1 /*
2 * Copyright (C) 2016 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 #pragma once
18
19 #include <chrono>
20 #include <future>
21
22 #include <hidl/Status.h>
23 #include <utils/Errors.h>
24
25 namespace android {
26 namespace lshal {
27
28 // Call function on interfaceObject and wait for result until the given timeout has reached.
29 // Callback functions pass to timeoutIPC() may be executed after the this function
30 // has returned, especially if deadline has been reached. Hence, care must be taken when passing
31 // data between the background thread and the main thread. See b/311143089.
32 template<class R, class P, class Function, class I, class... Args>
33 typename std::invoke_result<Function, I *, Args...>::type
timeoutIPC(std::chrono::duration<R,P> wait,const sp<I> & interfaceObject,Function && func,Args &&...args)34 timeoutIPC(std::chrono::duration<R, P> wait, const sp<I> &interfaceObject, Function &&func,
35 Args &&... args) {
36 using ::android::hardware::Status;
37
38 // Execute on a background thread but do not defer execution.
39 auto future =
40 std::async(std::launch::async, func, interfaceObject, std::forward<Args>(args)...);
41 auto status = future.wait_for(wait);
42 if (status == std::future_status::ready) {
43 return future.get();
44 }
45
46 // This future belongs to a background thread that we no longer care about.
47 // Putting this in the global list avoids std::future::~future() that may wait for the
48 // result to come back.
49 // This leaks memory, but lshal is a debugging tool, so this is fine.
50 static std::vector<decltype(future)> gDeadPool{};
51 gDeadPool.emplace_back(std::move(future));
52
53 if (status == std::future_status::timeout) {
54 return Status::fromStatusT(TIMED_OUT);
55 }
56 return Status::fromExceptionCode(Status::Exception::EX_ILLEGAL_STATE, "Illegal future_status");
57 }
58 } // namespace lshal
59 } // namespace android
60