apc_cache.c

/*
  +----------------------------------------------------------------------+
  | APC                                                                  |
  +----------------------------------------------------------------------+
  | Copyright (c) 2006-2011 The PHP Group                                |
  +----------------------------------------------------------------------+
  | This source file is subject to version 3.01 of the PHP license,      |
  | that is bundled with this package in the file LICENSE, and is        |
  | available through the world-wide-web at the following url:           |
  | http:www.php.net/license/3_01.txt                                    |
  | If you did not receive a copy of the PHP license and are unable to   |
  | obtain it through the world-wide-web, please send a note to          |
  | license@php.net so we can mail you a copy immediately.               |
  +----------------------------------------------------------------------+
  | Authors: Daniel Cowgill <dcowgill@communityconnect.com>              |
  |          Rasmus Lerdorf <rasmus@php.net>                             |
  |          Arun C. Murthy <arunc@yahoo-inc.com>                        |
  |          Gopal Vijayaraghavan <gopalv@yahoo-inc.com>                 |
  +----------------------------------------------------------------------+

   This software was contributed to PHP by Community Connect Inc. in 2002
   and revised in 2005 by Yahoo! Inc. to add support for PHP 5.1.
   Future revisions and derivatives of this source code must acknowledge
   Community Connect Inc. as the original contributor of this module by
   leaving this note intact in the source code.

   All other licensing and usage conditions are those of the PHP Group.

 */

#include "apc_cache.h"
#include "apc_sma.h"
#include "apc_globals.h"
#include "php_scandir.h"
#include "SAPI.h"
#include "TSRM.h"
#include "php_main.h"
#include "ext/standard/md5.h"
#include "ext/standard/php_var.h"
#include "zend_smart_str.h"

#if PHP_VERSION_ID < 70300
# define GC_SET_REFCOUNT(ref, rc) (GC_REFCOUNT(ref) = (rc))
# define GC_ADDREF(ref) GC_REFCOUNT(ref)++
#endif

#define APC_POOL_ALLOC(size) apc_pool_alloc(ctxt->pool, ctxt->sma, (size))
#define APC_POOL_STRING_DUP(str) apc_pool_string_dup(ctxt->pool, ctxt->sma, (str))

/* If recursive mutexes are used, there is no distinction between read and write locks.
 * As such, if we acquire a read-lock, it's really a write-lock and we are free to perform
 * increments without atomics. */
#ifdef APC_LOCK_RECURSIVE
# define ATOMIC_INC_RLOCKED(a) (a)++
#else
# define ATOMIC_INC_RLOCKED(a) ATOMIC_INC(a)
#endif

static APC_HOTSPOT zval* my_copy_zval(zval* dst, const zval* src, apc_context_t* ctxt);

/* {{{ make_prime */
static int const primes[] = {
  257, /*   256 */
  521, /*   512 */
 1031, /*  1024 */
 2053, /*  2048 */
 3079, /*  3072 */
 4099, /*  4096 */
 5147, /*  5120 */
 6151, /*  6144 */
 7177, /*  7168 */
 8209, /*  8192 */
 9221, /*  9216 */
10243, /* 10240 */
11273, /* 11264 */
12289, /* 12288 */
13313, /* 13312 */
14341, /* 14336 */
15361, /* 15360 */
16411, /* 16384 */
17417, /* 17408 */
18433, /* 18432 */
19457, /* 19456 */
20483, /* 20480 */
30727, /* 30720 */
40961, /* 40960 */
61441, /* 61440 */
81929, /* 81920 */
122887,/* 122880 */
163841,/* 163840 */
245771,/* 245760 */
327689,/* 327680 */
491527,/* 491520 */
655373,/* 655360 */
983063,/* 983040 */
0      /* sentinel */
};

static int make_prime(int n)
{
	int *k = (int*)primes;
	while(*k) {
		if((*k) > n) return *k;
		k++;
	}
	return *(k-1);
}
/* }}} */

static void free_entry(apc_cache_t *cache, apc_cache_entry_t *entry)
{
	apc_pool_destroy(entry->pool, cache->sma);
}

/* {{{ apc_cache_hash_slot
 Note: These calculations can and should be done outside of a lock */
static void apc_cache_hash_slot(
		apc_cache_t* cache, zend_string *key, zend_ulong* hash, zend_ulong* slot) {
	*hash = ZSTR_HASH(key);
	*slot = *hash % cache->nslots;
} /* }}} */

/* An entry is hard expired if the creation time if older than the per-entry TTL.
 * Hard expired entries must be treated indentially to non-existent entries. */
static zend_bool apc_cache_entry_hard_expired(apc_cache_entry_t *entry, time_t t) {
	return entry->ttl && (time_t) (entry->ctime + entry->ttl) < t;
}

/* An entry is soft expired if no per-entry TTL is set, a global cache TTL is set,
 * and the access time of the entry is older than the global TTL. Soft expired entries
 * are accessible by lookup operation, but may be removed from the cache at any time. */
static zend_bool apc_cache_entry_soft_expired(
		apc_cache_t *cache, apc_cache_entry_t *entry, time_t t) {
	return !entry->ttl && cache->ttl && (time_t) (entry->atime + cache->ttl) < t;
}

static zend_bool apc_cache_entry_expired(
		apc_cache_t *cache, apc_cache_entry_t *entry, time_t t) {
	return apc_cache_entry_hard_expired(entry, t)
		|| apc_cache_entry_soft_expired(cache, entry, t);
}

/* {{{ apc_cache_wlocked_remove_entry  */
static void apc_cache_wlocked_remove_entry(apc_cache_t *cache, apc_cache_entry_t **entry)
{
	apc_cache_entry_t *dead = *entry;

	/* think here is safer */
	*entry = (*entry)->next;

	/* adjust header info */
	if (cache->header->mem_size)
		cache->header->mem_size -= dead->mem_size;

	if (cache->header->nentries)
		cache->header->nentries--;

	/* remove if there are no references */
	if (dead->ref_count <= 0) {
		free_entry(cache, dead);
	} else {
		/* add to gc if there are still refs */
		dead->next = cache->header->gc;
		dead->dtime = time(0);
		cache->header->gc = dead;
	}
}
/* }}} */

/* {{{ apc_cache_wlocked_gc */
static void apc_cache_wlocked_gc(apc_cache_t* cache)
{
	/* This function scans the list of removed cache entries and deletes any
	 * entry whose reference count is zero  or that has been on the gc
	 * list for more than cache->gc_ttl seconds
	 *   (we issue a warning in the latter case).
	 */
	if (!cache->header->gc) {
		return;
	}

	{
		apc_cache_entry_t **entry = &cache->header->gc;
		time_t now = time(0);

		while (*entry != NULL) {
			time_t gc_sec = cache->gc_ttl ? (now - (*entry)->dtime) : 0;

			if (!(*entry)->ref_count || gc_sec > (time_t)cache->gc_ttl) {
				apc_cache_entry_t *dead = *entry;

				/* good ol' whining */
				if (dead->ref_count > 0) {
					apc_debug(
						"GC cache entry '%s' was on gc-list for %ld seconds",
						ZSTR_VAL(dead->key), gc_sec
					);
				}

				/* set next entry */
				*entry = (*entry)->next;

				/* free entry */
				free_entry(cache, dead);
			} else {
				entry = &(*entry)->next;
			}
		}
	}
}
/* }}} */

/* {{{ php serializer */
PHP_APCU_API int APC_SERIALIZER_NAME(php) (APC_SERIALIZER_ARGS)
{
	smart_str strbuf = {0};
	php_serialize_data_t var_hash;

	/* Lock in case apcu is accessed inside Serializer::serialize() */
	BG(serialize_lock)++;
	PHP_VAR_SERIALIZE_INIT(var_hash);
	php_var_serialize(&strbuf, (zval*) value, &var_hash);
	PHP_VAR_SERIALIZE_DESTROY(var_hash);
	BG(serialize_lock)--;

	if (strbuf.s != NULL) {
		*buf = (unsigned char *)estrndup(ZSTR_VAL(strbuf.s), ZSTR_LEN(strbuf.s));
		if (*buf == NULL)
			return 0;

		*buf_len = ZSTR_LEN(strbuf.s);
		smart_str_free(&strbuf);
		return 1;
	}
	return 0;
} /* }}} */

/* {{{ php unserializer */
PHP_APCU_API int APC_UNSERIALIZER_NAME(php) (APC_UNSERIALIZER_ARGS)
{
	const unsigned char *tmp = buf;
	php_unserialize_data_t var_hash;
	int result;

	/* Lock in case apcu is accessed inside Serializer::unserialize() */
	BG(serialize_lock)++;
	PHP_VAR_UNSERIALIZE_INIT(var_hash);
	result = php_var_unserialize(value, &tmp, buf + buf_len, &var_hash);
	PHP_VAR_UNSERIALIZE_DESTROY(var_hash);
	BG(serialize_lock)--;
	
	if (!result) {
		php_error_docref(NULL, E_NOTICE, "Error at offset %ld of %ld bytes", (zend_long)(tmp - buf), (zend_long)buf_len);
		ZVAL_NULL(value);
		return 0;
	}
	return 1;
} /* }}} */

/* {{{ apc_cache_create */
PHP_APCU_API apc_cache_t* apc_cache_create(apc_sma_t* sma, apc_serializer_t* serializer, zend_long size_hint, zend_long gc_ttl, zend_long ttl, zend_long smart, zend_bool defend) {
	apc_cache_t* cache;
	zend_long cache_size;
	zend_long nslots;

	/* calculate number of slots */
	nslots = make_prime(size_hint > 0 ? size_hint : 2000);

	/* allocate pointer by normal means */
	cache = (apc_cache_t*) apc_emalloc(sizeof(apc_cache_t));

	if (!cache) {
		apc_error("Unable to allocate memory for cache structures. (Perhaps your memory_limit isn't large enough?). ");
		return NULL;
	}

	/* calculate cache size for shm allocation */
	cache_size = sizeof(apc_cache_header_t) + nslots*sizeof(apc_cache_entry_t *);

	/* allocate shm */
	cache->shmaddr = sma->smalloc(cache_size);

	if(!cache->shmaddr) {
		apc_error("Unable to allocate shared memory for cache structures.  (Perhaps your shared memory size isn't large enough?). ");
		return NULL;
	}

	/* zero shm */
	memset(cache->shmaddr, 0, cache_size);

	/* set default header */
	cache->header = (apc_cache_header_t*) cache->shmaddr;

	cache->header->nhits = 0;
	cache->header->nmisses = 0;
	cache->header->nentries = 0;
	cache->header->nexpunges = 0;
	cache->header->gc = NULL;
	cache->header->stime = time(NULL);
	cache->header->state |= APC_CACHE_ST_NONE;

	/* set cache options */
	cache->slots = (apc_cache_entry_t **) (((char*) cache->shmaddr) + sizeof(apc_cache_header_t));
	cache->sma = sma;
	cache->serializer = serializer;
	cache->nslots = nslots;
	cache->gc_ttl = gc_ttl;
	cache->ttl = ttl;
	cache->smart = smart;
	cache->defend = defend;

	/* header lock */
	CREATE_LOCK(&cache->header->lock);

	/* zero slots */
	memset(cache->slots, 0, sizeof(apc_cache_entry_t *) * nslots);

	return cache;
} /* }}} */

static inline zend_bool apc_cache_wlocked_insert(
		apc_cache_t *cache, apc_cache_entry_t *new_entry, zend_bool exclusive) {
	zend_string *key = new_entry->key;
	time_t t = new_entry->ctime;

	/* process deleted list  */
	apc_cache_wlocked_gc(cache);

	/* make the insertion */
	{
		apc_cache_entry_t **entry;
		zend_ulong h, s;

		/* calculate hash and entry */
		apc_cache_hash_slot(cache, key, &h, &s);

		entry = &cache->slots[s];
		while (*entry) {
			/* check for a match by hash and string */
			if ((ZSTR_HASH((*entry)->key) == h) &&
				ZSTR_LEN((*entry)->key) == ZSTR_LEN(key) &&
				memcmp(ZSTR_VAL((*entry)->key), ZSTR_VAL(key), ZSTR_LEN(key)) == 0) {

				/*
				 * At this point we have found the user cache entry.  If we are doing
				 * an exclusive insert (apc_add) we are going to bail right away if
				 * the user entry already exists and is hard expired.
				 */
				if (exclusive && !apc_cache_entry_hard_expired(*entry, t)) {
					return 0;
				}

				apc_cache_wlocked_remove_entry(cache, entry);
				break;
			}

			/*
			 * This is a bit nasty. The idea here is to do runtime cleanup of the linked list of
			 * entry entries so we don't always have to skip past a bunch of stale entries.
			 */
			if (apc_cache_entry_expired(cache, *entry, t)) {
				apc_cache_wlocked_remove_entry(cache, entry);
				continue;
			}

			/* set next entry */
			entry = &(*entry)->next;
		}

		/* link in new entry */
		new_entry->next = *entry;
		*entry = new_entry;

		/* set value size from pool size */
		new_entry->mem_size = apc_pool_size(new_entry->pool);
		cache->header->mem_size += new_entry->mem_size;
		cache->header->nentries++;
		cache->header->ninserts++;
	}

	return 1;
}

static zend_bool apc_cache_make_copy_in_context(
		apc_cache_t* cache, apc_context_t* context, apc_pool_type pool_type);
static zend_bool apc_cache_destroy_context(apc_context_t *context);
static apc_cache_entry_t *apc_cache_make_entry(
		apc_context_t *ctxt, zend_string *key, const zval* val, const int32_t ttl, time_t t);

/* TODO This function may lead to a deadlock on expunge */
static inline zend_bool apc_cache_store_internal(
		apc_cache_t *cache, zend_string *key, const zval *val,
		const int32_t ttl, const zend_bool exclusive) {
	apc_cache_entry_t *entry;
	time_t t = apc_time();
	apc_context_t ctxt={0,};

	if (apc_cache_defense(cache, key, t)) {
		return 0;
	}

	/* initialize a context suitable for making an insert */
	if (!apc_cache_make_copy_in_context(cache, &ctxt, APC_SMALL_POOL)) {
		return 0;
	}

	/* initialize the entry for insertion */
	entry = apc_cache_make_entry(&ctxt, key, val, ttl, t);
	if (!entry) {
		apc_cache_destroy_context(&ctxt);
		return 0;
	}

	/* execute an insertion */
	if (!apc_cache_wlocked_insert(cache, entry, exclusive)) {
		apc_cache_destroy_context(&ctxt);
		return 0;
	}

	return 1;
}

/* Find entry, without updating stat counters or access time */
static inline apc_cache_entry_t *apc_cache_rlocked_find_nostat(
		apc_cache_t *cache, zend_string *key, time_t t) {
	apc_cache_entry_t *entry;
	zend_ulong h, s;

	/* calculate hash and slot */
	apc_cache_hash_slot(cache, key, &h, &s);

	entry = cache->slots[s];
	while (entry) {
		/* check for a matching key by has and identifier */
		if (h == ZSTR_HASH(entry->key) &&
			ZSTR_LEN(entry->key) == ZSTR_LEN(key) &&
			memcmp(ZSTR_VAL(entry->key), ZSTR_VAL(key), ZSTR_LEN(key)) == 0) {

			/* Check to make sure this entry isn't expired by a hard TTL */
			if (apc_cache_entry_hard_expired(entry, t)) {
				break;
			}

			return entry;
		}

		entry = entry->next;
	}

	return NULL;
}

/* Find entry, updating stat counters and access time */
static inline apc_cache_entry_t *apc_cache_rlocked_find(
		apc_cache_t *cache, zend_string *key, time_t t) {
	apc_cache_entry_t *entry;
	zend_ulong h, s;

	/* calculate hash and slot */
	apc_cache_hash_slot(cache, key, &h, &s);

	entry = cache->slots[s];
	while (entry) {
		/* check for a matching key by has and identifier */
		if (h == ZSTR_HASH(entry->key) &&
			ZSTR_LEN(entry->key) == ZSTR_LEN(key) &&
			memcmp(ZSTR_VAL(entry->key), ZSTR_VAL(key), ZSTR_LEN(key)) == 0) {

			/* Check to make sure this entry isn't expired by a hard TTL */
			if (apc_cache_entry_hard_expired(entry, t)) {
				break;
			}

			ATOMIC_INC_RLOCKED(cache->header->nhits);
			ATOMIC_INC_RLOCKED(entry->nhits);
			entry->atime = t;

			return entry;
		}

		entry = entry->next;
	}

	ATOMIC_INC_RLOCKED(cache->header->nmisses);
	return NULL;
}

static inline apc_cache_entry_t *apc_cache_rlocked_find_incref(
		apc_cache_t *cache, zend_string *key, time_t t) {
	apc_cache_entry_t *entry = apc_cache_rlocked_find(cache, key, t);
	if (!entry) {
		return NULL;
	}

	ATOMIC_INC_RLOCKED(entry->ref_count);
	return entry;
}

/* {{{ apc_cache_store */
PHP_APCU_API zend_bool apc_cache_store(
		apc_cache_t* cache, zend_string *key, const zval *val,
		const int32_t ttl, const zend_bool exclusive) {
	apc_cache_entry_t *entry;
	time_t t = apc_time();
	apc_context_t ctxt={0,};
	zend_bool ret = 0;

	/* run cache defense */
	if (apc_cache_defense(cache, key, t)) {
		return 0;
	}

	/* initialize a context suitable for making an insert */
	if (!apc_cache_make_copy_in_context(cache, &ctxt, APC_SMALL_POOL)) {
		return 0;
	}

	/* initialize the entry for insertion */
	entry = apc_cache_make_entry(&ctxt, key, val, ttl, t);
	if (!entry) {
		apc_cache_destroy_context(&ctxt);
		return 0;
	}

	/* execute an insertion */
	if (!APC_WLOCK(cache->header)) {
		apc_cache_destroy_context(&ctxt);
		return 0;
	}

	php_apc_try {
		ret = apc_cache_wlocked_insert(cache, entry, exclusive);
	} php_apc_finally {
		APC_WUNLOCK(cache->header);
	} php_apc_end_try();

	/* destroy context if insertion failed */
	if (!ret) {
		apc_cache_destroy_context(&ctxt);
	}

	return ret;
} /* }}} */

#ifndef ZTS
/* {{{ data_unserialize */
static zval data_unserialize(const char *filename)
{
	zval retval;
	zend_long len = 0;
	zend_stat_t sb;
	char *contents, *tmp;
	FILE *fp;
	php_unserialize_data_t var_hash = {0,};

	if(VCWD_STAT(filename, &sb) == -1) {
		return EG(uninitialized_zval);
	}

	fp = fopen(filename, "rb");

	len = sizeof(char)*sb.st_size;

	tmp = contents = malloc(len);

	if(!contents) {
		fclose(fp);
		return EG(uninitialized_zval);
	}

	if(fread(contents, 1, len, fp) < 1) {
		fclose(fp);
		free(contents);
		return EG(uninitialized_zval);
	}

	ZVAL_UNDEF(&retval);

	PHP_VAR_UNSERIALIZE_INIT(var_hash);

	/* I wish I could use json */
	if(!php_var_unserialize(&retval, (const unsigned char**)&tmp, (const unsigned char*)(contents+len), &var_hash)) {
		fclose(fp);
		free(contents);
		return EG(uninitialized_zval);
	}

	PHP_VAR_UNSERIALIZE_DESTROY(var_hash);

	free(contents);
	fclose(fp);

	return retval;
}

static int apc_load_data(apc_cache_t* cache, const char *data_file)
{
	char *p;
	char key[MAXPATHLEN] = {0,};
	unsigned int key_len;
	zval data;

	p = strrchr(data_file, DEFAULT_SLASH);

	if(p && p[1]) {
		strlcpy(key, p+1, sizeof(key));
		p = strrchr(key, '.');

		if(p) {
			p[0] = '\0';
			key_len = strlen(key);

			data = data_unserialize(data_file);
			if(Z_TYPE(data) != IS_UNDEF) {
				zend_string *name = zend_string_init(key, key_len, 0);
				apc_cache_store(
					cache, name, &data, 0, 1);
				zend_string_release(name);
				zval_dtor(&data);
			}
			return 1;
		}
	}

	return 0;
}
#endif

/* {{{ apc_cache_preload shall load the prepared data files in path into the specified cache */
PHP_APCU_API zend_bool apc_cache_preload(apc_cache_t* cache, const char *path)
{
#ifndef ZTS
	zend_bool result = 0;
	char file[MAXPATHLEN]={0,};
	int ndir, i;
	char *p = NULL;
	struct dirent **namelist = NULL;

	if ((ndir = php_scandir(path, &namelist, 0, php_alphasort)) > 0) {
		for (i = 0; i < ndir; i++) {
			/* check for extension */
			if (!(p = strrchr(namelist[i]->d_name, '.'))
					|| (p && strcmp(p, ".data"))) {
				free(namelist[i]);
				continue;
			}

			snprintf(file, MAXPATHLEN, "%s%c%s",
					path, DEFAULT_SLASH, namelist[i]->d_name);

			if(apc_load_data(cache, file)) {
				result = 1;
			}
			free(namelist[i]);
		}
		free(namelist);
	}
	return result;
#else
	apc_error("Cannot load data from apc.preload_path=%s in thread-safe mode", path);
	return 0;
#endif
} /* }}} */

/* {{{ apc_cache_entry_release */
PHP_APCU_API void apc_cache_entry_release(apc_cache_t *cache, apc_cache_entry_t *entry)
{
	ATOMIC_DEC(entry->ref_count);
}
/* }}} */

/* {{{ apc_cache_destroy */
PHP_APCU_API void apc_cache_destroy(apc_cache_t* cache)
{
	if (!cache) {
		return;
	}

	/* destroy lock */
	DESTROY_LOCK(&cache->header->lock);

	/* XXX this is definitely a leak, but freeing this causes all the apache
		children to freeze. It might be because the segment is shared between
		several processes. To figure out is how to free this safely. */
	/*apc_sma_free(cache->shmaddr);*/
	apc_efree(cache);
}
/* }}} */

/* {{{ apc_cache_wlocked_real_expunge */
static void apc_cache_wlocked_real_expunge(apc_cache_t* cache) {
	/* increment counter */
	cache->header->nexpunges++;

	/* expunge */
	{
		zend_ulong i;

		for (i = 0; i < cache->nslots; i++) {
			apc_cache_entry_t **entry = &cache->slots[i];
			while (*entry) {
				apc_cache_wlocked_remove_entry(cache, entry);
			}
		}
	}

	/* set new time so counters make sense */
	cache->header->stime = apc_time();

	/* reset counters */
	cache->header->ninserts = 0;
	cache->header->nentries = 0;
	cache->header->nhits = 0;
	cache->header->nmisses = 0;

	/* resets lastkey */
	memset(&cache->header->lastkey, 0, sizeof(apc_cache_slam_key_t));
} /* }}} */

/* {{{ apc_cache_clear */
PHP_APCU_API void apc_cache_clear(apc_cache_t* cache)
{
	/* check there is a cache and it is not busy */
	if (!cache || apc_cache_busy(cache)) {
		return;
	}

	/* lock header */
	if (!APC_WLOCK(cache->header)) {
		return;
	}

	/* set busy */
	cache->header->state |= APC_CACHE_ST_BUSY;

	/* expunge cache */
	apc_cache_wlocked_real_expunge(cache);

	/* set info */
	cache->header->stime = apc_time();
	cache->header->nexpunges = 0;

	/* unset busy */
	cache->header->state &= ~APC_CACHE_ST_BUSY;

	/* unlock header */
	APC_WUNLOCK(cache->header);
}
/* }}} */

/* {{{ apc_cache_default_expunge */
PHP_APCU_API void apc_cache_default_expunge(apc_cache_t* cache, size_t size)
{
	time_t t = apc_time();
	size_t suitable = 0L;
	size_t available = 0L;


	/* check there is a cache, and it is not busy */
	if(!cache || apc_cache_busy(cache)) {
		return;
	}

	/* get the lock for header */
	if (!APC_WLOCK(cache->header)) {
		return;
	}

	/* update state in header */
	cache->header->state |= APC_CACHE_ST_BUSY;

	/* make suitable selection */
	suitable = (cache->smart > 0L) ? (size_t) (cache->smart * size) : (size_t) (cache->sma->size/2);

	/* gc */
	apc_cache_wlocked_gc(cache);

	/* get available */
	available = cache->sma->get_avail_mem();

	/* perform expunge processing */
	if (!cache->ttl) {
		/* check it is necessary to expunge */
		if (available < suitable) {
			apc_cache_wlocked_real_expunge(cache);
		}
	} else {
		/* check that expunge is necessary */
		if (available < suitable) {
			zend_ulong i;

			/* look for junk */
			for (i = 0; i < cache->nslots; i++) {
				apc_cache_entry_t **entry = &cache->slots[i];
				while (*entry) {
					if (apc_cache_entry_expired(cache, *entry, t)) {
						apc_cache_wlocked_remove_entry(cache, entry);
						continue;
					}

					/* grab next entry */
					entry = &(*entry)->next;
				}
			}

			/* if the cache now has space, then reset last key */
			if (cache->sma->get_avail_size(size)) {
				/* wipe lastkey */
				memset(&cache->header->lastkey, 0, sizeof(apc_cache_slam_key_t));
			} else {
				/* with not enough space left in cache, we are forced to expunge */
				apc_cache_wlocked_real_expunge(cache);
			}
		}
	}

	/* we are done */
	cache->header->state &= ~APC_CACHE_ST_BUSY;

	/* unlock header */
	APC_WUNLOCK(cache->header);
}
/* }}} */

static zend_bool apc_cache_make_copy_in_context(
		apc_cache_t* cache, apc_context_t* context, apc_pool_type pool_type) {
	/* attempt to create the pool */
	context->pool = apc_pool_create(pool_type, cache->sma);
	if (!context->pool) {
		apc_warning("Unable to allocate memory for pool");
		return 0;
	}

	/* set context information */
	context->sma = cache->sma;
	context->serializer = cache->serializer;
	context->copy = APC_COPY_IN;

	/* set this to avoid memory errors */
	memset(&context->copied, 0, sizeof(HashTable));

	return 1;
}

/* {{{ apc_cache_destroy_context */
static zend_bool apc_cache_destroy_context(apc_context_t *context) {
	if (!context->pool) {
		return 0;
	}

	apc_pool_destroy(context->pool, context->sma);

	return 1;
} /* }}} */

/* {{{ apc_cache_find */
PHP_APCU_API apc_cache_entry_t* apc_cache_find(apc_cache_t* cache, zend_string *key, time_t t)
{
	apc_cache_entry_t *entry;

	/* check we are able to deal with the request */
	if (!cache || apc_cache_busy(cache)) {
		return NULL;
	}

	APC_RLOCK(cache->header);
	entry = apc_cache_rlocked_find_incref(cache, key, t);
	APC_RUNLOCK(cache->header);

	return entry;
}
/* }}} */

/* {{{ apc_cache_fetch */
PHP_APCU_API zend_bool apc_cache_fetch(apc_cache_t* cache, zend_string *key, time_t t, zval **dst)
{
	apc_cache_entry_t *entry;
	zend_bool retval = 0;

	/* check we are able to deal with the request */
	if (!cache || apc_cache_busy(cache)) {
		return 0;
	}

	APC_RLOCK(cache->header);
	entry = apc_cache_rlocked_find_incref(cache, key, t);
	APC_RUNLOCK(cache->header);

	if (!entry) {
		return 0;
	}

	php_apc_try {
		retval = apc_cache_entry_fetch_zval(cache, entry, *dst);
	} php_apc_finally {
		apc_cache_entry_release(cache, entry);
	} php_apc_end_try();

	return retval;
} /* }}} */

/* {{{ apc_cache_exists */
PHP_APCU_API zend_bool apc_cache_exists(apc_cache_t* cache, zend_string *key, time_t t)
{
	apc_cache_entry_t *entry;

	if (apc_cache_busy(cache)) {
		/* cache cleanup in progress */
		return 0;
	}

	APC_RLOCK(cache->header);
	entry = apc_cache_rlocked_find_nostat(cache, key, t);
	APC_RUNLOCK(cache->header);

	return entry != NULL;
}
/* }}} */

/* {{{ apc_cache_update */
PHP_APCU_API zend_bool apc_cache_update(
		apc_cache_t *cache, zend_string *key, apc_cache_updater_t updater, void *data,
		zend_bool insert_if_not_found, zend_long ttl)
{
	apc_cache_entry_t **entry;

	zend_bool retval = 0;
	zend_ulong h, s;
	time_t t = apc_time();

	if (apc_cache_busy(cache)) {
		/* cannot service request right now */
		return 0;
	}

	/* calculate hash */
	apc_cache_hash_slot(cache, key, &h, &s);

retry_update:
	if (!APC_WLOCK(cache->header)) {
		return 0;
	}

	php_apc_try {
		/* find head */
		entry = &cache->slots[s];

		while (*entry) {
			/* check for a match by hash and identifier */
			if (h == ZSTR_HASH((*entry)->key) &&
				ZSTR_LEN((*entry)->key) == ZSTR_LEN(key) &&
				memcmp(ZSTR_VAL((*entry)->key), ZSTR_VAL(key), ZSTR_LEN(key)) == 0 &&
				!apc_cache_entry_hard_expired(*entry, t)
			) {
				/* attempt to perform update */
				switch (Z_TYPE((*entry)->val)) {
					case IS_ARRAY:
					case IS_OBJECT:
						if (cache->serializer) {
							retval = 0;
							break;
						}
						/* break intentionally omitted */

					default:
						/* executing update */
						retval = updater(cache, *entry, data);
						/* set modified time */
						(*entry)->mtime = t;
						break;
				}

				APC_WUNLOCK(cache->header);
				php_apc_try_finish();
				return retval;
			}

			/* set next entry */
			entry = &(*entry)->next;
		}
	} php_apc_finally {
		APC_WUNLOCK(cache->header);
	} php_apc_end_try();

	if (insert_if_not_found) {
		/* Failed to find matching entry. Add key with value 0 and run the updater again. */
		zval val;
		ZVAL_LONG(&val, 0);

		/* We do not check the return value of the exclusive-store (add), as the entry might have
		 * been added between the cache unlock and the store call. In this case we just want to
		 * update the entry created by a different process. */
		apc_cache_store(cache, key, &val, ttl, 1);

		/* Only attempt to perform insertion once. */
		insert_if_not_found = 0;
		goto retry_update;
	}

	return 0;
}
/* }}} */

/* {{{ apc_cache_delete */
PHP_APCU_API zend_bool apc_cache_delete(apc_cache_t *cache, zend_string *key)
{
	apc_cache_entry_t **entry;
	zend_ulong h, s;

	if (!cache) {
		return 1;
	}

	/* calculate hash and slot */
	apc_cache_hash_slot(cache, key, &h, &s);

	/* lock cache */
	if (!APC_WLOCK(cache->header)) {
		return 1;
	}

	/* find head */
	entry = &cache->slots[s];

	while (*entry) {
		/* check for a match by hash and identifier */
		if (h == ZSTR_HASH((*entry)->key) &&
			ZSTR_LEN((*entry)->key) == ZSTR_LEN(key) &&
			memcmp(ZSTR_VAL((*entry)->key), ZSTR_VAL(key), ZSTR_LEN(key)) == SUCCESS) {

			/* executing removal */
			apc_cache_wlocked_remove_entry(cache, entry);

			/* unlock header */
			APC_WUNLOCK(cache->header);
			return 1;
		}

		entry = &(*entry)->next;
	}

	/* unlock header */
	APC_WUNLOCK(cache->header);
	return 0;
}
/* }}} */

/* {{{ my_serialize_object */
static zval* my_serialize_object(zval* dst, const zval* src, apc_context_t* ctxt)
{
	unsigned char *buf = NULL;
	size_t buf_len = 0;

	apc_serialize_t serialize = APC_SERIALIZER_NAME(php);
	void *config = NULL;
	zend_string *serial = NULL;

	if (ctxt->serializer) {
		serialize = ctxt->serializer->serialize;
		config = ctxt->serializer->config;
	}

	ZVAL_NULL(dst);

	if (serialize(&buf, &buf_len, src, config)) {
		if (!(serial = apc_pool_string_init(ctxt->pool, ctxt->sma, (char *) buf, buf_len))) {
			efree(buf);

			return dst;
		}

		ZVAL_STR(dst, serial);
		/* Give this the type of a refcounted object/array. */
		Z_TYPE_INFO_P(dst) = Z_TYPE_P(src) | (IS_TYPE_REFCOUNTED << Z_TYPE_FLAGS_SHIFT);
		efree(buf);
	}

	return dst;
}
/* }}} */

/* {{{ my_unserialize_object */
static zval* my_unserialize_object(zval* dst, const zval* src, apc_context_t* ctxt)
{
	apc_unserialize_t unserialize = APC_UNSERIALIZER_NAME(php);
	void *config = NULL;

	if (ctxt->serializer) {
		unserialize = ctxt->serializer->unserialize;
		config = ctxt->serializer->config;
	}

	if (unserialize(dst, (unsigned char *)Z_STRVAL_P(src), Z_STRLEN_P(src), config)) {
		return dst;
	} else {
		zval_dtor(dst);
		ZVAL_NULL(dst);
	}
	return dst;
}
/* }}} */

static const uint32_t uninitialized_bucket[-HT_MIN_MASK] = {HT_INVALID_IDX, HT_INVALID_IDX};

static zend_always_inline int apc_array_dup_element(apc_context_t *ctxt, HashTable *source, HashTable *target, uint32_t idx, Bucket *p, Bucket *q, int packed, int with_holes)
{
	zval *data = &p->val;

	if (with_holes) {
		if (!packed && Z_TYPE_INFO_P(data) == IS_INDIRECT) {
			data = Z_INDIRECT_P(data);
		}
		if (UNEXPECTED(Z_TYPE_INFO_P(data) == IS_UNDEF)) {
			return 0;
		}
	} else if (!packed) {
		/* INDIRECT element may point to UNDEF-ined slots */
		if (Z_TYPE_INFO_P(data) == IS_INDIRECT) {
			data = Z_INDIRECT_P(data);
			if (UNEXPECTED(Z_TYPE_INFO_P(data) == IS_UNDEF)) {
				return 0;
			}
		}
	}

	if (Z_ISREF_P(data) && Z_REFCOUNT_P(data) == 1 &&
		(Z_TYPE_P(Z_REFVAL_P(data)) != IS_ARRAY ||
		  Z_ARRVAL_P(Z_REFVAL_P(data)) != source)) {
		data = Z_REFVAL_P(data);
	}

	if (my_copy_zval(&q->val, data, ctxt) == NULL)
		return 0;

	q->h = p->h;
	if (packed) {
		q->key = NULL;
	} else {
		uint32_t nIndex;

		q->key = p->key;
		if (q->key) {
			if (ctxt->copy == APC_COPY_IN) {
				q->key = APC_POOL_STRING_DUP(q->key);
			} else {
				q->key = zend_string_dup(p->key, 0);
			}
		}

		nIndex = q->h | target->nTableMask;
		Z_NEXT(q->val) = HT_HASH(target, nIndex);
		HT_HASH(target, nIndex) = HT_IDX_TO_HASH(idx);
	}
	return 1;
}

static zend_always_inline void apc_array_dup_packed_elements(apc_context_t *ctxt, HashTable *source, HashTable *target, int with_holes)
{
	Bucket *p = source->arData;
	Bucket *q = target->arData;
	Bucket *end = p + source->nNumUsed;

	do {
		if (!apc_array_dup_element(ctxt, source, target, 0, p, q, 1, with_holes)) {
			if (with_holes) {
				ZVAL_UNDEF(&q->val);
			}
		}
		p++; q++;
	} while (p != end);
}

static zend_always_inline uint32_t apc_array_dup_elements(apc_context_t *ctxt, HashTable *source, HashTable *target, int with_holes)
{
	uint32_t idx = 0;
	Bucket *p = source->arData;
	Bucket *q = target->arData;
	Bucket *end = p + source->nNumUsed;

	do {
		if (apc_array_dup_element(ctxt, source, target, idx, p, q, 0, with_holes)) {
			idx++;
			q++;
		}
		p++;
	} while (p != end);
	return idx;
}

static APC_HOTSPOT HashTable* my_copy_hashtable(HashTable *source, apc_context_t *ctxt) {
	uint32_t idx;
	HashTable *target;

	if (ctxt->copy == APC_COPY_IN) {
		target = APC_POOL_ALLOC(sizeof(HashTable));
	} else {
		ALLOC_HASHTABLE(target);
	}

	if (target == NULL)
		goto bad;

	GC_SET_REFCOUNT(target, 1);
	GC_TYPE_INFO(target) = IS_ARRAY;
	zend_hash_index_update_ptr(&ctxt->copied, (uintptr_t) source, target);

	target->nTableSize = source->nTableSize;
	target->pDestructor = source->pDestructor;

	if (source->nNumUsed == 0) {
#if PHP_VERSION_ID >= 70300
		target->u.flags = (source->u.flags & ~(HASH_FLAG_INITIALIZED|HASH_FLAG_PACKED)) | HASH_FLAG_STATIC_KEYS;
#else
		target->u.flags = (source->u.flags & ~(HASH_FLAG_INITIALIZED|HASH_FLAG_PACKED|HASH_FLAG_PERSISTENT)) | HASH_FLAG_APPLY_PROTECTION | HASH_FLAG_STATIC_KEYS;
#endif
		target->nTableMask = HT_MIN_MASK;
		target->nNumUsed = 0;
		target->nNumOfElements = 0;
		target->nNextFreeElement = 0;
		target->nInternalPointer = HT_INVALID_IDX;
		HT_SET_DATA_ADDR(target, &uninitialized_bucket);
	} else if (source->u.flags & HASH_FLAG_PACKED) {
#if PHP_VERSION_ID >= 70300
		target->u.flags = source->u.flags;
#else
		target->u.flags = (source->u.flags & ~HASH_FLAG_PERSISTENT) | HASH_FLAG_APPLY_PROTECTION;
#endif
		target->nTableMask = source->nTableMask;
		target->nNumUsed = source->nNumUsed;
		target->nNumOfElements = source->nNumOfElements;
		target->nNextFreeElement = source->nNextFreeElement;
		if (ctxt->copy == APC_COPY_IN) {
			HT_SET_DATA_ADDR(target, APC_POOL_ALLOC(HT_SIZE(target)));
		} else
			HT_SET_DATA_ADDR(target, emalloc(HT_SIZE(target)));

		if (HT_GET_DATA_ADDR(target) == NULL)
			goto bad;

		HT_HASH_RESET_PACKED(target);

		if (target->nNumUsed == target->nNumOfElements) {
			apc_array_dup_packed_elements(ctxt, source, target, 0);
		} else {
			apc_array_dup_packed_elements(ctxt, source, target, 1);
		}
		if (target->nNumOfElements > 0) {
			idx = 0;
			while (Z_TYPE(target->arData[idx].val) == IS_UNDEF) {
				idx++;
			}
			target->nInternalPointer = idx;
		} else {
			target->nInternalPointer = HT_INVALID_IDX;
		}
	} else {
#if PHP_VERSION_ID >= 70300
		target->u.flags = (source->u.flags & ~HASH_FLAG_STATIC_KEYS);
#else
		target->u.flags = (source->u.flags & ~(HASH_FLAG_PERSISTENT|HASH_FLAG_STATIC_KEYS)) | HASH_FLAG_APPLY_PROTECTION;
#endif
		target->nTableMask = source->nTableMask;
		target->nNextFreeElement = source->nNextFreeElement;
		if (ctxt->copy == APC_COPY_IN) {
			HT_SET_DATA_ADDR(target, APC_POOL_ALLOC(HT_SIZE(target)));
		} else
			HT_SET_DATA_ADDR(target, emalloc(HT_SIZE(target)));

		if (HT_GET_DATA_ADDR(target) == NULL)
			goto bad;

		HT_HASH_RESET(target);

		if (source->nNumUsed == source->nNumOfElements) {
			idx = apc_array_dup_elements(ctxt, source, target, 0);
		} else {
			idx = apc_array_dup_elements(ctxt, source, target, 1);
		}
		target->nNumUsed = idx;
		target->nNumOfElements = idx;
		if (idx > 0) {
			target->nInternalPointer = 0;
		} else {
			target->nInternalPointer = HT_INVALID_IDX;
		}
	}
	return target;

  bad:
	/* some kind of memory allocation failure */
	if (target) {
		if (ctxt->copy == APC_COPY_IN) {
			/* will be mass-freed */
		} else {
			FREE_HASHTABLE(target);
		}
	}

	return NULL;
}

static APC_HOTSPOT zend_reference* my_copy_reference(const zend_reference* src, apc_context_t *ctxt) {
	zend_reference *dst;

	assert(src != NULL);

	if (ctxt->copied.nTableSize) {
		zend_reference *rc = zend_hash_index_find_ptr(&ctxt->copied, (uintptr_t) src);
		if (rc) {
			GC_ADDREF(rc);
			return rc;
		}
	}

	if (ctxt->copy == APC_COPY_IN) {
		dst = APC_POOL_ALLOC(sizeof(zend_reference));
	} else {
		dst = emalloc(sizeof(zend_reference));
	}

	if (dst == NULL)
		return NULL;

	GC_SET_REFCOUNT(dst, 1);
	GC_TYPE_INFO(dst) = IS_REFERENCE;

	if (my_copy_zval(&dst->val, &src->val, ctxt) == NULL) {
		return NULL;
	}

	if (ctxt->copied.nTableSize) {
		zend_hash_index_update_ptr(&ctxt->copied, (uintptr_t) src, dst);
	}

	return dst;
}

/* {{{ my_copy_zval */
/* This function initializes *dst (temporary zval with request lifetime) with the (possibly serialized) contents of the serialized value in *src */
static APC_HOTSPOT zval* my_copy_zval(zval* dst, const zval* src, apc_context_t* ctxt)
{
	assert(dst != NULL);
	assert(src != NULL);

	/* If src was already unserialized, then make dst a copy of the unserialization of src */
	if (Z_REFCOUNTED_P(src)) {
		if (zend_hash_num_elements(&ctxt->copied)) {
			zval *rc = zend_hash_index_find(
					&ctxt->copied, (uintptr_t) Z_COUNTED_P(src));
			if (rc) {
				/* this does not allocate memory, so always succeeds */
				ZVAL_COPY(dst, rc);
				return dst;
			}
		}
	}

	/* Copy the raw bytes of the type, value, and type flags */
	memcpy(dst, src, sizeof(zval));

	switch (Z_TYPE_P(src)) {
	case IS_RESOURCE:
	case IS_TRUE:
	case IS_FALSE:
	case IS_LONG:
	case IS_DOUBLE:
	case IS_NULL:
		/* No additional work for scalars, they aren't ref counted */
		break;

	case IS_REFERENCE:
		if ((Z_REF_P(dst) = my_copy_reference(Z_REF_P(src), ctxt)) == NULL)
			return NULL;
		break;

	case IS_STRING:
		if (ctxt->copy == APC_COPY_OUT) {
			ZVAL_STR(dst, zend_string_dup(Z_STR_P(src), 0));
		} else {
			Z_TYPE_INFO_P(dst) = IS_STRING_EX;
			Z_STR_P(dst) = APC_POOL_STRING_DUP(Z_STR_P(src));
		}
		if (Z_STR_P(dst) == NULL)
			return NULL;
		break;

	case IS_ARRAY:
		if(ctxt->serializer == NULL) {
			HashTable *ht = my_copy_hashtable(Z_ARRVAL_P(src), ctxt);
			if (!ht) {
				return NULL;
			}
			ZVAL_ARR(dst, ht);
			break;
		}

		/* break intentionally omitted */

	case IS_OBJECT:
		if (ctxt->copy == APC_COPY_IN) {
			/* For objects and arrays, their pointer points to a serialized string instead of a zend_array or zend_object. */
			/* Unserialize that, and on success, give dst the default type flags for an object/array (We check Z_REFCOUNTED_P below). */
			dst = my_serialize_object(dst, src, ctxt);
		} else
			dst = my_unserialize_object(dst, src, ctxt);
		if (dst == NULL)
			return NULL;
		break;

	default:
		assert(0);
	}

	if (Z_REFCOUNTED_P(dst) && ctxt->copied.nTableSize) {
		zend_hash_index_update(&ctxt->copied, (uintptr_t) Z_COUNTED_P(src), dst);
	}

	return dst;
}
/* }}} */

/* {{{ apc_copy_zval */
PHP_APCU_API zval* apc_copy_zval(zval* dst, const zval* src, apc_context_t* ctxt)
{
	return my_copy_zval(dst, src, ctxt);
}
/* }}} */

/* {{{ apc_cache_store_zval */
PHP_APCU_API zval* apc_cache_store_zval(zval* dst, const zval* src, apc_context_t* ctxt)
{
	if (Z_TYPE_P(src) == IS_ARRAY) {
		/* Maintain a list of zvals we've copied to properly handle recursive structures */
		zend_hash_init(&ctxt->copied, 16, NULL, NULL, 0);
		dst = apc_copy_zval(dst, src, ctxt);
		/* remove from copied regardless if allocation failure */
		zend_hash_destroy(&ctxt->copied);
		ctxt->copied.nTableSize=0;
	} else {
		dst = apc_copy_zval(dst, src, ctxt);
	}

	if (dst == NULL || EG(exception)) {
		return NULL;
	}

	return dst;
}
/* }}} */

/* {{{ apc_cache_entry_fetch_zval */
PHP_APCU_API zend_bool apc_cache_entry_fetch_zval(
		apc_cache_t *cache, apc_cache_entry_t *entry, zval *dst)
{
	apc_context_t ctxt = {0, };

	/* set context information */
	ctxt.pool = NULL;
	ctxt.serializer = cache->serializer;
	ctxt.copy = APC_COPY_OUT;

	/* set this to avoid memory errors */
	memset(&ctxt.copied, 0, sizeof(HashTable));

	if (Z_TYPE(entry->val) == IS_ARRAY) {
		/* Maintain a list of zvals we've copied to properly handle recursive structures */
		zend_hash_init(&ctxt.copied, 16, NULL, NULL, 0);
		dst = apc_copy_zval(dst, &entry->val, &ctxt);
		/* remove from copied regardless if allocation failure */
		zend_hash_destroy(&ctxt.copied);
		ctxt.copied.nTableSize=0;
	} else {
		dst = apc_copy_zval(dst, &entry->val, &ctxt);
	}

	return dst != NULL;
}
/* }}} */

/* {{{ apc_cache_make_entry */
static apc_cache_entry_t *apc_cache_make_entry(
		apc_context_t *ctxt, zend_string *key, const zval* val, const int32_t ttl, time_t t)
{
	zend_string *copied_key;
	apc_cache_entry_t *entry = APC_POOL_ALLOC(sizeof(apc_cache_entry_t));
	if (!entry) {
		return NULL;
	}

	/* copy key into pool */
	copied_key = APC_POOL_STRING_DUP(key);
	if (!copied_key) {
		return NULL;
	}

	if (!apc_cache_store_zval(&entry->val, val, ctxt)) {
		return NULL;
	}

	entry->pool = ctxt->pool;
	entry->ttl = ttl;
	entry->key = copied_key;

	entry->next = NULL;
	entry->ref_count = 0;
	entry->mem_size = 0; /* TODO Initialize here already? */
	entry->nhits = 0;
	entry->ctime = t;
	entry->mtime = t;
	entry->atime = t;
	entry->dtime = 0;

	return entry;
}
/* }}} */

/* {{{ apc_cache_link_info */
static zval apc_cache_link_info(apc_cache_t *cache, apc_cache_entry_t *p)
{
	zval link;

	array_init(&link);

	add_assoc_str(&link, "info", zend_string_dup(p->key, 0));
	add_assoc_long(&link, "ttl", p->ttl);

	add_assoc_double(&link, "num_hits", (double)p->nhits);
	add_assoc_long(&link, "mtime", p->mtime);
	add_assoc_long(&link, "creation_time", p->ctime);
	add_assoc_long(&link, "deletion_time", p->dtime);
	add_assoc_long(&link, "access_time", p->atime);
	add_assoc_long(&link, "ref_count", p->ref_count);
	add_assoc_long(&link, "mem_size", p->mem_size);

	return link;
}
/* }}} */

/* {{{ apc_cache_info */
PHP_APCU_API zend_bool apc_cache_info(zval *info, apc_cache_t *cache, zend_bool limited)
{
	zval list;
	zval gc;
	zval slots;
	apc_cache_entry_t *p;
	zend_ulong i, j;

	if (!cache) {
		ZVAL_NULL(info);
		return 0;
	}

	APC_RLOCK(cache->header);
	php_apc_try {
		array_init(info);
		add_assoc_long(info, "num_slots", cache->nslots);
		add_assoc_long(info, "ttl", cache->ttl);
		add_assoc_double(info, "num_hits", (double)cache->header->nhits);
		add_assoc_double(info, "num_misses", (double)cache->header->nmisses);
		add_assoc_double(info, "num_inserts", (double)cache->header->ninserts);
		add_assoc_long(info,   "num_entries", cache->header->nentries);
		add_assoc_double(info, "expunges", (double)cache->header->nexpunges);
		add_assoc_long(info, "start_time", cache->header->stime);
		add_assoc_double(info, "mem_size", (double)cache->header->mem_size);

#if APC_MMAP
		add_assoc_stringl(info, "memory_type", "mmap", sizeof("mmap")-1);
#else
		add_assoc_stringl(info, "memory_type", "IPC shared", sizeof("IPC shared")-1);
#endif

		if (!limited) {
			/* For each hashtable slot */
			array_init(&list);
			array_init(&slots);

			for (i = 0; i < cache->nslots; i++) {
				p = cache->slots[i];
				j = 0;
				for (; p != NULL; p = p->next) {
					zval link = apc_cache_link_info(cache, p);
					add_next_index_zval(&list, &link);
					j++;
				}
				if (j != 0) {
					add_index_long(&slots, (ulong)i, j);
				}
			}

			/* For each slot pending deletion */
			array_init(&gc);

			for (p = cache->header->gc; p != NULL; p = p->next) {
				zval link = apc_cache_link_info(cache, p);
				add_next_index_zval(&gc, &link);
			}

			add_assoc_zval(info, "cache_list", &list);
			add_assoc_zval(info, "deleted_list", &gc);
			add_assoc_zval(info, "slot_distribution", &slots);
		}
	} php_apc_finally {
		APC_RUNLOCK(cache->header);
	} php_apc_end_try();

	return 1;
}
/* }}} */

/*
 fetches information about the key provided
*/
PHP_APCU_API zval *apc_cache_stat(apc_cache_t *cache, zend_string *key, zval *stat) {
	zend_ulong h, s;

	/* calculate hash and slot */
	apc_cache_hash_slot(cache, key, &h, &s);

	APC_RLOCK(cache->header);
	php_apc_try {
		/* find head */
		apc_cache_entry_t *entry = cache->slots[s];

		while (entry) {
			/* check for a matching key by has and identifier */
			if (h == ZSTR_HASH(entry->key) &&
				ZSTR_LEN(entry->key) == ZSTR_LEN(key) &&
				memcmp(ZSTR_VAL(entry->key), ZSTR_VAL(key), ZSTR_LEN(key)) == SUCCESS
			) {
				array_init(stat);

				add_assoc_long(stat, "hits",  entry->nhits);
				add_assoc_long(stat, "access_time", entry->atime);
				add_assoc_long(stat, "mtime", entry->mtime);
				add_assoc_long(stat, "creation_time", entry->ctime);
				add_assoc_long(stat, "deletion_time", entry->dtime);
				add_assoc_long(stat, "ttl", entry->ttl);
				add_assoc_long(stat, "refs", entry->ref_count);

				break;
			}

			/* next */
			entry = entry->next;
		}
	} php_apc_finally {
		APC_RUNLOCK(cache->header);
	} php_apc_end_try();

	return stat;
}

/* {{{ apc_cache_busy */
PHP_APCU_API zend_bool apc_cache_busy(apc_cache_t* cache)
{
	return (cache->header->state & APC_CACHE_ST_BUSY);
}
/* }}} */

/* {{{ apc_cache_defense */
PHP_APCU_API zend_bool apc_cache_defense(apc_cache_t *cache, zend_string *key, time_t t)
{
	zend_bool result = 0;

	/* only continue if slam defense is enabled */
	if (cache->defend) {

		/* for copy of locking key struct */
		apc_cache_slam_key_t *last = &cache->header->lastkey;

		if (!last->hash) {
			return 0;
		}

		/* check the hash and length match */
		if (last->hash == ZSTR_HASH(key) && last->len == ZSTR_LEN(key)) {
			apc_cache_owner_t owner;
#ifdef ZTS
			owner = TSRMLS_CACHE;
#else
			owner = getpid();
#endif

			/* check the time (last second considered slam) and context */
			if (last->mtime == t && last->owner != owner) {
				/* potential cache slam */
				apc_debug(
					"Potential cache slam averted for key '%s'", ZSTR_VAL(key));
				result = 1;
			} else {
				/* sets enough information for an educated guess, but is not exact */
				last->hash = ZSTR_HASH(key);
				last->len = ZSTR_LEN(key);
				last->mtime = t;
				last->owner = owner;
			}
		}
	}

	return result;
}
/* }}} */

/* {{{ apc_cache_serializer */
PHP_APCU_API void apc_cache_serializer(apc_cache_t* cache, const char* name) {
	if (cache && !cache->serializer) {
		cache->serializer = apc_find_serializer(name);
	}
} /* }}} */

PHP_APCU_API void apc_cache_entry(apc_cache_t *cache, zval *key, zend_fcall_info *fci, zend_fcall_info_cache *fcc, zend_long ttl, zend_long now, zval *return_value) {/*{{{*/
	apc_cache_entry_t *entry = NULL;

	if(!cache || apc_cache_busy(cache)) {
		return;
	}

	if (!key || Z_TYPE_P(key) != IS_STRING) {
		/* only strings, for now */
		return;
	}

#ifndef APC_LOCK_RECURSIVE
	if (APCG(recursion)++ == 0) {
		if (!APC_WLOCK(cache->header)) {
			APCG(recursion)--;
			return;
		}
	}
#else
	if (!APC_WLOCK(cache->header)) {
		return;
	}
#endif

	php_apc_try {
		entry = apc_cache_rlocked_find_incref(cache, Z_STR_P(key), now);
		if (!entry) {
			int result;
			zval params[1];
			ZVAL_COPY(&params[0], key);

			fci->retval = return_value;
			fci->param_count = 1;
			fci->params = params;

			result = zend_call_function(fci, fcc);

			zval_ptr_dtor(&params[0]);

			if (result == SUCCESS && !EG(exception)) {
				apc_cache_store_internal(
					cache, Z_STR_P(key), return_value, (uint32_t) ttl, 1);
			}
		} else {
			apc_cache_entry_fetch_zval(cache, entry, return_value);
			apc_cache_entry_release(cache, entry);
		}
	} php_apc_finally {
#ifndef APC_LOCK_RECURSIVE
		if (--APCG(recursion) == 0) {
			APC_WUNLOCK(cache->header);
		}
#else
		APC_WUNLOCK(cache->header);
#endif

	} php_apc_end_try();
}
/*}}}*/

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * End:
 * vim>600: noexpandtab sw=4 ts=4 sts=4 fdm=marker
 * vim<600: noexpandtab sw=4 ts=4 sts=4
 */