2 * Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1998-2001 Internet Software Consortium.
5 * Permission to use, copy, modify, and distribute this software for any
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18 /* $Id: timer.h,v 1.28.2.1 2004/03/09 06:12:03 marka Exp $ */
30 * Provides timers which are event sources in the task system.
32 * Three types of timers are supported:
34 * 'ticker' timers generate a periodic tick event.
36 * 'once' timers generate an idle timeout event if they are idle for too
37 * long, and generate a life timeout event if their lifetime expires.
38 * They are used to implement both (possibly expiring) idle timers and
41 * 'inactive' timers generate no events.
43 * Timers can change type. It is typical to create a timer as
44 * an 'inactive' timer and then change it into a 'ticker' or
48 * The module ensures appropriate synchronization of data structures it
49 * 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.
55 * The caller must ensure that isc_timermgr_destroy() is called only
56 * once for a given manager.
59 * No anticipated impact.
65 * No anticipated impact.
76 #include <isc/types.h>
77 #include <isc/event.h>
78 #include <isc/eventclass.h>
88 isc_timertype_ticker = 0,
89 isc_timertype_once = 1,
90 isc_timertype_inactive = 2
93 typedef struct isc_timerevent {
94 struct isc_event common;
97 #define ISC_TIMEREVENT_FIRSTEVENT (ISC_EVENTCLASS_TIMER + 0)
98 #define ISC_TIMEREVENT_TICK (ISC_EVENTCLASS_TIMER + 1)
99 #define ISC_TIMEREVENT_IDLE (ISC_EVENTCLASS_TIMER + 2)
100 #define ISC_TIMEREVENT_LIFE (ISC_EVENTCLASS_TIMER + 3)
101 #define ISC_TIMEREVENT_LASTEVENT (ISC_EVENTCLASS_TIMER + 65535)
104 *** Timer and Timer Manager Functions
106 *** Note: all Ensures conditions apply only if the result is success for
107 *** those functions which return an isc_result_t.
111 isc_timer_create(isc_timermgr_t *manager,
112 isc_timertype_t type,
114 isc_interval_t *interval,
116 isc_taskaction_t action,
118 isc_timer_t **timerp);
120 * Create a new 'type' timer managed by 'manager'. The timers parameters
121 * are specified by 'expires' and 'interval'. Events will be posted to
122 * 'task' and when dispatched 'action' will be called with 'arg' as the
123 * arg value. The new timer is returned in 'timerp'.
127 * For ticker timers, the timer will generate a 'tick' event every
128 * 'interval' seconds. The value of 'expires' is ignored.
130 * For once timers, 'expires' specifies the time when a life timeout
131 * event should be generated. If 'expires' is 0 (the epoch), then no life
132 * timeout will be generated. 'interval' specifies how long the timer
133 * can be idle before it generates an idle timeout. If 0, then no
134 * idle timeout will be generated.
136 * If 'expires' is NULL, the epoch will be used.
138 * If 'interval' is NULL, the zero interval will be used.
142 * 'manager' is a valid manager
144 * 'task' is a valid task
146 * 'action' is a valid action
148 * 'expires' points to a valid time, or is NULL.
150 * 'interval' points to a valid interval, or is NULL.
152 * type == isc_timertype_inactive ||
153 * ('expires' and 'interval' are not both 0)
155 * 'timerp' is a valid pointer, and *timerp == NULL
159 * '*timerp' is attached to the newly created timer
161 * The timer is attached to the task
163 * An idle timeout will not be generated until at least Now + the
164 * timer's interval if 'timer' is a once timer with a non-zero
175 isc_timer_reset(isc_timer_t *timer,
176 isc_timertype_t type,
178 isc_interval_t *interval,
179 isc_boolean_t purge);
181 * Change the timer's type, expires, and interval values to the given
182 * values. If 'purge' is TRUE, any pending events from this timer
183 * are purged from its task's event queue.
187 * If 'expires' is NULL, the epoch will be used.
189 * If 'interval' is NULL, the zero interval will be used.
193 * 'timer' is a valid timer
195 * The same requirements that isc_timer_create() imposes on 'type',
196 * 'expires' and 'interval' apply.
200 * An idle timeout will not be generated until at least Now + the
201 * timer's interval if 'timer' is a once timer with a non-zero
212 isc_timer_touch(isc_timer_t *timer);
214 * Set the last-touched time of 'timer' to the current time.
218 * 'timer' is a valid once timer.
222 * An idle timeout will not be generated until at least Now + the
223 * timer's interval if 'timer' is a once timer with a non-zero
233 isc_timer_attach(isc_timer_t *timer, isc_timer_t **timerp);
235 * Attach *timerp to timer.
239 * 'timer' is a valid timer.
241 * 'timerp' points to a NULL timer.
245 * *timerp is attached to timer.
249 isc_timer_detach(isc_timer_t **timerp);
251 * Detach *timerp from its timer.
255 * 'timerp' points to a valid timer.
261 * If '*timerp' is the last reference to the timer,
264 * The timer will be shutdown
266 * The timer will detach from its task
268 * All resources used by the timer have been freed
270 * Any events already posted by the timer will be purged.
271 * Therefore, if isc_timer_detach() is called in the context
272 * of the timer's task, it is guaranteed that no more
273 * timer event callbacks will run after the call.
277 isc_timermgr_create(isc_mem_t *mctx, isc_timermgr_t **managerp);
279 * Create a timer manager.
283 * All memory will be allocated in memory context 'mctx'.
287 * 'mctx' is a valid memory context.
289 * 'managerp' points to a NULL isc_timermgr_t.
293 * '*managerp' is a valid isc_timermgr_t.
303 isc_timermgr_destroy(isc_timermgr_t **managerp);
305 * Destroy a timer manager.
309 * This routine blocks until there are no timers left in the manager,
310 * so if the caller holds any timer references using the manager, it
311 * must detach them before calling isc_timermgr_destroy() or it will
316 * '*managerp' is a valid isc_timermgr_t.
322 * All resources used by the manager have been freed.
327 #endif /* ISC_TIMER_H */