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_; }
+  // TODO(yhirano): These return incorrect values. Remove these from
+  // ReceivedData before enabling Mojo-Loading.
+  int encoded_data_length() const override { return length_; }
+  int encoded_body_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,
+    base::SingleThreadTaskRunner* task_runner)
+    : request_id_(request_id),
+      resource_dispatcher_(resource_dispatcher),
+      handle_(std::move(handle)),
+      has_seen_end_of_data_(!handle_.is_valid()) {
+  handle_watcher_.Start(
+      handle_.get(), MOJO_HANDLE_SIGNAL_READABLE,
+      base::Bind(&URLResponseBodyConsumer::OnReadable, base::Unretained(this)));
+  task_runner->PostTask(
+      FROM_HERE, base::Bind(&URLResponseBodyConsumer::OnReadable, AsWeakPtr(),
+                            MOJO_RESULT_OK));
+}
+
+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_.Cancel();
+}
+
+void URLResponseBodyConsumer::Reclaim(uint32_t size) {
+  MojoResult result = mojo::EndReadDataRaw(handle_.get(), size);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+}
+
+void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
+  if (has_been_cancelled_ || has_seen_end_of_data_)
+    return;
+
+  // TODO(yhirano): Suppress notification when deferred.
+  // TODO(yhirano): Run this operation on the loading task runner.
+  while (!has_been_cancelled_) {
+    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_SHOULD_WAIT)
+      return;
+    if (result == MOJO_RESULT_FAILED_PRECONDITION) {
+      has_seen_end_of_data_ = true;
+      NotifyCompletionIfAppropriate();
+      return;
+    }
+    if (result != MOJO_RESULT_OK) {
+      completion_status_.error_code = net::ERR_FAILED;
+      has_seen_end_of_data_ = true;
+      has_received_completion_ = true;
+      NotifyCompletionIfAppropriate();
+      return;
+    }
+    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)));
+  }
+}
+
+void URLResponseBodyConsumer::NotifyCompletionIfAppropriate() {
+  if (has_been_cancelled_)
+    return;
+  if (!has_received_completion_ || !has_seen_end_of_data_)
+    return;
+  // 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