Implement content::WebSocketBlobSender

content/browser/renderer_host/websocket_blob_sender.h

+// Copyright 2016 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_WEBSOCKET_BLOB_SENDER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_WEBSOCKET_BLOB_SENDER_H_
+
+#include <stdint.h>
+#include <iosfwd>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/common/content_export.h"
+#include "net/base/completion_callback.h"
+#include "net/websockets/websocket_event_interface.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace net {
+class IOBuffer;
+}
+
+namespace storage {
+class BlobReader;
+class BlobStorageContext;
+class FileSystemContext;
+}
+
+namespace content {
+
+class WebSocketHost;
+
+// Read the contents of a Blob and write it to a WebSocket. Single-use: a new
+// object must be created each time a Blob is sent. Destroying the object
+// cancels all pending operations.
+class CONTENT_EXPORT WebSocketBlobSender final {
+ public:
+  // An abstraction of the WebSocketChannel this object will send frames to.
+  class Channel {
+   public:
+    using ChannelState = net::WebSocketEventInterface::ChannelState;
+
+    Channel() {}
+    virtual ~Channel() {}
+
+    // The currently available quota for sending. It must not decrease without
+    // SendFrame() being called.
+    virtual int GetSendQuota() const = 0;

[dcheng, 2016/01/26 22:09:32]

Can this actually be negative? I'm guessing this is an int because
WebSocketChannel::current_sent_quota_ is ultimately an int too, but it's not
clear to me why that's an int either.

It seems like using uint64_t here would avoid some casts.

[Adam Rice, 2016/01/27 01:52:57]

I changed it to size_t, since that is the direction I want to go in. An amount
of quota larger than the available memory would not make sense.

+
+    // Send a binary frame. |fin| is true for the final frame of the message.
+    // |data| is the contents of the frame. data.size() must be less than
+    // GetSendQuota(). If this call returns CHANNEL_DELETED, WebSocketBlobSender
+    // will assume that it has been deleted and return without calling any
+    // callbacks or accessing any other member data.
+    virtual ChannelState SendFrame(bool fin, const std::vector<char>& data) = 0;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Channel);
+  };
+
+  // |channel| will be destroyed when this object is.
+  explicit WebSocketBlobSender(scoped_ptr<Channel> channel);
+  ~WebSocketBlobSender();
+
+  // Checks that the blob identified by |uuid| exists, has the size
+  // |expected_size| and then starts sending it via |channel_|. Returns
+  // ERR_IO_PENDING to indicate that |callback| will be called later with the
+  // result. net::OK indicates synchronous success. Any other net error code
+  // indicates synchronous failure. This method may result in the destruction of
+  // the channel, in which case |*channel_state| will be set to CHANNEL_DELETED.
+  int Start(const std::string& uuid,
+            uint64_t expected_size,
+            storage::BlobStorageContext* context,
+            storage::FileSystemContext* file_system_context,
+            base::SingleThreadTaskRunner* file_task_runner,
+            net::WebSocketEventInterface::ChannelState* channel_state,
+            const net::CompletionCallback& callback);
+
+  // Sends more data if the object was waiting for quota and the new value of
+  // GetSendQuota() is large enough.
+  void OnNewSendQuota();
+
+  uint64_t expected_size() const { return expected_size_; }
+
+  // ActualSize() should only be called after completion: ie. Start() returned a
+  // value other than ERR_IO_PENDING or |callback_| has been called.
+  uint64_t ActualSize() const;
+
+ private:
+  // State proceeds through READ_SIZE and READ_SIZE_COMPLETE, then
+  // loops WAIT_FOR_QUOTA -> WAIT_FOR_QUOTA_COMPLETE -> READ
+  // -> READ_COMPLETE -> WAIT_FOR_QUOTA until the Blob is completely
+  // sent.
+  enum class State {
+    NONE = 0,
+    READ_SIZE,
+    READ_SIZE_COMPLETE,
+    WAIT_FOR_QUOTA,
+    WAIT_FOR_QUOTA_COMPLETE,
+    READ,
+    READ_COMPLETE,
+  };
+
+  // This is needed to make DCHECK_EQ(), etc. compile.
+  friend std::ostream& operator<<(std::ostream& os, State state);
+
+  void OnReadComplete(int rv);
+  void OnSizeCalculated(int rv);
+  // |channel_state| should point to CHANNEL_ALIVE when called. If it is
+  // CHANNEL_DELETED on return, the object has been deleted.
+  int DoLoop(int result, Channel::ChannelState* channel_state);
+  void DoLoopAsync(int result);
+  int DoReadSize();
+  int DoReadSizeComplete(int result);
+  int DoWaitForQuota();
+  int DoWaitForQuotaComplete();
+  int DoRead();
+  int DoReadComplete(int result, Channel::ChannelState* channel_state);
+
+  State next_state_ = State::NONE;
+  uint64_t expected_size_ = 0;
+  uint64_t bytes_left_ = 0;
+  net::CompletionCallback callback_;
+  scoped_refptr<net::IOBuffer> buffer_;
+  scoped_ptr<storage::BlobReader> reader_;
+  const scoped_ptr<Channel> channel_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebSocketBlobSender);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_WEBSOCKET_BLOB_SENDER_H_