327 lines
8.3 KiB
C
327 lines
8.3 KiB
C
/*
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* Copyright (C) 2009, 2012 Internet Systems Consortium, Inc. ("ISC")
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id$ */
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/*! \file */
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#include <config.h>
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#include <string.h>
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#include <isc/atomic.h>
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#include <isc/buffer.h>
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#include <isc/magic.h>
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#include <isc/mem.h>
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#include <isc/platform.h>
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#include <isc/print.h>
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#include <isc/rwlock.h>
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#include <isc/stats.h>
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#include <isc/util.h>
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#define ISC_STATS_MAGIC ISC_MAGIC('S', 't', 'a', 't')
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#define ISC_STATS_VALID(x) ISC_MAGIC_VALID(x, ISC_STATS_MAGIC)
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#ifndef ISC_STATS_USEMULTIFIELDS
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#if defined(ISC_RWLOCK_USEATOMIC) && defined(ISC_PLATFORM_HAVEXADD) && !defined(ISC_PLATFORM_HAVEXADDQ)
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#define ISC_STATS_USEMULTIFIELDS 1
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#else
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#define ISC_STATS_USEMULTIFIELDS 0
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#endif
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#endif /* ISC_STATS_USEMULTIFIELDS */
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#if ISC_STATS_USEMULTIFIELDS
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typedef struct {
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isc_uint32_t hi;
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isc_uint32_t lo;
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} isc_stat_t;
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#else
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typedef isc_uint64_t isc_stat_t;
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#endif
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struct isc_stats {
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/*% Unlocked */
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unsigned int magic;
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isc_mem_t *mctx;
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int ncounters;
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isc_mutex_t lock;
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unsigned int references; /* locked by lock */
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/*%
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* Locked by counterlock or unlocked if efficient rwlock is not
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* available.
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*/
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_t counterlock;
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#endif
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isc_stat_t *counters;
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/*%
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* We don't want to lock the counters while we are dumping, so we first
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* copy the current counter values into a local array. This buffer
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* will be used as the copy destination. It's allocated on creation
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* of the stats structure so that the dump operation won't fail due
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* to memory allocation failure.
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* XXX: this approach is weird for non-threaded build because the
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* additional memory and the copy overhead could be avoided. We prefer
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* simplicity here, however, under the assumption that this function
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* should be only rarely called.
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*/
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isc_uint64_t *copiedcounters;
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};
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static isc_result_t
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create_stats(isc_mem_t *mctx, int ncounters, isc_stats_t **statsp) {
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isc_stats_t *stats;
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isc_result_t result = ISC_R_SUCCESS;
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REQUIRE(statsp != NULL && *statsp == NULL);
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stats = isc_mem_get(mctx, sizeof(*stats));
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if (stats == NULL)
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return (ISC_R_NOMEMORY);
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result = isc_mutex_init(&stats->lock);
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if (result != ISC_R_SUCCESS)
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goto clean_stats;
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stats->counters = isc_mem_get(mctx, sizeof(isc_stat_t) * ncounters);
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if (stats->counters == NULL) {
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result = ISC_R_NOMEMORY;
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goto clean_mutex;
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}
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stats->copiedcounters = isc_mem_get(mctx,
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sizeof(isc_uint64_t) * ncounters);
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if (stats->copiedcounters == NULL) {
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result = ISC_R_NOMEMORY;
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goto clean_counters;
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}
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#ifdef ISC_RWLOCK_USEATOMIC
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result = isc_rwlock_init(&stats->counterlock, 0, 0);
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if (result != ISC_R_SUCCESS)
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goto clean_copiedcounters;
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#endif
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stats->references = 1;
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memset(stats->counters, 0, sizeof(isc_stat_t) * ncounters);
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stats->mctx = NULL;
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isc_mem_attach(mctx, &stats->mctx);
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stats->ncounters = ncounters;
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stats->magic = ISC_STATS_MAGIC;
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*statsp = stats;
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return (result);
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clean_counters:
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isc_mem_put(mctx, stats->counters, sizeof(isc_stat_t) * ncounters);
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#ifdef ISC_RWLOCK_USEATOMIC
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clean_copiedcounters:
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isc_mem_put(mctx, stats->copiedcounters,
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sizeof(isc_stat_t) * ncounters);
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#endif
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clean_mutex:
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DESTROYLOCK(&stats->lock);
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clean_stats:
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isc_mem_put(mctx, stats, sizeof(*stats));
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return (result);
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}
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void
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isc_stats_attach(isc_stats_t *stats, isc_stats_t **statsp) {
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REQUIRE(ISC_STATS_VALID(stats));
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REQUIRE(statsp != NULL && *statsp == NULL);
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LOCK(&stats->lock);
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stats->references++;
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UNLOCK(&stats->lock);
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*statsp = stats;
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}
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void
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isc_stats_detach(isc_stats_t **statsp) {
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isc_stats_t *stats;
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REQUIRE(statsp != NULL && ISC_STATS_VALID(*statsp));
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stats = *statsp;
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*statsp = NULL;
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LOCK(&stats->lock);
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stats->references--;
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UNLOCK(&stats->lock);
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if (stats->references == 0) {
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isc_mem_put(stats->mctx, stats->copiedcounters,
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sizeof(isc_stat_t) * stats->ncounters);
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isc_mem_put(stats->mctx, stats->counters,
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sizeof(isc_stat_t) * stats->ncounters);
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DESTROYLOCK(&stats->lock);
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_destroy(&stats->counterlock);
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#endif
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isc_mem_putanddetach(&stats->mctx, stats, sizeof(*stats));
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}
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}
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int
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isc_stats_ncounters(isc_stats_t *stats) {
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REQUIRE(ISC_STATS_VALID(stats));
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return (stats->ncounters);
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}
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static inline void
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incrementcounter(isc_stats_t *stats, int counter) {
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isc_int32_t prev;
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#ifdef ISC_RWLOCK_USEATOMIC
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/*
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* We use a "read" lock to prevent other threads from reading the
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* counter while we "writing" a counter field. The write access itself
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* is protected by the atomic operation.
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*/
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isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
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#endif
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#if ISC_STATS_USEMULTIFIELDS
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prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, 1);
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/*
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* If the lower 32-bit field overflows, increment the higher field.
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* Note that it's *theoretically* possible that the lower field
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* overlaps again before the higher field is incremented. It doesn't
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* matter, however, because we don't read the value until
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* isc_stats_copy() is called where the whole process is protected
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* by the write (exclusive) lock.
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*/
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if (prev == (isc_int32_t)0xffffffff)
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isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi, 1);
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#elif defined(ISC_PLATFORM_HAVEXADDQ)
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UNUSED(prev);
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isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], 1);
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#else
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UNUSED(prev);
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stats->counters[counter]++;
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#endif
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
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#endif
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}
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static inline void
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decrementcounter(isc_stats_t *stats, int counter) {
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isc_int32_t prev;
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
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#endif
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#if ISC_STATS_USEMULTIFIELDS
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prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, -1);
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if (prev == 0)
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isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi,
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-1);
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#elif defined(ISC_PLATFORM_HAVEXADDQ)
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UNUSED(prev);
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isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], -1);
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#else
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UNUSED(prev);
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stats->counters[counter]--;
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#endif
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
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#endif
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}
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static void
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copy_counters(isc_stats_t *stats) {
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int i;
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#ifdef ISC_RWLOCK_USEATOMIC
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/*
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* We use a "write" lock before "reading" the statistics counters as
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* an exclusive lock.
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*/
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isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write);
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#endif
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#if ISC_STATS_USEMULTIFIELDS
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for (i = 0; i < stats->ncounters; i++) {
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stats->copiedcounters[i] =
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(isc_uint64_t)(stats->counters[i].hi) << 32 |
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stats->counters[i].lo;
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}
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#else
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UNUSED(i);
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memcpy(stats->copiedcounters, stats->counters,
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stats->ncounters * sizeof(isc_stat_t));
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#endif
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#ifdef ISC_RWLOCK_USEATOMIC
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isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write);
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#endif
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}
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isc_result_t
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isc_stats_create(isc_mem_t *mctx, isc_stats_t **statsp, int ncounters) {
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REQUIRE(statsp != NULL && *statsp == NULL);
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return (create_stats(mctx, ncounters, statsp));
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}
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void
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isc_stats_increment(isc_stats_t *stats, isc_statscounter_t counter) {
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REQUIRE(ISC_STATS_VALID(stats));
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REQUIRE(counter < stats->ncounters);
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incrementcounter(stats, (int)counter);
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}
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void
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isc_stats_decrement(isc_stats_t *stats, isc_statscounter_t counter) {
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REQUIRE(ISC_STATS_VALID(stats));
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REQUIRE(counter < stats->ncounters);
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decrementcounter(stats, (int)counter);
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}
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void
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isc_stats_dump(isc_stats_t *stats, isc_stats_dumper_t dump_fn,
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void *arg, unsigned int options)
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{
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int i;
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REQUIRE(ISC_STATS_VALID(stats));
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copy_counters(stats);
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for (i = 0; i < stats->ncounters; i++) {
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if ((options & ISC_STATSDUMP_VERBOSE) == 0 &&
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stats->copiedcounters[i] == 0)
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continue;
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dump_fn((isc_statscounter_t)i, stats->copiedcounters[i], arg);
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}
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}
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