1 /*
2 * Copyright (c) 2016, The OpenThread Authors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the copyright holder nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file
31 * This file implements the tasklet scheduler.
32 */
33
34 #include "tasklet.hpp"
35
36 #include "common/code_utils.hpp"
37 #include "common/locator_getters.hpp"
38
39 namespace ot {
40
Post(void)41 void Tasklet::Post(void)
42 {
43 if (!IsPosted())
44 {
45 Get<Scheduler>().PostTasklet(*this);
46 }
47 }
48
PostTasklet(Tasklet & aTasklet)49 void Tasklet::Scheduler::PostTasklet(Tasklet &aTasklet)
50 {
51 // Tasklets are saved in a circular singly linked list.
52
53 if (mTail == nullptr)
54 {
55 mTail = &aTasklet;
56 mTail->mNext = mTail;
57 otTaskletsSignalPending(&aTasklet.GetInstance());
58 }
59 else
60 {
61 aTasklet.mNext = mTail->mNext;
62 mTail->mNext = &aTasklet;
63 mTail = &aTasklet;
64 }
65 }
66
ProcessQueuedTasklets(void)67 void Tasklet::Scheduler::ProcessQueuedTasklets(void)
68 {
69 Tasklet *tail = mTail;
70
71 // This method processes all tasklets queued when this is called. We
72 // keep a copy the current list and then clear the main list by
73 // setting `mTail` to nullptr. A newly posted tasklet while processing
74 // the currently queued tasklets will then trigger a call to
75 // `otTaskletsSignalPending()`.
76
77 mTail = nullptr;
78
79 while (tail != nullptr)
80 {
81 Tasklet *tasklet = tail->mNext;
82
83 if (tasklet == tail)
84 {
85 tail = nullptr;
86 }
87 else
88 {
89 tail->mNext = tasklet->mNext;
90 }
91
92 tasklet->mNext = nullptr;
93 tasklet->RunTask();
94 }
95 }
96
97 } // namespace ot
98
