contrib/bind-9.5.2/lib/isc/include/isc/timer.h

   1 /*
   2  * Copyright (C) 2004-2008  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1998-2002  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: timer.h,v 1.38.128.2 2008/06/24 23:46:26 tbox Exp $ */
  19
  20 #ifndef ISC_TIMER_H
  21 #define ISC_TIMER_H 1
  22
  23 /*****
  24  ***** Module Info
  25  *****/
  26
  27 /*! \file isc/timer.h
  28  * \brief Provides timers which are event sources in the task system.
  29  *
  30  * Three types of timers are supported:
  31  *
  32  *\li   'ticker' timers generate a periodic tick event.
  33  *
  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
  37  *      'one-shot' timers.
  38  *
  39  *\li   'limited' timers generate a periodic tick event until they reach
  40  *      their lifetime when they generate a life timeout event.
  41  *
  42  *\li   'inactive' timers generate no events.
  43  *
  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
  46  * 'once' timer.
  47  *
  48  *\li MP:
  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.
  56  *
  57  * \li Reliability:
  58  *      No anticipated impact.
  59  *
  60  * \li Resources:
  61  *      TBS
  62  *
  63  * \li Security:
  64  *      No anticipated impact.
  65  *
  66  * \li Standards:
  67  *      None.
  68  */
  69
  70
  71 /***
  72  *** Imports
  73  ***/
  74
  75 #include <isc/types.h>
  76 #include <isc/event.h>
  77 #include <isc/eventclass.h>
  78 #include <isc/lang.h>
  79 #include <isc/time.h>
  80
  81 ISC_LANG_BEGINDECLS
  82
  83 /***
  84  *** Types
  85  ***/
  86
  87 /*% Timer Type */
  88 typedef enum {
  89         isc_timertype_ticker = 0,       /*%< Ticker */
  90         isc_timertype_once = 1,         /*%< Once */
  91         isc_timertype_limited = 2,      /*%< Limited */
  92         isc_timertype_inactive = 3      /*%< Inactive */
  93 } isc_timertype_t;
  94
  95 typedef struct isc_timerevent {
  96         struct isc_event        common;
  97         isc_time_t              due;
  98 } isc_timerevent_t;
  99
 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)
 105
 106 /***
 107  *** Timer and Timer Manager Functions
 108  ***
 109  *** Note: all Ensures conditions apply only if the result is success for
 110  *** those functions which return an isc_result_t.
 111  ***/
 112
 113 isc_result_t
 114 isc_timer_create(isc_timermgr_t *manager,
 115                  isc_timertype_t type,
 116                  isc_time_t *expires,
 117                  isc_interval_t *interval,
 118                  isc_task_t *task,
 119                  isc_taskaction_t action,
 120                  const void *arg,
 121                  isc_timer_t **timerp);
 122 /*%<
 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'.
 127  *
 128  * Notes:
 129  *
 130  *\li   For ticker timers, the timer will generate a 'tick' event every
 131  *      'interval' seconds.  The value of 'expires' is ignored.
 132  *
 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.
 138  *
 139  *\li   If 'expires' is NULL, the epoch will be used.
 140  *
 141  *      If 'interval' is NULL, the zero interval will be used.
 142  *
 143  * Requires:
 144  *
 145  *\li   'manager' is a valid manager
 146  *
 147  *\li   'task' is a valid task
 148  *
 149  *\li   'action' is a valid action
 150  *
 151  *\li   'expires' points to a valid time, or is NULL.
 152  *
 153  *\li   'interval' points to a valid interval, or is NULL.
 154  *
 155  *\li   type == isc_timertype_inactive ||
 156  *      ('expires' and 'interval' are not both 0)
 157  *
 158  *\li   'timerp' is a valid pointer, and *timerp == NULL
 159  *
 160  * Ensures:
 161  *
 162  *\li   '*timerp' is attached to the newly created timer
 163  *
 164  *\li   The timer is attached to the task
 165  *
 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
 168  *      interval.
 169  *
 170  * Returns:
 171  *
 172  *\li   Success
 173  *\li   No memory
 174  *\li   Unexpected error
 175  */
 176
 177 isc_result_t
 178 isc_timer_reset(isc_timer_t *timer,
 179                 isc_timertype_t type,
 180                 isc_time_t *expires,
 181                 isc_interval_t *interval,
 182                 isc_boolean_t purge);
 183 /*%<
 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.
 187  *
 188  * Notes:
 189  *
 190  *\li   If 'expires' is NULL, the epoch will be used.
 191  *
 192  *\li   If 'interval' is NULL, the zero interval will be used.
 193  *
 194  * Requires:
 195  *
 196  *\li   'timer' is a valid timer
 197  *
 198  *\li   The same requirements that isc_timer_create() imposes on 'type',
 199  *      'expires' and 'interval' apply.
 200  *
 201  * Ensures:
 202  *
 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
 205  *      interval.
 206  *
 207  * Returns:
 208  *
 209  *\li   Success
 210  *\li   No memory
 211  *\li   Unexpected error
 212  */
 213
 214 isc_result_t
 215 isc_timer_touch(isc_timer_t *timer);
 216 /*%<
 217  * Set the last-touched time of 'timer' to the current time.
 218  *
 219  * Requires:
 220  *
 221  *\li   'timer' is a valid once timer.
 222  *
 223  * Ensures:
 224  *
 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
 227  *      interval.
 228  *
 229  * Returns:
 230  *
 231  *\li   Success
 232  *\li   Unexpected error
 233  */
 234
 235 void
 236 isc_timer_attach(isc_timer_t *timer, isc_timer_t **timerp);
 237 /*%<
 238  * Attach *timerp to timer.
 239  *
 240  * Requires:
 241  *
 242  *\li   'timer' is a valid timer.
 243  *
 244  *\li   'timerp' points to a NULL timer.
 245  *
 246  * Ensures:
 247  *
 248  *\li   *timerp is attached to timer.
 249  */
 250
 251 void
 252 isc_timer_detach(isc_timer_t **timerp);
 253 /*%<
 254  * Detach *timerp from its timer.
 255  *
 256  * Requires:
 257  *
 258  *\li   'timerp' points to a valid timer.
 259  *
 260  * Ensures:
 261  *
 262  *\li   *timerp is NULL.
 263  *
 264  *\li   If '*timerp' is the last reference to the timer,
 265  *      then:
 266  *
 267  *\code
 268  *              The timer will be shutdown
 269  *
 270  *              The timer will detach from its task
 271  *
 272  *              All resources used by the timer have been freed
 273  *
 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.
 278  *\endcode
 279  */
 280
 281 isc_timertype_t
 282 isc_timer_gettype(isc_timer_t *timer);
 283 /*%<
 284  * Return the timer type.
 285  *
 286  * Requires:
 287  *
 288  *\li   'timer' to be a valid timer.
 289  */
 290
 291 isc_result_t
 292 isc_timermgr_create(isc_mem_t *mctx, isc_timermgr_t **managerp);
 293 /*%<
 294  * Create a timer manager.
 295  *
 296  * Notes:
 297  *
 298  *\li   All memory will be allocated in memory context 'mctx'.
 299  *
 300  * Requires:
 301  *
 302  *\li   'mctx' is a valid memory context.
 303  *
 304  *\li   'managerp' points to a NULL isc_timermgr_t.
 305  *
 306  * Ensures:
 307  *
 308  *\li   '*managerp' is a valid isc_timermgr_t.
 309  *
 310  * Returns:
 311  *
 312  *\li   Success
 313  *\li   No memory
 314  *\li   Unexpected error
 315  */
 316
 317 void
 318 isc_timermgr_destroy(isc_timermgr_t **managerp);
 319 /*%<
 320  * Destroy a timer manager.
 321  *
 322  * Notes:
 323  *
 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
 327  *      block forever.
 328  *
 329  * Requires:
 330  *
 331  *\li   '*managerp' is a valid isc_timermgr_t.
 332  *
 333  * Ensures:
 334  *
 335  *\li   *managerp == NULL
 336  *
 337  *\li   All resources used by the manager have been freed.
 338  */
 339
 340 void isc_timermgr_poke(isc_timermgr_t *m);
 341
 342 ISC_LANG_ENDDECLS
 343
 344 #endif /* ISC_TIMER_H */