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3 * Copyright (C) 1998-2002 Internet Software Consortium.
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18 /* $Id: timer.h,v 1.40 2008/06/23 23:47:11 tbox Exp $ */
28 * \brief Provides timers which are event sources in the task system.
30 * Three types of timers are supported:
32 *\li 'ticker' timers generate a periodic tick event.
34 *\li 'once' timers generate an idle timeout event if they are idle for too
35 * long, and generate a life timeout event if their lifetime expires.
36 * They are used to implement both (possibly expiring) idle timers and
39 *\li 'limited' timers generate a periodic tick event until they reach
40 * their lifetime when they generate a life timeout event.
42 *\li 'inactive' timers generate no events.
44 * Timers can change type. It is typical to create a timer as
45 * an 'inactive' timer and then change it into a 'ticker' or
49 * The module ensures appropriate synchronization of data structures it
50 * creates and manipulates.
51 * Clients of this module must not be holding a timer's task's lock when
52 * making a call that affects that timer. Failure to follow this rule
53 * can result in deadlock.
54 * The caller must ensure that isc_timermgr_destroy() is called only
55 * once for a given manager.
58 * No anticipated impact.
64 * No anticipated impact.
75 #include <isc/types.h>
76 #include <isc/event.h>
77 #include <isc/eventclass.h>
89 isc_timertype_ticker = 0, /*%< Ticker */
90 isc_timertype_once = 1, /*%< Once */
91 isc_timertype_limited = 2, /*%< Limited */
92 isc_timertype_inactive = 3 /*%< Inactive */
95 typedef struct isc_timerevent {
96 struct isc_event common;
100 #define ISC_TIMEREVENT_FIRSTEVENT (ISC_EVENTCLASS_TIMER + 0)
101 #define ISC_TIMEREVENT_TICK (ISC_EVENTCLASS_TIMER + 1)
102 #define ISC_TIMEREVENT_IDLE (ISC_EVENTCLASS_TIMER + 2)
103 #define ISC_TIMEREVENT_LIFE (ISC_EVENTCLASS_TIMER + 3)
104 #define ISC_TIMEREVENT_LASTEVENT (ISC_EVENTCLASS_TIMER + 65535)
107 *** Timer and Timer Manager Functions
109 *** Note: all Ensures conditions apply only if the result is success for
110 *** those functions which return an isc_result_t.
114 isc_timer_create(isc_timermgr_t *manager,
115 isc_timertype_t type,
117 isc_interval_t *interval,
119 isc_taskaction_t action,
121 isc_timer_t **timerp);
123 * Create a new 'type' timer managed by 'manager'. The timers parameters
124 * are specified by 'expires' and 'interval'. Events will be posted to
125 * 'task' and when dispatched 'action' will be called with 'arg' as the
126 * arg value. The new timer is returned in 'timerp'.
130 *\li For ticker timers, the timer will generate a 'tick' event every
131 * 'interval' seconds. The value of 'expires' is ignored.
133 *\li For once timers, 'expires' specifies the time when a life timeout
134 * event should be generated. If 'expires' is 0 (the epoch), then no life
135 * timeout will be generated. 'interval' specifies how long the timer
136 * can be idle before it generates an idle timeout. If 0, then no
137 * idle timeout will be generated.
139 *\li If 'expires' is NULL, the epoch will be used.
141 * If 'interval' is NULL, the zero interval will be used.
145 *\li 'manager' is a valid manager
147 *\li 'task' is a valid task
149 *\li 'action' is a valid action
151 *\li 'expires' points to a valid time, or is NULL.
153 *\li 'interval' points to a valid interval, or is NULL.
155 *\li type == isc_timertype_inactive ||
156 * ('expires' and 'interval' are not both 0)
158 *\li 'timerp' is a valid pointer, and *timerp == NULL
162 *\li '*timerp' is attached to the newly created timer
164 *\li The timer is attached to the task
166 *\li An idle timeout will not be generated until at least Now + the
167 * timer's interval if 'timer' is a once timer with a non-zero
174 *\li Unexpected error
178 isc_timer_reset(isc_timer_t *timer,
179 isc_timertype_t type,
181 isc_interval_t *interval,
182 isc_boolean_t purge);
184 * Change the timer's type, expires, and interval values to the given
185 * values. If 'purge' is TRUE, any pending events from this timer
186 * are purged from its task's event queue.
190 *\li If 'expires' is NULL, the epoch will be used.
192 *\li If 'interval' is NULL, the zero interval will be used.
196 *\li 'timer' is a valid timer
198 *\li The same requirements that isc_timer_create() imposes on 'type',
199 * 'expires' and 'interval' apply.
203 *\li An idle timeout will not be generated until at least Now + the
204 * timer's interval if 'timer' is a once timer with a non-zero
211 *\li Unexpected error
215 isc_timer_touch(isc_timer_t *timer);
217 * Set the last-touched time of 'timer' to the current time.
221 *\li 'timer' is a valid once timer.
225 *\li An idle timeout will not be generated until at least Now + the
226 * timer's interval if 'timer' is a once timer with a non-zero
232 *\li Unexpected error
236 isc_timer_attach(isc_timer_t *timer, isc_timer_t **timerp);
238 * Attach *timerp to timer.
242 *\li 'timer' is a valid timer.
244 *\li 'timerp' points to a NULL timer.
248 *\li *timerp is attached to timer.
252 isc_timer_detach(isc_timer_t **timerp);
254 * Detach *timerp from its timer.
258 *\li 'timerp' points to a valid timer.
262 *\li *timerp is NULL.
264 *\li If '*timerp' is the last reference to the timer,
268 * The timer will be shutdown
270 * The timer will detach from its task
272 * All resources used by the timer have been freed
274 * Any events already posted by the timer will be purged.
275 * Therefore, if isc_timer_detach() is called in the context
276 * of the timer's task, it is guaranteed that no more
277 * timer event callbacks will run after the call.
282 isc_timer_gettype(isc_timer_t *timer);
284 * Return the timer type.
288 *\li 'timer' to be a valid timer.
292 isc_timermgr_create(isc_mem_t *mctx, isc_timermgr_t **managerp);
294 * Create a timer manager.
298 *\li All memory will be allocated in memory context 'mctx'.
302 *\li 'mctx' is a valid memory context.
304 *\li 'managerp' points to a NULL isc_timermgr_t.
308 *\li '*managerp' is a valid isc_timermgr_t.
314 *\li Unexpected error
318 isc_timermgr_destroy(isc_timermgr_t **managerp);
320 * Destroy a timer manager.
324 *\li This routine blocks until there are no timers left in the manager,
325 * so if the caller holds any timer references using the manager, it
326 * must detach them before calling isc_timermgr_destroy() or it will
331 *\li '*managerp' is a valid isc_timermgr_t.
335 *\li *managerp == NULL
337 *\li All resources used by the manager have been freed.
340 void isc_timermgr_poke(isc_timermgr_t *m);
344 #endif /* ISC_TIMER_H */