list))
-    return net::ERR_INVALID_ARGUMENT;
-
-  socket_.reset(new net::TCPClientSocket(address_list, NULL,
-                                         net::NetLog::Source()));
-
-  int result = socket_->Connect(base::Bind(
-      &TCPSocket::OnConnect, base::Unretained(this)));
-  if (result == net::OK) {
-    is_connected_ = true;
+void TCPSocket::Connect(const std::string& address,
+                        int port,
+                        const CompletionCallback& callback) {
+  DCHECK(!callback.is_null());
+
+  if (!connect_callback_.is_null()) {
+    callback.Run(net::ERR_CONNECTION_FAILED);
+    return;
   }
-  return result;
+  connect_callback_ = callback;
+
+  int result = net::ERR_CONNECTION_FAILED;
+  do {
+    if (is_connected_)
+      break;
+
+    net::AddressList address_list;
+    if (!StringAndPortToAddressList(address, port, &address_list)) {
+      result = net::ERR_ADDRESS_INVALID;
+      break;
+    }
+
+    socket_.reset(new net::TCPClientSocket(address_list, NULL,
+                                           net::NetLog::Source()));
+    connect_callback_ = callback;
+    result = socket_->Connect(base::Bind(
+        &TCPSocket::OnConnectComplete, base::Unretained(this)));
+  } while (false);
+
+  if (result != net::ERR_IO_PENDING)
+    OnConnectComplete(result);
 }
 
 void TCPSocket::Disconnect() {
@@ -67,42 +81,102 @@ int TCPSocket::Bind(const std::string& address, int port) {
   return net::ERR_FAILED;
 }
 
-int TCPSocket::Read(scoped_refptr<net::IOBuffer> io_buffer, int io_buffer_len) {
-  if (!socket_.get() || !socket_->IsConnected())
-    return net::ERR_SOCKET_NOT_CONNECTED;
+void TCPSocket::Read(int count,
+                     const ReadCompletionCallback& callback) {
+  DCHECK(!callback.is_null());
+
+  if (!read_callback_.is_null()) {
+    callback.Run(net::ERR_TRY_AGAIN, NULL);

[agl, 2012/05/04 16:52:17]

In net/ there is a convention that functions that take a callback either perform
their action without blocking (and return a status), or return ERR_IO_PENDING.
ERR_IO_PENDING means that the callback will be made at a later time.

Here, it appears that the callback is always called. This means that the
callback will hairpin, which is typically error-prone and avoiding hairpins is
the reason for the ERR_IO_PENDING pattern in net/.

But since this code is outside of net/, and written in a different discipline, I
don't feel that adding a new error code is appropriate. In net/ we would DCHECK
this condition. If that's not appropriate here then I think ERR_IO_PENDING is
probably the best, small change.

However, I would urge you to consider following the net/ calling discipline if
possible. It will likely save you headaches in the future.

+    return;
+  } else {
+    read_callback_ = callback;
+  }
 
-  return socket_->Read(
-      io_buffer.get(),
-      io_buffer_len,
-      base::Bind(&Socket::OnDataRead, base::Unretained(this), io_buffer,
-          static_cast<net::IPEndPoint*>(NULL)));
+  int result = net::ERR_FAILED;
+  scoped_refptr<net::IOBuffer> io_buffer;
+  do {
+    if (count < 0) {
+      result = net::ERR_INVALID_ARGUMENT;
+      break;
+    }
+
+    if (!socket_.get() || !socket_->IsConnected()) {
+        result = net::ERR_SOCKET_NOT_CONNECTED;
+        break;
+    }
+
+    io_buffer = new net::IOBuffer(count);
+    result = socket_->Read(io_buffer.get(), count,
+        base::Bind(&TCPSocket::OnReadComplete, base::Unretained(this),
+            io_buffer));
+  } while (false);
+
+  if (result != net::ERR_IO_PENDING)
+    OnReadComplete(io_buffer, result);
 }
 
-int TCPSocket::Write(scoped_refptr<net::IOBuffer> io_buffer, int byte_count) {
-  if (!socket_.get() || !socket_->IsConnected())
-    return net::ERR_SOCKET_NOT_CONNECTED;
+void TCPSocket::Write(scoped_refptr<net::IOBuffer> io_buffer,
+                      int byte_count,
+                      const CompletionCallback& callback) {
+  DCHECK(!callback.is_null());
+
+  if (!write_callback_.is_null()) {
+    // TODO(penghuang): Put requests in a pending queue to support multiple
+    // write calls.
+    callback.Run(net::ERR_TRY_AGAIN);
+    return;
+  } else {
+    write_callback_ = callback;
+  }
+
+  int result = net::ERR_FAILED;
+  do {
+    if (!socket_.get() || !socket_->IsConnected()) {
+      result = net::ERR_SOCKET_NOT_CONNECTED;
+      break;
+    }
 
-  return socket_->Write(
-      io_buffer.get(), byte_count,
-      base::Bind(&Socket::OnWriteComplete, base::Unretained(this)));
+    result = socket_->Write(
+        io_buffer.get(), byte_count,
+        base::Bind(&TCPSocket::OnWriteComplete, base::Unretained(this)));
+  } while (false);
+
+  if (result != net::ERR_IO_PENDING)
+    OnWriteComplete(result);
 }
 
-int TCPSocket::RecvFrom(scoped_refptr<net::IOBuffer> io_buffer,
-                        int io_buffer_len,
-                        net::IPEndPoint* address) {
-  return net::ERR_FAILED;
+void TCPSocket::RecvFrom(int count,
+                         const RecvFromCompletionCallback& callback) {
+  callback.Run(net::ERR_FAILED, NULL, NULL, 0);
 }
 
-int TCPSocket::SendTo(scoped_refptr<net::IOBuffer> io_buffer,
-                      int byte_count,
-                      const std::string& address,
-                      int port) {
-  return net::ERR_FAILED;
+void TCPSocket::SendTo(scoped_refptr<net::IOBuffer> io_buffer,
+                       int byte_count,
+                       const std::string& address,
+                       int port,
+                       const CompletionCallback& callback) {
+  callback.Run(net::ERR_FAILED);
 }
 
-void TCPSocket::OnConnect(int result) {
+void TCPSocket::OnConnectComplete(int result) {
+  DCHECK(!connect_callback_.is_null());
+  DCHECK(!is_connected_);
   is_connected_ = result == net::OK;
-  event_notifier()->OnConnectComplete(result);
+  connect_callback_.Run(result);
+  connect_callback_.Reset();
+}
+
+void TCPSocket::OnReadComplete(scoped_refptr<net::IOBuffer> io_buffer,
+                               int result) {
+  DCHECK(!read_callback_.is_null());
+  read_callback_.Run(result, io_buffer);
+  read_callback_.Reset();
+}
+
+void TCPSocket::OnWriteComplete(int result) {
+  DCHECK(!write_callback_.is_null());
+  write_callback_.Run(result);
+  write_callback_.Reset();
 }
 
 }  // namespace extensions