| // Copyright 2013 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. |
| |
| #ifndef MOJO_SYSTEM_CHANNEL_H_ |
| #define MOJO_SYSTEM_CHANNEL_H_ |
| |
| #include <stdint.h> |
| |
| #include "base/compiler_specific.h" |
| #include "base/containers/hash_tables.h" |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/scoped_ptr.h" |
| #include "base/strings/string_piece.h" |
| #include "base/synchronization/lock.h" |
| #include "base/threading/thread_checker.h" |
| #include "mojo/embedder/scoped_platform_handle.h" |
| #include "mojo/public/c/system/types.h" |
| #include "mojo/system/channel_endpoint.h" |
| #include "mojo/system/message_in_transit.h" |
| #include "mojo/system/message_pipe.h" |
| #include "mojo/system/raw_channel.h" |
| #include "mojo/system/system_impl_export.h" |
| |
| namespace mojo { |
| |
| namespace embedder { |
| class PlatformSupport; |
| } |
| |
| namespace system { |
| |
| class ChannelEndpoint; |
| |
| // This class is mostly thread-safe. It must be created on an I/O thread. |
| // |Init()| must be called on that same thread before it becomes thread-safe (in |
| // particular, before references are given to any other thread) and |Shutdown()| |
| // must be called on that same thread before destruction. Its public methods are |
| // otherwise thread-safe. (Many private methods are restricted to the creation |
| // thread.) It may be destroyed on any thread, in the sense that the last |
| // reference to it may be released on any thread, with the proviso that |
| // |Shutdown()| must have been called first (so the pattern is that a "main" |
| // reference is kept on its creation thread and is released after |Shutdown()| |
| // is called, but other threads may have temporarily "dangling" references). |
| // |
| // Note the lock order (in order of allowable acquisition): |MessagePipe|, |
| // |ChannelEndpoint|, |Channel|. Thus |Channel| may not call into |
| // |ChannelEndpoint| with |Channel|'s lock held. |
| class MOJO_SYSTEM_IMPL_EXPORT Channel |
| : public base::RefCountedThreadSafe<Channel>, |
| public RawChannel::Delegate { |
| public: |
| // The first message pipe endpoint attached will have this as its local ID. |
| static const MessageInTransit::EndpointId kBootstrapEndpointId = 1; |
| |
| // |platform_support| (typically owned by |Core|) must remain alive until |
| // after |Shutdown()| is called. |
| explicit Channel(embedder::PlatformSupport* platform_support); |
| |
| // This must be called on the creation thread before any other methods are |
| // called, and before references to this object are given to any other |
| // threads. |raw_channel| should be uninitialized. Returns true on success. On |
| // failure, no other methods should be called (including |Shutdown()|). |
| bool Init(scoped_ptr<RawChannel> raw_channel); |
| |
| // This must be called on the creation thread before destruction (which can |
| // happen on any thread). |
| void Shutdown(); |
| |
| // Signals that |Shutdown()| will be called soon (this may be called from any |
| // thread, unlike |Shutdown()|). Warnings will be issued if, e.g., messages |
| // are written after this is called; other warnings may be suppressed. (This |
| // may be called multiple times, or not at all.) |
| void WillShutdownSoon(); |
| |
| // Attaches the given endpoint to this channel. This assigns it a local ID, |
| // which it returns. The first endpoint attached will always have |
| // |kBootstrapEndpointId| as its local ID. (For bootstrapping, this occurs on |
| // both sides, so one should use |kBootstrapEndpointId| for the remote ID for |
| // the first message pipe across a channel.) Returns |kInvalidEndpointId| on |
| // failure. |
| // TODO(vtl): This should be combined with "run", and it should take a |
| // |ChannelEndpoint| instead. |
| // TODO(vtl): Maybe limit the number of attached message pipes. |
| MessageInTransit::EndpointId AttachEndpoint( |
| scoped_refptr<ChannelEndpoint> endpoint); |
| |
| // Runs the message pipe with the given |local_id| (previously attached), with |
| // the given |remote_id| (negotiated using some other means, e.g., over an |
| // existing message pipe; see comments above for the bootstrap case). Returns |
| // false on failure, in particular if no message pipe with |local_id| is |
| // attached. |
| bool RunMessagePipeEndpoint(MessageInTransit::EndpointId local_id, |
| MessageInTransit::EndpointId remote_id); |
| |
| // Tells the other side of the channel to run a message pipe endpoint (which |
| // must already be attached); |local_id| and |remote_id| are relative to this |
| // channel (i.e., |local_id| is the other side's remote ID and |remote_id| is |
| // its local ID). |
| // TODO(vtl): Maybe we should just have a flag argument to |
| // |RunMessagePipeEndpoint()| that tells it to do this. |
| void RunRemoteMessagePipeEndpoint(MessageInTransit::EndpointId local_id, |
| MessageInTransit::EndpointId remote_id); |
| |
| // This forwards |message| verbatim to |raw_channel_|. |
| bool WriteMessage(scoped_ptr<MessageInTransit> message); |
| |
| // See |RawChannel::IsWriteBufferEmpty()|. |
| // TODO(vtl): Maybe we shouldn't expose this, and instead have a |
| // |FlushWriteBufferAndShutdown()| or something like that. |
| bool IsWriteBufferEmpty(); |
| |
| // This removes the message pipe/port's endpoint (with the given local ID and |
| // given remote ID, which should be |kInvalidEndpointId| if not yet running), |
| // returned by |AttachEndpoint()| from this channel. After this is called, |
| // |local_id| may be reused for another message pipe. |
| void DetachMessagePipeEndpoint(MessageInTransit::EndpointId local_id, |
| MessageInTransit::EndpointId remote_id); |
| |
| // See |RawChannel::GetSerializedPlatformHandleSize()|. |
| size_t GetSerializedPlatformHandleSize() const; |
| |
| embedder::PlatformSupport* platform_support() const { |
| return platform_support_; |
| } |
| |
| private: |
| friend class base::RefCountedThreadSafe<Channel>; |
| virtual ~Channel(); |
| |
| // |RawChannel::Delegate| implementation (only called on the creation thread): |
| virtual void OnReadMessage( |
| const MessageInTransit::View& message_view, |
| embedder::ScopedPlatformHandleVectorPtr platform_handles) OVERRIDE; |
| virtual void OnError(Error error) OVERRIDE; |
| |
| // Helpers for |OnReadMessage| (only called on the creation thread): |
| void OnReadMessageForDownstream( |
| const MessageInTransit::View& message_view, |
| embedder::ScopedPlatformHandleVectorPtr platform_handles); |
| void OnReadMessageForChannel( |
| const MessageInTransit::View& message_view, |
| embedder::ScopedPlatformHandleVectorPtr platform_handles); |
| |
| // Removes the message pipe endpoint with the given local ID, which must exist |
| // and be a zombie, and given remote ID. Returns false on failure, in |
| // particular if no message pipe with |local_id| is attached. Only called on |
| // the creation thread. |
| bool RemoveMessagePipeEndpoint(MessageInTransit::EndpointId local_id, |
| MessageInTransit::EndpointId remote_id); |
| |
| // Handles errors (e.g., invalid messages) from the remote side. Callable from |
| // any thread. |
| void HandleRemoteError(const base::StringPiece& error_message); |
| // Handles internal errors/failures from the local side. Callable from any |
| // thread. |
| void HandleLocalError(const base::StringPiece& error_message); |
| |
| // Helper to send channel control messages. Returns true on success. Should be |
| // called *without* |lock_| held. Callable from any thread. |
| bool SendControlMessage(MessageInTransit::Subtype subtype, |
| MessageInTransit::EndpointId source_id, |
| MessageInTransit::EndpointId destination_id); |
| |
| base::ThreadChecker creation_thread_checker_; |
| |
| embedder::PlatformSupport* const platform_support_; |
| |
| // Note: |MessagePipe|s MUST NOT be used under |lock_|. I.e., |lock_| can only |
| // be acquired after |MessagePipe::lock_|, never before. Thus to call into a |
| // |MessagePipe|, a reference to the |MessagePipe| should be acquired from |
| // |local_id_to_endpoint_map_| under |lock_| and then the lock released. |
| base::Lock lock_; // Protects the members below. |
| |
| scoped_ptr<RawChannel> raw_channel_; |
| bool is_running_; |
| // Set when |WillShutdownSoon()| is called. |
| bool is_shutting_down_; |
| |
| typedef base::hash_map<MessageInTransit::EndpointId, |
| scoped_refptr<ChannelEndpoint>> IdToEndpointMap; |
| IdToEndpointMap local_id_to_endpoint_map_; |
| // The next local ID to try (when allocating new local IDs). Note: It should |
| // be checked for existence before use. |
| MessageInTransit::EndpointId next_local_id_; |
| |
| DISALLOW_COPY_AND_ASSIGN(Channel); |
| }; |
| |
| } // namespace system |
| } // namespace mojo |
| |
| #endif // MOJO_SYSTEM_CHANNEL_H_ |