Update ChannelReader to use AttachmentBroker.

ipc/ipc_channel_reader.cc

 // Copyright (c) 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.
 
 #include "ipc/ipc_channel_reader.h"
 
+#include <algorithm>
+
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_logging.h"
+#include "ipc/ipc_message.h"
+#include "ipc/ipc_message_attachment_set.h"
 #include "ipc/ipc_message_macros.h"
 
 namespace IPC {
 namespace internal {
 
 ChannelReader::ChannelReader(Listener* listener) : listener_(listener) {
   memset(input_buf_, 0, sizeof(input_buf_));
 }
 
 ChannelReader::~ChannelReader() {
+  if (!blocked_ids_.empty())
+    StopObservingAttachmentBroker();
 }
 
-bool ChannelReader::ProcessIncomingMessages() {
+ChannelReader::DispatchState ChannelReader::ProcessIncomingMessages() {
   while (true) {
     int bytes_read = 0;
     ReadState read_state = ReadData(input_buf_, Channel::kReadBufferSize,
                                     &bytes_read);
     if (read_state == READ_FAILED)
-      return false;
+      return DISPATCH_ERROR;
     if (read_state == READ_PENDING)
-      return true;
+      return DISPATCH_FINISHED;
 
     DCHECK(bytes_read > 0);
-    if (!DispatchInputData(input_buf_, bytes_read))
-      return false;
+    if (!TranslateInputData(input_buf_, bytes_read))
+      return DISPATCH_ERROR;
+
+    DispatchState state = DispatchMessages();
+    if (state != DISPATCH_FINISHED)
+      return state;
   }
 }
 
-bool ChannelReader::AsyncReadComplete(int bytes_read) {
-  return DispatchInputData(input_buf_, bytes_read);
+ChannelReader::DispatchState ChannelReader::AsyncReadComplete(int bytes_read) {
+  if (!TranslateInputData(input_buf_, bytes_read))
+    return DISPATCH_ERROR;
+
+  return DispatchMessages();
 }
 
 bool ChannelReader::IsInternalMessage(const Message& m) {
   return m.routing_id() == MSG_ROUTING_NONE &&
       m.type() >= Channel::CLOSE_FD_MESSAGE_TYPE &&
       m.type() <= Channel::HELLO_MESSAGE_TYPE;
 }
 
 bool ChannelReader::IsHelloMessage(const Message& m) {
   return m.routing_id() == MSG_ROUTING_NONE &&
       m.type() == Channel::HELLO_MESSAGE_TYPE;
 }
 
-bool ChannelReader::DispatchInputData(const char* input_data,
-                                      int input_data_len) {
+bool ChannelReader::TranslateInputData(const char* input_data,
+                                       int input_data_len) {
   const char* p;
   const char* end;
 
   // Possibly combine with the overflow buffer to make a larger buffer.
   if (input_overflow_buf_.empty()) {
     p = input_data;
     end = input_data + input_data_len;
   } else {
     if (input_overflow_buf_.size() + input_data_len >
         Channel::kMaximumMessageSize) {
       input_overflow_buf_.clear();
       LOG(ERROR) << "IPC message is too big";
       return false;
     }
     input_overflow_buf_.append(input_data, input_data_len);
     p = input_overflow_buf_.data();
     end = p + input_overflow_buf_.size();
   }
 
   // Dispatch all complete messages in the data buffer.
   while (p < end) {
     const char* message_tail = Message::FindNext(p, end);
     if (message_tail) {
       int len = static_cast<int>(message_tail - p);
-      Message m(p, len);
-      if (!WillDispatchInputMessage(&m))
+
+      Message translated_message(p, len);
+      if (!GetNonBrokeredAttachments(&translated_message))
         return false;
 
-#ifdef IPC_MESSAGE_LOG_ENABLED
-      std::string name;
-      Logging::GetInstance()->GetMessageText(m.type(), &name, &m, NULL);
-      TRACE_EVENT1("ipc,toplevel", "ChannelReader::DispatchInputData",
-                   "name", name);
-#else
-      TRACE_EVENT2("ipc,toplevel", "ChannelReader::DispatchInputData",
-                   "class", IPC_MESSAGE_ID_CLASS(m.type()),
-                   "line", IPC_MESSAGE_ID_LINE(m.type()));
-#endif
-      m.TraceMessageEnd();
-      if (IsInternalMessage(m))
-        HandleInternalMessage(m);
-      else
-        listener_->OnMessageReceived(m);
-      if (m.dispatch_error())
-        listener_->OnBadMessageReceived(m);
+      // If there are no queued messages, attempt to immediately dispatch the
+      // newly translated message.
+      if (queued_messages_.empty()) {
+        DCHECK(blocked_ids_.empty());
+        AttachmentIdSet blocked_ids =
+            GetBrokeredAttachments(&translated_message);
+
+        if (blocked_ids.empty()) {
+          // Dispatch the message and continue the loop.
+          DispatchMessage(&translated_message);
+          p = message_tail;
+          continue;
+        }
+
+        // While we could theoretically updated blocked_ids_ and call

[Tom Sepez, 2015/07/27 15:21:47]

nit: I didn't see the code to which this comment applies.

[erikchen, 2015/07/27 16:23:48]

This comment explains the lack of additional code here. Would you like me to
reword the comment to explain his more clearly?

[erikchen, 2015/07/27 17:15:38]

I started rewriting this comment several times in an attempt to explain why I
wasn't adding some code here. Eventually I decided it was much simpler to just
add the two lines of code that I was trying to avoid adding.

+        // StartObservingAttachmentBroker(), doing so adds unnecessary
+        // complexity. This attempt to dispatch |translated_message| is an
+        // optimization, and TranslateInputData() is guaranteed to be followed
+        // by DispatchMessages() which will do the same thing.
+      }
+
+      // Make a deep copy of |translated_message| to add to the queue.
+      scoped_ptr<Message> m(new Message(translated_message));
+      queued_messages_.push_back(m.release());
       p = message_tail;
     } else {
       // Last message is partial.
       break;
     }
   }
 
   // Save any partial data in the overflow buffer.
   input_overflow_buf_.assign(p, end - p);
 
   if (input_overflow_buf_.empty() && !DidEmptyInputBuffers())
     return false;
   return true;
 }
 
+ChannelReader::DispatchState ChannelReader::DispatchMessages() {
+  while (!queued_messages_.empty()) {
+    if (!blocked_ids_.empty())
+      return DISPATCH_WAITING_ON_BROKER;
+
+    Message* m = queued_messages_.front();
+
+    AttachmentIdSet blocked_ids = GetBrokeredAttachments(m);
+    if (!blocked_ids.empty()) {
+      blocked_ids_.swap(blocked_ids);
+      StartObservingAttachmentBroker();
+      return DISPATCH_WAITING_ON_BROKER;
+    }
+
+    DispatchMessage(m);
+    queued_messages_.erase(queued_messages_.begin());
+  }
+  return DISPATCH_FINISHED;
+}
+
+void ChannelReader::DispatchMessage(Message* m) {
+#ifdef IPC_MESSAGE_LOG_ENABLED
+  std::string name;
+  Logging::GetInstance()->GetMessageText(m->type(), &name, m, NULL);
+  TRACE_EVENT1("ipc,toplevel", "ChannelReader::DispatchInputData", "name",
+               name);
+#else
+  TRACE_EVENT2("ipc,toplevel", "ChannelReader::DispatchInputData", "class",
+               IPC_MESSAGE_ID_CLASS(m->type()), "line",
+               IPC_MESSAGE_ID_LINE(m->type()));
+#endif
+  m->TraceMessageEnd();
+  if (IsInternalMessage(*m))
+    HandleInternalMessage(*m);
+  else
+    listener_->OnMessageReceived(*m);
+  if (m->dispatch_error())
+    listener_->OnBadMessageReceived(*m);
+}
+
+ChannelReader::AttachmentIdSet ChannelReader::GetBrokeredAttachments(
+    Message* msg) {
+  std::set<BrokerableAttachment::AttachmentId> blocked_ids;
+
+#if USE_ATTACHMENT_BROKER
+  MessageAttachmentSet* set = msg->attachment_set();
+  for (const scoped_refptr<BrokerableAttachment>& attachment :
+       set->GetBrokerableAttachmentsForUpdating()) {
+    if (attachment->NeedsBrokering()) {
+      AttachmentBroker* broker = GetAttachmentBroker();
+      scoped_refptr<BrokerableAttachment> brokered_attachment;
+      bool result = broker->GetAttachmentWithId(attachment->GetIdentifier(),
+                                                &brokered_attachment);
+      if (!result) {
+        blocked_ids.insert(attachment->GetIdentifier());
+        continue;
+      }
+
+      attachment->PopulateWithAttachment(brokered_attachment.get());
+    }
+  }
+#endif  // USE_ATTACHMENT_BROKER
+
+  return blocked_ids;
+}
+
+void ChannelReader::ReceivedBrokerableAttachmentWithId(
+    const BrokerableAttachment::AttachmentId& id) {
+  if (blocked_ids_.empty())
+    return;
+
+  auto it = find(blocked_ids_.begin(), blocked_ids_.end(), id);
+  if (it != blocked_ids_.end())
+    blocked_ids_.erase(it);
+
+  if (blocked_ids_.empty()) {
+    StopObservingAttachmentBroker();
+    DispatchMessages();
+  }
+}
+
+void ChannelReader::StartObservingAttachmentBroker() {
+#if USE_ATTACHMENT_BROKER
+  GetAttachmentBroker()->AddObserver(this);
+#endif  // USE_ATTACHMENT_BROKER
+}
+
+void ChannelReader::StopObservingAttachmentBroker() {
+#if USE_ATTACHMENT_BROKER
+  GetAttachmentBroker()->RemoveObserver(this);
+#endif  // USE_ATTACHMENT_BROKER
+}
 
 }  // namespace internal
 }  // namespace IPC