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esp8266/cores/esp8266/Schedule.h
david gauchard 5a47cab77d
add documentation to scheduled functions (#6234)
* add documentation to scheduled functions
2019-06-27 12:09:27 +02:00

72 lines
2.9 KiB
C++

#ifndef ESP_SCHEDULE_H
#define ESP_SCHEDULE_H
#include <functional>
#define SCHEDULED_FN_MAX_COUNT 32
// The purpose of scheduled functions is to trigger, from SYS stack (like in
// an interrupt or a system event), registration of user code to be executed
// in user stack (called CONT stack) without the common restrictions from
// system context. Details are below.
// The purpose of recurrent scheduled function is to independantly execute
// user code in CONT stack on a regular basis.
// It has been introduced with ethernet service in mind, it can also be used
// for all libraries in the need of a regular `libdaemon_handlestuff()`.
// It allows these services to be run even from a user loop not going back
// to `loop()`.
// Ticker + scheduled function offer the same service but recurrent
// scheduled function happen more often: every yield() (vs every loop()),
// and time resolution is microsecond (vs millisecond). Details are below.
// scheduled functions called once:
//
// * internal queue is FIFO.
// * Add the given lambda to a fifo list of lambdas, which is run when
// `loop` function returns.
// * Use lambdas to pass arguments to a function, or call a class/static
// member function.
// * Please ensure variables or instances used from inside lambda will exist
// when lambda is later called.
// * There is no mechanism for cancelling scheduled functions.
// * `yield` can be called from inside lambdas.
// * Returns false if the number of scheduled functions exceeds
// SCHEDULED_FN_MAX_COUNT (or memory shortage).
// * Run the lambda only once next time.
// * A scheduled function can schedule a function.
bool schedule_function (const std::function<void(void)>& fn);
// Run all scheduled functions.
// Use this function if your are not using `loop`,
// or `loop` does not return on a regular basis.
void run_scheduled_functions();
// recurrent scheduled function:
//
// * Internal queue may not be a FIFO.
// * Run the lambda periodically about every <repeat_us> microseconds until
// it returns false.
// * Note that it may be more than <repeat_us> microseconds between calls if
// `yield` is not called frequently, and therefore should not be used for
// timing critical operations.
// * Please ensure variables or instances used from inside lambda will exist
// when lambda is later called.
// * There is no mechanism for externally cancelling recurrent scheduled
// functions. However a user function returning false will cancel itself.
// * Long running operations or yield() or delay() are not allowed in the
// recurrent function.
// * A recurrent function currently must not schedule another recurrent
// functions.
bool schedule_recurrent_function_us (const std::function<bool(void)>& fn, uint32_t repeat_us);
// Test recurrence and run recurrent scheduled functions.
// (internally called at every `yield()` and `loop()`)
void run_scheduled_recurrent_functions ();
#endif // ESP_SCHEDULE_H