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#ifndef ANDROID_HIDL_TASK_RUNNER_H
17#define ANDROID_HIDL_TASK_RUNNER_H
18
19#include <memory>
20#include <thread>
21
22namespace android {
23namespace hardware {
24namespace details {
25
26using Task = std::function<void(void)>;
27
28template <typename T>
29struct SynchronizedQueue;
30
31/*
32 * A background infinite loop that runs the Tasks push()'ed.
33 * Equivalent to a simple single-threaded Looper.
34 */
35class TaskRunner {
36public:
37
38    /* Create an empty task runner. Nothing will be done until start() is called. */
39    TaskRunner();
40
41    /*
42     * Notify the background thread to terminate and return immediately.
43     * Tasks in the queue will continue to be done sequentially in background
44     * until all tasks are finished.
45     */
46    ~TaskRunner();
47
48    /*
49     * Sets the queue limit. Fails the push operation once the limit is reached.
50     * This function is named start for legacy reasons and to maintain ABI
51     * stability, but the underlying thread running tasks isn't started until
52     * the first task is pushed.
53     */
54    void start(size_t limit);
55
56    /*
57     * Add a task. Return true if successful, false if
58     * the queue's size exceeds limit or t doesn't contain a callable target.
59     */
60    bool push(const Task &t);
61
62private:
63    std::shared_ptr<SynchronizedQueue<Task>> mQueue;
64};
65
66} // namespace details
67} // namespace hardware
68} // namespace android
69
70#endif // ANDROID_HIDL_TASK_RUNNER_H
71