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mbed_shared_queues.h
1 
2 /** \addtogroup events */
3 /** @{*/
4 /* events
5  * Copyright (c) 2017 ARM Limited
6  *
7  * Licensed under the Apache License, Version 2.0 (the "License");
8  * you may not use this file except in compliance with the License.
9  * You may obtain a copy of the License at
10  *
11  * http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing, software
14  * distributed under the License is distributed on an "AS IS" BASIS,
15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  * See the License for the specific language governing permissions and
17  * limitations under the License.
18  */
19 #ifndef MBED_SHARED_QUEUES_H
20 #define MBED_SHARED_QUEUES_H
21 
22 #include "events/EventQueue.h"
23 
24 namespace mbed {
25 
26 /**
27  * Return a pointer to an EventQueue, on which normal tasks can be queued.
28  *
29  * All calls to this return the same EventQueue - it and its dispatch thread
30  * are created on the first call to this function. The dispatch thread
31  * runs at default priority (currently osPriorityNormal).
32  *
33  * The EventQueue returned may be used to call() Events, or to chain() other
34  * EventQueues so that they are run in the same context.
35  *
36  * Events (or chained EventQueues) executing on the normal event queue should
37  * normally take less than 10ms to execute, to avoid starving other users. As
38  * such, users can expect that event latency will typically be 10ms or less,
39  * but could occasionally be significantly higher if many events are queued.
40  *
41  * If an RTOS is not present or the configuration option
42  * `events.shared-dispatch-from-application` is set to true, then this
43  * does not create a dedicated dispatch thread - instead the application is
44  * expected to run the EventQueue's dispatch, for example from main. This is
45  * necessary for the event loop to work without an RTOS, or an RTOS system can
46  * save memory by reusing the main stack.
47  *
48  * @note
49  * mbed_event_queue is not itself IRQ safe. To use the mbed_event_queue in
50  * interrupt context, you must first call `mbed_event_queue()` in threaded
51  * context and store the pointer for later use.
52  *
53  * @return pointer to event queue
54  */
55 events::EventQueue *mbed_event_queue();
56 
57 #ifdef MBED_CONF_RTOS_PRESENT
58 /**
59  * Return a pointer to an EventQueue, on which small high-priority tasks can
60  * be queues, such as simple deferrals from interrupt.
61  *
62  * All calls to this return the same EventQueue - it and its thread are
63  * created on the first call to this function. The dispatch thread
64  * runs at a high priority (currently osPriorityHigh).
65  *
66  * The EventQueue returned may be used to call() Events, or to chain() other
67  * EventQueues so that they are run in the same context.
68  *
69  * Events (or chained EventQueues) executing on the high-priority event queue
70  * should normally take less than 100us to execute, to avoid starving other
71  * users. As such, users can expect that event latency will typically be 100us
72  * or less, but could occasionally be significantly higher if many events are
73  * queued.
74  *
75  * @note
76  * mbed_highprio_event_queue is not itself IRQ safe. To use the
77  * mbed_highprio_event_queue in interrupt context, you must first call
78  * `mbed_highprio_event_queue()` in threaded context and store the pointer for
79  * later use.
80  *
81  * @return pointer to high-priority event queue
82  */
83 
84 events::EventQueue *mbed_highprio_event_queue();
85 
86 #endif // MBED_CONF_RTOS_PRESENT
87 
88 };
89 
90 #endif
91 
92 /** @}*/
events::EventQueue
EventQueue.
Definition: EventQueue.h:52
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