Send input event IPCs directly from the UI thread

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright 2012 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 146 matching lines @@
 #include "content/public/common/url_constants.h"
 #include "device/battery/battery_monitor_impl.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gpu_switches.h"
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "ipc/attachment_broker.h"
 #include "ipc/attachment_broker_privileged.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_logging.h"
+#include "ipc/ipc_sender.h"
 #include "ipc/ipc_switches.h"
 #include "ipc/mojo/ipc_channel_mojo.h"
 #include "media/base/media_switches.h"
 #include "mojo/edk/embedder/embedder.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "ppapi/shared_impl/ppapi_switches.h"
 #include "services/shell/runner/common/switches.h"
 #include "storage/browser/fileapi/sandbox_file_system_backend.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/ui_base_switches.h"
@@ skipping 263 matching lines @@
   for (auto it : vector) {
     if (!str.empty())
       str += ",";
     str += base::UintToString(it);
   }
   return str;
 }
 
 }  // namespace
 
+// SafeSenderProxy owns two IPC::Sender implementations which proxy to the
+// RPH's own ChannelProxy. One enables immediate sends while the other enables
+// IO-thread sends. These are both implemented via RPHI's SendImpl which safely
+// avoids dereferencing the underlying ChannelProxy if it's been reset (e.g.
+// after process death.)
+class RenderProcessHostImpl::SafeSenderProxy {
+ public:
+  // |process| must outlive this object.
+  explicit SafeSenderProxy(RenderProcessHostImpl* process)
+      : process_(process),
+        immediate_sender_(this, true /* send_now */),
+        io_thread_sender_(this, false /* send_now */) {}
+  ~SafeSenderProxy() {}
+
+  IPC::Sender* immediate_sender() { return &immediate_sender_; }
+  IPC::Sender* io_thread_sender() { return &io_thread_sender_; }
+
+  bool SendImpl(std::unique_ptr<IPC::Message> message, bool send_now) {
+    return process_->SendImpl(std::move(message), send_now);
+  }
+
+ private:
+  class SenderProxy : public IPC::Sender {
+   public:
+    SenderProxy(SafeSenderProxy* safe_proxy, bool send_now)
+        : safe_proxy_(safe_proxy), send_now_(send_now) {}
+    ~SenderProxy() override {}
+
+    // IPC::Sender:
+    bool Send(IPC::Message* message) override {
+      return safe_proxy_->SendImpl(base::WrapUnique(message), send_now_);

[Charlie Reis, 2016/05/23 23:33:12]

Is there a reason not to just store process_ on SenderProxy and put line 469
here?  Seems a bit indirect to get a SenderProxy from SafeSenderProxy and then
have to go through SafeSenderProxy to get to RPH on every send.  Then
SafeSenderProxy wouldn't need the pointer to RPH, and SenderProxy wouldn't need
a SafeSenderProxy pointer.

+    }
+
+   private:
+    SafeSenderProxy* const safe_proxy_;
+    const bool send_now_;
+
+    DISALLOW_COPY_AND_ASSIGN(SenderProxy);
+  };
+
+  RenderProcessHostImpl* process_;
+  SenderProxy immediate_sender_;
+  SenderProxy io_thread_sender_;
+
+  DISALLOW_COPY_AND_ASSIGN(SafeSenderProxy);
+};
+
 RendererMainThreadFactoryFunction g_renderer_main_thread_factory = NULL;
 
 base::MessageLoop* g_in_process_thread;
 
 base::MessageLoop*
 RenderProcessHostImpl::GetInProcessRendererThreadForTesting() {
   return g_in_process_thread;
 }
 
 // Stores the maximum number of renderer processes the content module can
@@ skipping 69 matching lines @@
 RenderProcessHostImpl::RenderProcessHostImpl(
     BrowserContext* browser_context,
     StoragePartitionImpl* storage_partition_impl,
     bool is_for_guests_only)
     : fast_shutdown_started_(false),
       deleting_soon_(false),
 #ifndef NDEBUG
       is_self_deleted_(false),
 #endif
       pending_views_(0),
+      safe_sender_(new SafeSenderProxy(this)),
       mojo_application_host_(new MojoApplicationHost),
       visible_widgets_(0),
       is_process_backgrounded_(false),
       is_initialized_(false),
       id_(ChildProcessHostImpl::GenerateChildProcessUniqueId()),
       browser_context_(browser_context),
       storage_partition_impl_(storage_partition_impl),
       sudden_termination_allowed_(true),
       ignore_input_events_(false),
       is_for_guests_only_(is_for_guests_only),
@@ skipping 92 matching lines @@
     ui::GpuSwitchingManager::GetInstance()->RemoveObserver(this);
     gpu_observer_registered_ = false;
   }
 
 #if USE_ATTACHMENT_BROKER
   IPC::AttachmentBroker::GetGlobal()->DeregisterCommunicationChannel(
       channel_.get());
 #endif
   // We may have some unsent messages at this point, but that's OK.
   channel_.reset();
-  while (!queued_messages_.empty()) {
-    delete queued_messages_.front();
+  while (!queued_messages_.empty())
     queued_messages_.pop();
-  }
 
   UnregisterHost(GetID());
 
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableGpuShaderDiskCache)) {
     BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
                             base::Bind(&RemoveShaderInfo, GetID()));
   }
 }
 
@@ skipping 343 matching lines @@
 #if defined(OS_CHROMEOS) || defined(OS_ANDROID)
   enable_web_bluetooth = true;
 #endif
 
   if (enable_web_bluetooth) {
     bluetooth_dispatcher_host_ = new BluetoothDispatcherHost(GetID());
     AddFilter(bluetooth_dispatcher_host_.get());
   }
 }
 
+bool RenderProcessHostImpl::SendImpl(std::unique_ptr<IPC::Message> msg,
+                                     bool send_now) {
+  TRACE_EVENT0("renderer_host", "RenderProcessHostImpl::SendImpl");
+#if !defined(OS_ANDROID)
+  DCHECK(!msg->is_sync());
+#endif
+
+  if (!channel_) {
+#if defined(OS_ANDROID)
+    if (msg->is_sync())
+      return false;
+#endif
+    if (!is_initialized_) {
+      queued_messages_.emplace(std::move(msg));
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  if (child_process_launcher_.get() && child_process_launcher_->IsStarting()) {
+#if defined(OS_ANDROID)
+    if (msg->is_sync())
+      return false;
+#endif
+    queued_messages_.emplace(std::move(msg));
+    return true;
+  }
+
+  if (send_now)
+    return channel_->SendNow(std::move(msg));
+
+  return channel_->SendOnIPCThread(std::move(msg));
+}
+
 void RenderProcessHostImpl::RegisterMojoServices() {
 #if !defined(OS_ANDROID)
   mojo_application_host_->service_registry()->AddService(
       base::Bind(&device::BatteryMonitorImpl::Create));
 #endif
 
   mojo_application_host_->service_registry()->AddService(
       base::Bind(&PermissionServiceContext::CreateService,
                  base::Unretained(permission_service_context_.get())));
 
@@ skipping 607 matching lines @@
 
   // Set this before ProcessDied() so observers can tell if the render process
   // died due to fast shutdown versus another cause.
   fast_shutdown_started_ = true;
 
   ProcessDied(false /* already_dead */, nullptr);
   return true;
 }
 
 bool RenderProcessHostImpl::Send(IPC::Message* msg) {
-  TRACE_EVENT0("renderer_host", "RenderProcessHostImpl::Send");
-#if !defined(OS_ANDROID)
-  DCHECK(!msg->is_sync());
-#endif
-
-  if (!channel_) {
-#if defined(OS_ANDROID)
-    if (msg->is_sync()) {
-      delete msg;
-      return false;
-    }
-#endif
-    if (!is_initialized_) {
-      queued_messages_.push(msg);
-      return true;
-    } else {
-      delete msg;
-      return false;
-    }
-  }
-
-  if (child_process_launcher_.get() && child_process_launcher_->IsStarting()) {
-#if defined(OS_ANDROID)
-    if (msg->is_sync()) {
-      delete msg;
-      return false;
-    }
-#endif
-    queued_messages_.push(msg);
-    return true;
-  }
-
-  return channel_->Send(msg);
+  return SendImpl(base::WrapUnique(msg), false /* send_now */);
 }
 
 bool RenderProcessHostImpl::OnMessageReceived(const IPC::Message& msg) {
   // If we're about to be deleted, or have initiated the fast shutdown sequence,
   // we ignore incoming messages.
 
   if (deleting_soon_ || fast_shutdown_started_)
     return false;
 
   mark_child_process_activity_time();
@@ skipping 335 matching lines @@
                    p2p_socket_dispatcher_host_);
   }
   return stop_rtp_dump_callback_;
 }
 #endif
 
 IPC::ChannelProxy* RenderProcessHostImpl::GetChannel() {
   return channel_.get();
 }
 
+IPC::Sender* RenderProcessHostImpl::GetImmediateSender() {
+  return safe_sender_->immediate_sender();
+}
+
+IPC::Sender* RenderProcessHostImpl::GetIOThreadSender() {
+  return safe_sender_->io_thread_sender();
+}
+
 void RenderProcessHostImpl::AddFilter(BrowserMessageFilter* filter) {
   channel_->AddFilter(filter->GetFilter());
 }
 
 bool RenderProcessHostImpl::FastShutdownForPageCount(size_t count) {
   if (GetActiveViewCount() == count)
     return FastShutdownIfPossible();
   return false;
 }
 
@@ skipping 325 matching lines @@
   }
 
   RendererClosedDetails details(status, exit_code);
 
   child_process_launcher_.reset();
 #if USE_ATTACHMENT_BROKER
   IPC::AttachmentBroker::GetGlobal()->DeregisterCommunicationChannel(
       channel_.get());
 #endif
   channel_.reset();
-  while (!queued_messages_.empty()) {
-    delete queued_messages_.front();
+  while (!queued_messages_.empty())
     queued_messages_.pop();
-  }
   UpdateProcessPriority();
   DCHECK(!is_process_backgrounded_);
 
   // RenderProcessExited observers and RenderProcessGone handlers might
   // navigate or perform other actions that require a connection. Ensure that
   // there is one before calling them.
   mojo_application_host_.reset(new MojoApplicationHost);
 
   within_process_died_observer_ = true;
   NotificationService::current()->Notify(
@@ skipping 156 matching lines @@
   // with state that must be there before any JavaScript executes.
   //
   // The queued messages contain such things as "navigate". If this notification
   // was after, we can end up executing JavaScript before the initialization
   // happens.
   NotificationService::current()->Notify(NOTIFICATION_RENDERER_PROCESS_CREATED,
                                          Source<RenderProcessHost>(this),
                                          NotificationService::NoDetails());
 
   while (!queued_messages_.empty()) {
-    Send(queued_messages_.front());
+    Send(queued_messages_.front().release());
     queued_messages_.pop();
   }
 
   if (IsReady()) {
     DCHECK(!sent_render_process_ready_);
     sent_render_process_ready_ = true;
     // Send RenderProcessReady only if the channel is already connected.
     FOR_EACH_OBSERVER(RenderProcessHostObserver,
                       observers_,
                       RenderProcessReady(this));
@@ skipping 191 matching lines @@
 
     // Skip widgets in other processes.
     if (rvh->GetProcess()->GetID() != GetID())
       continue;
 
     rvh->OnWebkitPreferencesChanged();
   }
 }
 
 }  // namespace content