Use mojo for Chrome Loading, Part 1

content/child/url_response_body_consumer.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/child/url_response_body_consumer.h"
+
+#include "base/bind.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "content/child/resource_dispatcher.h"
+#include "content/common/resource_messages.h"
+#include "content/common/resource_request_completion_status.h"
+#include "content/public/child/request_peer.h"
+
+namespace content {
+
+class URLResponseBodyConsumer::ReceivedData final
+    : public RequestPeer::ReceivedData {
+ public:
+  ReceivedData(const char* payload,
+               int length,
+               scoped_refptr<URLResponseBodyConsumer> consumer)
+      : payload_(payload), length_(length), consumer_(consumer) {}
+
+  ~ReceivedData() override { consumer_->Reclaim(length_); }
+
+  const char* payload() const override { return payload_; }
+  int length() const override { return length_; }
+  int encoded_length() const override { return length_; }
+
+ private:
+  const char* const payload_;
+  const uint32_t length_;
+
+  scoped_refptr<URLResponseBodyConsumer> consumer_;
+
+  DISALLOW_COPY_AND_ASSIGN(ReceivedData);
+};
+
+URLResponseBodyConsumer::URLResponseBodyConsumer(
+    int request_id,
+    ResourceDispatcher* resource_dispatcher,
+    mojo::ScopedDataPipeConsumerHandle handle)
+    : request_id_(request_id),
+      resource_dispatcher_(resource_dispatcher),
+      handle_(std::move(handle)),
+      has_seen_end_of_data_(!handle_.is_valid()) {
+  StartWatching();
+}
+
+URLResponseBodyConsumer::~URLResponseBodyConsumer() {}
+
+void URLResponseBodyConsumer::OnComplete(
+    const ResourceRequestCompletionStatus& status) {
+  if (has_been_cancelled_)
+    return;
+  has_received_completion_ = true;
+  completion_status_ = status;
+  NotifyCompletionIfAppropriate();
+}
+
+void URLResponseBodyConsumer::Cancel() {
+  has_been_cancelled_ = true;
+  handle_watcher_.Stop();
+}
+
+void URLResponseBodyConsumer::Reclaim(uint32_t size) {
+  MojoResult result = mojo::EndReadDataRaw(handle_.get(), size);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+  StartWatching();
+}
+
+void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
+  DCHECK(!has_been_cancelled_);
+
+  // TODO(yhirano): Suppress notification when deferred.
+  // TODO(yhirano): Run this operation on the loading task runner.
+  const void* buffer = nullptr;
+  uint32_t available = 0;
+  MojoResult result = mojo::BeginReadDataRaw(handle_.get(), &buffer, &available,
+                                             MOJO_READ_DATA_FLAG_NONE);
+  if (result == MOJO_RESULT_OK) {
+    ResourceDispatcher::PendingRequestInfo* request_info =
+        resource_dispatcher_->GetPendingRequestInfo(request_id_);
+    DCHECK(request_info);
+    request_info->peer->OnReceivedData(base::WrapUnique(
+        new ReceivedData(static_cast<const char*>(buffer), available, this)));
+    // |this| may be deleted.
+    return;
+  }
+  if (result == MOJO_RESULT_FAILED_PRECONDITION) {
+    has_seen_end_of_data_ = true;
+    NotifyCompletionIfAppropriate();
+    // |this| may be deleted.
+    return;
+  }
+  if (result == MOJO_RESULT_SHOULD_WAIT) {
+    StartWatching();
+    return;
+  }
+  completion_status_.error_code = net::ERR_FAILED;
+  has_seen_end_of_data_ = true;
+  has_received_completion_ = true;
+  NotifyCompletionIfAppropriate();
+  // |this| may be deleted.
+}
+
+void URLResponseBodyConsumer::StartWatching() {
+  if (has_been_cancelled_ || has_seen_end_of_data_)
+    return;
+  handle_watcher_.Start(
+      handle_.get(), MOJO_HANDLE_SIGNAL_READABLE, MOJO_DEADLINE_INDEFINITE,
+      base::Bind(&URLResponseBodyConsumer::OnReadable, base::Unretained(this)));
+}
+
+void URLResponseBodyConsumer::NotifyCompletionIfAppropriate() {
+  if (has_been_cancelled_)
+    return;
+  if (has_received_completion_ && has_seen_end_of_data_) {
+    // Cancel this instance in order not to notify twice.
+    Cancel();
+
+    resource_dispatcher_->OnMessageReceived(
+        ResourceMsg_RequestComplete(request_id_, completion_status_));
+    // |this| may be deleted.
+  }
+}
+
+}  // namespace content