Wed Oct 28 15:47:56 2009

Asterisk developer's documentation


sched.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief Scheduler Routines (derived from cheops)
00021  */
00022 
00023 #ifndef _ASTERISK_SCHED_H
00024 #define _ASTERISK_SCHED_H
00025 
00026 #if defined(__cplusplus) || defined(c_plusplus)
00027 extern "C" {
00028 #endif
00029 
00030 /*! Max num of schedule structs */
00031 /*!
00032  * The max number of schedule structs to keep around
00033  * for use.  Undefine to disable schedule structure
00034  * caching. (Only disable this on very low memory 
00035  * machines)
00036  */
00037 #define SCHED_MAX_CACHE 128
00038 
00039 struct sched_context;
00040 
00041 /*! New schedule context */
00042 /* !
00043  * Create a scheduling context
00044  * Returns a malloc'd sched_context structure, NULL on failure
00045  */
00046 extern struct sched_context *sched_context_create(void);
00047 
00048 /*! destroys a schedule context */
00049 /*!
00050  * \param c Context to free
00051  * Destroys (free's) the given sched_context structure
00052  * Returns 0 on success, -1 on failure
00053  */
00054 void sched_context_destroy(struct sched_context *c);
00055 
00056 /*! callback for a cheops scheduler */
00057 /*! 
00058  * A cheops scheduler callback takes a pointer with callback data and
00059  * returns a 0 if it should not be run again, or non-zero if it should be
00060  * rescheduled to run again
00061  */
00062 typedef int (*ast_sched_cb)(void *data);
00063 #define AST_SCHED_CB(a) ((ast_sched_cb)(a))
00064 
00065 /*!Adds a scheduled event */
00066 /*! 
00067  * \param con Scheduler context to add
00068  * \param when how many milliseconds to wait for event to occur
00069  * \param callback function to call when the amount of time expires
00070  * \param data data to pass to the callback
00071  * Schedule an event to take place at some point in the future.  callback 
00072  * will be called with data as the argument, when milliseconds into the
00073  * future (approximately)
00074  * If callback returns 0, no further events will be re-scheduled
00075  * Returns a schedule item ID on success, -1 on failure
00076  */
00077 extern int ast_sched_add(struct sched_context *con, int when, ast_sched_cb callback, void *data);
00078 
00079 /*!Adds a scheduled event */
00080 /*! 
00081  * \param con Scheduler context to add
00082  * \param when how many milliseconds to wait for event to occur
00083  * \param callback function to call when the amount of time expires
00084  * \param data data to pass to the callback
00085  * \param variable If true, the result value of callback function will be 
00086  *       used for rescheduling
00087  * Schedule an event to take place at some point in the future.  callback 
00088  * will be called with data as the argument, when milliseconds into the
00089  * future (approximately)
00090  * If callback returns 0, no further events will be re-scheduled
00091  * Returns a schedule item ID on success, -1 on failure
00092  */
00093 extern int ast_sched_add_variable(struct sched_context *con, int when, ast_sched_cb callback, void *data, int variable);
00094 
00095 /*! Deletes a scheduled event */
00096 /*!
00097  * \param con scheduling context to delete item from
00098  * \param id ID of the scheduled item to delete
00099  * Remove this event from being run.  A procedure should not remove its
00100  * own event, but return 0 instead.
00101  * Returns 0 on success, -1 on failure
00102  */
00103 extern int ast_sched_del(struct sched_context *con, int id);
00104 
00105 /*! Determines number of seconds until the next outstanding event to take place */
00106 /*!
00107  * \param con context to act upon
00108  * Determine the number of seconds until the next outstanding event
00109  * should take place, and return the number of milliseconds until
00110  * it needs to be run.  This value is perfect for passing to the poll
00111  * call.  Returns "-1" if there is nothing there are no scheduled events
00112  * (and thus the poll should not timeout)
00113  */
00114 extern int ast_sched_wait(struct sched_context *con);
00115 
00116 /*! Runs the queue */
00117 /*!
00118  * \param con Scheduling context to run
00119  * Run the queue, executing all callbacks which need to be performed
00120  * at this time.  Returns the number of events processed.
00121  */
00122 extern int ast_sched_runq(struct sched_context *con);
00123 
00124 /*!Dumps the scheduler contents */
00125 /*!
00126  * \param con Context to dump
00127  * Debugging: Dump the contents of the scheduler to stderr
00128  */
00129 extern void ast_sched_dump(const struct sched_context *con);
00130 
00131 /*!Returns the number of seconds before an event takes place */
00132 /*!
00133  * \param con Context to use
00134  * \param id Id to dump
00135  */
00136 extern long ast_sched_when(struct sched_context *con,int id);
00137 
00138 /*
00139  *! Convenience macro for objects and reference (add)
00140  *
00141  */
00142 #define ast_sched_add_object(obj,con,when,callback) ast_sched_add((con),(when),(callback), ASTOBJ_REF((obj)))
00143 
00144 /*
00145  *! Convenience macro for objects and reference (del)
00146  *
00147  */
00148 #define ast_sched_del_object(obj,destructor,con,id) do { \
00149    if ((id) > -1) { \
00150       ast_sched_del((con),(id)); \
00151       (id) = -1; \
00152       ASTOBJ_UNREF((obj),(destructor)); \
00153    } \
00154 } while(0)
00155 
00156 #if defined(__cplusplus) || defined(c_plusplus)
00157 }
00158 #endif
00159 
00160 #endif /* _ASTERISK_SCHED_H */

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