1 files changed, 326 insertions, 0 deletions
diff --git a/lib/isc/stats.c b/lib/isc/stats.c
new file mode 100644
index 0000000..8b624b2
--- /dev/null
+++ b/lib/isc/stats.c
@@ -0,0 +1,326 @@
+/*
+ * Copyright (C) 2009, 2012  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id$ */
+
+/*! \file */
+
+#include <config.h>
+
+#include <string.h>
+
+#include <isc/atomic.h>
+#include <isc/buffer.h>
+#include <isc/magic.h>
+#include <isc/mem.h>
+#include <isc/platform.h>
+#include <isc/print.h>
+#include <isc/rwlock.h>
+#include <isc/stats.h>
+#include <isc/util.h>
+
+#define ISC_STATS_MAGIC			ISC_MAGIC('S', 't', 'a', 't')
+#define ISC_STATS_VALID(x)		ISC_MAGIC_VALID(x, ISC_STATS_MAGIC)
+
+#ifndef ISC_STATS_USEMULTIFIELDS
+#if defined(ISC_RWLOCK_USEATOMIC) && defined(ISC_PLATFORM_HAVEXADD) && !defined(ISC_PLATFORM_HAVEXADDQ)
+#define ISC_STATS_USEMULTIFIELDS 1
+#else
+#define ISC_STATS_USEMULTIFIELDS 0
+#endif
+#endif	/* ISC_STATS_USEMULTIFIELDS */
+
+#if ISC_STATS_USEMULTIFIELDS
+typedef struct {
+	isc_uint32_t hi;
+	isc_uint32_t lo;
+} isc_stat_t;
+#else
+typedef isc_uint64_t isc_stat_t;
+#endif
+
+struct isc_stats {
+	/*% Unlocked */
+	unsigned int	magic;
+	isc_mem_t	*mctx;
+	int		ncounters;
+
+	isc_mutex_t	lock;
+	unsigned int	references; /* locked by lock */
+
+	/*%
+	 * Locked by counterlock or unlocked if efficient rwlock is not
+	 * available.
+	 */
+#ifdef ISC_RWLOCK_USEATOMIC
+	isc_rwlock_t	counterlock;
+#endif
+	isc_stat_t	*counters;
+
+	/*%
+	 * We don't want to lock the counters while we are dumping, so we first
+	 * copy the current counter values into a local array.  This buffer
+	 * will be used as the copy destination.  It's allocated on creation
+	 * of the stats structure so that the dump operation won't fail due
+	 * to memory allocation failure.
+	 * XXX: this approach is weird for non-threaded build because the
+	 * additional memory and the copy overhead could be avoided.  We prefer
+	 * simplicity here, however, under the assumption that this function
+	 * should be only rarely called.
+	 */
+	isc_uint64_t	*copiedcounters;
+};
+
+static isc_result_t
+create_stats(isc_mem_t *mctx, int ncounters, isc_stats_t **statsp) {
+	isc_stats_t *stats;
+	isc_result_t result = ISC_R_SUCCESS;
+
+	REQUIRE(statsp != NULL && *statsp == NULL);
+
+	stats = isc_mem_get(mctx, sizeof(*stats));
+	if (stats == NULL)
+		return (ISC_R_NOMEMORY);
+
+	result = isc_mutex_init(&stats->lock);
+	if (result != ISC_R_SUCCESS)
+		goto clean_stats;
+
+	stats->counters = isc_mem_get(mctx, sizeof(isc_stat_t) * ncounters);
+	if (stats->counters == NULL) {
+		result = ISC_R_NOMEMORY;
+		goto clean_mutex;
+	}
+	stats->copiedcounters = isc_mem_get(mctx,
+					    sizeof(isc_uint64_t) * ncounters);
+	if (stats->copiedcounters == NULL) {
+		result = ISC_R_NOMEMORY;
+		goto clean_counters;
+	}
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	result = isc_rwlock_init(&stats->counterlock, 0, 0);
+	if (result != ISC_R_SUCCESS)
+		goto clean_copiedcounters;
+#endif
+
+	stats->references = 1;
+	memset(stats->counters, 0, sizeof(isc_stat_t) * ncounters);
+	stats->mctx = NULL;
+	isc_mem_attach(mctx, &stats->mctx);
+	stats->ncounters = ncounters;
+	stats->magic = ISC_STATS_MAGIC;
+
+	*statsp = stats;
+
+	return (result);
+
+clean_counters:
+	isc_mem_put(mctx, stats->counters, sizeof(isc_stat_t) * ncounters);
+
+#ifdef ISC_RWLOCK_USEATOMIC
+clean_copiedcounters:
+	isc_mem_put(mctx, stats->copiedcounters,
+		    sizeof(isc_stat_t) * ncounters);
+#endif
+
+clean_mutex:
+	DESTROYLOCK(&stats->lock);
+
+clean_stats:
+	isc_mem_put(mctx, stats, sizeof(*stats));
+
+	return (result);
+}
+
+void
+isc_stats_attach(isc_stats_t *stats, isc_stats_t **statsp) {
+	REQUIRE(ISC_STATS_VALID(stats));
+	REQUIRE(statsp != NULL && *statsp == NULL);
+
+	LOCK(&stats->lock);
+	stats->references++;
+	UNLOCK(&stats->lock);
+
+	*statsp = stats;
+}
+
+void
+isc_stats_detach(isc_stats_t **statsp) {
+	isc_stats_t *stats;
+
+	REQUIRE(statsp != NULL && ISC_STATS_VALID(*statsp));
+
+	stats = *statsp;
+	*statsp = NULL;
+
+	LOCK(&stats->lock);
+	stats->references--;
+	UNLOCK(&stats->lock);
+
+	if (stats->references == 0) {
+		isc_mem_put(stats->mctx, stats->copiedcounters,
+			    sizeof(isc_stat_t) * stats->ncounters);
+		isc_mem_put(stats->mctx, stats->counters,
+			    sizeof(isc_stat_t) * stats->ncounters);
+		DESTROYLOCK(&stats->lock);
+#ifdef ISC_RWLOCK_USEATOMIC
+		isc_rwlock_destroy(&stats->counterlock);
+#endif
+		isc_mem_putanddetach(&stats->mctx, stats, sizeof(*stats));
+	}
+}
+
+int
+isc_stats_ncounters(isc_stats_t *stats) {
+	REQUIRE(ISC_STATS_VALID(stats));
+
+	return (stats->ncounters);
+}
+
+static inline void
+incrementcounter(isc_stats_t *stats, int counter) {
+	isc_int32_t prev;
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	/*
+	 * We use a "read" lock to prevent other threads from reading the
+	 * counter while we "writing" a counter field.  The write access itself
+	 * is protected by the atomic operation.
+	 */
+	isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
+#endif
+
+#if ISC_STATS_USEMULTIFIELDS
+	prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, 1);
+	/*
+	 * If the lower 32-bit field overflows, increment the higher field.
+	 * Note that it's *theoretically* possible that the lower field
+	 * overlaps again before the higher field is incremented.  It doesn't
+	 * matter, however, because we don't read the value until
+	 * isc_stats_copy() is called where the whole process is protected
+	 * by the write (exclusive) lock.
+	 */
+	if (prev == (isc_int32_t)0xffffffff)
+		isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi, 1);
+#elif defined(ISC_PLATFORM_HAVEXADDQ)
+	UNUSED(prev);
+	isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], 1);
+#else
+	UNUSED(prev);
+	stats->counters[counter]++;
+#endif
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
+#endif
+}
+
+static inline void
+decrementcounter(isc_stats_t *stats, int counter) {
+	isc_int32_t prev;
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
+#endif
+
+#if ISC_STATS_USEMULTIFIELDS
+	prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, -1);
+	if (prev == 0)
+		isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi,
+				-1);
+#elif defined(ISC_PLATFORM_HAVEXADDQ)
+	UNUSED(prev);
+	isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], -1);
+#else
+	UNUSED(prev);
+	stats->counters[counter]--;
+#endif
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
+#endif
+}
+
+static void
+copy_counters(isc_stats_t *stats) {
+	int i;
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	/*
+	 * We use a "write" lock before "reading" the statistics counters as
+	 * an exclusive lock.
+	 */
+	isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write);
+#endif
+
+#if ISC_STATS_USEMULTIFIELDS
+	for (i = 0; i < stats->ncounters; i++) {
+		stats->copiedcounters[i] =
+				(isc_uint64_t)(stats->counters[i].hi) << 32 |
+				stats->counters[i].lo;
+	}
+#else
+	UNUSED(i);
+	memcpy(stats->copiedcounters, stats->counters,
+	       stats->ncounters * sizeof(isc_stat_t));
+#endif
+
+#ifdef ISC_RWLOCK_USEATOMIC
+	isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write);
+#endif
+}
+
+isc_result_t
+isc_stats_create(isc_mem_t *mctx, isc_stats_t **statsp, int ncounters) {
+	REQUIRE(statsp != NULL && *statsp == NULL);
+
+	return (create_stats(mctx, ncounters, statsp));
+}
+
+void
+isc_stats_increment(isc_stats_t *stats, isc_statscounter_t counter) {
+	REQUIRE(ISC_STATS_VALID(stats));
+	REQUIRE(counter < stats->ncounters);
+
+	incrementcounter(stats, (int)counter);
+}
+
+void
+isc_stats_decrement(isc_stats_t *stats, isc_statscounter_t counter) {
+	REQUIRE(ISC_STATS_VALID(stats));
+	REQUIRE(counter < stats->ncounters);
+
+	decrementcounter(stats, (int)counter);
+}
+
+void
+isc_stats_dump(isc_stats_t *stats, isc_stats_dumper_t dump_fn,
+	       void *arg, unsigned int options)
+{
+	int i;
+
+	REQUIRE(ISC_STATS_VALID(stats));
+
+	copy_counters(stats);
+
+	for (i = 0; i < stats->ncounters; i++) {
+		if ((options & ISC_STATSDUMP_VERBOSE) == 0 &&
+		    stats->copiedcounters[i] == 0)
+				continue;
+		dump_fn((isc_statscounter_t)i, stats->copiedcounters[i], arg);
+	}
+}