/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */ #include "memcached.h" #include "bipbuffer.h" #include "slab_automove.h" #ifdef EXTSTORE #include "storage.h" #endif #include #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); static unsigned int lru_type_map[4] = {HOT_LRU, WARM_LRU, COLD_LRU, TEMP_LRU}; #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; /* items reclaimed but never touched */ uint64_t evicted_unfetched; /* items evicted but never touched */ uint64_t evicted_active; /* items evicted that should have been shuffled */ 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; uint64_t hits_to_hot; uint64_t hits_to_warm; uint64_t hits_to_cold; uint64_t hits_to_temp; rel_time_t evicted_time; } itemstats_t; static item *heads[LARGEST_ID]; static item *tails[LARGEST_ID]; static itemstats_t itemstats[LARGEST_ID]; static unsigned int sizes[LARGEST_ID]; static uint64_t sizes_bytes[LARGEST_ID]; static unsigned int *stats_sizes_hist = NULL; static uint64_t stats_sizes_cas_min = 0; static int stats_sizes_buckets = 0; static volatile int do_run_lru_maintainer_thread = 0; static int lru_maintainer_initialized = 0; static pthread_mutex_t lru_maintainer_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t cas_id_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t stats_sizes_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]); } } /* called with class lru lock held */ void do_item_stats_add_crawl(const int i, const uint64_t reclaimed, const uint64_t unfetched, const uint64_t checked) { itemstats[i].crawler_reclaimed += reclaimed; itemstats[i].expired_unfetched += unfetched; itemstats[i].crawler_items_checked += checked; } typedef struct _lru_bump_buf { struct _lru_bump_buf *prev; struct _lru_bump_buf *next; pthread_mutex_t mutex; bipbuf_t *buf; uint64_t dropped; } lru_bump_buf; typedef struct { item *it; uint32_t hv; } lru_bump_entry; static lru_bump_buf *bump_buf_head = NULL; static lru_bump_buf *bump_buf_tail = NULL; static pthread_mutex_t bump_buf_lock = PTHREAD_MUTEX_INITIALIZER; /* TODO: tunable? Need bench results */ #define LRU_BUMP_BUF_SIZE 8192 static bool lru_bump_async(lru_bump_buf *b, item *it, uint32_t hv); static uint64_t lru_total_bumps_dropped(void); /* 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 temp_lru_size(int slabs_clsid) { int id = CLEAR_LRU(slabs_clsid); id |= TEMP_LRU; unsigned int ret; pthread_mutex_lock(&lru_locks[id]); ret = sizes_bytes[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 unsigned int flags, const int nbytes, char *suffix, uint8_t *nsuffix) { if (settings.inline_ascii_response) { /* suffix is defined at 40 chars elsewhere.. */ *nsuffix = (uint8_t) snprintf(suffix, 40, " %u %d\r\n", flags, nbytes - 2); } else { if (flags == 0) { *nsuffix = 0; } else { *nsuffix = sizeof(flags); } } return sizeof(item) + nkey + *nsuffix + nbytes; } item *do_item_alloc_pull(const size_t ntotal, const unsigned int id) { item *it = NULL; int i; /* 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 < 10; i++) { uint64_t total_bytes; /* Try to reclaim memory first */ if (!settings.lru_segmented) { lru_pull_tail(id, COLD_LRU, 0, 0, 0, NULL); } it = slabs_alloc(ntotal, id, &total_bytes, 0); if (settings.temp_lru) total_bytes -= temp_lru_size(id); if (it == NULL) { if (lru_pull_tail(id, COLD_LRU, total_bytes, LRU_PULL_EVICT, 0, NULL) <= 0) { if (settings.lru_segmented) { lru_pull_tail(id, HOT_LRU, total_bytes, 0, 0, NULL); } else { break; } } } else { break; } } if (i > 0) { pthread_mutex_lock(&lru_locks[id]); itemstats[id].direct_reclaims += i; pthread_mutex_unlock(&lru_locks[id]); } return it; } /* Chain another chunk onto this chunk. */ /* slab mover: if it finds a chunk without ITEM_CHUNK flag, and no ITEM_LINKED * flag, it counts as busy and skips. * I think it might still not be safe to do linking outside of the slab lock */ item_chunk *do_item_alloc_chunk(item_chunk *ch, const size_t bytes_remain) { // TODO: Should be a cleaner way of finding real size with slabber calls size_t size = bytes_remain + sizeof(item_chunk); if (size > settings.slab_chunk_size_max) size = settings.slab_chunk_size_max; unsigned int id = slabs_clsid(size); item_chunk *nch = (item_chunk *) do_item_alloc_pull(size, id); if (nch == NULL) return NULL; // link in. // ITEM_CHUNK[ED] bits need to be protected by the slabs lock. slabs_mlock(); nch->head = ch->head; ch->next = nch; nch->prev = ch; nch->next = 0; nch->used = 0; nch->slabs_clsid = id; nch->size = size - sizeof(item_chunk); nch->it_flags |= ITEM_CHUNK; slabs_munlock(); return nch; } item *do_item_alloc(char *key, const size_t nkey, const unsigned int flags, const rel_time_t exptime, const int nbytes) { uint8_t nsuffix; item *it = NULL; char suffix[40]; // Avoid potential underflows. if (nbytes < 2) return 0; 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); unsigned int hdr_id = 0; if (id == 0) return 0; /* This is a large item. Allocate a header object now, lazily allocate * chunks while reading the upload. */ if (ntotal > settings.slab_chunk_size_max) { /* We still link this item into the LRU for the larger slab class, but * we're pulling a header from an entirely different slab class. The * free routines handle large items specifically. */ int htotal = nkey + 1 + nsuffix + sizeof(item) + sizeof(item_chunk); if (settings.use_cas) { htotal += sizeof(uint64_t); } hdr_id = slabs_clsid(htotal); it = do_item_alloc_pull(htotal, hdr_id); /* setting ITEM_CHUNKED is fine here because we aren't LINKED yet. */ if (it != NULL) it->it_flags |= ITEM_CHUNKED; } else { it = do_item_alloc_pull(ntotal, 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 = 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.temp_lru && exptime - current_time <= settings.temporary_ttl) { id |= TEMP_LRU; } else if (settings.lru_segmented) { 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; if (settings.inline_ascii_response) { memcpy(ITEM_suffix(it), suffix, (size_t)nsuffix); } else if (nsuffix > 0) { memcpy(ITEM_suffix(it), &flags, sizeof(flags)); } it->nsuffix = nsuffix; /* Initialize internal chunk. */ if (it->it_flags & ITEM_CHUNKED) { item_chunk *chunk = (item_chunk *) ITEM_data(it); chunk->next = 0; chunk->prev = 0; chunk->used = 0; chunk->size = 0; chunk->head = it; chunk->orig_clsid = hdr_id; } it->h_next = 0; 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; if (nbytes < 2) return false; 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]++; sizes_bytes[it->slabs_clsid] += ITEM_ntotal(it); 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 item_link_q_warm(item *it) { pthread_mutex_lock(&lru_locks[it->slabs_clsid]); do_item_link_q(it); itemstats[it->slabs_clsid].moves_to_warm++; 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]--; sizes_bytes[it->slabs_clsid] -= ITEM_ntotal(it); 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_state.curr_bytes += ITEM_ntotal(it); stats_state.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); item_stats_sizes_add(it); 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_state.curr_bytes -= ITEM_ntotal(it); stats_state.curr_items -= 1; STATS_UNLOCK(); item_stats_sizes_remove(it); 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_state.curr_bytes -= ITEM_ntotal(it); stats_state.curr_items -= 1; STATS_UNLOCK(); item_stats_sizes_remove(it); 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) == 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); /* Hits to COLD_LRU immediately move to WARM. */ if (settings.lru_segmented) { assert((it->it_flags & ITEM_SLABBED) == 0); if ((it->it_flags & ITEM_LINKED) != 0) { if (ITEM_lruid(it) == COLD_LRU && (it->it_flags & ITEM_ACTIVE)) { it->time = current_time; item_unlink_q(it); it->slabs_clsid = ITEM_clsid(it); it->slabs_clsid |= WARM_LRU; it->it_flags &= ~ITEM_ACTIVE; item_link_q_warm(it); } else if (it->time < current_time - ITEM_UPDATE_INTERVAL) { it->time = current_time; } } } else 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; 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. */ 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; 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; %llu s]\r\n", key_temp, it->nbytes - 2, it->exptime == 0 ? 0 : (unsigned long 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; } /* With refactoring of the various stats code the automover won't need a * custom function here. */ void fill_item_stats_automove(item_stats_automove *am) { int n; for (n = 0; n < MAX_NUMBER_OF_SLAB_CLASSES; n++) { item_stats_automove *cur = &am[n]; // outofmemory records into HOT int i = n | HOT_LRU; pthread_mutex_lock(&lru_locks[i]); cur->outofmemory = itemstats[i].outofmemory; pthread_mutex_unlock(&lru_locks[i]); // evictions and tail age are from COLD i = n | COLD_LRU; pthread_mutex_lock(&lru_locks[i]); cur->evicted = itemstats[i].evicted; if (tails[i]) { cur->age = current_time - tails[i]->time; } else { cur->age = 0; } pthread_mutex_unlock(&lru_locks[i]); } } 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_active += itemstats[i].evicted_active; 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); if (settings.lru_maintainer_thread) { APPEND_STAT("evicted_active", "%llu", (unsigned long long)totals.evicted_active); } 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); APPEND_STAT("lru_bumps_dropped", "%llu", (unsigned long long)lru_total_bumps_dropped()); } } void item_stats(ADD_STAT add_stats, void *c) { struct thread_stats thread_stats; threadlocal_stats_aggregate(&thread_stats); 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 age_hot = 0; unsigned int age_warm = 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.evicted_active += itemstats[i].evicted_active; 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; } else if (lru_type_map[x] == HOT_LRU && tails[i] != NULL) { age_hot = current_time - tails[i]->time; } else if (lru_type_map[x] == WARM_LRU && tails[i] != NULL) { age_warm = current_time - tails[i]->time; } if (lru_type_map[x] == COLD_LRU) totals.evicted_time = itemstats[i].evicted_time; switch (lru_type_map[x]) { case HOT_LRU: totals.hits_to_hot = thread_stats.lru_hits[i]; break; case WARM_LRU: totals.hits_to_warm = thread_stats.lru_hits[i]; break; case COLD_LRU: totals.hits_to_cold = thread_stats.lru_hits[i]; break; case TEMP_LRU: totals.hits_to_temp = thread_stats.lru_hits[i]; break; } 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.temp_lru) { APPEND_NUM_FMT_STAT(fmt, n, "number_temp", "%u", lru_size_map[3]); } APPEND_NUM_FMT_STAT(fmt, n, "age_hot", "%u", age_hot); APPEND_NUM_FMT_STAT(fmt, n, "age_warm", "%u", age_warm); } 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); if (settings.lru_maintainer_thread) { APPEND_NUM_FMT_STAT(fmt, n, "evicted_active", "%llu", (unsigned long long)totals.evicted_active); } 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); APPEND_NUM_FMT_STAT(fmt, n, "hits_to_hot", "%llu", (unsigned long long)totals.hits_to_hot); APPEND_NUM_FMT_STAT(fmt, n, "hits_to_warm", "%llu", (unsigned long long)totals.hits_to_warm); APPEND_NUM_FMT_STAT(fmt, n, "hits_to_cold", "%llu", (unsigned long long)totals.hits_to_cold); APPEND_NUM_FMT_STAT(fmt, n, "hits_to_temp", "%llu", (unsigned long long)totals.hits_to_temp); } } /* getting here means both ascii and binary terminators fit */ add_stats(NULL, 0, NULL, 0, c); } bool item_stats_sizes_status(void) { bool ret = false; mutex_lock(&stats_sizes_lock); if (stats_sizes_hist != NULL) ret = true; mutex_unlock(&stats_sizes_lock); return ret; } void item_stats_sizes_init(void) { if (stats_sizes_hist != NULL) return; stats_sizes_buckets = settings.item_size_max / 32 + 1; stats_sizes_hist = calloc(stats_sizes_buckets, sizeof(int)); stats_sizes_cas_min = (settings.use_cas) ? get_cas_id() : 0; } void item_stats_sizes_enable(ADD_STAT add_stats, void *c) { mutex_lock(&stats_sizes_lock); if (!settings.use_cas) { APPEND_STAT("sizes_status", "error", ""); APPEND_STAT("sizes_error", "cas_support_disabled", ""); } else if (stats_sizes_hist == NULL) { item_stats_sizes_init(); if (stats_sizes_hist != NULL) { APPEND_STAT("sizes_status", "enabled", ""); } else { APPEND_STAT("sizes_status", "error", ""); APPEND_STAT("sizes_error", "no_memory", ""); } } else { APPEND_STAT("sizes_status", "enabled", ""); } mutex_unlock(&stats_sizes_lock); } void item_stats_sizes_disable(ADD_STAT add_stats, void *c) { mutex_lock(&stats_sizes_lock); if (stats_sizes_hist != NULL) { free(stats_sizes_hist); stats_sizes_hist = NULL; } APPEND_STAT("sizes_status", "disabled", ""); mutex_unlock(&stats_sizes_lock); } void item_stats_sizes_add(item *it) { if (stats_sizes_hist == NULL || stats_sizes_cas_min > ITEM_get_cas(it)) return; int ntotal = ITEM_ntotal(it); int bucket = ntotal / 32; if ((ntotal % 32) != 0) bucket++; if (bucket < stats_sizes_buckets) stats_sizes_hist[bucket]++; } /* I think there's no way for this to be accurate without using the CAS value. * Since items getting their time value bumped will pass this validation. */ void item_stats_sizes_remove(item *it) { if (stats_sizes_hist == NULL || stats_sizes_cas_min > ITEM_get_cas(it)) return; int ntotal = ITEM_ntotal(it); int bucket = ntotal / 32; if ((ntotal % 32) != 0) bucket++; if (bucket < stats_sizes_buckets) stats_sizes_hist[bucket]--; } /** 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) { mutex_lock(&stats_sizes_lock); if (stats_sizes_hist != NULL) { int i; for (i = 0; i < stats_sizes_buckets; i++) { if (stats_sizes_hist[i] != 0) { char key[8]; snprintf(key, sizeof(key), "%d", i * 32); APPEND_STAT(key, "%u", stats_sizes_hist[i]); } } } else { APPEND_STAT("sizes_status", "disabled", ""); } add_stats(NULL, 0, NULL, 0, c); mutex_unlock(&stats_sizes_lock); } /** 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, const bool do_update) { item *it = assoc_find(key, nkey, hv); if (it != NULL) { refcount_incr(it); /* 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 "); } for (ii = 0; ii < nkey; ++ii) { fprintf(stderr, "%c", key[ii]); } } if (it != NULL) { was_found = 1; if (item_is_flushed(it)) { do_item_unlink(it, hv); STORAGE_delete(c->thread->storage, it); do_item_remove(it); it = NULL; pthread_mutex_lock(&c->thread->stats.mutex); c->thread->stats.get_flushed++; pthread_mutex_unlock(&c->thread->stats.mutex); if (settings.verbose > 2) { fprintf(stderr, " -nuked by flush"); } was_found = 2; } else if (it->exptime != 0 && it->exptime <= current_time) { do_item_unlink(it, hv); STORAGE_delete(c->thread->storage, it); 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 (settings.verbose > 2) { fprintf(stderr, " -nuked by expire"); } was_found = 3; } else { if (do_update) { /* We update the hit markers only during fetches. * An item needs to be hit twice overall to be considered * ACTIVE, but only needs a single hit to maintain activity * afterward. * FETCHED tells if an item has ever been active. */ if (settings.lru_segmented) { if ((it->it_flags & ITEM_ACTIVE) == 0) { if ((it->it_flags & ITEM_FETCHED) == 0) { it->it_flags |= ITEM_FETCHED; } else { it->it_flags |= ITEM_ACTIVE; if (ITEM_lruid(it) != COLD_LRU) { do_item_update(it); // bump LA time } else if (!lru_bump_async(c->thread->lru_bump_buf, it, hv)) { // add flag before async bump to avoid race. it->it_flags &= ~ITEM_ACTIVE; } } } } else { it->it_flags |= ITEM_FETCHED; do_item_update(it); } } DEBUG_REFCNT(it, '+'); } } if (settings.verbose > 2) fprintf(stderr, "\n"); /* For now this is in addition to the above verbose logging. */ LOGGER_LOG(c->thread->l, LOG_FETCHERS, LOGGER_ITEM_GET, NULL, was_found, key, nkey, (it) ? ITEM_clsid(it) : 0); 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, DO_UPDATE); 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 */ int lru_pull_tail(const int orig_id, const int cur_lru, const uint64_t total_bytes, const uint8_t flags, const rel_time_t max_age, struct lru_pull_tail_return *ret_it) { 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 = 0; 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. */ if (flags & LRU_PULL_CRAWL_BLOCKS) { pthread_mutex_unlock(&lru_locks[id]); return 0; } 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 ((hold_lock = item_trylock(hv)) == NULL) continue; /* Now see if the item is refcount locked */ if (refcount_incr(search) != 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_bytes * settings.hot_lru_pct / 100; case WARM_LRU: if (limit == 0) limit = total_bytes * settings.warm_lru_pct / 100; /* Rescue ACTIVE items aggressively */ if ((search->it_flags & ITEM_ACTIVE) != 0) { search->it_flags &= ~ITEM_ACTIVE; removed++; if (cur_lru == WARM_LRU) { itemstats[id].moves_within_lru++; do_item_update_nolock(search); do_item_remove(search); item_trylock_unlock(hold_lock); } else { /* Active HOT_LRU items flow to WARM */ itemstats[id].moves_to_warm++; move_to_lru = WARM_LRU; do_item_unlink_q(search); it = search; } } else if (sizes_bytes[id] > limit || current_time - search->time > max_age) { itemstats[id].moves_to_cold++; move_to_lru = COLD_LRU; do_item_unlink_q(search); it = search; removed++; break; } 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 (flags & LRU_PULL_EVICT) { if (settings.evict_to_free == 0) { /* Don't think we need a counter for this. It'll OOM. */ break; } 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 ((search->it_flags & ITEM_ACTIVE)) { itemstats[id].evicted_active++; } LOGGER_LOG(NULL, LOG_EVICTIONS, LOGGER_EVICTION, search); do_item_unlink_nolock(search, hv); removed++; if (settings.slab_automove == 2) { slabs_reassign(-1, orig_id); } } else if (flags & LRU_PULL_RETURN_ITEM) { /* Keep a reference to this item and return it. */ ret_it->it = it; ret_it->hv = hv; } else if ((search->it_flags & ITEM_ACTIVE) != 0 && settings.lru_segmented) { itemstats[id].moves_to_warm++; search->it_flags &= ~ITEM_ACTIVE; move_to_lru = WARM_LRU; do_item_unlink_q(search); removed++; } break; case TEMP_LRU: it = search; /* Kill the loop. Parent only interested in reclaims */ 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); } if ((flags & LRU_PULL_RETURN_ITEM) == 0) { do_item_remove(it); item_trylock_unlock(hold_lock); } } return removed; } /* TODO: Third place this code needs to be deduped */ static void lru_bump_buf_link_q(lru_bump_buf *b) { pthread_mutex_lock(&bump_buf_lock); assert(b != bump_buf_head); b->prev = 0; b->next = bump_buf_head; if (b->next) b->next->prev = b; bump_buf_head = b; if (bump_buf_tail == 0) bump_buf_tail = b; pthread_mutex_unlock(&bump_buf_lock); return; } void *item_lru_bump_buf_create(void) { lru_bump_buf *b = calloc(1, sizeof(lru_bump_buf)); if (b == NULL) { return NULL; } b->buf = bipbuf_new(sizeof(lru_bump_entry) * LRU_BUMP_BUF_SIZE); if (b->buf == NULL) { free(b); return NULL; } pthread_mutex_init(&b->mutex, NULL); lru_bump_buf_link_q(b); return b; } static bool lru_bump_async(lru_bump_buf *b, item *it, uint32_t hv) { bool ret = true; refcount_incr(it); pthread_mutex_lock(&b->mutex); lru_bump_entry *be = (lru_bump_entry *) bipbuf_request(b->buf, sizeof(lru_bump_entry)); if (be != NULL) { be->it = it; be->hv = hv; if (bipbuf_push(b->buf, sizeof(lru_bump_entry)) == 0) { ret = false; b->dropped++; } } else { ret = false; b->dropped++; } if (!ret) { refcount_decr(it); } pthread_mutex_unlock(&b->mutex); return ret; } /* TODO: Might be worth a micro-optimization of having bump buffers link * themselves back into the central queue when queue goes from zero to * non-zero, then remove from list if zero more than N times. * If very few hits on cold this would avoid extra memory barriers from LRU * maintainer thread. If many hits, they'll just stay in the list. */ static bool lru_maintainer_bumps(void) { lru_bump_buf *b; lru_bump_entry *be; unsigned int size; unsigned int todo; bool bumped = false; pthread_mutex_lock(&bump_buf_lock); for (b = bump_buf_head; b != NULL; b=b->next) { pthread_mutex_lock(&b->mutex); be = (lru_bump_entry *) bipbuf_peek_all(b->buf, &size); pthread_mutex_unlock(&b->mutex); if (be == NULL) { continue; } todo = size; bumped = true; while (todo) { item_lock(be->hv); do_item_update(be->it); do_item_remove(be->it); item_unlock(be->hv); be++; todo -= sizeof(lru_bump_entry); } pthread_mutex_lock(&b->mutex); be = (lru_bump_entry *) bipbuf_poll(b->buf, size); pthread_mutex_unlock(&b->mutex); } pthread_mutex_unlock(&bump_buf_lock); return bumped; } static uint64_t lru_total_bumps_dropped(void) { uint64_t total = 0; lru_bump_buf *b; pthread_mutex_lock(&bump_buf_lock); for (b = bump_buf_head; b != NULL; b=b->next) { pthread_mutex_lock(&b->mutex); total += b->dropped; pthread_mutex_unlock(&b->mutex); } pthread_mutex_unlock(&bump_buf_lock); return total; } /* 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; uint64_t total_bytes = 0; unsigned int chunks_perslab = 0; //unsigned int chunks_free = 0; /* TODO: if free_chunks below high watermark, increase aggressiveness */ slabs_available_chunks(slabs_clsid, NULL, &total_bytes, &chunks_perslab); if (settings.temp_lru) { /* Only looking for reclaims. Run before we size the LRU. */ for (i = 0; i < 500; i++) { if (lru_pull_tail(slabs_clsid, TEMP_LRU, 0, 0, 0, NULL) <= 0) { break; } else { did_moves++; } } total_bytes -= temp_lru_size(slabs_clsid); } rel_time_t cold_age = 0; rel_time_t hot_age = 0; rel_time_t warm_age = 0; /* If LRU is in flat mode, force items to drain into COLD via max age */ if (settings.lru_segmented) { pthread_mutex_lock(&lru_locks[slabs_clsid|COLD_LRU]); if (tails[slabs_clsid|COLD_LRU]) { cold_age = current_time - tails[slabs_clsid|COLD_LRU]->time; } pthread_mutex_unlock(&lru_locks[slabs_clsid|COLD_LRU]); hot_age = cold_age * settings.hot_max_factor; warm_age = cold_age * settings.warm_max_factor; } /* Juggle HOT/WARM up to N times */ for (i = 0; i < 500; i++) { int do_more = 0; if (lru_pull_tail(slabs_clsid, HOT_LRU, total_bytes, LRU_PULL_CRAWL_BLOCKS, hot_age, NULL) || lru_pull_tail(slabs_clsid, WARM_LRU, total_bytes, LRU_PULL_CRAWL_BLOCKS, warm_age, NULL)) { do_more++; } if (settings.lru_segmented) { do_more += lru_pull_tail(slabs_clsid, COLD_LRU, total_bytes, LRU_PULL_CRAWL_BLOCKS, 0, NULL); } 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(struct crawler_expired_data *cdata, logger *l) { int i; static rel_time_t next_crawls[POWER_LARGEST]; static rel_time_t next_crawl_wait[POWER_LARGEST]; uint8_t todo[POWER_LARGEST]; memset(todo, 0, sizeof(uint8_t) * POWER_LARGEST); bool do_run = false; unsigned int tocrawl_limit = 0; // TODO: If not segmented LRU, skip non-cold for (i = POWER_SMALLEST; i < POWER_LARGEST; i++) { crawlerstats_t *s = &cdata->crawlerstats[i]; /* We've not successfully kicked off a crawl yet. */ if (s->run_complete) { char *lru_name = "na"; pthread_mutex_lock(&cdata->lock); 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 = (possible_reclaims / 100) + 1; rel_time_t since_run = current_time - s->end_time; /* Don't bother if the payoff is too low. */ for (x = 0; x < 60; x++) { available_reclaims += s->histo[x]; if (available_reclaims > low_watermark) { if (next_crawl_wait[i] < (x * 60)) { next_crawl_wait[i] += 60; } else if (next_crawl_wait[i] >= 60) { next_crawl_wait[i] -= 60; } break; } } if (available_reclaims == 0) { next_crawl_wait[i] += 60; } if (next_crawl_wait[i] > MAX_MAINTCRAWL_WAIT) { next_crawl_wait[i] = MAX_MAINTCRAWL_WAIT; } next_crawls[i] = current_time + next_crawl_wait[i] + 5; switch (GET_LRU(i)) { case HOT_LRU: lru_name = "hot"; break; case WARM_LRU: lru_name = "warm"; break; case COLD_LRU: lru_name = "cold"; break; case TEMP_LRU: lru_name = "temp"; break; } LOGGER_LOG(l, LOG_SYSEVENTS, LOGGER_CRAWLER_STATUS, NULL, CLEAR_LRU(i), lru_name, (unsigned long long)low_watermark, (unsigned long long)available_reclaims, (unsigned int)since_run, next_crawls[i] - current_time, s->end_time - s->start_time, s->seen, s->reclaimed); // Got our calculation, avoid running until next actual run. s->run_complete = false; pthread_mutex_unlock(&cdata->lock); } if (current_time > next_crawls[i]) { pthread_mutex_lock(&lru_locks[i]); if (sizes[i] > tocrawl_limit) { tocrawl_limit = sizes[i]; } pthread_mutex_unlock(&lru_locks[i]); todo[i] = 1; do_run = true; next_crawls[i] = current_time + 5; // minimum retry wait. } } if (do_run) { if (settings.lru_crawler_tocrawl && settings.lru_crawler_tocrawl < tocrawl_limit) { tocrawl_limit = settings.lru_crawler_tocrawl; } lru_crawler_start(todo, tocrawl_limit, CRAWLER_AUTOEXPIRE, cdata, NULL, 0); } } 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) { #ifdef EXTSTORE void *storage = arg; int x; #endif int i; useconds_t to_sleep = MIN_LRU_MAINTAINER_SLEEP; useconds_t last_sleep = MIN_LRU_MAINTAINER_SLEEP; rel_time_t last_crawler_check = 0; rel_time_t last_automove_check = 0; useconds_t next_juggles[MAX_NUMBER_OF_SLAB_CLASSES] = {0}; useconds_t backoff_juggles[MAX_NUMBER_OF_SLAB_CLASSES] = {0}; struct crawler_expired_data *cdata = calloc(1, sizeof(struct crawler_expired_data)); if (cdata == NULL) { fprintf(stderr, "Failed to allocate crawler data for LRU maintainer thread\n"); abort(); } pthread_mutex_init(&cdata->lock, NULL); cdata->crawl_complete = true; // kick off the crawler. logger *l = logger_create(); if (l == NULL) { fprintf(stderr, "Failed to allocate logger for LRU maintainer thread\n"); abort(); } double last_ratio = settings.slab_automove_ratio; void *am = slab_automove_init(settings.slab_automove_window, settings.slab_automove_ratio); pthread_mutex_lock(&lru_maintainer_lock); if (settings.verbose > 2) fprintf(stderr, "Starting LRU maintainer background thread\n"); while (do_run_lru_maintainer_thread) { pthread_mutex_unlock(&lru_maintainer_lock); if (to_sleep) usleep(to_sleep); pthread_mutex_lock(&lru_maintainer_lock); /* A sleep of zero counts as a minimum of a 1ms wait */ last_sleep = to_sleep > 1000 ? to_sleep : 1000; to_sleep = MAX_LRU_MAINTAINER_SLEEP; STATS_LOCK(); stats.lru_maintainer_juggles++; STATS_UNLOCK(); /* Each slab class gets its own sleep to avoid hammering locks */ for (i = POWER_SMALLEST; i < MAX_NUMBER_OF_SLAB_CLASSES; i++) { next_juggles[i] = next_juggles[i] > last_sleep ? next_juggles[i] - last_sleep : 0; if (next_juggles[i] > 0) { // Sleep the thread just for the minimum amount (or not at all) if (next_juggles[i] < to_sleep) to_sleep = next_juggles[i]; continue; } int did_moves = lru_maintainer_juggle(i); #ifdef EXTSTORE // Deeper loop to speed up pushing to storage. if (storage) { for (x = 0; x < 500; x++) { int found; found = lru_maintainer_store(storage, i); if (found) { did_moves += found; } else { break; } } } #endif if (did_moves == 0) { if (backoff_juggles[i] != 0) { backoff_juggles[i] += backoff_juggles[i] / 8; } else { backoff_juggles[i] = MIN_LRU_MAINTAINER_SLEEP; } if (backoff_juggles[i] > MAX_LRU_MAINTAINER_SLEEP) backoff_juggles[i] = MAX_LRU_MAINTAINER_SLEEP; } else if (backoff_juggles[i] > 0) { backoff_juggles[i] /= 2; if (backoff_juggles[i] < MIN_LRU_MAINTAINER_SLEEP) { backoff_juggles[i] = 0; } } next_juggles[i] = backoff_juggles[i]; if (next_juggles[i] < to_sleep) to_sleep = next_juggles[i]; } /* Minimize the sleep if we had async LRU bumps to process */ if (settings.lru_segmented && lru_maintainer_bumps() && to_sleep > 1000) { to_sleep = 1000; } /* Once per second at most */ if (settings.lru_crawler && last_crawler_check != current_time) { lru_maintainer_crawler_check(cdata, l); last_crawler_check = current_time; } if (settings.slab_automove == 1 && last_automove_check != current_time) { if (last_ratio != settings.slab_automove_ratio) { slab_automove_free(am); am = slab_automove_init(settings.slab_automove_window, settings.slab_automove_ratio); last_ratio = settings.slab_automove_ratio; } int src, dst; slab_automove_run(am, &src, &dst); if (src != -1 && dst != -1) { slabs_reassign(src, dst); LOGGER_LOG(l, LOG_SYSEVENTS, LOGGER_SLAB_MOVE, NULL, src, dst); } // dst == 0 means reclaim to global pool, be more aggressive if (dst != 0) { last_automove_check = current_time; } else if (dst == 0) { // also ensure we minimize the thread sleep to_sleep = 1000; } } } pthread_mutex_unlock(&lru_maintainer_lock); slab_automove_free(am); // LRU crawler *must* be stopped. free(cdata); 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 *arg) { 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, arg)) != 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; } /* Tail linkers and crawler for the LRU crawler. */ void do_item_linktail_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; } void do_item_unlinktail_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. */ item *do_item_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 */ }