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

google_apis/gcm/base/socket_stream.cc

+// 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.
+
+#include "google_apis/gcm/base/socket_stream.h"
+
+#include "base/callback.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/socket/stream_socket.h"
+
+namespace gcm {
+
+// TODO(zea): consider having dynamically sized buffers if this becomes too
+// expensive.
+const uint32 kDefaultBufferSize = 8*1024;
+
+SocketInputStream::SocketInputStream(net::StreamSocket* socket)
+    : socket_(socket),
+      io_buffer_(new net::IOBufferWithSize(kDefaultBufferSize)),
+      drainable_io_buffer_(new net::DrainableIOBuffer(io_buffer_.get(),
+                                                      io_buffer_->size())),
+      buffer_read_pos_(0),
+      buffer_write_pos_(0),
+      backup_bytes_(0),
+      skipped_bytes_(0),
+      last_error_(net::OK),
+      state_(EMPTY),
+      weak_ptr_factory_(this) {
+  DCHECK(socket->IsConnected());
+}
+
+SocketInputStream::~SocketInputStream() {
+}
+
+bool SocketInputStream::Next(const void** data, int* size) {
+  DCHECK_NE(state_, CLOSED);
+  DCHECK_NE(state_, READING);
+
+  if (state_ == EMPTY) {
+    DVLOG(1) << "No unread data remaining, ending read.";
+    return false;
+  }
+
+  if (backup_bytes_ > 0) {
+    *size = backup_bytes_;
+    *data = io_buffer_->data() + buffer_read_pos_ - backup_bytes_;
+    backup_bytes_ = 0;
+    DCHECK_GT(*size, 0);
+    DVLOG(1) << "Consuming " << *size << " bytes in input buffer.";
+    if (backup_bytes_ == 0 && buffer_read_pos_ == buffer_write_pos_)
+      state_ = EMPTY;
+    return true;
+  }
+
+  DCHECK_EQ(state_, READY)
+      << " Input stream must have pending data before reading.";
+  DCHECK_NE(buffer_write_pos_, buffer_read_pos_);
+  *data = io_buffer_->data() + buffer_read_pos_;
+  *size = buffer_write_pos_ - buffer_read_pos_;
+  buffer_read_pos_ = buffer_write_pos_;
+  state_ = EMPTY;
+  DVLOG(1) << "Consuming " << *size << " bytes in input buffer.";
+  return true;
+}
+
+void SocketInputStream::BackUp(int count) {
+  DCHECK(state_ == READY || state_ == EMPTY);
+  DCHECK_GE(backup_bytes_, 0);
+  DCHECK_LE(backup_bytes_, buffer_read_pos_);
+  DCHECK_EQ(skipped_bytes_, 0);
+
+  backup_bytes_ += count;
+  state_ = READY;
+  DVLOG(1) << "Backing up " << count << " bytes in input buffer. "
+           << "Current position now at " << buffer_read_pos_ - backup_bytes_
+           << " of " << buffer_write_pos_;
+}
+
+bool SocketInputStream::Skip(int count) {
+  DCHECK_EQ(state_, READY);
+  DCHECK_GT(count, 0);
+  DVLOG(1) << "Skipping " << count << " bytes in stream.";
+
+  if (backup_bytes_ >= count) {
+    // We have more data left over than we're trying to skip.  Just chop it.
+    backup_bytes_ -= count;
+    return true;
+  }
+
+  count -= backup_bytes_;
+  backup_bytes_ = 0;
+  skipped_bytes_ += count;
+  state_ = EMPTY;
+
+  return true;
+}
+
+int64 SocketInputStream::ByteCount() const {
+  DCHECK_NE(state_, CLOSED);
+  DCHECK_NE(state_, READING);
+  return buffer_write_pos_;
+}
+
+void SocketInputStream::Refresh(const base::Closure& callback,
+                                int byte_limit) {
+  DCHECK_NE(state_, CLOSED);
+  DCHECK_NE(state_, READING);
+  DCHECK_GT(byte_limit, 0);
+  DCHECK_LE(byte_limit, drainable_io_buffer_->BytesRemaining());
+
+  if (buffer_write_pos_ + byte_limit > io_buffer_->size()) {
+    LOG(ERROR) << "Out of buffer space, closing input stream.";
+    CloseStream(net::ERR_UNEXPECTED, callback);
+    return;
+  }
+
+  if (!socket_->IsConnected()) {
+    LOG(ERROR) << "Socket was disconnected, closing input stream";
+    CloseStream(net::ERR_CONNECTION_CLOSED, callback);
+    return;
+  }
+
+  state_ = READING;
+
+  DVLOG(1) << "Refreshing input stream, limit of " << byte_limit << " bytes.";
+  int result = socket_->Read(
+      drainable_io_buffer_,
+      byte_limit,
+      base::Bind(&SocketInputStream::RefreshCompletionCallback,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 callback));
+  DVLOG(1) << "Read returned " << result;
+  if (result != net::ERR_IO_PENDING)
+    RefreshCompletionCallback(callback, result);
+}
+
+void SocketInputStream::RebuildBuffer() {
+  DCHECK_EQ(skipped_bytes_, 0);
+  DVLOG(1) << "Resetting input stream, consumed "
+           << buffer_read_pos_ - backup_bytes_ << " bytes.";
+  DCHECK_NE(state_, READING);
+  DCHECK_NE(state_, CLOSED);
+
+  int last_read_pos = buffer_read_pos_ - backup_bytes_;
+  char* unread_data_ptr = io_buffer_->data() + last_read_pos;
+  int unread_buffer_size = buffer_write_pos_ - last_read_pos;
+  ResetInternal();
+
+  if (unread_buffer_size > 0) {
+    buffer_write_pos_ = unread_buffer_size;
+    drainable_io_buffer_->SetOffset(buffer_write_pos_);
+    state_ = READY;
+
+    if (last_read_pos != 0) {
+      DVLOG(1) << "Have " << buffer_write_pos_
+               << " unread bytes remaining, shifting.";
+      // Move any remaining unread data to the start of the buffer;
+      std::memmove(io_buffer_->data(), unread_data_ptr, buffer_write_pos_);
+    } else {
+      DVLOG(1) << "Have " << buffer_write_pos_ << " unread bytes remaining.";
+    }
+  }
+}
+
+int SocketInputStream::last_error() const {
+  return last_error_;
+}
+
+SocketInputStream::State SocketInputStream::state() const {
+  return state_;
+}
+
+void SocketInputStream::RefreshCompletionCallback(
+    const base::Closure& callback, int result) {
+  DCHECK_EQ(state_, READING);
+  if (state_ == CLOSED) {
+    // An error occured before the completion callback could complete. Ignore
+    // the result.
+    return;
+  }
+
+  if (result < net::OK) {
+    DVLOG(1) << "Failed to refresh socket: " << result;
+    CloseStream(result, callback);
+    return;
+  }
+  DCHECK_GT(result, 0);
+
+  state_ = READY;
+  buffer_write_pos_ += result;
+  int bytes_to_skip = std::min(skipped_bytes_, result);
+  buffer_read_pos_ += bytes_to_skip;
+  skipped_bytes_ = std::max(skipped_bytes_ - result, 0);
+  drainable_io_buffer_->SetOffset(buffer_write_pos_);
+  if (buffer_read_pos_ - backup_bytes_ == buffer_write_pos_)
+    state_ = EMPTY;
+
+  DVLOG(1) << "Refresh complete with " << result << " new bytes. "
+           << "Current position " << buffer_read_pos_ - backup_bytes_
+           << " of " << buffer_write_pos_ << ".";
+
+  if (!callback.is_null()) callback.Run();
+}
+
+void SocketInputStream::ResetInternal() {
+  weak_ptr_factory_.InvalidateWeakPtrs();  // Invalidate any callbacks.
+  buffer_write_pos_ = 0;
+  buffer_read_pos_ = 0;
+  backup_bytes_ = 0;
+  skipped_bytes_ = 0;
+  state_ = EMPTY;
+
+  last_error_ = net::OK;
+
+  // Reset the offset by creating a new one. Note that DrainableIOBuffers don't
+  // actually allocate their own buffer memory like normal IOBuffers. This will
+  // just reset the pointers to point to the beginning of io_buffer_'s data.
+  drainable_io_buffer_ = new net::DrainableIOBuffer(io_buffer_.get(),
+                                                    io_buffer_->size());
+}
+
+void SocketInputStream::CloseStream(int error, const base::Closure& callback) {
+  ResetInternal();
+  state_ = CLOSED;
+  last_error_ = error;
+  LOG(ERROR) << "Closing stream with result " << error;
+  if (!callback.is_null()) callback.Run();
+}
+
+SocketOutputStream::SocketOutputStream(net::StreamSocket* socket)
+    : socket_(socket),
+      io_buffer_(new net::IOBufferWithSize(kDefaultBufferSize)),
+      drainable_io_buffer_(new net::DrainableIOBuffer(io_buffer_.get(),
+                                                      io_buffer_->size())),
+      buffer_used_(0),
+      state_(EMPTY),
+      weak_ptr_factory_(this) {
+  DCHECK(socket->IsConnected());
+}
+
+SocketOutputStream::~SocketOutputStream() {
+}
+
+bool SocketOutputStream::Next(void** data, int* size) {
+  DCHECK_NE(state_, CLOSED);
+  DCHECK_NE(state_, FLUSHING);
+  if (buffer_used_ == io_buffer_->size())
+    return false;
+
+  *data = io_buffer_->data() + buffer_used_;
+  *size = io_buffer_->size() - buffer_used_;
+  buffer_used_ = io_buffer_->size();
+  state_ = READY;
+  return true;
+}
+
+void SocketOutputStream::BackUp(int count) {
+  DCHECK_GE(count, 0);
+  if (count > buffer_used_)
+    buffer_used_ = 0;
+  buffer_used_ -= count;
+  DVLOG(1) << "Backing up " << count << " bytes in output buffer. "
+           << buffer_used_ << " bytes used.";
+}
+
+int64 SocketOutputStream::ByteCount() const {
+  DCHECK_NE(state_, CLOSED);
+  DCHECK_NE(state_, FLUSHING);
+  return buffer_used_;
+}
+
+void SocketOutputStream::Flush(const base::Closure& callback) {
+  DCHECK_EQ(state_, READY);
+  state_ = FLUSHING;
+
+  if (!socket_->IsConnected()) {
+    LOG(ERROR) << "Socket was disconnected, closing output stream";
+    last_error_ = net::ERR_CONNECTION_CLOSED;
+    state_ = CLOSED;
+    if (!callback.is_null()) callback.Run();
+    return;
+  }
+
+  DVLOG(1) << "Flushing " << buffer_used_ << " bytes into socket.";
+  int result = socket_->Write(
+      drainable_io_buffer_,
+      buffer_used_,
+      base::Bind(&SocketOutputStream::FlushCompletionCallback,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 callback));
+  DVLOG(1) << "Write returned " << result;
+  if (result != net::ERR_IO_PENDING)
+    FlushCompletionCallback(callback, result);
+}
+
+SocketOutputStream::State SocketOutputStream::state() const{
+  return state_;
+}
+
+int SocketOutputStream::last_error() const {
+  return last_error_;
+}
+
+void SocketOutputStream::FlushCompletionCallback(
+    const base::Closure& callback, int result) {
+  DCHECK_EQ(state_, FLUSHING);
+  if (result < net::OK) {
+    LOG(ERROR) << "Failed to flush socket.";
+    last_error_ = result;
+    state_ = CLOSED;
+    if (!callback.is_null()) callback.Run();
+    return;
+  }
+
+  state_ = READY;
+  if (drainable_io_buffer_->BytesConsumed() + result < buffer_used_) {
+    DVLOG(1) << "Partial flush complete. Retrying.";
+     // Only a partial write was completed. Flush again to finish the write.
+    drainable_io_buffer_->SetOffset(
+        drainable_io_buffer_->BytesConsumed() + result);
+    Flush(callback);
+    return;
+  }
+
+  DVLOG(1) << "Socket flush complete.";
+  drainable_io_buffer_ = new net::DrainableIOBuffer(io_buffer_.get(),
+                                                    io_buffer_->size());
+  state_ = EMPTY;
+  buffer_used_ = 0;
+  if (!callback.is_null()) callback.Run();
+}
+
+}  // namespace gcm