Use mojo for Chrome Loading, Part 1

content/browser/loader/async_resource_handler.cc

Index: content/browser/loader/async_resource_handler.cc
diff --git a/content/browser/loader/async_resource_handler.cc b/content/browser/loader/async_resource_handler.cc
index 3b3cb0c5b926d0db247ca97f2a391ecd9ec2dc0a..c72ac5c5f20a85b39c94c29a5b5ef88b56807b2c 100644
--- a/content/browser/loader/async_resource_handler.cc
+++ b/content/browser/loader/async_resource_handler.cc
@@ -29,6 +29,7 @@
 #include "content/public/browser/resource_dispatcher_host_delegate.h"
 #include "content/public/common/content_features.h"
 #include "content/public/common/resource_response.h"
+#include "mojo/message_pump/handle_watcher.h"
 #include "net/base/io_buffer.h"
 #include "net/base/load_flags.h"
 #include "net/log/net_log.h"
@@ -191,9 +192,75 @@ class DependentIOBuffer : public net::WrappedIOBuffer {
   scoped_refptr<ResourceBuffer> backing_;
 };
 
-AsyncResourceHandler::AsyncResourceHandler(
-    net::URLRequest* request,
-    ResourceDispatcherHostImpl* rdh)
+class AsyncResourceHandler::MojoHelper final {

[mmenke, 2016/05/23 17:34:53]

Think this class needs some docs

[yhirano, 2016/05/24 06:40:02]

Done.

+ public:
+  explicit MojoHelper(AsyncResourceHandler* owner) : owner_(owner) {}
+
+  void OnResponseStarted() {
+    MojoCreateDataPipeOptions options;
+    options.struct_size = sizeof(MojoCreateDataPipeOptions);
+    options.flags = MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE;
+    options.element_num_bytes = 1;
+    options.capacity_num_bytes = kMaxAllocationSize;
+    mojo::DataPipe data_pipe(options);
+
+    writer_ = std::move(data_pipe.producer_handle);
+    owner_->GetRequestInfo()->InstallBodyReader(
+        std::move(data_pipe.consumer_handle));
+  }
+
+  bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
+                  int* buf_size,
+                  int min_size) {
+    void* buffer = nullptr;
+    uint32_t available = 0;
+    MojoResult result = mojo::BeginWriteDataRaw(
+        writer_.get(), &buffer, &available, MOJO_WRITE_DATA_FLAG_NONE);
+    // Note that we cannot handle SHOULD_WAIT here. It should be handled in
+    // OnReadCompleted.

[mmenke, 2016/05/23 17:34:53]

Avoid "we" in comments.

[yhirano, 2016/05/24 06:40:03]

Done.

+    if (result == MOJO_RESULT_OK) {
+      *buf = new net::WrappedIOBuffer(static_cast<const char*>(buffer));
+      *buf_size = available;
+      return true;
+    }
+    return false;
+  }
+
+  bool OnReadCompleted(int bytes_read, bool* defer) {
+    MojoResult result = mojo::EndWriteDataRaw(writer_.get(), bytes_read);
+    if (result != MOJO_RESULT_OK)
+      return false;
+    void* buffer = nullptr;
+    uint32_t available = 0;
+    // To see if we can continue writing.
+    result = mojo::BeginWriteDataRaw(writer_.get(), &buffer, &available,
+                                     MOJO_WRITE_DATA_FLAG_NONE);
+    if (result == MOJO_RESULT_SHOULD_WAIT ||
+        (result == MOJO_RESULT_OK && available == 0)) {
+      *defer = owner_->did_defer_ = true;
+      owner_->OnDefer();
+      handle_watcher_.Start(
+          writer_.get(), MOJO_HANDLE_SIGNAL_WRITABLE, MOJO_DEADLINE_INDEFINITE,
+          base::Bind(&MojoHelper::OnWritable, base::Unretained(this)));
+    }
+    if (result == MOJO_RESULT_OK)
+      mojo::EndWriteDataRaw(writer_.get(), 0);
+    return true;
+  }
+
+ private:
+  void OnWritable(MojoResult result) { owner_->ResumeIfDeferred(); }
+
+  mojo::ScopedDataPipeProducerHandle writer_;
+  mojo::common::HandleWatcher handle_watcher_;
+  AsyncResourceHandler* owner_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoHelper);
+};
+
+AsyncResourceHandler::AsyncResourceHandler(net::URLRequest* request,
+                                           ResourceDispatcherHostImpl* rdh,
+                                           bool using_mojo_data_handle)
     : ResourceHandler(request),
       ResourceMessageDelegate(request),
       rdh_(rdh),
@@ -206,7 +273,8 @@ AsyncResourceHandler::AsyncResourceHandler(
       inlining_helper_(new InliningHelper),
       last_upload_position_(0),
       waiting_for_upload_progress_ack_(false),
-      reported_transfer_size_(0) {
+      reported_transfer_size_(0),
+      mojo_helper_(using_mojo_data_handle ? new MojoHelper(this) : nullptr) {
   InitializeResourceBufferConstants();
 }
 
@@ -355,6 +423,9 @@ bool AsyncResourceHandler::OnResponseStarted(ResourceResponse* response,
 
   response->head.request_start = request()->creation_time();
   response->head.response_start = TimeTicks::Now();
+  if (mojo_helper_)
+    mojo_helper_->OnResponseStarted();
+
   info->filter()->Send(new ResourceMsg_ReceivedResponse(GetRequestID(),
                                                         response->head));
   sent_received_response_msg_ = true;
@@ -396,6 +467,9 @@ bool AsyncResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
   if (!CheckForSufficientResource())
     return false;
 
+  if (mojo_helper_)
+    return mojo_helper_->OnWillRead(buf, buf_size, min_size);

[mmenke, 2016/05/23 17:34:53]

When using the helper, we also send the results over IPC?

[yhirano, 2016/05/24 06:40:03]

No.

+
   // Return early if InliningHelper allocates the buffer, so that we should
   // inline the data into the IPC message without allocating SharedMemory.
   if (inlining_helper_->PrepareInlineBufferIfApplicable(buf, buf_size))
@@ -420,6 +494,9 @@ bool AsyncResourceHandler::OnReadCompleted(int bytes_read, bool* defer) {
   if (!bytes_read)
     return true;
 
+  if (mojo_helper_)
+    return mojo_helper_->OnReadCompleted(bytes_read, defer);
+
   ResourceMessageFilter* filter = GetFilter();
   if (!filter)
     return false;