[GCM] Initial work to set up directory structure and introduce socket integration

google_apis/gcm/base/socket_stream.h

+// Copyright (c) 2013 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.
+//
+// Protobuf ZeroCopy[Input/Output]Stream implementations capable of using a
+// net::StreamSocket. Built to work with Protobuf CodedStreams.
+// Note that any caller must first check the state() of the stream before
+// using it. It is not valid to use a CLOSED stream.
+
+#ifndef GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_
+#define GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "google/protobuf/io/zero_copy_stream.h"
+#include "google_apis/gcm/base/gcm_export.h"
+
+namespace net {
+class DrainableIOBuffer;
+class IOBufferWithSize;
+class StreamSocket;
+}
+
+namespace gcm {
+
+class GCM_EXPORT SocketInputStream

[Ryan Sleevi, 2013/09/25 23:30:24]

style nit: Can you provide a brief description of this class here?

In particular, address comments like does it take ownership of the socket,
what's the right way to use it to read a sample message, etc.

I realize this may be asking for a bit much, but it's good to setup a good
pattern here.

[Nicolas Zea, 2013/10/02 22:56:03]

Added better comments to both input and output stream.

+    : public google::protobuf::io::ZeroCopyInputStream {
+ public:
+  enum State {
+    // No valid data to read. This means the buffer is either empty or all data
+    // in the buffer has already been consumed.
+    EMPTY,
+    // Valid data to read.
+    READY,
+    // In the process of reading new data from the socket.
+    READING,
+    // An permanent error occurred and the stream is now closed.
+    CLOSED,
+  };
+
+  // |socket| should already be connected.
+  explicit SocketInputStream(net::StreamSocket* socket);
+  virtual ~SocketInputStream();
+
+  // ZeroCopyInputStream implementation.
+  virtual bool Next(const void** data, int* size) OVERRIDE;
+  virtual void BackUp(int count) OVERRIDE;
+  virtual bool Skip(int count) OVERRIDE;
+  virtual int64 ByteCount() const OVERRIDE;
+
+  // Reads and appends a max of |byte_limit| bytes onto the read buffer.
+  // |callback| is invoked upon read completion, even if an error was
+  // encountered (state() and ByteCount() must be checked to see if forward
+  // progress was made).
+  void Refresh(const base::Closure& callback, int byte_limit);
+
+  // Rebuilds the buffer state by copying over any unread data to the beginning
+  // of the buffer and resetting the buffer read/write positions.
+  // Note: it is not valid to call Rebuild() if state() == CLOSED. The stream
+  // must be recreated from scratch in such a scenario.
+  void RebuildBuffer();
+
+  // Returns the last fatal error encountered. Only valid if state() == CLOSED.
+  int last_error() const;
+
+  // Returns the current state.
+  State state() const;
+
+ private:
+  // Clears the local state.
+  void ResetInternal();
+
+  // Callback for Socket::Read calls.
+  void RefreshCompletionCallback(const base::Closure& callback, int result);
+
+  // Permanently closes the stream.
+  void CloseStream(int error, const base::Closure& callback);
+
+  // Internal net components.
+  net::StreamSocket* socket_;
+  scoped_refptr<net::IOBufferWithSize> io_buffer_;
+  scoped_refptr<net::DrainableIOBuffer> drainable_io_buffer_;
+
+  // The amount of data within |io_buffer_| that has already been read.
+  int buffer_read_pos_;
+
+  // The amount of data written within |io_buffer_|.
+  int buffer_write_pos_;
+
+  // The number of bytes the stream has been backed up by. These bytes need to
+  // be returned on the subsequent Next(..) call.
+  // 0 <= backup_bytes_ <= buffer_pos_
+  int backup_bytes_;
+
+  // The number of bytes to skip from the next successful refresh.
+  int skipped_bytes_;
+
+  // If < net::OK, the last net error received.
+  int last_error_;
+
+  // The current state.
+  State state_;
+
+  base::WeakPtrFactory<SocketInputStream> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SocketInputStream);
+};
+
+class GCM_EXPORT SocketOutputStream
+    : public google::protobuf::io::ZeroCopyOutputStream {
+ public:
+  enum State {
+    // No valid data yet.
+    EMPTY,
+    // Ready for flushing (some data is present).
+    READY,
+    // In the process of flushing into the socket.
+    FLUSHING,
+    // A permanent error occurred, and the stream is now closed.
+    CLOSED,
+  };
+
+  // |socket| should already be connected.
+  explicit SocketOutputStream(net::StreamSocket* socket);
+  virtual ~SocketOutputStream();
+
+  // ZeroCopyOutputStream implementation.
+  virtual bool Next(void** data, int* size) OVERRIDE;
+  virtual void BackUp(int count) OVERRIDE;
+  virtual int64 ByteCount() const OVERRIDE;
+
+  // Writes the buffer into the Socket.
+  void Flush(const base::Closure& callback);
+
+  // Returns the current state.
+  State state() const;
+
+  // Returns the last fatal error encountered. Only valid if state() == CLOSED.
+  int last_error() const;
+
+ private:
+  void FlushCompletionCallback(const base::Closure& callback, int result);
+
+  // Internal net components.
+  net::StreamSocket* socket_;
+  scoped_refptr<net::IOBufferWithSize> io_buffer_;
+  scoped_refptr<net::DrainableIOBuffer> drainable_io_buffer_;
+
+  // The amount of valid buffer data. This is the amount of data written on the
+  // next call to Flush().
+  int buffer_used_;
+
+  // If < net::OK, the last net error received.
+  int last_error_;
+
+  // The current state.
+  State state_;
+
+  base::WeakPtrFactory<SocketOutputStream> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SocketOutputStream);
+};
+
+}  // namespace gcm
+
+#endif  // GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_