1 // Copyright 2013 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 #ifndef MOJO_PUBLIC_CPP_BINDINGS_CONNECTOR_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_CONNECTOR_H_ 7 8 #include <memory> 9 10 #include "base/callback.h" 11 #include "base/memory/ref_counted.h" 12 #include "base/memory/weak_ptr.h" 13 #include "base/single_thread_task_runner.h" 14 #include "base/threading/thread_checker.h" 15 #include "mojo/public/cpp/bindings/message.h" 16 #include "mojo/public/cpp/bindings/sync_handle_watcher.h" 17 #include "mojo/public/cpp/system/core.h" 18 #include "mojo/public/cpp/system/watcher.h" 19 20 namespace base { 21 class Lock; 22 } 23 24 namespace mojo { 25 26 // The Connector class is responsible for performing read/write operations on a 27 // MessagePipe. It writes messages it receives through the MessageReceiver 28 // interface that it subclasses, and it forwards messages it reads through the 29 // MessageReceiver interface assigned as its incoming receiver. 30 // 31 // NOTE: 32 // - MessagePipe I/O is non-blocking. 33 // - Sending messages can be configured to be thread safe (please see comments 34 // of the constructor). Other than that, the object should only be accessed 35 // on the creating thread. 36 class Connector : public MessageReceiver { 37 public: 38 enum ConnectorConfig { 39 // Connector::Accept() is only called from a single thread. 40 SINGLE_THREADED_SEND, 41 // Connector::Accept() is allowed to be called from multiple threads. 42 MULTI_THREADED_SEND 43 }; 44 45 // The Connector takes ownership of |message_pipe|. 46 Connector(ScopedMessagePipeHandle message_pipe, 47 ConnectorConfig config, 48 scoped_refptr<base::SingleThreadTaskRunner> runner); 49 ~Connector() override; 50 51 // Sets the receiver to handle messages read from the message pipe. The 52 // Connector will read messages from the pipe regardless of whether or not an 53 // incoming receiver has been set. 54 void set_incoming_receiver(MessageReceiver* receiver) { 55 DCHECK(thread_checker_.CalledOnValidThread()); 56 incoming_receiver_ = receiver; 57 } 58 59 // Errors from incoming receivers will force the connector into an error 60 // state, where no more messages will be processed. This method is used 61 // during testing to prevent that from happening. 62 void set_enforce_errors_from_incoming_receiver(bool enforce) { 63 DCHECK(thread_checker_.CalledOnValidThread()); 64 enforce_errors_from_incoming_receiver_ = enforce; 65 } 66 67 // Sets the error handler to receive notifications when an error is 68 // encountered while reading from the pipe or waiting to read from the pipe. 69 void set_connection_error_handler(const base::Closure& error_handler) { 70 DCHECK(thread_checker_.CalledOnValidThread()); 71 connection_error_handler_ = error_handler; 72 } 73 74 // Returns true if an error was encountered while reading from the pipe or 75 // waiting to read from the pipe. 76 bool encountered_error() const { 77 DCHECK(thread_checker_.CalledOnValidThread()); 78 return error_; 79 } 80 81 // Closes the pipe. The connector is put into a quiescent state. 82 // 83 // Please note that this method shouldn't be called unless it results from an 84 // explicit request of the user of bindings (e.g., the user sets an 85 // InterfacePtr to null or closes a Binding). 86 void CloseMessagePipe(); 87 88 // Releases the pipe. Connector is put into a quiescent state. 89 ScopedMessagePipeHandle PassMessagePipe(); 90 91 // Enters the error state. The upper layer may do this for unrecoverable 92 // issues such as invalid messages are received. If a connection error handler 93 // has been set, it will be called asynchronously. 94 // 95 // It is a no-op if the connector is already in the error state or there isn't 96 // a bound message pipe. Otherwise, it closes the message pipe, which notifies 97 // the other end and also prevents potential danger (say, the caller raises 98 // an error because it believes the other end is malicious). In order to 99 // appear to the user that the connector still binds to a message pipe, it 100 // creates a new message pipe, closes one end and binds to the other. 101 void RaiseError(); 102 103 // Is the connector bound to a MessagePipe handle? 104 bool is_valid() const { 105 DCHECK(thread_checker_.CalledOnValidThread()); 106 return message_pipe_.is_valid(); 107 } 108 109 // Waits for the next message on the pipe, blocking until one arrives, 110 // |deadline| elapses, or an error happens. Returns |true| if a message has 111 // been delivered, |false| otherwise. 112 bool WaitForIncomingMessage(MojoDeadline deadline); 113 114 // See Binding for details of pause/resume. 115 void PauseIncomingMethodCallProcessing(); 116 void ResumeIncomingMethodCallProcessing(); 117 118 // MessageReceiver implementation: 119 bool Accept(Message* message) override; 120 121 MessagePipeHandle handle() const { 122 DCHECK(thread_checker_.CalledOnValidThread()); 123 return message_pipe_.get(); 124 } 125 126 // Allows |message_pipe_| to be watched while others perform sync handle 127 // watching on the same thread. Please see comments of 128 // SyncHandleWatcher::AllowWokenUpBySyncWatchOnSameThread(). 129 void AllowWokenUpBySyncWatchOnSameThread(); 130 131 // Watches |message_pipe_| (as well as other handles registered to be watched 132 // together) synchronously. 133 // This method: 134 // - returns true when |should_stop| is set to true; 135 // - return false when any error occurs, including |message_pipe_| being 136 // closed. 137 bool SyncWatch(const bool* should_stop); 138 139 // Whether currently the control flow is inside the sync handle watcher 140 // callback. 141 bool during_sync_handle_watcher_callback() const { 142 return sync_handle_watcher_callback_count_ > 0; 143 } 144 145 base::SingleThreadTaskRunner* task_runner() const { 146 return task_runner_.get(); 147 } 148 149 private: 150 // Callback of mojo::Watcher. 151 void OnWatcherHandleReady(MojoResult result); 152 // Callback of SyncHandleWatcher. 153 void OnSyncHandleWatcherHandleReady(MojoResult result); 154 void OnHandleReadyInternal(MojoResult result); 155 156 void WaitToReadMore(); 157 158 // Returns false if |this| was destroyed during message dispatch. 159 WARN_UNUSED_RESULT bool ReadSingleMessage(MojoResult* read_result); 160 161 // |this| can be destroyed during message dispatch. 162 void ReadAllAvailableMessages(); 163 164 // If |force_pipe_reset| is true, this method replaces the existing 165 // |message_pipe_| with a dummy message pipe handle (whose peer is closed). 166 // If |force_async_handler| is true, |connection_error_handler_| is called 167 // asynchronously. 168 void HandleError(bool force_pipe_reset, bool force_async_handler); 169 170 // Cancels any calls made to |waiter_|. 171 void CancelWait(); 172 173 void EnsureSyncWatcherExists(); 174 175 base::Closure connection_error_handler_; 176 177 ScopedMessagePipeHandle message_pipe_; 178 MessageReceiver* incoming_receiver_; 179 180 scoped_refptr<base::SingleThreadTaskRunner> task_runner_; 181 Watcher handle_watcher_; 182 183 bool error_; 184 bool drop_writes_; 185 bool enforce_errors_from_incoming_receiver_; 186 187 bool paused_; 188 189 // If sending messages is allowed from multiple threads, |lock_| is used to 190 // protect modifications to |message_pipe_| and |drop_writes_|. 191 std::unique_ptr<base::Lock> lock_; 192 193 std::unique_ptr<SyncHandleWatcher> sync_watcher_; 194 bool allow_woken_up_by_others_; 195 // If non-zero, currently the control flow is inside the sync handle watcher 196 // callback. 197 size_t sync_handle_watcher_callback_count_; 198 199 base::ThreadChecker thread_checker_; 200 201 // Create a single weak ptr and use it everywhere, to avoid the malloc/free 202 // cost of creating a new weak ptr whenever it is needed. 203 base::WeakPtr<Connector> weak_self_; 204 base::WeakPtrFactory<Connector> weak_factory_; 205 206 DISALLOW_COPY_AND_ASSIGN(Connector); 207 }; 208 209 } // namespace mojo 210 211 #endif // MOJO_PUBLIC_CPP_BINDINGS_CONNECTOR_H_ 212
