1/* $NetBSD: stats.c,v 1.1.1.1 2009/12/13 16:54:17 kardel Exp $ */ 2 3/* 4 * Copyright (C) 2009 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/* Id: stats.c,v 1.3.6.2 2009/01/29 23:47:44 tbox Exp */ 20 21/*! \file */ 22 23#include <config.h> 24 25#include <string.h> 26 27#include <isc/atomic.h> 28#include <isc/buffer.h> 29#include <isc/magic.h> 30#include <isc/mem.h> 31#include <isc/platform.h> 32#include <isc/print.h> 33#include <isc/rwlock.h> 34#include <isc/stats.h> 35#include <isc/util.h> 36 37#define ISC_STATS_MAGIC ISC_MAGIC('S', 't', 'a', 't') 38#define ISC_STATS_VALID(x) ISC_MAGIC_VALID(x, ISC_STATS_MAGIC) 39 40#ifndef ISC_STATS_USEMULTIFIELDS 41#if defined(ISC_RWLOCK_USEATOMIC) && defined(ISC_PLATFORM_HAVEXADD) && !defined(ISC_PLATFORM_HAVEXADDQ) 42#define ISC_STATS_USEMULTIFIELDS 1 43#else 44#define ISC_STATS_USEMULTIFIELDS 0 45#endif 46#endif /* ISC_STATS_USEMULTIFIELDS */ 47 48#if ISC_STATS_USEMULTIFIELDS 49typedef struct { 50 isc_uint32_t hi; 51 isc_uint32_t lo; 52} isc_stat_t; 53#else 54typedef isc_uint64_t isc_stat_t; 55#endif 56 57struct isc_stats { 58 /*% Unlocked */ 59 unsigned int magic; 60 isc_mem_t *mctx; 61 int ncounters; 62 63 isc_mutex_t lock; 64 unsigned int references; /* locked by lock */ 65 66 /*% 67 * Locked by counterlock or unlocked if efficient rwlock is not 68 * available. 69 */ 70#ifdef ISC_RWLOCK_USEATOMIC 71 isc_rwlock_t counterlock; 72#endif 73 isc_stat_t *counters; 74 75 /*% 76 * We don't want to lock the counters while we are dumping, so we first 77 * copy the current counter values into a local array. This buffer 78 * will be used as the copy destination. It's allocated on creation 79 * of the stats structure so that the dump operation won't fail due 80 * to memory allocation failure. 81 * XXX: this approach is weird for non-threaded build because the 82 * additional memory and the copy overhead could be avoided. We prefer 83 * simplicity here, however, under the assumption that this function 84 * should be only rarely called. 85 */ 86 isc_uint64_t *copiedcounters; 87}; 88 89static isc_result_t 90create_stats(isc_mem_t *mctx, int ncounters, isc_stats_t **statsp) { 91 isc_stats_t *stats; 92 isc_result_t result = ISC_R_SUCCESS; 93 94 REQUIRE(statsp != NULL && *statsp == NULL); 95 96 stats = isc_mem_get(mctx, sizeof(*stats)); 97 if (stats == NULL) 98 return (ISC_R_NOMEMORY); 99 100 result = isc_mutex_init(&stats->lock); 101 if (result != ISC_R_SUCCESS) 102 goto clean_stats; 103 104 stats->counters = isc_mem_get(mctx, sizeof(isc_stat_t) * ncounters); 105 if (stats->counters == NULL) { 106 result = ISC_R_NOMEMORY; 107 goto clean_mutex; 108 } 109 stats->copiedcounters = isc_mem_get(mctx, 110 sizeof(isc_uint64_t) * ncounters); 111 if (stats->copiedcounters == NULL) { 112 result = ISC_R_NOMEMORY; 113 goto clean_counters; 114 } 115 116#ifdef ISC_RWLOCK_USEATOMIC 117 result = isc_rwlock_init(&stats->counterlock, 0, 0); 118 if (result != ISC_R_SUCCESS) 119 goto clean_copiedcounters; 120#endif 121 122 stats->references = 1; 123 memset(stats->counters, 0, sizeof(isc_stat_t) * ncounters); 124 stats->mctx = NULL; 125 isc_mem_attach(mctx, &stats->mctx); 126 stats->ncounters = ncounters; 127 stats->magic = ISC_STATS_MAGIC; 128 129 *statsp = stats; 130 131 return (result); 132 133clean_counters: 134 isc_mem_put(mctx, stats->counters, sizeof(isc_stat_t) * ncounters); 135 136#ifdef ISC_RWLOCK_USEATOMIC 137clean_copiedcounters: 138 isc_mem_put(mctx, stats->copiedcounters, 139 sizeof(isc_stat_t) * ncounters); 140#endif 141 142clean_mutex: 143 DESTROYLOCK(&stats->lock); 144 145clean_stats: 146 isc_mem_put(mctx, stats, sizeof(*stats)); 147 148 return (result); 149} 150 151void 152isc_stats_attach(isc_stats_t *stats, isc_stats_t **statsp) { 153 REQUIRE(ISC_STATS_VALID(stats)); 154 REQUIRE(statsp != NULL && *statsp == NULL); 155 156 LOCK(&stats->lock); 157 stats->references++; 158 UNLOCK(&stats->lock); 159 160 *statsp = stats; 161} 162 163void 164isc_stats_detach(isc_stats_t **statsp) { 165 isc_stats_t *stats; 166 167 REQUIRE(statsp != NULL && ISC_STATS_VALID(*statsp)); 168 169 stats = *statsp; 170 *statsp = NULL; 171 172 LOCK(&stats->lock); 173 stats->references--; 174 UNLOCK(&stats->lock); 175 176 if (stats->references == 0) { 177 isc_mem_put(stats->mctx, stats->copiedcounters, 178 sizeof(isc_stat_t) * stats->ncounters); 179 isc_mem_put(stats->mctx, stats->counters, 180 sizeof(isc_stat_t) * stats->ncounters); 181 DESTROYLOCK(&stats->lock); 182#ifdef ISC_RWLOCK_USEATOMIC 183 isc_rwlock_destroy(&stats->counterlock); 184#endif 185 isc_mem_putanddetach(&stats->mctx, stats, sizeof(*stats)); 186 } 187} 188 189int 190isc_stats_ncounters(isc_stats_t *stats) { 191 REQUIRE(ISC_STATS_VALID(stats)); 192 193 return (stats->ncounters); 194} 195 196static inline void 197incrementcounter(isc_stats_t *stats, int counter) { 198 isc_int32_t prev; 199 200#ifdef ISC_RWLOCK_USEATOMIC 201 /* 202 * We use a "read" lock to prevent other threads from reading the 203 * counter while we "writing" a counter field. The write access itself 204 * is protected by the atomic operation. 205 */ 206 isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read); 207#endif 208 209#if ISC_STATS_USEMULTIFIELDS 210 prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, 1); 211 /* 212 * If the lower 32-bit field overflows, increment the higher field. 213 * Note that it's *theoretically* possible that the lower field 214 * overlaps again before the higher field is incremented. It doesn't 215 * matter, however, because we don't read the value until 216 * isc_stats_copy() is called where the whole process is protected 217 * by the write (exclusive) lock. 218 */ 219 if (prev == (isc_int32_t)0xffffffff) 220 isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi, 1); 221#elif defined(ISC_PLATFORM_HAVEXADDQ) 222 UNUSED(prev); 223 isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], 1); 224#else 225 UNUSED(prev); 226 stats->counters[counter]++; 227#endif 228 229#ifdef ISC_RWLOCK_USEATOMIC 230 isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read); 231#endif 232} 233 234static inline void 235decrementcounter(isc_stats_t *stats, int counter) { 236 isc_int32_t prev; 237 238#ifdef ISC_RWLOCK_USEATOMIC 239 isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read); 240#endif 241 242#if ISC_STATS_USEMULTIFIELDS 243 prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, -1); 244 if (prev == 0) 245 isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi, 246 -1); 247#elif defined(ISC_PLATFORM_HAVEXADDQ) 248 UNUSED(prev); 249 isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], -1); 250#else 251 UNUSED(prev); 252 stats->counters[counter]--; 253#endif 254 255#ifdef ISC_RWLOCK_USEATOMIC 256 isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read); 257#endif 258} 259 260static void 261copy_counters(isc_stats_t *stats) { 262 int i; 263 264#ifdef ISC_RWLOCK_USEATOMIC 265 /* 266 * We use a "write" lock before "reading" the statistics counters as 267 * an exclusive lock. 268 */ 269 isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write); 270#endif 271 272#if ISC_STATS_USEMULTIFIELDS 273 for (i = 0; i < stats->ncounters; i++) { 274 stats->copiedcounters[i] = 275 (isc_uint64_t)(stats->counters[i].hi) << 32 | 276 stats->counters[i].lo; 277 } 278#else 279 UNUSED(i); 280 memcpy(stats->copiedcounters, stats->counters, 281 stats->ncounters * sizeof(isc_stat_t)); 282#endif 283 284#ifdef ISC_RWLOCK_USEATOMIC 285 isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write); 286#endif 287} 288 289isc_result_t 290isc_stats_create(isc_mem_t *mctx, isc_stats_t **statsp, int ncounters) { 291 REQUIRE(statsp != NULL && *statsp == NULL); 292 293 return (create_stats(mctx, ncounters, statsp)); 294} 295 296void 297isc_stats_increment(isc_stats_t *stats, isc_statscounter_t counter) { 298 REQUIRE(ISC_STATS_VALID(stats)); 299 REQUIRE(counter < stats->ncounters); 300 301 incrementcounter(stats, (int)counter); 302} 303 304void 305isc_stats_decrement(isc_stats_t *stats, isc_statscounter_t counter) { 306 REQUIRE(ISC_STATS_VALID(stats)); 307 REQUIRE(counter < stats->ncounters); 308 309 decrementcounter(stats, (int)counter); 310} 311 312void 313isc_stats_dump(isc_stats_t *stats, isc_stats_dumper_t dump_fn, 314 void *arg, unsigned int options) 315{ 316 int i; 317 318 REQUIRE(ISC_STATS_VALID(stats)); 319 320 copy_counters(stats); 321 322 for (i = 0; i < stats->ncounters; i++) { 323 if ((options & ISC_STATSDUMP_VERBOSE) == 0 && 324 stats->copiedcounters[i] == 0) 325 continue; 326 dump_fn((isc_statscounter_t)i, stats->copiedcounters[i], arg); 327 } 328} 329