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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "mojo/system/channel_endpoint.h"
      6 
      7 #include "base/logging.h"
      8 #include "mojo/system/channel.h"
      9 #include "mojo/system/message_pipe.h"
     10 
     11 namespace mojo {
     12 namespace system {
     13 
     14 ChannelEndpoint::ChannelEndpoint(MessagePipe* message_pipe, unsigned port)
     15     : state_(STATE_NORMAL),
     16       message_pipe_(message_pipe),
     17       port_(port),
     18       channel_(),
     19       local_id_(MessageInTransit::kInvalidEndpointId),
     20       remote_id_(MessageInTransit::kInvalidEndpointId) {
     21   DCHECK(message_pipe_.get());
     22   DCHECK(port_ == 0 || port_ == 1);
     23 }
     24 
     25 void ChannelEndpoint::TakeMessages(MessageInTransitQueue* message_queue) {
     26   DCHECK(paused_message_queue_.IsEmpty());
     27   paused_message_queue_.Swap(message_queue);
     28 }
     29 
     30 bool ChannelEndpoint::EnqueueMessage(scoped_ptr<MessageInTransit> message) {
     31   DCHECK(message);
     32 
     33   base::AutoLock locker(lock_);
     34 
     35   if (!channel_ || remote_id_ == MessageInTransit::kInvalidEndpointId) {
     36     // We may reach here if we haven't been attached or run yet.
     37     // TODO(vtl): We may also reach here if the channel is shut down early for
     38     // some reason (with live message pipes on it). We can't check |state_| yet,
     39     // until it's protected under lock, but in this case we should return false
     40     // (and not enqueue any messages).
     41     paused_message_queue_.AddMessage(message.Pass());
     42     return true;
     43   }
     44 
     45   // TODO(vtl): Currently, this only works in the "running" case.
     46   DCHECK_NE(remote_id_, MessageInTransit::kInvalidEndpointId);
     47 
     48   return WriteMessageNoLock(message.Pass());
     49 }
     50 
     51 void ChannelEndpoint::DetachFromMessagePipe() {
     52   // TODO(vtl): Once |message_pipe_| is under |lock_|, we should null it out
     53   // here. For now, get the channel to do so for us.
     54 
     55   scoped_refptr<Channel> channel;
     56   {
     57     base::AutoLock locker(lock_);
     58     if (!channel_)
     59       return;
     60     DCHECK_NE(local_id_, MessageInTransit::kInvalidEndpointId);
     61     // TODO(vtl): Once we combine "run" into "attach", |remote_id_| should valid
     62     // here as well.
     63     channel = channel_;
     64   }
     65   // Don't call this under |lock_|, since it'll call us back.
     66   // TODO(vtl): This seems pretty suboptimal.
     67   channel->DetachMessagePipeEndpoint(local_id_, remote_id_);
     68 }
     69 
     70 void ChannelEndpoint::AttachToChannel(Channel* channel,
     71                                       MessageInTransit::EndpointId local_id) {
     72   DCHECK(channel);
     73   DCHECK_NE(local_id, MessageInTransit::kInvalidEndpointId);
     74 
     75   base::AutoLock locker(lock_);
     76   DCHECK(!channel_);
     77   DCHECK_EQ(local_id_, MessageInTransit::kInvalidEndpointId);
     78   channel_ = channel;
     79   local_id_ = local_id;
     80 }
     81 
     82 void ChannelEndpoint::Run(MessageInTransit::EndpointId remote_id) {
     83   DCHECK_NE(remote_id, MessageInTransit::kInvalidEndpointId);
     84 
     85   base::AutoLock locker(lock_);
     86   DCHECK(channel_);
     87   DCHECK_EQ(remote_id_, MessageInTransit::kInvalidEndpointId);
     88   remote_id_ = remote_id;
     89 
     90   while (!paused_message_queue_.IsEmpty()) {
     91     LOG_IF(WARNING, !WriteMessageNoLock(paused_message_queue_.GetMessage()))
     92         << "Failed to write enqueue message to channel";
     93   }
     94 }
     95 
     96 void ChannelEndpoint::DetachFromChannel() {
     97   base::AutoLock locker(lock_);
     98   DCHECK(channel_);
     99   DCHECK_NE(local_id_, MessageInTransit::kInvalidEndpointId);
    100   // TODO(vtl): Once we combine "run" into "attach", |remote_id_| should valid
    101   // here as well.
    102   channel_ = nullptr;
    103   local_id_ = MessageInTransit::kInvalidEndpointId;
    104   remote_id_ = MessageInTransit::kInvalidEndpointId;
    105 }
    106 
    107 ChannelEndpoint::~ChannelEndpoint() {
    108   DCHECK(!channel_);
    109   DCHECK_EQ(local_id_, MessageInTransit::kInvalidEndpointId);
    110   DCHECK_EQ(remote_id_, MessageInTransit::kInvalidEndpointId);
    111 }
    112 
    113 bool ChannelEndpoint::WriteMessageNoLock(scoped_ptr<MessageInTransit> message) {
    114   DCHECK(message);
    115 
    116   lock_.AssertAcquired();
    117 
    118   DCHECK(channel_);
    119   DCHECK_NE(local_id_, MessageInTransit::kInvalidEndpointId);
    120   DCHECK_NE(remote_id_, MessageInTransit::kInvalidEndpointId);
    121 
    122   message->SerializeAndCloseDispatchers(channel_);
    123   message->set_source_id(local_id_);
    124   message->set_destination_id(remote_id_);
    125   return channel_->WriteMessage(message.Pass());
    126 }
    127 
    128 }  // namespace system
    129 }  // namespace mojo
    130