circuitpython/supervisor/background_callback 2.h

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2020-08-13 19:59:00 -04:00
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2020 Jeff Epler for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef CIRCUITPY_INCLUDED_SUPERVISOR_BACKGROUND_CALLBACK_H
#define CIRCUITPY_INCLUDED_SUPERVISOR_BACKGROUND_CALLBACK_H
/** Background callbacks are a linked list of tasks to call in the background.
*
* Include a member of type `background_callback_t` inside an object
* which needs to queue up background work, and zero-initialize it.
*
* To schedule the work, use background_callback_add, with fun as the
* function to call and data pointing to the object itself.
*
* Next time run_background_tasks_if_tick is called, the callback will
* be run and removed from the linked list.
*
* Queueing a task that is already queued does nothing. Unconditionally
* re-queueing it from its own background task will cause it to run during the
* very next background-tasks invocation, leading to a CircuitPython freeze, so
* don't do that.
*
* background_callback_add can be called from interrupt context.
*/
typedef void (*background_callback_fun)(void *data);
typedef struct background_callback {
background_callback_fun fun;
void *data;
struct background_callback *next;
struct background_callback *prev;
} background_callback_t;
/* Add a background callback for which 'fun' and 'data' were previously set */
void background_callback_add_core(background_callback_t *cb);
/* Add a background callback to the given function with the given data. When
* the callback involves an object on the GC heap, the 'data' must be a pointer
* to that object itself, not an internal pointer. Otherwise, it can be the
* case that no other references to the object itself survive, and the object
* becomes garbage collected while an outstanding background callback still
* exists.
*/
void background_callback_add(background_callback_t *cb, background_callback_fun fun, void *data);
/* Run all background callbacks. Normally, this is done by the supervisor
* whenever the list is non-empty */
void background_callback_run_all(void);
/* During soft reset, remove all pending callbacks and clear the critical section flag */
void background_callback_reset(void);
/* Sometimes background callbacks must be blocked. Use these functions to
* bracket the section of code where this is the case. These calls nest, and
* begins must be balanced with ends.
*/
void background_callback_begin_critical_section(void);
void background_callback_end_critical_section(void);
/*
* Background callbacks may stop objects from being collected
*/
void background_callback_gc_collect(void);
#endif