s_mysql_mysql_scheduler Struct Reference

The Scheduler queueing interface. More...

#include <mysql_scheduler.h>

Public Attributes
mysql_service_status_t(*	create )(mysql_scheduler_runnable_handle *out_handle, mysql_scheduler_runnable_function runnable, void *arg, const char *name, const char *comment, int interval_secs)
	Schedule a runnable task. More...
mysql_service_status_t(*	destroy )(mysql_scheduler_runnable_handle handle)
	End a scheduled task/subtask. More...

Detailed Description

The Scheduler queueing interface.

This is a service that will allow registering a callback to be called every X seconds.

Each callback has a name. And a comment for the DBA to check.

A caller registers a callback together with its argument and gets a handle back. The callback will be put in rotation immediately and will be called after the defined interval. And it will keep being called until it's unregisterered using the handle.

Passing an argument is useful if you are to reuse the callback function to operate on many different states through registering it in multiple scheduled events. Having the argument passed down from the registering code to the callback saves the need of the callback to consult a global structure in a multi- thread safe fashion.

Warning

Keep the runnable function SHORT! Or design a way for it to be graciously shut down through a flag inside the argument.

To use it one would do something like this:

bool sheduled_callback(mysql_scheduler_runnable_handle handle, void *arg) {
   int *ctr = reinterpret_cast<std::atomic<int> *>(arg);
   *ctr++;
}
 
REQUIRES_SERVICE(mysql_scheduler);
 
int caller() {
   std::atomic<int> data= 0;
   mysql_scheduler_runnable_handle handle = nullptr;
   mysql_service_mysql_scheduler->create(
     &handle, sheduled_callback,
     (void *)&data,
     "gizmo", "This is a sheduled task to call gizmo",
     10);
 
   ....
 
   mysql_service_mysql_scheduler->destroy(handle);
   handle = nullptr;
}

See also

mysql_scheduler_runnable_handle, mysql_scheduler_runnable_function

Member Data Documentation

create

mysql_service_status_t(* s_mysql_mysql_scheduler::create) (mysql_scheduler_runnable_handle *out_handle, mysql_scheduler_runnable_function runnable, void *arg, const char *name, const char *comment, int interval_secs)

Schedule a runnable task.

Parameters

[out]	out_handle	The context of the newly scheduled task. To be kept as an interaction vector with the running task.
	runnable	The function to call
	arg	An argument to pass to the runnable. Must be valid until unregistered.
	name	The name of the runnable in UTF8.
	comment	A free form comment in UTF8. No more than 1024 bytes.
	interval_secs	How frequently to schedule the task (in seconds). Must be greater than 1 since this is the resolution.

Return values

false	success
true	failure

destroy

mysql_service_status_t(* s_mysql_mysql_scheduler::destroy) (mysql_scheduler_runnable_handle handle)

End a scheduled task/subtask.

This will: unschedule the task wait for the scheduled task runnable to end, if running currently

Parameters

handle

The context of the task to end

Return values

false	success
true	failure

---

The documentation for this struct was generated from the following file:

• include/mysql/components/services/mysql_scheduler.h