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Diffstat (limited to 'lib/isc/stats.c')
| -rw-r--r-- | lib/isc/stats.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/lib/isc/stats.c b/lib/isc/stats.c new file mode 100644 index 0000000..196099e --- /dev/null +++ b/lib/isc/stats.c @@ -0,0 +1,454 @@ +/* + * Copyright (C) Internet Systems Consortium, Inc. ("ISC") + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * See the COPYRIGHT file distributed with this work for additional + * information regarding copyright ownership. + */ + + +/*! \file */ + +#include <config.h> + +#include <inttypes.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> + +#if defined(ISC_PLATFORM_HAVESTDATOMIC) +#if defined(__cplusplus) +#include <isc/stdatomic.h> +#else +#include <stdatomic.h> +#endif +#endif + +#define ISC_STATS_MAGIC ISC_MAGIC('S', 't', 'a', 't') +#define ISC_STATS_VALID(x) ISC_MAGIC_VALID(x, ISC_STATS_MAGIC) + +/*% + * Local macro confirming prescence of 64-bit + * increment and store operations, just to make + * the later macros simpler + */ +#if (defined(ISC_PLATFORM_HAVESTDATOMIC) && defined(ATOMIC_LONG_LOCK_FREE)) || \ + (defined(ISC_PLATFORM_HAVEXADDQ) && defined(ISC_PLATFORM_HAVEATOMICSTOREQ)) +#define ISC_STATS_HAVEATOMICQ 1 +#if (defined(ISC_PLATFORM_HAVESTDATOMIC) && defined(ATOMIC_LONG_LOCK_FREE)) +#define ISC_STATS_HAVESTDATOMICQ 1 +#endif +#else +#define ISC_STATS_HAVEATOMICQ 0 +#endif + +/*% + * Only lock the counters if 64-bit atomic operations are + * not available but cheap atomic lock operations are. + * On a modern 64-bit system this should never be the case. + * + * Normal locks are too expensive to be used whenever a counter + * is updated. + */ +#if !ISC_STATS_HAVEATOMICQ && defined(ISC_RWLOCK_HAVEATOMIC) +#define ISC_STATS_LOCKCOUNTERS 1 +#else +#define ISC_STATS_LOCKCOUNTERS 0 +#endif + +/*% + * If 64-bit atomic operations are not available but + * 32-bit operations are then split the counter into two, + * using the atomic operations to try to ensure that any carry + * from the low word is correctly carried into the high word. + * + * Otherwise, just rely on standard 64-bit data types + * and operations + */ +#if !ISC_STATS_HAVEATOMICQ && ((defined(ISC_PLATFORM_HAVESTDATOMIC) && defined(ATOMIC_INT_LOCK_FREE)) || defined(ISC_PLATFORM_HAVEXADD)) +#define ISC_STATS_USEMULTIFIELDS 1 +#if (defined(ISC_PLATFORM_HAVESTDATOMIC) && defined(ATOMIC_INT_LOCK_FREE)) +#define ISC_STATS_HAVESTDATOMIC 1 +#endif +#else +#define ISC_STATS_USEMULTIFIELDS 0 +#endif + +#if ISC_STATS_USEMULTIFIELDS +typedef struct { +#if defined(ISC_STATS_HAVESTDATOMIC) + atomic_int_fast32_t hi; + atomic_int_fast32_t lo; +#else + uint32_t hi; + uint32_t lo; +#endif +} isc_stat_t; +#else +#if defined(ISC_STATS_HAVESTDATOMICQ) +typedef atomic_int_fast64_t isc_stat_t; +#else +typedef uint64_t isc_stat_t; +#endif +#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. + */ +#if ISC_STATS_LOCKCOUNTERS + 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. + */ + 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(uint64_t) * ncounters); + if (stats->copiedcounters == NULL) { + result = ISC_R_NOMEMORY; + goto clean_counters; + } + +#if ISC_STATS_LOCKCOUNTERS + 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); + +#if ISC_STATS_LOCKCOUNTERS +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--; + + 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); + UNLOCK(&stats->lock); + DESTROYLOCK(&stats->lock); +#if ISC_STATS_LOCKCOUNTERS + isc_rwlock_destroy(&stats->counterlock); +#endif + isc_mem_putanddetach(&stats->mctx, stats, sizeof(*stats)); + return; + } + + UNLOCK(&stats->lock); +} + +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) { + int32_t prev; + +#if ISC_STATS_LOCKCOUNTERS + /* + * 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 +#if defined(ISC_STATS_HAVESTDATOMIC) + prev = atomic_fetch_add_explicit(&stats->counters[counter].lo, 1, + memory_order_relaxed); +#else + prev = isc_atomic_xadd((int32_t *)&stats->counters[counter].lo, 1); +#endif + /* + * 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 == (int32_t)0xffffffff) { +#if defined(ISC_STATS_HAVESTDATOMIC) + atomic_fetch_add_explicit(&stats->counters[counter].hi, 1, + memory_order_relaxed); +#else + isc_atomic_xadd((int32_t *)&stats->counters[counter].hi, 1); +#endif + } +#elif ISC_STATS_HAVEATOMICQ + UNUSED(prev); +#if defined(ISC_STATS_HAVESTDATOMICQ) + atomic_fetch_add_explicit(&stats->counters[counter], 1, + memory_order_relaxed); +#else + isc_atomic_xaddq((int64_t *)&stats->counters[counter], 1); +#endif +#else + UNUSED(prev); + stats->counters[counter]++; +#endif + +#if ISC_STATS_LOCKCOUNTERS + isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read); +#endif +} + +static inline void +decrementcounter(isc_stats_t *stats, int counter) { + int32_t prev; + +#if ISC_STATS_LOCKCOUNTERS + isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read); +#endif + +#if ISC_STATS_USEMULTIFIELDS +#if defined(ISC_STATS_HAVESTDATOMIC) + prev = atomic_fetch_sub_explicit(&stats->counters[counter].lo, 1, + memory_order_relaxed); +#else + prev = isc_atomic_xadd((int32_t *)&stats->counters[counter].lo, -1); +#endif + if (prev == 0) { +#if defined(ISC_STATS_HAVESTDATOMIC) + atomic_fetch_sub_explicit(&stats->counters[counter].hi, 1, + memory_order_relaxed); +#else + isc_atomic_xadd((int32_t *)&stats->counters[counter].hi, + -1); +#endif + } +#elif ISC_STATS_HAVEATOMICQ + UNUSED(prev); +#if defined(ISC_STATS_HAVESTDATOMICQ) + atomic_fetch_sub_explicit(&stats->counters[counter], 1, + memory_order_relaxed); +#else + isc_atomic_xaddq((int64_t *)&stats->counters[counter], -1); +#endif +#else + UNUSED(prev); + stats->counters[counter]--; +#endif + +#if ISC_STATS_LOCKCOUNTERS + isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read); +#endif +} + +static void +copy_counters(isc_stats_t *stats) { + int i; + +#if ISC_STATS_LOCKCOUNTERS + /* + * We use a "write" lock before "reading" the statistics counters as + * an exclusive lock. + */ + isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write); +#endif + + for (i = 0; i < stats->ncounters; i++) { +#if ISC_STATS_USEMULTIFIELDS + stats->copiedcounters[i] = + (uint64_t)(stats->counters[i].hi) << 32 | + stats->counters[i].lo; +#elif ISC_STATS_HAVEATOMICQ +#if defined(ISC_STATS_HAVESTDATOMICQ) + stats->copiedcounters[i] = + atomic_load_explicit(&stats->counters[i], + memory_order_relaxed); +#else + /* use xaddq(..., 0) as an atomic load */ + stats->copiedcounters[i] = + (uint64_t)isc_atomic_xaddq((int64_t *)&stats->counters[i], 0); +#endif +#else + stats->copiedcounters[i] = stats->counters[i]; +#endif + } + +#if ISC_STATS_LOCKCOUNTERS + 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); + } +} + +void +isc_stats_set(isc_stats_t *stats, uint64_t val, + isc_statscounter_t counter) +{ + REQUIRE(ISC_STATS_VALID(stats)); + REQUIRE(counter < stats->ncounters); + +#if ISC_STATS_LOCKCOUNTERS + /* + * 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 + stats->counters[counter].hi = (uint32_t)((val >> 32) & 0xffffffff); + stats->counters[counter].lo = (uint32_t)(val & 0xffffffff); +#elif ISC_STATS_HAVEATOMICQ +#if defined(ISC_STATS_HAVESTDATOMICQ) + atomic_store_explicit(&stats->counters[counter], val, + memory_order_relaxed); +#else + isc_atomic_storeq((int64_t *)&stats->counters[counter], val); +#endif +#else + stats->counters[counter] = val; +#endif + +#if ISC_STATS_LOCKCOUNTERS + isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write); +#endif +} |