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 #include "trunks/background_command_transceiver.h"
18
19 #include <base/bind.h>
20 #include <base/callback.h>
21 #include <base/location.h>
22 #include <base/logging.h>
23 #include <base/single_thread_task_runner.h>
24 #include <base/synchronization/waitable_event.h>
25 #include <base/thread_task_runner_handle.h>
26
27 namespace {
28
29 // A simple callback useful when waiting for an asynchronous call.
AssignAndSignal(std::string * destination,base::WaitableEvent * event,const std::string & source)30 void AssignAndSignal(std::string* destination,
31 base::WaitableEvent* event,
32 const std::string& source) {
33 *destination = source;
34 event->Signal();
35 }
36
37 // A callback which posts another |callback| to a given |task_runner|.
PostCallbackToTaskRunner(const trunks::CommandTransceiver::ResponseCallback & callback,scoped_refptr<base::SingleThreadTaskRunner> task_runner,const std::string & response)38 void PostCallbackToTaskRunner(
39 const trunks::CommandTransceiver::ResponseCallback& callback,
40 scoped_refptr<base::SingleThreadTaskRunner> task_runner,
41 const std::string& response) {
42 base::Closure task = base::Bind(callback, response);
43 task_runner->PostTask(FROM_HERE, task);
44 }
45
46 } // namespace
47
48 namespace trunks {
49
BackgroundCommandTransceiver(CommandTransceiver * next_transceiver,const scoped_refptr<base::SequencedTaskRunner> & task_runner)50 BackgroundCommandTransceiver::BackgroundCommandTransceiver(
51 CommandTransceiver* next_transceiver,
52 const scoped_refptr<base::SequencedTaskRunner>& task_runner)
53 : next_transceiver_(next_transceiver),
54 task_runner_(task_runner),
55 weak_factory_(this) {}
56
~BackgroundCommandTransceiver()57 BackgroundCommandTransceiver::~BackgroundCommandTransceiver() {}
58
SendCommand(const std::string & command,const ResponseCallback & callback)59 void BackgroundCommandTransceiver::SendCommand(
60 const std::string& command,
61 const ResponseCallback& callback) {
62 if (task_runner_.get()) {
63 ResponseCallback background_callback = base::Bind(
64 PostCallbackToTaskRunner,
65 callback,
66 base::ThreadTaskRunnerHandle::Get());
67 // Use SendCommandTask instead of binding to next_transceiver_ directly to
68 // leverage weak pointer semantics.
69 base::Closure task = base::Bind(
70 &BackgroundCommandTransceiver::SendCommandTask,
71 GetWeakPtr(),
72 command,
73 background_callback);
74 task_runner_->PostNonNestableTask(FROM_HERE, task);
75 } else {
76 next_transceiver_->SendCommand(command, callback);
77 }
78 }
79
SendCommandAndWait(const std::string & command)80 std::string BackgroundCommandTransceiver::SendCommandAndWait(
81 const std::string& command) {
82 if (task_runner_.get()) {
83 std::string response;
84 base::WaitableEvent response_ready(true, // manual_reset
85 false); // initially_signaled
86 ResponseCallback callback =
87 base::Bind(&AssignAndSignal, &response, &response_ready);
88 // Use SendCommandTask instead of binding to next_transceiver_ directly to
89 // leverage weak pointer semantics.
90 base::Closure task = base::Bind(
91 &BackgroundCommandTransceiver::SendCommandTask,
92 GetWeakPtr(),
93 command,
94 callback);
95 task_runner_->PostNonNestableTask(FROM_HERE, task);
96 response_ready.Wait();
97 return response;
98 } else {
99 return next_transceiver_->SendCommandAndWait(command);
100 }
101 }
102
SendCommandTask(const std::string & command,const ResponseCallback & callback)103 void BackgroundCommandTransceiver::SendCommandTask(
104 const std::string& command,
105 const ResponseCallback& callback) {
106 next_transceiver_->SendCommand(command, callback);
107 }
108
109 } // namespace trunks
110