Use mojo for Chrome Loading, Part 1

content/browser/loader/mojo_async_resource_handler.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/loader/mojo_async_resource_handler.h"
+
+#include <utility>
+
+#include "base/command_line.h"
+#include "base/containers/hash_tables.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/time/time.h"
+#include "content/browser/loader/netlog_observer.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
+#include "content/browser/loader/resource_request_info_impl.h"
+#include "content/common/resource_request_completion_status.h"
+#include "content/public/browser/resource_dispatcher_host_delegate.h"
+#include "content/public/common/resource_response.h"
+#include "mojo/public/c/system/data_pipe.h"
+#include "mojo/public/cpp/system/data_pipe.h"
+#include "net/base/io_buffer.h"
+#include "net/base/load_flags.h"
+#include "net/base/mime_sniffer.h"
+#include "net/log/net_log.h"
+#include "net/url_request/redirect_info.h"
+
+namespace content {
+namespace {
+
+int g_allocation_size = MojoAsyncResourceHandler::kDefaultAllocationSize;

[kinuko, 2016/08/03 18:20:07]

nit: add a blank line here?

[yhirano, 2016/08/04 12:50:51]

Done.

+// MimeTypeResourceHandler *implicitly* requires that the buffer size
+// returned from OnWillRead should be larger than certain size.
+// TODO(yhirano): Fix MimeTypeResourceHandler.
+constexpr size_t kMinAllocationSize = 2 * net::kMaxBytesToSniff;
+
+constexpr size_t kMaxChunkSize = 32 * 1024;
+
+void GetNumericArg(const std::string& name, int* result) {
+  const std::string& value =
+      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(name);
+  if (!value.empty())
+    base::StringToInt(value, result);
+}
+
+void InitializeResourceBufferConstants() {
+  static bool did_init = false;
+  if (did_init)
+    return;
+  did_init = true;
+
+  GetNumericArg("resource-buffer-size", &g_allocation_size);
+}
+
+}  // namespace
+
+// This class is for sharing the ownership of a ScopedDataPipeProducerHandle.

[kinuko, 2016/08/03 18:20:07]

nit: maybe this comment could be even more specific, e.g. 'is to share the
ownership of a ... between WriterIOBuffer and MojoAsyncResourceHandler'.

[yhirano, 2016/08/04 12:50:51]

Done.

+class MojoAsyncResourceHandler::SharedWriter final
+    : public base::RefCountedThreadSafe<SharedWriter> {
+ public:
+  explicit SharedWriter(mojo::ScopedDataPipeProducerHandle writer)
+      : writer_(std::move(writer)) {}
+  mojo::DataPipeProducerHandle writer() { return writer_.get(); }
+
+ private:
+  friend class base::RefCountedThreadSafe<SharedWriter>;
+  ~SharedWriter() {}
+
+  const mojo::ScopedDataPipeProducerHandle writer_;
+
+  DISALLOW_COPY_AND_ASSIGN(SharedWriter);
+};
+
+// This class is a IOBuffer subclass for data gotten from a
+// ScopedDataPipeProducerHandle.
+class MojoAsyncResourceHandler::WriterIOBuffer final
+    : public net::IOBufferWithSize {
+ public:
+  // |data| and |size| should be gotten from |writer| via BeginWriteDataRaw.
+  // They will be accesible via IOBuffer methods. As |writer| is stored in this
+  // instance, |data| will be kept valid as long as the following conditions
+  // hold:
+  //  1. |data| is not invalidated via EndWriteDataRaw.
+  //  2. |this| instance is alive.
+  WriterIOBuffer(scoped_refptr<MojoAsyncResourceHandler::SharedWriter> writer,

[kinuko, 2016/08/03 18:20:07]

nit: I guess MojoAsyncResourceHandler:: is not necessary here

[yhirano, 2016/08/04 12:50:51]

Done.

+                 void* data,
+                 size_t size)
+      : net::IOBufferWithSize(static_cast<char*>(data), size),
+        writer_(std::move(writer)) {}
+
+ private:
+  ~WriterIOBuffer() override {
+    // Avoid deleting |data_| in the IOBuffer destructor.
+    data_ = nullptr;
+  }
+
+  // This member is for keeping the writer alive.
+  scoped_refptr<MojoAsyncResourceHandler::SharedWriter> writer_;

[kinuko, 2016/08/03 18:20:07]

ditto

[yhirano, 2016/08/04 12:50:51]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(WriterIOBuffer);
+};
+
+MojoAsyncResourceHandler::MojoAsyncResourceHandler(
+    net::URLRequest* request,
+    ResourceDispatcherHostImpl* rdh,
+    mojo::InterfaceRequest<mojom::URLLoader> mojo_request,
+    mojom::URLLoaderClientPtr url_loader_client)
+    : ResourceHandler(request),
+      rdh_(rdh),
+      binding_(this, std::move(mojo_request)),
+      url_loader_client_(std::move(url_loader_client)) {
+  DCHECK(url_loader_client_);
+  InitializeResourceBufferConstants();
+}
+
+MojoAsyncResourceHandler::~MojoAsyncResourceHandler() {
+  if (has_checked_for_sufficient_resources_)
+    rdh_->FinishedWithResourcesForRequest(request());
+}
+
+bool MojoAsyncResourceHandler::OnRequestRedirected(
+    const net::RedirectInfo& redirect_info,
+    ResourceResponse* response,
+    bool* defer) {
+  // Not implemented.
+  return false;
+}
+
+bool MojoAsyncResourceHandler::OnResponseStarted(ResourceResponse* response,
+                                                 bool* defer) {
+  const ResourceRequestInfoImpl* info = GetRequestInfo();
+
+  if (rdh_->delegate()) {
+    rdh_->delegate()->OnResponseStarted(request(), info->GetContext(),
+                                        response);
+  }
+
+  NetLogObserver::PopulateResponseInfo(request(), response);
+
+  response->head.request_start = request()->creation_time();
+  response->head.response_start = base::TimeTicks::Now();
+  sent_received_response_message_ = true;
+  url_loader_client_->OnReceiveResponse(response->head);
+  return true;
+}
+
+bool MojoAsyncResourceHandler::OnWillStart(const GURL& url, bool* defer) {
+  return true;
+}
+
+bool MojoAsyncResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
+                                          int* buf_size,
+                                          int min_size) {
+  DCHECK_EQ(-1, min_size);
+
+  if (!CheckForSufficientResource())
+    return false;
+
+  if (!shared_writer_) {
+    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 = g_allocation_size;
+    mojo::DataPipe data_pipe(options);
+
+    url_loader_client_->OnStartLoadingResponseBody(
+        std::move(data_pipe.consumer_handle));
+    if (!data_pipe.producer_handle.is_valid())
+      return false;
+
+    shared_writer_ = new SharedWriter(std::move(data_pipe.producer_handle));
+
+    bool defer = false;
+    scoped_refptr<net::IOBufferWithSize> buffer;
+    if (!AllocateBuffer(&buffer, &defer))
+      return false;
+    if (!defer && static_cast<size_t>(buffer->size()) >= kMinAllocationSize) {
+      *buf = buffer_ = buffer;
+      *buf_size = buffer_->size();
+      return true;
+    }
+    if (!defer) {
+      // The allocated buffer is too small.
+      if (EndWrite(0) != MOJO_RESULT_OK)
+        return false;
+    }

[kinuko, 2016/08/04 16:07:02]

nit: I feel merging the above two conditions might make the code slightly easier
to follow

if (!defer) {
  if (buffer->size() >= kMinAllocationSize) {
    // We're ready to read.
    *buf = buffer_ = buffer;
    *buf_size = buffer_->size();
    return true;
  }

  // The allocation buffer is too small, not using buffer
  // in the writer.
  if (EndWrite(0) != OK)
    return false;
}

[yhirano, 2016/08/05 12:21:39]

Done.

+    DCHECK(!is_using_io_buffer_not_from_writer_);
+    is_using_io_buffer_not_from_writer_ = true;

[kinuko, 2016/08/03 18:20:07]

(Hm this flag feels a bit unfortunate...)

[mmenke, 2016/08/03 18:25:57]

I agree - we may want to make this method able to complete asynchronously, and
make this the method that waits instead of OnResponseCompleted.  But that's a
bit enough change that I don't think it belongs in this CL.

[yhirano, 2016/08/04 12:50:51]

+1

[kinuko, 2016/08/04 16:07:02]

Yup, sounds good.

+    buffer_ = new net::IOBufferWithSize(kMinAllocationSize);
+  }
+
+  DCHECK_EQ(0u, buffer_offset_);
+  *buf = buffer_;
+  *buf_size = buffer_->size();
+  return true;
+}
+
+bool MojoAsyncResourceHandler::OnReadCompleted(int bytes_read, bool* defer) {
+  DCHECK_GE(bytes_read, 0);
+  DCHECK(buffer_);
+
+  if (!bytes_read)
+    return true;
+
+  if (is_using_io_buffer_not_from_writer_) {
+    // Couldn't allocate a buffer on the data pipe in OnWillRead.
+    DCHECK_EQ(0u, buffer_bytes_read_);
+    buffer_bytes_read_ = bytes_read;
+    if (!CopyReadData(defer))
+      return false;
+    if (*defer)
+      OnDefer();
+    return true;
+  }
+
+  if (EndWrite(bytes_read) != MOJO_RESULT_OK)
+    return false;
+  // Allocate a buffer for the next OnWillRead call here, because OnWillRead
+  // doesn't have |defer| parameter.
+  if (!AllocateBuffer(&buffer_, defer))
+    return false;
+  if (*defer)
+    OnDefer();
+  return true;
+}
+
+void MojoAsyncResourceHandler::OnDataDownloaded(int bytes_downloaded) {
+  // Not implemented.
+}
+
+void MojoAsyncResourceHandler::FollowRedirect() {
+  NOTIMPLEMENTED();
+}
+
+void MojoAsyncResourceHandler::Cancel() {
+  NOTIMPLEMENTED();
+}
+
+void MojoAsyncResourceHandler::ResumeForTesting() {
+  Resume();
+}
+
+void MojoAsyncResourceHandler::SetAllocationSizeForTesting(size_t size) {
+  g_allocation_size = size;
+}
+
+MojoResult MojoAsyncResourceHandler::BeginWrite(void** data,
+                                                uint32_t* available) {
+  MojoResult result = mojo::BeginWriteDataRaw(
+      shared_writer_->writer(), data, available, MOJO_WRITE_DATA_FLAG_NONE);
+  if (result == MOJO_RESULT_OK)
+    *available = std::min(*available, static_cast<uint32_t>(kMaxChunkSize));
+  return result;
+}
+
+MojoResult MojoAsyncResourceHandler::EndWrite(uint32_t written) {
+  return mojo::EndWriteDataRaw(shared_writer_->writer(), written);
+}
+
+void MojoAsyncResourceHandler::OnResponseCompleted(
+    const net::URLRequestStatus& status,
+    const std::string& security_info,
+    bool* defer) {
+  shared_writer_ = nullptr;
+  buffer_ = nullptr;
+  handle_watcher_.Stop();
+
+  const ResourceRequestInfoImpl* info = GetRequestInfo();
+
+  // TODO(gavinp): Remove this CHECK when we figure out the cause of
+  // http://crbug.com/124680 . This check mirrors closely check in
+  // WebURLLoaderImpl::OnCompletedRequest that routes this message to a WebCore
+  // ResourceHandleInternal which asserts on its state and crashes. By crashing
+  // when the message is sent, we should get better crash reports.
+  CHECK(status.status() != net::URLRequestStatus::SUCCESS ||
+        sent_received_response_message_);
+
+  int error_code = status.error();
+  bool was_ignored_by_handler = info->WasIgnoredByHandler();
+
+  DCHECK_NE(status.status(), net::URLRequestStatus::IO_PENDING);
+  // If this check fails, then we're in an inconsistent state because all
+  // requests ignored by the handler should be canceled (which should result in
+  // the ERR_ABORTED error code).
+  DCHECK(!was_ignored_by_handler || error_code == net::ERR_ABORTED);
+
+  ResourceRequestCompletionStatus request_complete_data;
+  request_complete_data.error_code = error_code;
+  request_complete_data.was_ignored_by_handler = was_ignored_by_handler;
+  request_complete_data.exists_in_cache = request()->response_info().was_cached;
+  request_complete_data.security_info = security_info;
+  request_complete_data.completion_time = base::TimeTicks::Now();
+  request_complete_data.encoded_data_length =
+      request()->GetTotalReceivedBytes();
+
+  url_loader_client_->OnComplete(request_complete_data);
+}
+
+bool MojoAsyncResourceHandler::CopyReadData(bool* defer) {
+  while (true) {
+    scoped_refptr<net::IOBufferWithSize> dest;
+    if (!AllocateBuffer(&dest, defer))
+      return false;
+    if (*defer)
+      return true;
+    if (buffer_bytes_read_ == 0) {
+      // All bytes are copied. Save the buffer for the next OnWillRead call.
+      buffer_ = std::move(dest);
+      return true;
+    }
+
+    size_t copied_size =
+        std::min(buffer_bytes_read_, static_cast<size_t>(dest->size()));
+    memcpy(dest->data(), buffer_->data() + buffer_offset_, copied_size);
+    buffer_offset_ += copied_size;
+    buffer_bytes_read_ -= copied_size;
+    if (EndWrite(copied_size) != MOJO_RESULT_OK)
+      return false;
+
+    if (buffer_bytes_read_ == 0) {
+      // All bytes are copied.
+      buffer_offset_ = 0;
+      is_using_io_buffer_not_from_writer_ = false;
+    }
+  }
+}
+
+bool MojoAsyncResourceHandler::AllocateBuffer(
+    scoped_refptr<net::IOBufferWithSize>* buf,
+    bool* defer) {
+  void* data = nullptr;
+  uint32_t available = 0;
+  MojoResult result = BeginWrite(&data, &available);
+  if (result == MOJO_RESULT_SHOULD_WAIT) {
+    *defer = true;
+    return true;
+  }
+  if (result != MOJO_RESULT_OK)
+    return false;
+  *buf = new WriterIOBuffer(shared_writer_, data, available);
+  return true;
+}
+
+void MojoAsyncResourceHandler::Resume() {
+  bool defer = false;
+  if (is_using_io_buffer_not_from_writer_) {
+    // |buffer_| is set to a net::IOBufferWithSize. Write the buffer contents
+    // to the data pipe.
+    DCHECK_GT(buffer_bytes_read_, 0u);
+    if (!CopyReadData(&defer)) {
+      controller()->CancelWithError(net::ERR_FAILED);
+      return;
+    }
+  } else {
+    // Allocate a buffer for the next OnWillRead call here.
+    if (!AllocateBuffer(&buffer_, &defer)) {
+      controller()->CancelWithError(net::ERR_FAILED);
+      return;
+    }
+  }
+
+  if (defer) {
+    // Continue waiting.
+    handle_watcher_.Start(shared_writer_->writer(), MOJO_HANDLE_SIGNAL_WRITABLE,
+                          MOJO_DEADLINE_INDEFINITE,
+                          base::Bind(&MojoAsyncResourceHandler::OnWritable,
+                                     base::Unretained(this)));
+    return;
+  }
+  request()->LogUnblocked();
+  controller()->Resume();
+}
+
+void MojoAsyncResourceHandler::OnDefer() {
+  request()->LogBlockedBy("MojoAsyncResourceHandler");
+  handle_watcher_.Start(shared_writer_->writer(), MOJO_HANDLE_SIGNAL_WRITABLE,
+                        MOJO_DEADLINE_INDEFINITE,
+                        base::Bind(&MojoAsyncResourceHandler::OnWritable,
+                                   base::Unretained(this)));
+}
+
+bool MojoAsyncResourceHandler::CheckForSufficientResource() {
+  if (has_checked_for_sufficient_resources_)
+    return true;
+  has_checked_for_sufficient_resources_ = true;
+
+  if (rdh_->HasSufficientResourcesForRequest(request()))
+    return true;
+
+  controller()->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);
+  return false;
+}
+
+void MojoAsyncResourceHandler::OnWritable(MojoResult unused) {
+  Resume();
+}
+
+}  // namespace content