external/bsd/bind/dist/lib/isc/counter.c

   1 /*      $NetBSD: counter.c,v 1.1.1.2 2014/12/10 03:34:43 christos Exp $ */
   2
   3 /*
   4  * Copyright (C) 2014  Internet Systems Consortium, Inc. ("ISC")
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  11  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  12  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  13  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  14  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  15  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  16  * PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 /*! \file */
  20
  21 #include <config.h>
  22
  23 #include <stddef.h>
  24
  25 #include <isc/counter.h>
  26 #include <isc/magic.h>
  27 #include <isc/mem.h>
  28 #include <isc/util.h>
  29
  30 #define COUNTER_MAGIC                   ISC_MAGIC('C', 'n', 't', 'r')
  31 #define VALID_COUNTER(r)                ISC_MAGIC_VALID(r, COUNTER_MAGIC)
  32
  33 struct isc_counter {
  34         unsigned int    magic;
  35         isc_mem_t       *mctx;
  36         isc_mutex_t     lock;
  37         unsigned int    references;
  38         unsigned int    limit;
  39         unsigned int    used;
  40 };
  41
  42 isc_result_t
  43 isc_counter_create(isc_mem_t *mctx, int limit, isc_counter_t **counterp) {
  44         isc_result_t result;
  45         isc_counter_t *counter;
  46
  47         REQUIRE(counterp != NULL && *counterp == NULL);
  48
  49         counter = isc_mem_get(mctx, sizeof(*counter));
  50         if (counter == NULL)
  51                 return (ISC_R_NOMEMORY);
  52
  53         result = isc_mutex_init(&counter->lock);
  54         if (result != ISC_R_SUCCESS) {
  55                 isc_mem_put(mctx, counter, sizeof(*counter));
  56                 return (result);
  57         }
  58
  59         counter->mctx = NULL;
  60         isc_mem_attach(mctx, &counter->mctx);
  61
  62         counter->references = 1;
  63         counter->limit = limit;
  64         counter->used = 0;
  65
  66         counter->magic = COUNTER_MAGIC;
  67         *counterp = counter;
  68         return (ISC_R_SUCCESS);
  69 }
  70
  71 isc_result_t
  72 isc_counter_increment(isc_counter_t *counter) {
  73         isc_result_t result = ISC_R_SUCCESS;
  74
  75         LOCK(&counter->lock);
  76         counter->used++;
  77         if (counter->limit != 0 && counter->used >= counter->limit)
  78                 result = ISC_R_QUOTA;
  79         UNLOCK(&counter->lock);
  80
  81         return (result);
  82 }
  83
  84 unsigned int
  85 isc_counter_used(isc_counter_t *counter) {
  86         REQUIRE(VALID_COUNTER(counter));
  87
  88         return (counter->used);
  89 }
  90
  91 void
  92 isc_counter_setlimit(isc_counter_t *counter, int limit) {
  93         REQUIRE(VALID_COUNTER(counter));
  94
  95         LOCK(&counter->lock);
  96         counter->limit = limit;
  97         UNLOCK(&counter->lock);
  98 }
  99
 100 void
 101 isc_counter_attach(isc_counter_t *source, isc_counter_t **targetp) {
 102         REQUIRE(VALID_COUNTER(source));
 103         REQUIRE(targetp != NULL && *targetp == NULL);
 104
 105         LOCK(&source->lock);
 106         source->references++;
 107         INSIST(source->references > 0);
 108         UNLOCK(&source->lock);
 109
 110         *targetp = source;
 111 }
 112
 113 static void
 114 destroy(isc_counter_t *counter) {
 115         counter->magic = 0;
 116         isc_mutex_destroy(&counter->lock);
 117         isc_mem_putanddetach(&counter->mctx, counter, sizeof(*counter));
 118 }
 119
 120 void
 121 isc_counter_detach(isc_counter_t **counterp) {
 122         isc_counter_t *counter;
 123         isc_boolean_t want_destroy = ISC_FALSE;
 124
 125         REQUIRE(counterp != NULL && *counterp != NULL);
 126         counter = *counterp;
 127         REQUIRE(VALID_COUNTER(counter));
 128
 129         *counterp = NULL;
 130
 131         LOCK(&counter->lock);
 132         INSIST(counter->references > 0);
 133         counter->references--;
 134         if (counter->references == 0)
 135                 want_destroy = ISC_TRUE;
 136         UNLOCK(&counter->lock);
 137
 138         if (want_destroy)
 139                 destroy(counter);
 140 }