81 lines
2.9 KiB
C++
81 lines
2.9 KiB
C++
//
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// Copyright (C) 2015 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#ifndef TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_
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#define TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_
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#include "trunks/command_transceiver.h"
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#include <string>
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#include <base/memory/ref_counted.h>
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#include <base/memory/weak_ptr.h>
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#include <base/sequenced_task_runner.h>
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#include "trunks/trunks_export.h"
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namespace trunks {
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// Sends commands to another CommandTransceiver on a background thread. Response
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// callbacks are called on the original calling thread.
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// Example:
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// base::Thread background_thread("my thread");
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// ...
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// BackgroundCommandTransceiver background_transceiver(
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// next_transceiver,
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// background_thread.message_loop_proxy());
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// ...
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// background_transceiver.SendCommand(my_command, MyCallback);
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class TRUNKS_EXPORT BackgroundCommandTransceiver : public CommandTransceiver {
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public:
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// All commands will be forwarded to |next_transceiver| on |task_runner|,
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// regardless of whether the synchronous or asynchronous method is used. This
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// class will hold a reference count to |task_runner|. If |task_runner| is
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// nullptr, all commands will be forwarded on the current thread. This class
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// does not take ownership of |next_transceiver|; it must remain valid for
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// the lifetime of the object.
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explicit BackgroundCommandTransceiver(
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CommandTransceiver* next_transceiver,
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const scoped_refptr<base::SequencedTaskRunner>& task_runner);
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~BackgroundCommandTransceiver() override;
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// CommandTranceiver methods.
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void SendCommand(const std::string& command,
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const ResponseCallback& callback) override;
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std::string SendCommandAndWait(const std::string& command) override;
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private:
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// Sends a |command| to the |next_transceiver_| and invokes a |callback| with
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// the command response.
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void SendCommandTask(const std::string& command,
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const ResponseCallback& callback);
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base::WeakPtr<BackgroundCommandTransceiver> GetWeakPtr() {
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return weak_factory_.GetWeakPtr();
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}
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CommandTransceiver* next_transceiver_;
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scoped_refptr<base::SequencedTaskRunner> task_runner_;
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// Declared last so weak pointers are invalidated first on destruction.
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base::WeakPtrFactory<BackgroundCommandTransceiver> weak_factory_;
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DISALLOW_COPY_AND_ASSIGN(BackgroundCommandTransceiver);
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};
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} // namespace trunks
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#endif // TRUNKS_BACKGROUND_COMMAND_TRANSCEIVER_H_
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