contrib/bind-9.2.4rc7/lib/isc/include/isc/quota.h

   1 /*
   2  * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 2000, 2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and 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: quota.h,v 1.8.2.1 2004/03/09 06:11:59 marka Exp $ */
  19
  20 #ifndef ISC_QUOTA_H
  21 #define ISC_QUOTA_H 1
  22
  23 /*****
  24  ***** Module Info
  25  *****/
  26
  27 /*
  28  * Quota
  29  *
  30  * The isc_quota_t object is a simple helper object for implementing
  31  * quotas on things like the number of simultaneous connections to
  32  * a server.  It keeps track of the amount of quota in use, and
  33  * encapsulates the locking necessary to allow multiple tasks to
  34  * share a quota.
  35  */
  36
  37 /***
  38  *** Imports.
  39  ***/
  40
  41 #include <isc/lang.h>
  42 #include <isc/mutex.h>
  43 #include <isc/types.h>
  44
  45 /*****
  46  ***** Types.
  47  *****/
  48
  49 ISC_LANG_BEGINDECLS
  50
  51 struct isc_quota {
  52         isc_mutex_t     lock;
  53         /* Locked by lock. */
  54         int             max;
  55         int             used;
  56 };
  57
  58 isc_result_t
  59 isc_quota_init(isc_quota_t *quota, int max);
  60 /*
  61  * Initialize a quota object.
  62  *
  63  * Returns:
  64  *      ISC_R_SUCCESS
  65  *      Other error     Lock creation failed.
  66  */
  67
  68 void
  69 isc_quota_destroy(isc_quota_t *quota);
  70 /*
  71  * Destroy a quota object.
  72  */
  73
  74 isc_result_t
  75 isc_quota_reserve(isc_quota_t *quota);
  76 /*
  77  * Attempt to reserve one unit of 'quota'.
  78  *
  79  * Returns:
  80  *      ISC_R_SUCCESS   Success
  81  *      ISC_R_QUOTA     Quota is full
  82  */
  83
  84 void
  85 isc_quota_release(isc_quota_t *quota);
  86 /*
  87  * Release one unit of quota.
  88  */
  89
  90 isc_result_t
  91 isc_quota_attach(isc_quota_t *quota, isc_quota_t **p);
  92 /*
  93  * Like isc_quota_reserve, and also attaches '*p' to the
  94  * quota if successful.
  95  */
  96
  97 void
  98 isc_quota_detach(isc_quota_t **p);
  99 /*
 100  * Like isc_quota_release, and also detaches '*p' from the
 101  * quota.
 102  */
 103
 104 ISC_LANG_ENDDECLS
 105
 106 #endif /* ISC_QUOTA_H */