1 // Copyright 2023 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14 #include "pw_async_basic/dispatcher.h"
15
16 #include "pw_assert/check.h"
17 #include "pw_chrono/system_clock.h"
18 #include "pw_log/log.h"
19
20 using namespace std::chrono_literals;
21
22 namespace pw::async {
23
24 const chrono::SystemClock::duration SLEEP_DURATION = 5s;
25
~BasicDispatcher()26 BasicDispatcher::~BasicDispatcher() {
27 RequestStop();
28 lock_.lock();
29 DrainTaskQueue();
30 lock_.unlock();
31 }
32
Run()33 void BasicDispatcher::Run() {
34 lock_.lock();
35 while (!stop_requested_) {
36 MaybeSleep();
37 ExecuteDueTasks();
38 }
39 DrainTaskQueue();
40 lock_.unlock();
41 }
42
RunUntilIdle()43 void BasicDispatcher::RunUntilIdle() {
44 lock_.lock();
45 ExecuteDueTasks();
46 if (stop_requested_) {
47 DrainTaskQueue();
48 }
49 lock_.unlock();
50 }
51
RunUntil(chrono::SystemClock::time_point end_time)52 void BasicDispatcher::RunUntil(chrono::SystemClock::time_point end_time) {
53 lock_.lock();
54 while (end_time < now() && !stop_requested_) {
55 MaybeSleep();
56 ExecuteDueTasks();
57 }
58 if (stop_requested_) {
59 DrainTaskQueue();
60 }
61 lock_.unlock();
62 }
63
RunFor(chrono::SystemClock::duration duration)64 void BasicDispatcher::RunFor(chrono::SystemClock::duration duration) {
65 RunUntil(now() + duration);
66 }
67
MaybeSleep()68 void BasicDispatcher::MaybeSleep() {
69 if (task_queue_.empty() || task_queue_.front().due_time_ > now()) {
70 // Sleep until a notification is received or until the due time of the
71 // next task. Notifications are sent when tasks are posted or 'stop' is
72 // requested.
73 chrono::SystemClock::time_point wake_time =
74 task_queue_.empty() ? now() + SLEEP_DURATION
75 : task_queue_.front().due_time_;
76
77 lock_.unlock();
78 PW_LOG_DEBUG("no task due; waiting for signal");
79 timed_notification_.try_acquire_until(wake_time);
80 lock_.lock();
81 }
82 }
83
ExecuteDueTasks()84 void BasicDispatcher::ExecuteDueTasks() {
85 while (!task_queue_.empty() && task_queue_.front().due_time_ <= now() &&
86 !stop_requested_) {
87 backend::NativeTask& task = task_queue_.front();
88 task_queue_.pop_front();
89
90 if (task.interval().has_value()) {
91 PostTaskInternal(task, task.due_time_ + task.interval().value());
92 }
93
94 lock_.unlock();
95 PW_LOG_DEBUG("running task");
96 Context ctx{this, &task.task_};
97 task(ctx, OkStatus());
98 lock_.lock();
99 }
100 }
101
RequestStop()102 void BasicDispatcher::RequestStop() {
103 std::lock_guard lock(lock_);
104 PW_LOG_DEBUG("stop requested");
105 stop_requested_ = true;
106 timed_notification_.release();
107 }
108
DrainTaskQueue()109 void BasicDispatcher::DrainTaskQueue() {
110 PW_LOG_DEBUG("draining task queue");
111 while (!task_queue_.empty()) {
112 backend::NativeTask& task = task_queue_.front();
113 task_queue_.pop_front();
114
115 lock_.unlock();
116 PW_LOG_DEBUG("running cancelled task");
117 Context ctx{this, &task.task_};
118 task(ctx, Status::Cancelled());
119 lock_.lock();
120 }
121 }
122
Post(Task & task)123 void BasicDispatcher::Post(Task& task) { PostAt(task, now()); }
124
PostAfter(Task & task,chrono::SystemClock::duration delay)125 void BasicDispatcher::PostAfter(Task& task,
126 chrono::SystemClock::duration delay) {
127 PostAt(task, now() + delay);
128 }
129
PostAt(Task & task,chrono::SystemClock::time_point time)130 void BasicDispatcher::PostAt(Task& task, chrono::SystemClock::time_point time) {
131 lock_.lock();
132 PW_LOG_DEBUG("posting task");
133 PostTaskInternal(task.native_type(), time);
134 lock_.unlock();
135 }
136
PostPeriodic(Task & task,chrono::SystemClock::duration interval)137 void BasicDispatcher::PostPeriodic(Task& task,
138 chrono::SystemClock::duration interval) {
139 PostPeriodicAt(task, interval, now());
140 }
141
PostPeriodicAt(Task & task,chrono::SystemClock::duration interval,chrono::SystemClock::time_point start_time)142 void BasicDispatcher::PostPeriodicAt(
143 Task& task,
144 chrono::SystemClock::duration interval,
145 chrono::SystemClock::time_point start_time) {
146 PW_DCHECK(interval != chrono::SystemClock::duration::zero());
147 task.native_type().set_interval(interval);
148 PostAt(task, start_time);
149 }
150
Cancel(Task & task)151 bool BasicDispatcher::Cancel(Task& task) {
152 std::lock_guard lock(lock_);
153 return task_queue_.remove(task.native_type());
154 }
155
PostTaskInternal(backend::NativeTask & task,chrono::SystemClock::time_point time_due)156 void BasicDispatcher::PostTaskInternal(
157 backend::NativeTask& task, chrono::SystemClock::time_point time_due) {
158 task.due_time_ = time_due;
159 auto it_front = task_queue_.begin();
160 auto it_behind = task_queue_.before_begin();
161 while (it_front != task_queue_.end() && time_due > it_front->due_time_) {
162 ++it_front;
163 ++it_behind;
164 }
165 task_queue_.insert_after(it_behind, task);
166 timed_notification_.release();
167 }
168
169 } // namespace pw::async
170