Implement content::WebSocketBlobSender

content/browser/renderer_host/websocket_blob_sender.cc

+// 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.
+
+#include "content/browser/renderer_host/websocket_blob_sender.h"
+
+#include <algorithm>
+#include <ostream>
+#include <utility>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/callback_helpers.h"
+#include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "content/browser/renderer_host/websocket_dispatcher_host.h"
+#include "content/browser/renderer_host/websocket_host.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/websockets/websocket_channel.h"
+#include "net/websockets/websocket_frame.h"
+#include "storage/browser/blob/blob_data_handle.h"
+#include "storage/browser/blob/blob_reader.h"
+#include "storage/browser/blob/blob_storage_context.h"
+
+namespace content {
+
+namespace {
+
+using storage::BlobReader;
+using storage::BlobDataHandle;
+using storage::BlobStorageContext;
+
+// This must be smaller than the send quota high water mark or this class will
+// never send anything.
+const int kMinimumNonFinalFrameSize = 8 * 1024;
+
+// The IOBuffer has a fixed size for simplicity.
+const size_t kBufferSize = 128 * 1024;
+
+}  // namespace
+
+// This is needed to make DCHECK_EQ(), etc. compile.
+std::ostream& operator<<(std::ostream& os, WebSocketBlobSender::State state) {
+  static const char* const kStateStrings[] = {
+      "NONE",
+      "READ_SIZE",
+      "READ_SIZE_COMPLETE",
+      "WAIT_FOR_QUOTA",
+      "WAIT_FOR_QUOTA_COMPLETE",
+      "READ",
+      "READ_COMPLETE",
+  };
+  if (state < WebSocketBlobSender::State::NONE ||
+      state > WebSocketBlobSender::State::READ_COMPLETE) {
+    return os << "Bad State (" << static_cast<int>(state) << ")";
+  }
+  return os << kStateStrings[static_cast<int>(state)];
+}
+
+WebSocketBlobSender::WebSocketBlobSender(scoped_ptr<Channel> channel)
+    : channel_(std::move(channel)) {}
+
+WebSocketBlobSender::~WebSocketBlobSender() {}
+
+int WebSocketBlobSender::Start(
+    const std::string& uuid,
+    uint64_t expected_size,
+    BlobStorageContext* context,
+    storage::FileSystemContext* file_system_context,
+    base::SingleThreadTaskRunner* file_task_runner,
+    net::WebSocketEventInterface::ChannelState* channel_state,
+    const net::CompletionCallback& callback) {
+  DCHECK(context);
+  DCHECK(channel_state);
+  scoped_ptr<storage::BlobDataHandle> data_handle(
+      context->GetBlobDataFromUUID(uuid));
+  if (!data_handle)
+    return net::ERR_INVALID_HANDLE;
+  reader_ = data_handle->CreateReader(file_system_context, file_task_runner);
+  expected_size_ = expected_size;
+  next_state_ = State::READ_SIZE;
+  int rv = DoLoop(net::OK, channel_state);
+  if (*channel_state == net::WebSocketEventInterface::CHANNEL_ALIVE &&
+      rv == net::ERR_IO_PENDING) {
+    callback_ = callback;
+  }
+  return rv;
+}
+
+void WebSocketBlobSender::OnNewSendQuota() {
+  if (next_state_ == State::WAIT_FOR_QUOTA)
+    DoLoopAsync(net::OK);
+  // |this| may be deleted.
+}
+
+uint64_t WebSocketBlobSender::ActualSize() const {
+  return reader_->total_size();
+}
+
+void WebSocketBlobSender::OnReadComplete(int rv) {
+  CHECK_EQ(State::READ_COMPLETE, next_state_);

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

DCHECK_EQ here, line 108, and line 115 (as far as I can tell, this is all driven
by state changes wholly inside the browser process)

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

Done.

+  DoLoopAsync(rv);
+  // |this| may be deleted.
+}
+
+void WebSocketBlobSender::OnSizeCalculated(int rv) {
+  CHECK_EQ(State::READ_SIZE_COMPLETE, next_state_);
+  DoLoopAsync(rv);
+  // |this| may be deleted.
+}
+
+int WebSocketBlobSender::DoLoop(int result,
+                                Channel::ChannelState* channel_state) {
+  CHECK_NE(State::NONE, next_state_);
+  int rv = result;
+  do {
+    State state = next_state_;
+    next_state_ = State::NONE;
+    switch (state) {
+      case State::READ_SIZE:
+        DCHECK_EQ(net::OK, rv);
+        rv = DoReadSize();
+        break;
+
+      case State::READ_SIZE_COMPLETE:
+        rv = DoReadSizeComplete(rv);
+        break;
+
+      case State::WAIT_FOR_QUOTA:
+        DCHECK_EQ(net::OK, rv);
+        rv = DoWaitForQuota();
+        break;
+
+      case State::WAIT_FOR_QUOTA_COMPLETE:
+        DCHECK_EQ(net::OK, rv);
+        rv = DoWaitForQuotaComplete();
+        break;
+
+      case State::READ:
+        DCHECK_EQ(net::OK, rv);
+        rv = DoRead();
+        break;
+
+      case State::READ_COMPLETE:
+        rv = DoReadComplete(rv, channel_state);
+        break;
+
+      default:
+        NOTREACHED();
+        break;
+    }
+  } while (*channel_state != net::WebSocketEventInterface::CHANNEL_DELETED &&
+           rv != net::ERR_IO_PENDING && next_state_ != State::NONE);
+  return rv;
+}
+
+void WebSocketBlobSender::DoLoopAsync(int result) {
+  Channel::ChannelState channel_state =
+      net::WebSocketEventInterface::CHANNEL_ALIVE;
+  int rv = DoLoop(result, &channel_state);
+  if (channel_state == net::WebSocketEventInterface::CHANNEL_ALIVE &&
+      rv != net::ERR_IO_PENDING) {
+    ResetAndReturn(&callback_).Run(rv);
+  }
+  // |this| may be deleted.
+}
+
+int WebSocketBlobSender::DoReadSize() {
+  next_state_ = State::READ_SIZE_COMPLETE;
+  // This use of base::Unretained() is safe because BlobReader cannot call the
+  // callback after it has been destroyed, and it is owned by this object.
+  BlobReader::Status status = reader_->CalculateSize(base::Bind(
+      &WebSocketBlobSender::OnSizeCalculated, base::Unretained(this)));
+  switch (status) {
+    case BlobReader::Status::NET_ERROR:
+      return reader_->net_error();
+
+    case BlobReader::Status::IO_PENDING:
+      return net::ERR_IO_PENDING;
+
+    case BlobReader::Status::DONE:
+      return net::OK;
+  }
+  NOTREACHED();
+  return net::ERR_UNEXPECTED;
+}
+
+int WebSocketBlobSender::DoReadSizeComplete(int result) {
+  if (result < 0)
+    return result;
+  if (reader_->total_size() != expected_size_)
+    return net::ERR_UPLOAD_FILE_CHANGED;
+  bytes_left_ = expected_size_;
+  // The result of the call to std::min() must fit inside a size_t because
+  // kBufferSize is type size_t.
+  size_t buffer_size = static_cast<size_t>(
+      std::min(bytes_left_, base::strict_cast<uint64_t>(kBufferSize)));
+  buffer_ = new net::IOBuffer(buffer_size);
+  next_state_ = State::WAIT_FOR_QUOTA;
+  return net::OK;
+}
+
+// The WAIT_FOR_QUOTA state has a self-edge; it will wait in this state until
+// there is enough quota to send some data.
+int WebSocketBlobSender::DoWaitForQuota() {
+  int quota = channel_->GetSendQuota();
+  if (kMinimumNonFinalFrameSize <= quota ||
+      bytes_left_ <= base::checked_cast<uint64_t>(quota)) {
+    next_state_ = State::WAIT_FOR_QUOTA_COMPLETE;
+    return net::OK;
+  }
+  next_state_ = State::WAIT_FOR_QUOTA;
+  return net::ERR_IO_PENDING;
+}
+
+// State::WAIT_FOR_QUOTA_COMPLETE exists just to give the state machine the
+// expected shape. It should be mostly optimised out.
+int WebSocketBlobSender::DoWaitForQuotaComplete() {
+  next_state_ = State::READ;
+  return net::OK;
+}
+
+int WebSocketBlobSender::DoRead() {
+  next_state_ = State::READ_COMPLETE;
+  uint64_t quota = base::checked_cast<uint64_t>(channel_->GetSendQuota());

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

Ultimately, where does the send quota come from? Is it really OK to kill the
browser process?

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

It comes from net::WebSocketChannel. It's OK in the sense that if this value is
negative you have memory corruption and we can't recover from it. Having said
that, I removed the checked_casts.

+  uint64_t desired_bytes = std::min(bytes_left_, quota);
+
+  // |bytes_to_read| must fit in a size_t because |kBufferSize| is of type
+  // size_t and so cannot be larger than its maximum value. For simplicity this
+  // method only reads as many bytes as are currently needed.
+  size_t bytes_to_read = static_cast<size_t>(
+      std::min(desired_bytes, base::strict_cast<uint64_t>(kBufferSize)));
+  int bytes_read = 0;
+  DCHECK(reader_);
+  DCHECK(buffer_);
+
+  // This use of base::Unretained is safe because the BlobReader object won't
+  // call the callback after it has been destroyed, and it belongs to this
+  // object.
+  BlobReader::Status status = reader_->Read(
+      buffer_.get(), bytes_to_read, &bytes_read,
+      base::Bind(&WebSocketBlobSender::OnReadComplete, base::Unretained(this)));
+
+  switch (status) {
+    case BlobReader::Status::NET_ERROR:
+      return reader_->net_error();
+
+    case BlobReader::Status::IO_PENDING:
+      return net::ERR_IO_PENDING;
+
+    case BlobReader::Status::DONE:
+      return bytes_read;
+  }
+  NOTREACHED();
+  return net::ERR_UNEXPECTED;
+}
+
+int WebSocketBlobSender::DoReadComplete(int result,
+                                        Channel::ChannelState* channel_state) {
+  if (result < 0)
+    return result;
+  DCHECK_GE(channel_->GetSendQuota(), result);
+  uint64_t bytes_read = base::checked_cast<uint64_t>(result);

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

Similar comment to above: it seems like this is the network stack doing this
work.

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

I would expect this checked_cast<> to be optimised out because of the if (result
< 0) expression above. static_cast<> makes me uncomfortable.

Having said that, I changed it.

+  CHECK_GE(bytes_left_, bytes_read);

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

Similarly, I would expect this to be an assert: it should "never" happen.

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

Done.

+  bytes_left_ -= bytes_read;
+  bool fin = bytes_left_ == 0;
+  std::vector<char> data(buffer_->data(), buffer_->data() + bytes_read);
+  DCHECK(fin || data.size() > 0u) << "Non-final frames should be non-empty";
+  *channel_state = channel_->SendFrame(fin, data);
+  if (*channel_state == net::WebSocketEventInterface::CHANNEL_DELETED) {
+    // |this| is deleted.
+    return net::ERR_CONNECTION_RESET;
+  }
+
+  // It is important not to set next_state_ until after the call to SendFrame()
+  // because SendFrame() will sometimes call OnNewSendQuota() synchronously.
+  if (!fin)
+    next_state_ = State::WAIT_FOR_QUOTA;
+  return net::OK;
+}
+
+}  // namespace content