1 // 2 // Copyright (C) 2015 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #ifndef TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_ 18 #define TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_ 19 20 #include "trunks/command_transceiver.h" 21 22 #include <string> 23 24 #include <base/memory/ref_counted.h> 25 #include <base/memory/weak_ptr.h> 26 #include <base/sequenced_task_runner.h> 27 28 #include "trunks/trunks_export.h" 29 30 namespace trunks { 31 32 // Sends commands to another CommandTransceiver on a background thread. Response 33 // callbacks are called on the original calling thread. 34 // Example: 35 // base::Thread background_thread("my thread"); 36 // ... 37 // BackgroundCommandTransceiver background_transceiver( 38 // next_transceiver, 39 // background_thread.message_loop_proxy()); 40 // ... 41 // background_transceiver.SendCommand(my_command, MyCallback); 42 class TRUNKS_EXPORT BackgroundCommandTransceiver : public CommandTransceiver { 43 public: 44 // All commands will be forwarded to |next_transceiver| on |task_runner|, 45 // regardless of whether the synchronous or asynchronous method is used. This 46 // class will hold a reference count to |task_runner|. If |task_runner| is 47 // nullptr, all commands will be forwarded on the current thread. This class 48 // does not take ownership of |next_transceiver|; it must remain valid for 49 // the lifetime of the object. 50 explicit BackgroundCommandTransceiver( 51 CommandTransceiver* next_transceiver, 52 const scoped_refptr<base::SequencedTaskRunner>& task_runner); 53 ~BackgroundCommandTransceiver() override; 54 55 // CommandTranceiver methods. 56 void SendCommand(const std::string& command, 57 const ResponseCallback& callback) override; 58 std::string SendCommandAndWait(const std::string& command) override; 59 60 private: 61 // Sends a |command| to the |next_transceiver_| and invokes a |callback| with 62 // the command response. 63 void SendCommandTask(const std::string& command, 64 const ResponseCallback& callback); 65 66 base::WeakPtr<BackgroundCommandTransceiver> GetWeakPtr() { 67 return weak_factory_.GetWeakPtr(); 68 } 69 70 CommandTransceiver* next_transceiver_; 71 scoped_refptr<base::SequencedTaskRunner> task_runner_; 72 73 // Declared last so weak pointers are invalidated first on destruction. 74 base::WeakPtrFactory<BackgroundCommandTransceiver> weak_factory_; 75 76 DISALLOW_COPY_AND_ASSIGN(BackgroundCommandTransceiver); 77 }; 78 79 } // namespace trunks 80 81 #endif // TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_ 82
