/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */ #include "memcached.h" #include #include #include #include #include #include #include #include #include #include #include #include #include /* Forward Declarations */ static void item_link_q(item *it); static void item_unlink_q(item *it); #define HOT_LRU 0 #define WARM_LRU 64 #define COLD_LRU 128 #define NOEXP_LRU 192 static unsigned int lru_type_map[4] = {HOT_LRU, WARM_LRU, COLD_LRU, NOEXP_LRU}; #define CLEAR_LRU(id) (id & ~(3<<6)) #define LARGEST_ID POWER_LARGEST typedef struct { uint64_t evicted; uint64_t evicted_nonzero; uint64_t reclaimed; uint64_t outofmemory; uint64_t tailrepairs; uint64_t expired_unfetched; uint64_t evicted_unfetched; uint64_t crawler_reclaimed; uint64_t crawler_items_checked; uint64_t lrutail_reflocked; uint64_t moves_to_cold; uint64_t moves_to_warm; uint64_t moves_within_lru; uint64_t direct_reclaims; rel_time_t evicted_time; } itemstats_t; typedef struct { uint64_t histo[61]; uint64_t ttl_hourplus; uint64_t noexp; uint64_t reclaimed; uint64_t seen; rel_time_t start_time; rel_time_t end_time; bool run_complete; } crawlerstats_t; static item *heads[LARGEST_ID]; static item *tails[LARGEST_ID]; static crawler crawlers[LARGEST_ID]; static itemstats_t itemstats[LARGEST_ID]; static unsigned int sizes[LARGEST_ID]; static crawlerstats_t crawlerstats[MAX_NUMBER_OF_SLAB_CLASSES]; static int crawler_count = 0; static volatile int do_run_lru_crawler_thread = 0; static volatile int do_run_lru_maintainer_thread = 0; static int lru_crawler_initialized = 0; static int lru_maintainer_initialized = 0; static int lru_maintainer_check_clsid = 0; static pthread_mutex_t lru_crawler_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_cond_t lru_crawler_cond = PTHREAD_COND_INITIALIZER; static pthread_mutex_t lru_crawler_stats_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t lru_maintainer_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t cas_id_lock = PTHREAD_MUTEX_INITIALIZER; void item_stats_reset(void) { int i; for (i = 0; i < LARGEST_ID; i++) { pthread_mutex_lock(&lru_locks[i]); memset(&itemstats[i], 0, sizeof(itemstats_t)); pthread_mutex_unlock(&lru_locks[i]); } } static int lru_pull_tail(const int orig_id, const int cur_lru, const unsigned int total_chunks, const bool do_evict, const uint32_t cur_hv); static int lru_crawler_start(uint32_t id, uint32_t remaining); /* Get the next CAS id for a new item. */ /* TODO: refactor some atomics for this. */ uint64_t get_cas_id(void) { static uint64_t cas_id = 0; pthread_mutex_lock(&cas_id_lock); uint64_t next_id = ++cas_id; pthread_mutex_unlock(&cas_id_lock); return next_id; } int item_is_flushed(item *it) { rel_time_t oldest_live = settings.oldest_live; uint64_t cas = ITEM_get_cas(it); uint64_t oldest_cas = settings.oldest_cas; if (oldest_live == 0 || oldest_live > current_time) return 0; if ((it->time <= oldest_live) || (oldest_cas != 0 && cas != 0 && cas < oldest_cas)) { return 1; } return 0; } static unsigned int noexp_lru_size(int slabs_clsid) { int id = CLEAR_LRU(slabs_clsid); id |= NOEXP_LRU; unsigned int ret; pthread_mutex_lock(&lru_locks[id]); ret = sizes[id]; pthread_mutex_unlock(&lru_locks[id]); return ret; } /* Enable this for reference-count debugging. */ #if 0 # define DEBUG_REFCNT(it,op) \ fprintf(stderr, "item %x refcnt(%c) %d %c%c%c\n", \ it, op, it->refcount, \ (it->it_flags & ITEM_LINKED) ? 'L' : ' ', \ (it->it_flags & ITEM_SLABBED) ? 'S' : ' ') #else # define DEBUG_REFCNT(it,op) while(0) #endif /** * Generates the variable-sized part of the header for an object. * * key - The key * nkey - The length of the key * flags - key flags * nbytes - Number of bytes to hold value and addition CRLF terminator * suffix - Buffer for the "VALUE" line suffix (flags, size). * nsuffix - The length of the suffix is stored here. * * Returns the total size of the header. */ static size_t item_make_header(const uint8_t nkey, const int flags, const int nbytes, char *suffix, uint8_t *nsuffix) { /* suffix is defined at 40 chars elsewhere.. */ *nsuffix = (uint8_t) snprintf(suffix, 40, " %d %d\r\n", flags, nbytes - 2); return sizeof(item) + nkey + *nsuffix + nbytes; } item *do_item_alloc(char *key, const size_t nkey, const int flags, const rel_time_t exptime, const int nbytes, const uint32_t cur_hv) { int i; uint8_t nsuffix; item *it = NULL; char suffix[40]; unsigned int total_chunks; size_t ntotal = item_make_header(nkey + 1, flags, nbytes, suffix, &nsuffix); if (settings.use_cas) { ntotal += sizeof(uint64_t); } unsigned int id = slabs_clsid(ntotal); if (id == 0) return 0; /* If no memory is available, attempt a direct LRU juggle/eviction */ /* This is a race in order to simplify lru_pull_tail; in cases where * locked items are on the tail, you want them to fall out and cause * occasional OOM's, rather than internally work around them. * This also gives one fewer code path for slab alloc/free */ for (i = 0; i < 5; i++) { /* Try to reclaim memory first */ if (!settings.lru_maintainer_thread) { lru_pull_tail(id, COLD_LRU, 0, false, cur_hv); } it = slabs_alloc(ntotal, id, &total_chunks, 0); if (settings.expirezero_does_not_evict) total_chunks -= noexp_lru_size(id); if (it == NULL) { if (settings.lru_maintainer_thread) { lru_pull_tail(id, HOT_LRU, total_chunks, false, cur_hv); lru_pull_tail(id, WARM_LRU, total_chunks, false, cur_hv); lru_pull_tail(id, COLD_LRU, total_chunks, true, cur_hv); } else { lru_pull_tail(id, COLD_LRU, 0, true, cur_hv); } } else { break; } } if (i > 0) { pthread_mutex_lock(&lru_locks[id]); itemstats[id].direct_reclaims += i; pthread_mutex_unlock(&lru_locks[id]); } if (it == NULL) { pthread_mutex_lock(&lru_locks[id]); itemstats[id].outofmemory++; pthread_mutex_unlock(&lru_locks[id]); return NULL; } assert(it->slabs_clsid == 0); //assert(it != heads[id]); /* Refcount is seeded to 1 by slabs_alloc() */ it->next = it->prev = it->h_next = 0; /* Items are initially loaded into the HOT_LRU. This is '0' but I want at * least a note here. Compiler (hopefully?) optimizes this out. */ if (settings.lru_maintainer_thread) { if (exptime == 0 && settings.expirezero_does_not_evict) { id |= NOEXP_LRU; } else { id |= HOT_LRU; } } else { /* There is only COLD in compat-mode */ id |= COLD_LRU; } it->slabs_clsid = id; DEBUG_REFCNT(it, '*'); it->it_flags = settings.use_cas ? ITEM_CAS : 0; it->nkey = nkey; it->nbytes = nbytes; memcpy(ITEM_key(it), key, nkey); it->exptime = exptime; memcpy(ITEM_suffix(it), suffix, (size_t)nsuffix); it->nsuffix = nsuffix; return it; } void item_free(item *it) { size_t ntotal = ITEM_ntotal(it); unsigned int clsid; assert((it->it_flags & ITEM_LINKED) == 0); assert(it != heads[it->slabs_clsid]); assert(it != tails[it->slabs_clsid]); assert(it->refcount == 0); /* so slab size changer can tell later if item is already free or not */ clsid = ITEM_clsid(it); DEBUG_REFCNT(it, 'F'); slabs_free(it, ntotal, clsid); } /** * Returns true if an item will fit in the cache (its size does not exceed * the maximum for a cache entry.) */ bool item_size_ok(const size_t nkey, const int flags, const int nbytes) { char prefix[40]; uint8_t nsuffix; size_t ntotal = item_make_header(nkey + 1, flags, nbytes, prefix, &nsuffix); if (settings.use_cas) { ntotal += sizeof(uint64_t); } return slabs_clsid(ntotal) != 0; } static void do_item_link_q(item *it) { /* item is the new head */ item **head, **tail; assert((it->it_flags & ITEM_SLABBED) == 0); head = &heads[it->slabs_clsid]; tail = &tails[it->slabs_clsid]; assert(it != *head); assert((*head && *tail) || (*head == 0 && *tail == 0)); it->prev = 0; it->next = *head; if (it->next) it->next->prev = it; *head = it; if (*tail == 0) *tail = it; sizes[it->slabs_clsid]++; return; } static void item_link_q(item *it) { pthread_mutex_lock(&lru_locks[it->slabs_clsid]); do_item_link_q(it); pthread_mutex_unlock(&lru_locks[it->slabs_clsid]); } static void do_item_unlink_q(item *it) { item **head, **tail; head = &heads[it->slabs_clsid]; tail = &tails[it->slabs_clsid]; if (*head == it) { assert(it->prev == 0); *head = it->next; } if (*tail == it) { assert(it->next == 0); *tail = it->prev; } assert(it->next != it); assert(it->prev != it); if (it->next) it->next->prev = it->prev; if (it->prev) it->prev->next = it->next; sizes[it->slabs_clsid]--; return; } static void item_unlink_q(item *it) { pthread_mutex_lock(&lru_locks[it->slabs_clsid]); do_item_unlink_q(it); pthread_mutex_unlock(&lru_locks[it->slabs_clsid]); } int do_item_link(item *it, const uint32_t hv) { MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes); assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0); it->it_flags |= ITEM_LINKED; it->time = current_time; STATS_LOCK(); stats.curr_bytes += ITEM_ntotal(it); stats.curr_items += 1; stats.total_items += 1; STATS_UNLOCK(); /* Allocate a new CAS ID on link. */ ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0); assoc_insert(it, hv); item_link_q(it); refcount_incr(&it->refcount); return 1; } void do_item_unlink(item *it, const uint32_t hv) { MEMCACHED_ITEM_UNLINK(ITEM_key(it), it->nkey, it->nbytes); if ((it->it_flags & ITEM_LINKED) != 0) { it->it_flags &= ~ITEM_LINKED; STATS_LOCK(); stats.curr_bytes -= ITEM_ntotal(it); stats.curr_items -= 1; STATS_UNLOCK(); assoc_delete(ITEM_key(it), it->nkey, hv); item_unlink_q(it); do_item_remove(it); } } /* FIXME: Is it necessary to keep this copy/pasted code? */ void do_item_unlink_nolock(item *it, const uint32_t hv) { MEMCACHED_ITEM_UNLINK(ITEM_key(it), it->nkey, it->nbytes); if ((it->it_flags & ITEM_LINKED) != 0) { it->it_flags &= ~ITEM_LINKED; STATS_LOCK(); stats.curr_bytes -= ITEM_ntotal(it); stats.curr_items -= 1; STATS_UNLOCK(); assoc_delete(ITEM_key(it), it->nkey, hv); do_item_unlink_q(it); do_item_remove(it); } } void do_item_remove(item *it) { MEMCACHED_ITEM_REMOVE(ITEM_key(it), it->nkey, it->nbytes); assert((it->it_flags & ITEM_SLABBED) == 0); assert(it->refcount > 0); if (refcount_decr(&it->refcount) == 0) { item_free(it); } } /* Copy/paste to avoid adding two extra branches for all common calls, since * _nolock is only used in an uncommon case where we want to relink. */ void do_item_update_nolock(item *it) { MEMCACHED_ITEM_UPDATE(ITEM_key(it), it->nkey, it->nbytes); if (it->time < current_time - ITEM_UPDATE_INTERVAL) { assert((it->it_flags & ITEM_SLABBED) == 0); if ((it->it_flags & ITEM_LINKED) != 0) { do_item_unlink_q(it); it->time = current_time; do_item_link_q(it); } } } /* Bump the last accessed time, or relink if we're in compat mode */ void do_item_update(item *it) { MEMCACHED_ITEM_UPDATE(ITEM_key(it), it->nkey, it->nbytes); if (it->time < current_time - ITEM_UPDATE_INTERVAL) { assert((it->it_flags & ITEM_SLABBED) == 0); if ((it->it_flags & ITEM_LINKED) != 0) { it->time = current_time; if (!settings.lru_maintainer_thread) { item_unlink_q(it); item_link_q(it); } } } } int do_item_replace(item *it, item *new_it, const uint32_t hv) { MEMCACHED_ITEM_REPLACE(ITEM_key(it), it->nkey, it->nbytes, ITEM_key(new_it), new_it->nkey, new_it->nbytes); assert((it->it_flags & ITEM_SLABBED) == 0); do_item_unlink(it, hv); return do_item_link(new_it, hv); } /*@null@*/ /* This is walking the line of violating lock order, but I think it's safe. * If the LRU lock is held, an item in the LRU cannot be wiped and freed. * The data could possibly be overwritten, but this is only accessing the * headers. * It may not be the best idea to leave it like this, but for now it's safe. * FIXME: only dumps the hot LRU with the new LRU's. */ char *item_cachedump(const unsigned int slabs_clsid, const unsigned int limit, unsigned int *bytes) { unsigned int memlimit = 2 * 1024 * 1024; /* 2MB max response size */ char *buffer; unsigned int bufcurr; item *it; unsigned int len; unsigned int shown = 0; char key_temp[KEY_MAX_LENGTH + 1]; char temp[512]; unsigned int id = slabs_clsid; if (!settings.lru_maintainer_thread) id |= COLD_LRU; pthread_mutex_lock(&lru_locks[id]); it = heads[id]; buffer = malloc((size_t)memlimit); if (buffer == 0) { return NULL; } bufcurr = 0; while (it != NULL && (limit == 0 || shown < limit)) { assert(it->nkey <= KEY_MAX_LENGTH); if (it->nbytes == 0 && it->nkey == 0) { it = it->next; continue; } /* Copy the key since it may not be null-terminated in the struct */ strncpy(key_temp, ITEM_key(it), it->nkey); key_temp[it->nkey] = 0x00; /* terminate */ len = snprintf(temp, sizeof(temp), "ITEM %s [%d b; %lu s]\r\n", key_temp, it->nbytes - 2, it->exptime == 0 ? 0 : (unsigned long)it->exptime + process_started); if (bufcurr + len + 6 > memlimit) /* 6 is END\r\n\0 */ break; memcpy(buffer + bufcurr, temp, len); bufcurr += len; shown++; it = it->next; } memcpy(buffer + bufcurr, "END\r\n", 6); bufcurr += 5; *bytes = bufcurr; pthread_mutex_unlock(&lru_locks[id]); return buffer; } void item_stats_totals(ADD_STAT add_stats, void *c) { itemstats_t totals; memset(&totals, 0, sizeof(itemstats_t)); int n; for (n = 0; n < MAX_NUMBER_OF_SLAB_CLASSES; n++) { int x; int i; for (x = 0; x < 4; x++) { i = n | lru_type_map[x]; pthread_mutex_lock(&lru_locks[i]); totals.expired_unfetched += itemstats[i].expired_unfetched; totals.evicted_unfetched += itemstats[i].evicted_unfetched; totals.evicted += itemstats[i].evicted; totals.reclaimed += itemstats[i].reclaimed; totals.crawler_reclaimed += itemstats[i].crawler_reclaimed; totals.crawler_items_checked += itemstats[i].crawler_items_checked; totals.lrutail_reflocked += itemstats[i].lrutail_reflocked; totals.moves_to_cold += itemstats[i].moves_to_cold; totals.moves_to_warm += itemstats[i].moves_to_warm; totals.moves_within_lru += itemstats[i].moves_within_lru; totals.direct_reclaims += itemstats[i].direct_reclaims; pthread_mutex_unlock(&lru_locks[i]); } } APPEND_STAT("expired_unfetched", "%llu", (unsigned long long)totals.expired_unfetched); APPEND_STAT("evicted_unfetched", "%llu", (unsigned long long)totals.evicted_unfetched); APPEND_STAT("evictions", "%llu", (unsigned long long)totals.evicted); APPEND_STAT("reclaimed", "%llu", (unsigned long long)totals.reclaimed); APPEND_STAT("crawler_reclaimed", "%llu", (unsigned long long)totals.crawler_reclaimed); APPEND_STAT("crawler_items_checked", "%llu", (unsigned long long)totals.crawler_items_checked); APPEND_STAT("lrutail_reflocked", "%llu", (unsigned long long)totals.lrutail_reflocked); if (settings.lru_maintainer_thread) { APPEND_STAT("moves_to_cold", "%llu", (unsigned long long)totals.moves_to_cold); APPEND_STAT("moves_to_warm", "%llu", (unsigned long long)totals.moves_to_warm); APPEND_STAT("moves_within_lru", "%llu", (unsigned long long)totals.moves_within_lru); APPEND_STAT("direct_reclaims", "%llu", (unsigned long long)totals.direct_reclaims); } } void item_stats(ADD_STAT add_stats, void *c) { itemstats_t totals; int n; for (n = 0; n < MAX_NUMBER_OF_SLAB_CLASSES; n++) { memset(&totals, 0, sizeof(itemstats_t)); int x; int i; unsigned int size = 0; unsigned int age = 0; unsigned int lru_size_map[4]; const char *fmt = "items:%d:%s"; char key_str[STAT_KEY_LEN]; char val_str[STAT_VAL_LEN]; int klen = 0, vlen = 0; for (x = 0; x < 4; x++) { i = n | lru_type_map[x]; pthread_mutex_lock(&lru_locks[i]); totals.evicted += itemstats[i].evicted; totals.evicted_nonzero += itemstats[i].evicted_nonzero; totals.outofmemory += itemstats[i].outofmemory; totals.tailrepairs += itemstats[i].tailrepairs; totals.reclaimed += itemstats[i].reclaimed; totals.expired_unfetched += itemstats[i].expired_unfetched; totals.evicted_unfetched += itemstats[i].evicted_unfetched; totals.crawler_reclaimed += itemstats[i].crawler_reclaimed; totals.crawler_items_checked += itemstats[i].crawler_items_checked; totals.lrutail_reflocked += itemstats[i].lrutail_reflocked; totals.moves_to_cold += itemstats[i].moves_to_cold; totals.moves_to_warm += itemstats[i].moves_to_warm; totals.moves_within_lru += itemstats[i].moves_within_lru; totals.direct_reclaims += itemstats[i].direct_reclaims; size += sizes[i]; lru_size_map[x] = sizes[i]; if (lru_type_map[x] == COLD_LRU && tails[i] != NULL) age = current_time - tails[i]->time; pthread_mutex_unlock(&lru_locks[i]); } if (size == 0) continue; APPEND_NUM_FMT_STAT(fmt, n, "number", "%u", size); if (settings.lru_maintainer_thread) { APPEND_NUM_FMT_STAT(fmt, n, "number_hot", "%u", lru_size_map[0]); APPEND_NUM_FMT_STAT(fmt, n, "number_warm", "%u", lru_size_map[1]); APPEND_NUM_FMT_STAT(fmt, n, "number_cold", "%u", lru_size_map[2]); if (settings.expirezero_does_not_evict) { APPEND_NUM_FMT_STAT(fmt, n, "number_noexp", "%u", lru_size_map[3]); } } APPEND_NUM_FMT_STAT(fmt, n, "age", "%u", age); APPEND_NUM_FMT_STAT(fmt, n, "evicted", "%llu", (unsigned long long)totals.evicted); APPEND_NUM_FMT_STAT(fmt, n, "evicted_nonzero", "%llu", (unsigned long long)totals.evicted_nonzero); APPEND_NUM_FMT_STAT(fmt, n, "evicted_time", "%u", totals.evicted_time); APPEND_NUM_FMT_STAT(fmt, n, "outofmemory", "%llu", (unsigned long long)totals.outofmemory); APPEND_NUM_FMT_STAT(fmt, n, "tailrepairs", "%llu", (unsigned long long)totals.tailrepairs); APPEND_NUM_FMT_STAT(fmt, n, "reclaimed", "%llu", (unsigned long long)totals.reclaimed); APPEND_NUM_FMT_STAT(fmt, n, "expired_unfetched", "%llu", (unsigned long long)totals.expired_unfetched); APPEND_NUM_FMT_STAT(fmt, n, "evicted_unfetched", "%llu", (unsigned long long)totals.evicted_unfetched); APPEND_NUM_FMT_STAT(fmt, n, "crawler_reclaimed", "%llu", (unsigned long long)totals.crawler_reclaimed); APPEND_NUM_FMT_STAT(fmt, n, "crawler_items_checked", "%llu", (unsigned long long)totals.crawler_items_checked); APPEND_NUM_FMT_STAT(fmt, n, "lrutail_reflocked", "%llu", (unsigned long long)totals.lrutail_reflocked); if (settings.lru_maintainer_thread) { APPEND_NUM_FMT_STAT(fmt, n, "moves_to_cold", "%llu", (unsigned long long)totals.moves_to_cold); APPEND_NUM_FMT_STAT(fmt, n, "moves_to_warm", "%llu", (unsigned long long)totals.moves_to_warm); APPEND_NUM_FMT_STAT(fmt, n, "moves_within_lru", "%llu", (unsigned long long)totals.moves_within_lru); APPEND_NUM_FMT_STAT(fmt, n, "direct_reclaims", "%llu", (unsigned long long)totals.direct_reclaims); } } /* getting here means both ascii and binary terminators fit */ add_stats(NULL, 0, NULL, 0, c); } /** dumps out a list of objects of each size, with granularity of 32 bytes */ /*@null@*/ /* Locks are correct based on a technicality. Holds LRU lock while doing the * work, so items can't go invalid, and it's only looking at header sizes * which don't change. */ void item_stats_sizes(ADD_STAT add_stats, void *c) { /* max 1MB object, divided into 32 bytes size buckets */ const int num_buckets = 32768; unsigned int *histogram = calloc(num_buckets, sizeof(int)); if (histogram != NULL) { int i; /* build the histogram */ for (i = 0; i < LARGEST_ID; i++) { pthread_mutex_lock(&lru_locks[i]); item *iter = heads[i]; while (iter) { int ntotal = ITEM_ntotal(iter); int bucket = ntotal / 32; if ((ntotal % 32) != 0) bucket++; if (bucket < num_buckets) histogram[bucket]++; iter = iter->next; } pthread_mutex_unlock(&lru_locks[i]); } /* write the buffer */ for (i = 0; i < num_buckets; i++) { if (histogram[i] != 0) { char key[8]; snprintf(key, sizeof(key), "%d", i * 32); APPEND_STAT(key, "%u", histogram[i]); } } free(histogram); } add_stats(NULL, 0, NULL, 0, c); } /** wrapper around assoc_find which does the lazy expiration logic */ item *do_item_get(const char *key, const size_t nkey, const uint32_t hv, conn *c) { item *it = assoc_find(key, nkey, hv); if (it != NULL) { refcount_incr(&it->refcount); /* Optimization for slab reassignment. prevents popular items from * jamming in busy wait. Can only do this here to satisfy lock order * of item_lock, slabs_lock. */ /* This was made unsafe by removal of the cache_lock: * slab_rebalance_signal and slab_rebal.* are modified in a separate * thread under slabs_lock. If slab_rebalance_signal = 1, slab_start = * NULL (0), but slab_end is still equal to some value, this would end * up unlinking every item fetched. * This is either an acceptable loss, or if slab_rebalance_signal is * true, slab_start/slab_end should be put behind the slabs_lock. * Which would cause a huge potential slowdown. * Could also use a specific lock for slab_rebal.* and * slab_rebalance_signal (shorter lock?) */ /*if (slab_rebalance_signal && ((void *)it >= slab_rebal.slab_start && (void *)it < slab_rebal.slab_end)) { do_item_unlink(it, hv); do_item_remove(it); it = NULL; }*/ } int was_found = 0; if (settings.verbose > 2) { int ii; if (it == NULL) { fprintf(stderr, "> NOT FOUND "); } else { fprintf(stderr, "> FOUND KEY "); was_found++; } for (ii = 0; ii < nkey; ++ii) { fprintf(stderr, "%c", key[ii]); } } if (it != NULL) { if (item_is_flushed(it)) { do_item_unlink(it, hv); do_item_remove(it); it = NULL; if (was_found) { fprintf(stderr, " -nuked by flush"); } } else if (it->exptime != 0 && it->exptime <= current_time) { do_item_unlink(it, hv); do_item_remove(it); it = NULL; pthread_mutex_lock(&c->thread->stats.mutex); c->thread->stats.get_expired++; pthread_mutex_unlock(&c->thread->stats.mutex); if (was_found) { fprintf(stderr, " -nuked by expire"); } } else { it->it_flags |= ITEM_FETCHED|ITEM_ACTIVE; DEBUG_REFCNT(it, '+'); } } if (settings.verbose > 2) fprintf(stderr, "\n"); return it; } item *do_item_touch(const char *key, size_t nkey, uint32_t exptime, const uint32_t hv, conn *c) { item *it = do_item_get(key, nkey, hv, c); if (it != NULL) { it->exptime = exptime; } return it; } /*** LRU MAINTENANCE THREAD ***/ /* Returns number of items remove, expired, or evicted. * Callable from worker threads or the LRU maintainer thread */ static int lru_pull_tail(const int orig_id, const int cur_lru, const unsigned int total_chunks, const bool do_evict, const uint32_t cur_hv) { item *it = NULL; int id = orig_id; int removed = 0; if (id == 0) return 0; int tries = 5; item *search; item *next_it; void *hold_lock = NULL; unsigned int move_to_lru = 0; uint64_t limit; id |= cur_lru; pthread_mutex_lock(&lru_locks[id]); search = tails[id]; /* We walk up *only* for locked items, and if bottom is expired. */ for (; tries > 0 && search != NULL; tries--, search=next_it) { /* we might relink search mid-loop, so search->prev isn't reliable */ next_it = search->prev; if (search->nbytes == 0 && search->nkey == 0 && search->it_flags == 1) { /* We are a crawler, ignore it. */ tries++; continue; } uint32_t hv = hash(ITEM_key(search), search->nkey); /* Attempt to hash item lock the "search" item. If locked, no * other callers can incr the refcount. Also skip ourselves. */ if (hv == cur_hv || (hold_lock = item_trylock(hv)) == NULL) continue; /* Now see if the item is refcount locked */ if (refcount_incr(&search->refcount) != 2) { /* Note pathological case with ref'ed items in tail. * Can still unlink the item, but it won't be reusable yet */ itemstats[id].lrutail_reflocked++; /* In case of refcount leaks, enable for quick workaround. */ /* WARNING: This can cause terrible corruption */ if (settings.tail_repair_time && search->time + settings.tail_repair_time < current_time) { itemstats[id].tailrepairs++; search->refcount = 1; /* This will call item_remove -> item_free since refcnt is 1 */ do_item_unlink_nolock(search, hv); item_trylock_unlock(hold_lock); continue; } } /* Expired or flushed */ if ((search->exptime != 0 && search->exptime < current_time) || item_is_flushed(search)) { itemstats[id].reclaimed++; if ((search->it_flags & ITEM_FETCHED) == 0) { itemstats[id].expired_unfetched++; } /* refcnt 2 -> 1 */ do_item_unlink_nolock(search, hv); /* refcnt 1 -> 0 -> item_free */ do_item_remove(search); item_trylock_unlock(hold_lock); removed++; /* If all we're finding are expired, can keep going */ continue; } /* If we're HOT_LRU or WARM_LRU and over size limit, send to COLD_LRU. * If we're COLD_LRU, send to WARM_LRU unless we need to evict */ switch (cur_lru) { case HOT_LRU: limit = total_chunks * settings.hot_lru_pct / 100; case WARM_LRU: limit = total_chunks * settings.warm_lru_pct / 100; if (sizes[id] > limit) { itemstats[id].moves_to_cold++; move_to_lru = COLD_LRU; do_item_unlink_q(search); it = search; removed++; break; } else if ((search->it_flags & ITEM_ACTIVE) != 0) { /* Only allow ACTIVE relinking if we're not too large. */ itemstats[id].moves_within_lru++; search->it_flags &= ~ITEM_ACTIVE; do_item_update_nolock(search); do_item_remove(search); item_trylock_unlock(hold_lock); } else { /* Don't want to move to COLD, not active, bail out */ it = search; } break; case COLD_LRU: it = search; /* No matter what, we're stopping */ if (do_evict) { logger *l; if (settings.evict_to_free == 0) { /* Don't think we need a counter for this. It'll OOM. */ break; } l = GET_LOGGER(); itemstats[id].evicted++; itemstats[id].evicted_time = current_time - search->time; if (search->exptime != 0) itemstats[id].evicted_nonzero++; if ((search->it_flags & ITEM_FETCHED) == 0) { itemstats[id].evicted_unfetched++; } if (l->eflags & LOG_EVICTIONS) logger_log(l, LOGGER_EVICTION, search); do_item_unlink_nolock(search, hv); removed++; if (settings.slab_automove == 2) { slabs_reassign(-1, orig_id); } } else if ((search->it_flags & ITEM_ACTIVE) != 0 && settings.lru_maintainer_thread) { itemstats[id].moves_to_warm++; search->it_flags &= ~ITEM_ACTIVE; move_to_lru = WARM_LRU; do_item_unlink_q(search); removed++; } break; } if (it != NULL) break; } pthread_mutex_unlock(&lru_locks[id]); if (it != NULL) { if (move_to_lru) { it->slabs_clsid = ITEM_clsid(it); it->slabs_clsid |= move_to_lru; item_link_q(it); } do_item_remove(it); item_trylock_unlock(hold_lock); } return removed; } /* Loop up to N times: * If too many items are in HOT_LRU, push to COLD_LRU * If too many items are in WARM_LRU, push to COLD_LRU * If too many items are in COLD_LRU, poke COLD_LRU tail * 1000 loops with 1ms min sleep gives us under 1m items shifted/sec. The * locks can't handle much more than that. Leaving a TODO for how to * autoadjust in the future. */ static int lru_maintainer_juggle(const int slabs_clsid) { int i; int did_moves = 0; bool mem_limit_reached = false; unsigned int total_chunks = 0; unsigned int chunks_perslab = 0; unsigned int chunks_free = 0; /* TODO: if free_chunks below high watermark, increase aggressiveness */ chunks_free = slabs_available_chunks(slabs_clsid, &mem_limit_reached, &total_chunks, &chunks_perslab); if (settings.expirezero_does_not_evict) total_chunks -= noexp_lru_size(slabs_clsid); /* If slab automove is enabled on any level, and we have more than 2 pages * worth of chunks free in this class, ask (gently) to reassign a page * from this class back into the global pool (0) */ if (settings.slab_automove > 0 && chunks_free > (chunks_perslab * 2.5)) { slabs_reassign(slabs_clsid, SLAB_GLOBAL_PAGE_POOL); } /* Juggle HOT/WARM up to N times */ for (i = 0; i < 1000; i++) { int do_more = 0; if (lru_pull_tail(slabs_clsid, HOT_LRU, total_chunks, false, 0) || lru_pull_tail(slabs_clsid, WARM_LRU, total_chunks, false, 0)) { do_more++; } do_more += lru_pull_tail(slabs_clsid, COLD_LRU, total_chunks, false, 0); if (do_more == 0) break; did_moves++; } return did_moves; } /* Will crawl all slab classes a minimum of once per hour */ #define MAX_MAINTCRAWL_WAIT 60 * 60 /* Hoping user input will improve this function. This is all a wild guess. * Operation: Kicks crawler for each slab id. Crawlers take some statistics as * to items with nonzero expirations. It then buckets how many items will * expire per minute for the next hour. * This function checks the results of a run, and if it things more than 1% of * expirable objects are ready to go, kick the crawler again to reap. * It will also kick the crawler once per minute regardless, waiting a minute * longer for each time it has no work to do, up to an hour wait time. * The latter is to avoid newly started daemons from waiting too long before * retrying a crawl. */ static void lru_maintainer_crawler_check(void) { int i; static rel_time_t last_crawls[MAX_NUMBER_OF_SLAB_CLASSES]; static rel_time_t next_crawl_wait[MAX_NUMBER_OF_SLAB_CLASSES]; for (i = POWER_SMALLEST; i < MAX_NUMBER_OF_SLAB_CLASSES; i++) { crawlerstats_t *s = &crawlerstats[i]; /* We've not successfully kicked off a crawl yet. */ if (last_crawls[i] == 0) { if (lru_crawler_start(i, 0) > 0) { last_crawls[i] = current_time; } } pthread_mutex_lock(&lru_crawler_stats_lock); if (s->run_complete) { int x; /* Should we crawl again? */ uint64_t possible_reclaims = s->seen - s->noexp; uint64_t available_reclaims = 0; /* Need to think we can free at least 1% of the items before * crawling. */ /* FIXME: Configurable? */ uint64_t low_watermark = (s->seen / 100) + 1; rel_time_t since_run = current_time - s->end_time; /* Don't bother if the payoff is too low. */ if (settings.verbose > 1) fprintf(stderr, "maint crawler: low_watermark: %llu, possible_reclaims: %llu, since_run: %u\n", (unsigned long long)low_watermark, (unsigned long long)possible_reclaims, (unsigned int)since_run); for (x = 0; x < 60; x++) { if (since_run < (x * 60) + 60) break; available_reclaims += s->histo[x]; } if (available_reclaims > low_watermark) { last_crawls[i] = 0; if (next_crawl_wait[i] > 60) next_crawl_wait[i] -= 60; } else if (since_run > 5 && since_run > next_crawl_wait[i]) { last_crawls[i] = 0; if (next_crawl_wait[i] < MAX_MAINTCRAWL_WAIT) next_crawl_wait[i] += 60; } if (settings.verbose > 1) fprintf(stderr, "maint crawler: available reclaims: %llu, next_crawl: %u\n", (unsigned long long)available_reclaims, next_crawl_wait[i]); } pthread_mutex_unlock(&lru_crawler_stats_lock); } } static pthread_t lru_maintainer_tid; #define MAX_LRU_MAINTAINER_SLEEP 1000000 #define MIN_LRU_MAINTAINER_SLEEP 1000 static void *lru_maintainer_thread(void *arg) { int i; useconds_t to_sleep = MIN_LRU_MAINTAINER_SLEEP; rel_time_t last_crawler_check = 0; pthread_mutex_lock(&lru_maintainer_lock); if (settings.verbose > 2) fprintf(stderr, "Starting LRU maintainer background thread\n"); while (do_run_lru_maintainer_thread) { int did_moves = 0; pthread_mutex_unlock(&lru_maintainer_lock); usleep(to_sleep); pthread_mutex_lock(&lru_maintainer_lock); STATS_LOCK(); stats.lru_maintainer_juggles++; STATS_UNLOCK(); /* We were asked to immediately wake up and poke a particular slab * class due to a low watermark being hit */ if (lru_maintainer_check_clsid != 0) { did_moves = lru_maintainer_juggle(lru_maintainer_check_clsid); lru_maintainer_check_clsid = 0; } else { for (i = POWER_SMALLEST; i < MAX_NUMBER_OF_SLAB_CLASSES; i++) { did_moves += lru_maintainer_juggle(i); } } if (did_moves == 0) { if (to_sleep < MAX_LRU_MAINTAINER_SLEEP) to_sleep += 1000; } else { to_sleep /= 2; if (to_sleep < MIN_LRU_MAINTAINER_SLEEP) to_sleep = MIN_LRU_MAINTAINER_SLEEP; } /* Once per second at most */ if (settings.lru_crawler && last_crawler_check != current_time) { lru_maintainer_crawler_check(); last_crawler_check = current_time; } } pthread_mutex_unlock(&lru_maintainer_lock); if (settings.verbose > 2) fprintf(stderr, "LRU maintainer thread stopping\n"); return NULL; } int stop_lru_maintainer_thread(void) { int ret; pthread_mutex_lock(&lru_maintainer_lock); /* LRU thread is a sleep loop, will die on its own */ do_run_lru_maintainer_thread = 0; pthread_mutex_unlock(&lru_maintainer_lock); if ((ret = pthread_join(lru_maintainer_tid, NULL)) != 0) { fprintf(stderr, "Failed to stop LRU maintainer thread: %s\n", strerror(ret)); return -1; } settings.lru_maintainer_thread = false; return 0; } int start_lru_maintainer_thread(void) { int ret; pthread_mutex_lock(&lru_maintainer_lock); do_run_lru_maintainer_thread = 1; settings.lru_maintainer_thread = true; if ((ret = pthread_create(&lru_maintainer_tid, NULL, lru_maintainer_thread, NULL)) != 0) { fprintf(stderr, "Can't create LRU maintainer thread: %s\n", strerror(ret)); pthread_mutex_unlock(&lru_maintainer_lock); return -1; } pthread_mutex_unlock(&lru_maintainer_lock); return 0; } /* If we hold this lock, crawler can't wake up or move */ void lru_maintainer_pause(void) { pthread_mutex_lock(&lru_maintainer_lock); } void lru_maintainer_resume(void) { pthread_mutex_unlock(&lru_maintainer_lock); } int init_lru_maintainer(void) { if (lru_maintainer_initialized == 0) { pthread_mutex_init(&lru_maintainer_lock, NULL); lru_maintainer_initialized = 1; } return 0; } /*** ITEM CRAWLER THREAD ***/ static void crawler_link_q(item *it) { /* item is the new tail */ item **head, **tail; assert(it->it_flags == 1); assert(it->nbytes == 0); head = &heads[it->slabs_clsid]; tail = &tails[it->slabs_clsid]; assert(*tail != 0); assert(it != *tail); assert((*head && *tail) || (*head == 0 && *tail == 0)); it->prev = *tail; it->next = 0; if (it->prev) { assert(it->prev->next == 0); it->prev->next = it; } *tail = it; if (*head == 0) *head = it; return; } static void crawler_unlink_q(item *it) { item **head, **tail; head = &heads[it->slabs_clsid]; tail = &tails[it->slabs_clsid]; if (*head == it) { assert(it->prev == 0); *head = it->next; } if (*tail == it) { assert(it->next == 0); *tail = it->prev; } assert(it->next != it); assert(it->prev != it); if (it->next) it->next->prev = it->prev; if (it->prev) it->prev->next = it->next; return; } /* This is too convoluted, but it's a difficult shuffle. Try to rewrite it * more clearly. */ static item *crawler_crawl_q(item *it) { item **head, **tail; assert(it->it_flags == 1); assert(it->nbytes == 0); head = &heads[it->slabs_clsid]; tail = &tails[it->slabs_clsid]; /* We've hit the head, pop off */ if (it->prev == 0) { assert(*head == it); if (it->next) { *head = it->next; assert(it->next->prev == it); it->next->prev = 0; } return NULL; /* Done */ } /* Swing ourselves in front of the next item */ /* NB: If there is a prev, we can't be the head */ assert(it->prev != it); if (it->prev) { if (*head == it->prev) { /* Prev was the head, now we're the head */ *head = it; } if (*tail == it) { /* We are the tail, now they are the tail */ *tail = it->prev; } assert(it->next != it); if (it->next) { assert(it->prev->next == it); it->prev->next = it->next; it->next->prev = it->prev; } else { /* Tail. Move this above? */ it->prev->next = 0; } /* prev->prev's next is it->prev */ it->next = it->prev; it->prev = it->next->prev; it->next->prev = it; /* New it->prev now, if we're not at the head. */ if (it->prev) { it->prev->next = it; } } assert(it->next != it); assert(it->prev != it); return it->next; /* success */ } /* I pulled this out to make the main thread clearer, but it reaches into the * main thread's values too much. Should rethink again. */ static void item_crawler_evaluate(item *search, uint32_t hv, int i) { int slab_id = CLEAR_LRU(i); crawlerstats_t *s = &crawlerstats[slab_id]; itemstats[i].crawler_items_checked++; if ((search->exptime != 0 && search->exptime < current_time) || item_is_flushed(search)) { itemstats[i].crawler_reclaimed++; s->reclaimed++; if (settings.verbose > 1) { int ii; char *key = ITEM_key(search); fprintf(stderr, "LRU crawler found an expired item (flags: %d, slab: %d): ", search->it_flags, search->slabs_clsid); for (ii = 0; ii < search->nkey; ++ii) { fprintf(stderr, "%c", key[ii]); } fprintf(stderr, "\n"); } if ((search->it_flags & ITEM_FETCHED) == 0) { itemstats[i].expired_unfetched++; } do_item_unlink_nolock(search, hv); do_item_remove(search); assert(search->slabs_clsid == 0); } else { s->seen++; refcount_decr(&search->refcount); if (search->exptime == 0) { s->noexp++; } else if (search->exptime - current_time > 3599) { s->ttl_hourplus++; } else { rel_time_t ttl_remain = search->exptime - current_time; int bucket = ttl_remain / 60; s->histo[bucket]++; } } } static void *item_crawler_thread(void *arg) { int i; int crawls_persleep = settings.crawls_persleep; pthread_mutex_lock(&lru_crawler_lock); pthread_cond_signal(&lru_crawler_cond); settings.lru_crawler = true; if (settings.verbose > 2) fprintf(stderr, "Starting LRU crawler background thread\n"); while (do_run_lru_crawler_thread) { pthread_cond_wait(&lru_crawler_cond, &lru_crawler_lock); while (crawler_count) { item *search = NULL; void *hold_lock = NULL; for (i = POWER_SMALLEST; i < LARGEST_ID; i++) { if (crawlers[i].it_flags != 1) { continue; } pthread_mutex_lock(&lru_locks[i]); search = crawler_crawl_q((item *)&crawlers[i]); if (search == NULL || (crawlers[i].remaining && --crawlers[i].remaining < 1)) { if (settings.verbose > 2) fprintf(stderr, "Nothing left to crawl for %d\n", i); crawlers[i].it_flags = 0; crawler_count--; crawler_unlink_q((item *)&crawlers[i]); pthread_mutex_unlock(&lru_locks[i]); pthread_mutex_lock(&lru_crawler_stats_lock); crawlerstats[CLEAR_LRU(i)].end_time = current_time; crawlerstats[CLEAR_LRU(i)].run_complete = true; pthread_mutex_unlock(&lru_crawler_stats_lock); continue; } uint32_t hv = hash(ITEM_key(search), search->nkey); /* Attempt to hash item lock the "search" item. If locked, no * other callers can incr the refcount */ if ((hold_lock = item_trylock(hv)) == NULL) { pthread_mutex_unlock(&lru_locks[i]); continue; } /* Now see if the item is refcount locked */ if (refcount_incr(&search->refcount) != 2) { refcount_decr(&search->refcount); if (hold_lock) item_trylock_unlock(hold_lock); pthread_mutex_unlock(&lru_locks[i]); continue; } /* Frees the item or decrements the refcount. */ /* Interface for this could improve: do the free/decr here * instead? */ pthread_mutex_lock(&lru_crawler_stats_lock); item_crawler_evaluate(search, hv, i); pthread_mutex_unlock(&lru_crawler_stats_lock); if (hold_lock) item_trylock_unlock(hold_lock); pthread_mutex_unlock(&lru_locks[i]); if (crawls_persleep <= 0 && settings.lru_crawler_sleep) { usleep(settings.lru_crawler_sleep); crawls_persleep = settings.crawls_persleep; } } } if (settings.verbose > 2) fprintf(stderr, "LRU crawler thread sleeping\n"); STATS_LOCK(); stats.lru_crawler_running = false; STATS_UNLOCK(); } pthread_mutex_unlock(&lru_crawler_lock); if (settings.verbose > 2) fprintf(stderr, "LRU crawler thread stopping\n"); return NULL; } static pthread_t item_crawler_tid; int stop_item_crawler_thread(void) { int ret; pthread_mutex_lock(&lru_crawler_lock); do_run_lru_crawler_thread = 0; pthread_cond_signal(&lru_crawler_cond); pthread_mutex_unlock(&lru_crawler_lock); if ((ret = pthread_join(item_crawler_tid, NULL)) != 0) { fprintf(stderr, "Failed to stop LRU crawler thread: %s\n", strerror(ret)); return -1; } settings.lru_crawler = false; return 0; } /* Lock dance to "block" until thread is waiting on its condition: * caller locks mtx. caller spawns thread. * thread blocks on mutex. * caller waits on condition, releases lock. * thread gets lock, sends signal. * caller can't wait, as thread has lock. * thread waits on condition, releases lock * caller wakes on condition, gets lock. * caller immediately releases lock. * thread is now safely waiting on condition before the caller returns. */ int start_item_crawler_thread(void) { int ret; if (settings.lru_crawler) return -1; pthread_mutex_lock(&lru_crawler_lock); do_run_lru_crawler_thread = 1; if ((ret = pthread_create(&item_crawler_tid, NULL, item_crawler_thread, NULL)) != 0) { fprintf(stderr, "Can't create LRU crawler thread: %s\n", strerror(ret)); pthread_mutex_unlock(&lru_crawler_lock); return -1; } /* Avoid returning until the crawler has actually started */ pthread_cond_wait(&lru_crawler_cond, &lru_crawler_lock); pthread_mutex_unlock(&lru_crawler_lock); return 0; } /* 'remaining' is passed in so the LRU maintainer thread can scrub the whole * LRU every time. */ static int do_lru_crawler_start(uint32_t id, uint32_t remaining) { int i; uint32_t sid; uint32_t tocrawl[3]; int starts = 0; tocrawl[0] = id | HOT_LRU; tocrawl[1] = id | WARM_LRU; tocrawl[2] = id | COLD_LRU; for (i = 0; i < 3; i++) { sid = tocrawl[i]; pthread_mutex_lock(&lru_locks[sid]); if (tails[sid] != NULL) { if (settings.verbose > 2) fprintf(stderr, "Kicking LRU crawler off for LRU %d\n", sid); crawlers[sid].nbytes = 0; crawlers[sid].nkey = 0; crawlers[sid].it_flags = 1; /* For a crawler, this means enabled. */ crawlers[sid].next = 0; crawlers[sid].prev = 0; crawlers[sid].time = 0; crawlers[sid].remaining = remaining; crawlers[sid].slabs_clsid = sid; crawler_link_q((item *)&crawlers[sid]); crawler_count++; starts++; } pthread_mutex_unlock(&lru_locks[sid]); } if (starts) { STATS_LOCK(); stats.lru_crawler_running = true; stats.lru_crawler_starts++; STATS_UNLOCK(); pthread_mutex_lock(&lru_crawler_stats_lock); memset(&crawlerstats[id], 0, sizeof(crawlerstats_t)); crawlerstats[id].start_time = current_time; pthread_mutex_unlock(&lru_crawler_stats_lock); } return starts; } static int lru_crawler_start(uint32_t id, uint32_t remaining) { int starts; if (pthread_mutex_trylock(&lru_crawler_lock) != 0) { return 0; } starts = do_lru_crawler_start(id, remaining); if (starts) { pthread_cond_signal(&lru_crawler_cond); } pthread_mutex_unlock(&lru_crawler_lock); return starts; } /* FIXME: Split this into two functions: one to kick a crawler for a sid, and one to * parse the string. LRU maintainer code is generating a string to set up a * sid. * Also only clear the crawlerstats once per sid. */ enum crawler_result_type lru_crawler_crawl(char *slabs) { char *b = NULL; uint32_t sid = 0; int starts = 0; uint8_t tocrawl[MAX_NUMBER_OF_SLAB_CLASSES]; if (pthread_mutex_trylock(&lru_crawler_lock) != 0) { return CRAWLER_RUNNING; } /* FIXME: I added this while debugging. Don't think it's needed? */ memset(tocrawl, 0, sizeof(uint8_t) * MAX_NUMBER_OF_SLAB_CLASSES); if (strcmp(slabs, "all") == 0) { for (sid = 0; sid < MAX_NUMBER_OF_SLAB_CLASSES; sid++) { tocrawl[sid] = 1; } } else { for (char *p = strtok_r(slabs, ",", &b); p != NULL; p = strtok_r(NULL, ",", &b)) { if (!safe_strtoul(p, &sid) || sid < POWER_SMALLEST || sid >= MAX_NUMBER_OF_SLAB_CLASSES-1) { pthread_mutex_unlock(&lru_crawler_lock); return CRAWLER_BADCLASS; } tocrawl[sid] = 1; } } for (sid = POWER_SMALLEST; sid < MAX_NUMBER_OF_SLAB_CLASSES; sid++) { if (tocrawl[sid]) starts += do_lru_crawler_start(sid, settings.lru_crawler_tocrawl); } if (starts) { pthread_cond_signal(&lru_crawler_cond); pthread_mutex_unlock(&lru_crawler_lock); return CRAWLER_OK; } else { pthread_mutex_unlock(&lru_crawler_lock); return CRAWLER_NOTSTARTED; } } /* If we hold this lock, crawler can't wake up or move */ void lru_crawler_pause(void) { pthread_mutex_lock(&lru_crawler_lock); } void lru_crawler_resume(void) { pthread_mutex_unlock(&lru_crawler_lock); } int init_lru_crawler(void) { if (lru_crawler_initialized == 0) { memset(&crawlerstats, 0, sizeof(crawlerstats_t) * MAX_NUMBER_OF_SLAB_CLASSES); if (pthread_cond_init(&lru_crawler_cond, NULL) != 0) { fprintf(stderr, "Can't initialize lru crawler condition\n"); return -1; } pthread_mutex_init(&lru_crawler_lock, NULL); lru_crawler_initialized = 1; } return 0; }