Mercurial > hg > memcached
view items.c @ 3:0b6ac95a09bb default tip
Fix unix sockets support under FreeBSD.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Wed, 03 Oct 2007 05:34:42 +0400 |
parents | 30782bb1fc04 |
children |
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/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */ /* $Id: items.c 551 2007-05-07 21:24:31Z plindner $ */ #include "memcached.h" #include <sys/stat.h> #include <sys/socket.h> #include <sys/signal.h> #include <sys/resource.h> #include <fcntl.h> #include <netinet/in.h> #include <errno.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <time.h> #include <assert.h> /* Forward Declarations */ static void item_link_q(item *it); static void item_unlink_q(item *it); /* * We only reposition items in the LRU queue if they haven't been repositioned * in this many seconds. That saves us from churning on frequently-accessed * items. */ #define ITEM_UPDATE_INTERVAL 60 #define LARGEST_ID 255 static item *heads[LARGEST_ID]; static item *tails[LARGEST_ID]; static unsigned int sizes[LARGEST_ID]; void item_init(void) { int i; for(i = 0; i < LARGEST_ID; i++) { heads[i] = NULL; tails[i] = NULL; sizes[i] = 0; } } /* 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' : ' ', \ (it->it_flags & ITEM_DELETED) ? 'D' : ' ') #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; } /*@null@*/ item *do_item_alloc(char *key, const size_t nkey, const int flags, const rel_time_t exptime, const int nbytes) { uint8_t nsuffix; item *it; char suffix[40]; size_t ntotal = item_make_header(nkey + 1, flags, nbytes, suffix, &nsuffix); unsigned int id = slabs_clsid(ntotal); if (id == 0) return 0; it = slabs_alloc(ntotal); if (it == 0) { int tries = 50; item *search; /* If requested to not push old items out of cache when memory runs out, * we're out of luck at this point... */ if (settings.evict_to_free == 0) return NULL; /* * try to get one off the right LRU * don't necessariuly unlink the tail because it may be locked: refcount>0 * search up from tail an item with refcount==0 and unlink it; give up after 50 * tries */ if (id > LARGEST_ID) return NULL; if (tails[id] == 0) return NULL; for (search = tails[id]; tries > 0 && search != NULL; tries--, search=search->prev) { if (search->refcount == 0) { if (search->exptime > current_time) { STATS_LOCK(); stats.evictions++; STATS_UNLOCK(); } do_item_unlink(search); break; } } it = slabs_alloc(ntotal); if (it == 0) return NULL; } assert(it->slabs_clsid == 0); it->slabs_clsid = id; assert(it != heads[it->slabs_clsid]); it->next = it->prev = it->h_next = 0; it->refcount = 1; /* the caller will have a reference */ DEBUG_REFCNT(it, '*'); it->it_flags = 0; it->nkey = nkey; it->nbytes = nbytes; strcpy(ITEM_key(it), key); 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); 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 */ it->slabs_clsid = 0; it->it_flags |= ITEM_SLABBED; DEBUG_REFCNT(it, 'F'); slabs_free(it, ntotal); } /* * 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; return slabs_clsid(item_make_header(nkey + 1, flags, nbytes, prefix, &nsuffix)) != 0; } static void item_link_q(item *it) { /* item is the new head */ item **head, **tail; /* always true, warns: assert(it->slabs_clsid <= LARGEST_ID); */ 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_unlink_q(item *it) { item **head, **tail; /* always true, warns: assert(it->slabs_clsid <= LARGEST_ID); */ 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; } int do_item_link(item *it) { assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0); assert(it->nbytes < 1048576); it->it_flags |= ITEM_LINKED; it->time = current_time; assoc_insert(it); STATS_LOCK(); stats.curr_bytes += ITEM_ntotal(it); stats.curr_items += 1; stats.total_items += 1; STATS_UNLOCK(); item_link_q(it); return 1; } void do_item_unlink(item *it) { 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); item_unlink_q(it); if (it->refcount == 0) item_free(it); } } void do_item_remove(item *it) { assert((it->it_flags & ITEM_SLABBED) == 0); if (it->refcount != 0) { it->refcount--; DEBUG_REFCNT(it, '-'); } assert((it->it_flags & ITEM_DELETED) == 0 || it->refcount != 0); if (it->refcount == 0 && (it->it_flags & ITEM_LINKED) == 0) { item_free(it); } } void do_item_update(item *it) { if (it->time < current_time - ITEM_UPDATE_INTERVAL) { assert((it->it_flags & ITEM_SLABBED) == 0); if (it->it_flags & ITEM_LINKED) { item_unlink_q(it); it->time = current_time; item_link_q(it); } } } int do_item_replace(item *it, item *new_it) { assert((it->it_flags & ITEM_SLABBED) == 0); do_item_unlink(it); return do_item_link(new_it); } /*@null@*/ char *item_cachedump(const unsigned int slabs_clsid, const unsigned int limit, unsigned int *bytes) { int memlimit = 2097152; /* 2097152: (2 * 1024 * 1024) */ char *buffer; unsigned int bufcurr; item *it; int len; int shown = 0; char temp[512]; if (slabs_clsid > LARGEST_ID) return NULL; it = heads[slabs_clsid]; buffer = malloc((size_t)memlimit); if (buffer == 0) return NULL; bufcurr = 0; while (it != NULL && (limit == 0 || shown < limit)) { len = snprintf(temp, 512, "ITEM %s [%d b; %lu s]\r\n", ITEM_key(it), it->nbytes - 2, it->time + stats.started); if (bufcurr + len + 6 > memlimit) /* 6 is END\r\n\0 */ break; strcpy(buffer + bufcurr, temp); bufcurr += len; shown++; it = it->next; } memcpy(buffer + bufcurr, "END\r\n", 6); bufcurr += 5; *bytes = bufcurr; return buffer; } void item_stats(char *buffer, const int buflen) { int i; char *bufcurr = buffer; rel_time_t now = current_time; if (buflen < 4096) { strcpy(buffer, "SERVER_ERROR out of memory"); return; } for (i = 0; i < LARGEST_ID; i++) { if (tails[i] != NULL) bufcurr += snprintf(bufcurr, (size_t)buflen, "STAT items:%d:number %u\r\nSTAT items:%d:age %u\r\n", i, sizes[i], i, now - tails[i]->time); } memcpy(bufcurr, "END", 4); return; } /* dumps out a list of objects of each size, with granularity of 32 bytes */ /*@null@*/ char* item_stats_sizes(int *bytes) { const int num_buckets = 32768; /* max 1MB object, divided into 32 bytes size buckets */ unsigned int *histogram = (unsigned int *)malloc((size_t)num_buckets * sizeof(int)); char *buf = (char *)malloc(2097152 * sizeof(char)); /* 2097152: 2 * 1024 * 1024 */ int i; if (histogram == 0 || buf == 0) { if (histogram) free(histogram); if (buf) free(buf); return NULL; } /* build the histogram */ memset(histogram, 0, (size_t)num_buckets * sizeof(int)); for (i = 0; i < LARGEST_ID; 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; } } /* write the buffer */ *bytes = 0; for (i = 0; i < num_buckets; i++) { if (histogram[i] != 0) { *bytes += sprintf(&buf[*bytes], "%d %u\r\n", i * 32, histogram[i]); } } *bytes += sprintf(&buf[*bytes], "END\r\n"); free(histogram); return buf; } /* returns true if a deleted item's delete-locked-time is over, and it should be removed from the namespace */ bool item_delete_lock_over (item *it) { assert(it->it_flags & ITEM_DELETED); return (current_time >= it->exptime); } /* wrapper around assoc_find which does the lazy expiration/deletion logic */ item *do_item_get_notedeleted(const char *key, const size_t nkey, bool *delete_locked) { item *it = assoc_find(key, nkey); if (delete_locked) *delete_locked = false; if (it && (it->it_flags & ITEM_DELETED)) { /* it's flagged as delete-locked. let's see if that condition is past due, and the 5-second delete_timer just hasn't gotten to it yet... */ if (!item_delete_lock_over(it)) { if (delete_locked) *delete_locked = true; it = 0; } } if (it != NULL && settings.oldest_live != 0 && settings.oldest_live <= current_time && it->time <= settings.oldest_live) { do_item_unlink(it); // MTSAFE - cache_lock held it = 0; } if (it != NULL && it->exptime != 0 && it->exptime <= current_time) { do_item_unlink(it); // MTSAFE - cache_lock held it = 0; } if (it != NULL) { it->refcount++; DEBUG_REFCNT(it, '+'); } return it; } item *item_get(const char *key, const size_t nkey) { return item_get_notedeleted(key, nkey, 0); } /* returns an item whether or not it's delete-locked or expired. */ item *do_item_get_nocheck(const char *key, const size_t nkey) { item *it = assoc_find(key, nkey); if (it) { it->refcount++; DEBUG_REFCNT(it, '+'); } return it; } /* expires items that are more recent than the oldest_live setting. */ void do_item_flush_expired(void) { int i; item *iter, *next; if (settings.oldest_live == 0) return; for (i = 0; i < LARGEST_ID; i++) { /* The LRU is sorted in decreasing time order, and an item's timestamp * is never newer than its last access time, so we only need to walk * back until we hit an item older than the oldest_live time. * The oldest_live checking will auto-expire the remaining items. */ for (iter = heads[i]; iter != NULL; iter = next) { if (iter->time >= settings.oldest_live) { next = iter->next; if ((iter->it_flags & ITEM_SLABBED) == 0) { do_item_unlink(iter); } } else { /* We've hit the first old item. Continue to the next queue. */ break; } } } }