mbed-os/events/mbed_shared_queues.h

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3.3 KiB
C++

/*
* Copyright (c) 2016-2019 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef MBED_SHARED_QUEUES_H
#define MBED_SHARED_QUEUES_H
#include "events/EventQueue.h"
namespace mbed {
/** \addtogroup events-public-api */
/** @{*/
/**
* Return a pointer to an EventQueue, on which normal tasks can be queued.
*
* All calls to this return the same EventQueue - it and its dispatch thread
* are created on the first call to this function. The dispatch thread
* runs at default priority (currently osPriorityNormal).
*
* The EventQueue returned may be used to call() Events, or to chain() other
* EventQueues so that they are run in the same context.
*
* Events (or chained EventQueues) executing on the normal event queue should
* normally take less than 10ms to execute, to avoid starving other users. As
* such, users can expect that event latency will typically be 10ms or less,
* but could occasionally be significantly higher if many events are queued.
*
* If an RTOS is not present or the configuration option
* `events.shared-dispatch-from-application` is set to true, then this
* does not create a dedicated dispatch thread - instead the application is
* expected to run the EventQueue's dispatch, for example from main. This is
* necessary for the event loop to work without an RTOS, or an RTOS system can
* save memory by reusing the main stack.
*
* @note
* mbed_event_queue is not itself IRQ safe. To use the mbed_event_queue in
* interrupt context, you must first call `mbed_event_queue()` in threaded
* context and store the pointer for later use.
*
* @return pointer to event queue
*/
events::EventQueue *mbed_event_queue();
#ifdef MBED_CONF_RTOS_PRESENT
/**
* Return a pointer to an EventQueue, on which small high-priority tasks can
* be queues, such as simple deferrals from interrupt.
*
* All calls to this return the same EventQueue - it and its thread are
* created on the first call to this function. The dispatch thread
* runs at a high priority (currently osPriorityHigh).
*
* The EventQueue returned may be used to call() Events, or to chain() other
* EventQueues so that they are run in the same context.
*
* Events (or chained EventQueues) executing on the high-priority event queue
* should normally take less than 100us to execute, to avoid starving other
* users. As such, users can expect that event latency will typically be 100us
* or less, but could occasionally be significantly higher if many events are
* queued.
*
* @note
* mbed_highprio_event_queue is not itself IRQ safe. To use the
* mbed_highprio_event_queue in interrupt context, you must first call
* `mbed_highprio_event_queue()` in threaded context and store the pointer for
* later use.
*
* @return pointer to high-priority event queue
*/
events::EventQueue *mbed_highprio_event_queue();
#endif // MBED_CONF_RTOS_PRESENT
/** @}*/
}
#endif