Copyright (C) 2016 Happy Fish / YuQing
libshmcache may be copied or modified under the terms of BSD License.
libshmcache is a local share memory cache for multi processes.
it is a high performance library because read mechanism is lockless.
libshmcache is 100+ times faster than a remote interface such as redis.
this project contains C library, PHP extension and Java JNI wrapper.
Its high performance features include:
- pthread mutex lock on write, read is lockless
- use hash table for quickly setting, getting and deletion
- use object pool (FIFO queue) for hash/KV entry allocation
- use striping/block buffer allocator. in a memory striping,
allocate value buffer in order. just only decrease allocator's
used size when free the value buffer. recycle the whole memory
striping/allocator when it's used size reach to zero after memory free up. - use FIFO elimination algorithm instead of LRU
stable features are:
- deadlock detection and auto unlock that caused by other crushed process
- check some key fields for consistency when init, old share memories
should be cleaned and reinit when the memory related parameters changed - add sleep time to avoid other processes reading dirty data when
recycle more than one valid (not expired) hash/KV entries
other features are:
- support both related processes (such as parent process and subprocesses)
and unrelated processes (such as php-fpm and php CLI, two php CLI processes, etc.) - incrementally allocate value buffer segment as need, this is controlled
by config parameter: segment_size - provide abundant stats info: counters for set, get and delete,
memory recycle stats, lock stats etc. - support atomic increment
- PHP extension support multiple serializers: igbinary, msgpack, php.
these serializers can coexist in a share memory.
utility commands in directory: src/tools, in /usr/bin/ after make && make install
-
shmcache_set: set a key
-
shmcache_get: get a key
-
shmcache_delete: delete a key
-
shmcache_remove_all: remove the share memory
-
shmcache_stats: show share memory statistics
-
Note: the key size can not be longer than 64 bytes
libshmcache PHP extension is supplied in the directory: php-shmcache, support PHP 5 and PHP 7
ShmCache::__construct(string $config_filename[, long $serializer =
ShmCache::SERIALIZER_IGBINARY])
- @param config_filename: the config filename as conf/libshmcache.conf
- @param serializer: the serializer type
- @throws ShmCacheException if the serializer not enabled
- @example: $cache = new ShmCache("/etc/libshmcache.conf");
- @note: igbinary and msgpack php extensions must be enabled before use them
boolean ShmCache::set(string $key, mixed $value, long $ttl)
- @param key: the key, must be a string variable
- @param value: the value, any php variable
- @param ttl: timeout / expire in seconds, such as 600 for ten minutes,
ShmCache::NEVER_EXPIRED for never expired - @return true for success, false for fail
- @throws ShmCacheException if $value is false
- @example: $cache->set($key, $value, 300);
long ShmCache::incr(string $key, long $increment, long $ttl)
- @desc: atomic increment
- @param key: the key, must be a string variable
- @param increment: the increment integer, can be negative, such as -1
- @param ttl: timeout / expire in seconds, such as 600 for ten minutes,
- @return the value after increase, false for fail
mixed ShmCache::get(string $key[, boolean $returnExpired = false])
- @param key: the key, must be a string variable
- @param returnExpired: if return expired key / value
- @return mixed value for success, false for key not exist or expired
- @example: $value = $cache->get($key);
long ShmCache::getExpires(string $key[, boolean $returnExpired = false])
- @desc: get expires time as unix timestamp
- @param key: the key, must be a string variable
- @param returnExpired: if return expired key / value
- @return expires timestamps such as 1483952635, 0 for never expired, false for not exist
- @example: $value = $cache->getExpires($key);
boolean ShmCache::setExpires(string $key, long $expires)
- @param key: the key, must be a string variable
- @param expires: expires timestamp (unix timestamp eg. 1591347245)
ShmCache::NEVER_EXPIRED for never expired - @return true for success, false for key not exist or expired or other error
- @throws ShmCacheException if $expires is invalid
- @example: $cache->setExpires($key, 1591347245);
boolean ShmCache::setTTL(string $key, long $ttl)
- @param key: the key, must be a string variable
- @param ttl: timeout / expire in seconds, such as 600 for ten minutes,
ShmCache::NEVER_EXPIRED for never expired - @return true for success, false for key not exist or expired or other error
- @throws ShmCacheException if $ttl is invalid
- @example: $cache->setTTL($key, 300);
boolean ShmCache::delete(string $key)
- @param key: the key, must be a string variable
- @return true for success, false for fail
- @example: $cache->delete($key);
array ShmCache::stats()
- @return stats array
- @example: echo json_encode($cache->stats(), JSON_PRETTY_PRINT);
boolean ShmCache::clear()
- @desc: clear hashtable to empty. use this function carefully because it will remove all keys in cache
- @return true for success, false for fail