The constants below are defined by this extension, and
will only be available when the extension has either
been compiled into PHP or dynamically loaded at runtime.
Memcached::OPT_COMPRESSION
-
Enables or disables payload compression. When enabled,
item values longer than a certain threshold (currently 2000 bytes) will be
compressed during storage and decompressed during retrieval
transparently. The threshold can be configured using the
memcached.compression_threshold
ini setting.
Type: bool, default: true
.
Memcached::OPT_COMPRESSION_TYPE
-
Specifies the compression algorithm to use, if compression is enabled.
The valid algorithms are
Memcached::COMPRESSION_FASTLZ
,
Memcached::COMPRESSION_ZLIB
and
Memcached::COMPRESSION_ZSTD
.
Type: int, default: Memcached::COMPRESSION_FASTLZ
.
Memcached::COMPRESSION_FASTLZ
-
The FASTLZ compression algorithm.
Memcached::COMPRESSION_ZLIB
-
The ZLIB compression algorithm.
Memcached::COMPRESSION_ZSTD
-
The ZSTD compression algorithm.
Available as of Memcached 3.3.0.
Memcached::OPT_COMPRESSION_LEVEL
-
Specifies the compression level to use, if compression is enabled.
Memcached::COMPRESSION_FASTLZ
does not support compression levels.
Memcached::COMPRESSION_ZSTD
: minimum level is -22
and maximum level is 22
.
Memcached::COMPRESSION_ZLIB
: minimum level is 0
and maximum level is 9
.
Type: int, default: 3
.
Memcached::OPT_SERIALIZER
-
Specifies the serializer to use for serializing non-scalar values.
The valid serializers are
Memcached::SERIALIZER_PHP
,
Memcached::SERIALIZER_IGBINARY
,
Memcached::SERIALIZER_JSON
,
Memcached::SERIALIZER_JSON_ARRAY
and
Memcached::SERIALIZER_MSGPACK
.
Type: int, default: Memcached::SERIALIZER_IGBINARY
if available,
then Memcached::SERIALIZER_MSGPACK
if available,
then Memcached::SERIALIZER_PHP
.
Memcached::SERIALIZER_PHP
-
The default PHP serializer.
Memcached::SERIALIZER_IGBINARY
-
The igbinary serializer.
Instead of textual representation it stores PHP data structures in a
compact binary form, resulting in space and time gains.
This serializer is supported only if memcached is configured with
--enable-memcached-igbinary option and the
igbinary extension is loaded.
Memcached::SERIALIZER_JSON
-
The JSON serializer. This serializer deserializes JSON to an object.
Memcached::SERIALIZER_JSON_ARRAY
-
The JSON array serializer.
This serializer deserializes JSON to an associative array
Memcached::SERIALIZER_MSGPACK
-
The » MessagePack serializer.
This serializer is supported only if memcached is configured with
--enable-memcached-msgpack option and the
msgpack
extension is loaded.
Memcached::OPT_PREFIX_KEY
-
This can be used to create a "domain" for your item keys. The value
specified here will be prefixed to each of the keys. It cannot be
longer than
128
characters and will reduce the
maximum available key size. The prefix is applied only to the item keys,
not to the server keys.
Type: string, default: ""
.
Memcached::OPT_HASH
-
Specifies the hashing algorithm used for the item keys. The valid
values are supplied via
Memcached::HASH_*
constants.
Each hash algorithm has its advantages and its disadvantages. Go with the
default if you don't know or don't care.
Type: int, default: Memcached::HASH_DEFAULT
Memcached::HASH_DEFAULT
-
The default (Jenkins one-at-a-time) item key hashing algorithm.
Memcached::HASH_MD5
-
MD5 item key hashing algorithm.
Memcached::HASH_CRC
-
CRC item key hashing algorithm.
Memcached::HASH_FNV1_64
-
FNV1_64 item key hashing algorithm.
Memcached::HASH_FNV1A_64
-
FNV1_64A item key hashing algorithm.
Memcached::HASH_FNV1_32
-
FNV1_32 item key hashing algorithm.
Memcached::HASH_FNV1A_32
-
FNV1_32A item key hashing algorithm.
Memcached::HASH_HSIEH
-
Hsieh item key hashing algorithm.
Memcached::HASH_MURMUR
-
Murmur item key hashing algorithm.
Memcached::OPT_DISTRIBUTION
-
Specifies the method of distributing item keys to the servers.
Currently supported methods are modulo and consistent hashing. Consistent
hashing delivers better distribution and allows servers to be added to
the cluster with minimal cache losses.
Type: int, default: Memcached::DISTRIBUTION_MODULA
.
Memcached::DISTRIBUTION_MODULA
-
Modulo-based key distribution algorithm.
Memcached::DISTRIBUTION_CONSISTENT
-
Consistent hashing key distribution algorithm (based on libketama).
Memcached::DISTRIBUTION_VIRTUAL_BUCKET
-
Virtual Bucket hashing key distribution algorithm (also called vbucket).
Memcached::OPT_LIBKETAMA_COMPATIBLE
-
Enables or disables compatibility with libketama-like behavior. When
enabled, the item key hashing algorithm is set to MD5 and distribution is
set to be weighted consistent hashing distribution. This is useful
because other libketama-based clients (Python, Ruby, etc.) with the same
server configuration will be able to access the keys transparently.
Note:
It is highly recommended to enable this option if you want to use
consistent hashing, and it may be enabled by default in future
releases.
Type: bool, default: false
.
Memcached::OPT_LIBKETAMA_HASH
-
Specifies the hashing algorithm for host mapping.
Type: int.
Memcached::OPT_TCP_KEEPALIVE
-
Enables TCP keep alive.
Type: bool, default: false
.
Memcached::OPT_BUFFER_WRITES
-
Enables or disables buffered I/O. Enabling buffered I/O causes
storage commands to "buffer" instead of being sent. Any action that
retrieves data causes this buffer to be sent to the remote connection.
Quitting the connection or closing down the connection will also cause
the buffered data to be pushed to the remote connection.
Type: bool, default: false
.
Memcached::OPT_BINARY_PROTOCOL
-
Enable the use of the binary protocol. Please note that you cannot
toggle this option on an open connection.
Type: bool, default: false
.
Memcached::OPT_NO_BLOCK
-
Enables or disables asynchronous I/O. This is the fastest transport
available for storage functions.
Type: bool, default: false
.
Memcached::OPT_NOREPLY
-
Enables or disables ignoring the result of storage commands
(set, add, replace, append, prepend, delete, increment, decrement, etc.).
Storage commands will be sent without spending time waiting for a reply
(there would be no reply).
Retrieval commands such as Memcached::get are unaffected by this setting.
Type: bool, default: false
.
Memcached::OPT_TCP_NODELAY
-
Enables or disables the no-delay feature for connecting sockets (may
be faster in some environments).
Type: bool, default: false
.
Memcached::OPT_SOCKET_SEND_SIZE
-
The maximum socket send buffer in bytes.
Type: int, default: varies by platform/kernel
configuration.
Memcached::OPT_SOCKET_RECV_SIZE
-
The maximum socket receive buffer in bytes.
Type: int, default: varies by platform/kernel
configuration.
Memcached::OPT_CONNECT_TIMEOUT
-
In non-blocking mode this set the value of the timeout during socket
connection, in milliseconds.
Type: int, default: 1000
.
Memcached::OPT_RETRY_TIMEOUT
-
The amount of time, in seconds, to wait until retrying a failed
connection attempt.
Type: int, default: 2
.
Memcached::OPT_DEAD_TIMEOUT
-
The amount of time, in seconds, to wait until retrying dead servers.
0
means no retry.
Type: int, default: 0
.
Memcached::OPT_SEND_TIMEOUT
-
Socket sending timeout, in microseconds. In cases where you cannot
use non-blocking I/O this will allow you to still have timeouts on the
sending of data.
Type: int, default: 0
.
Memcached::OPT_RECV_TIMEOUT
-
Socket reading timeout, in microseconds. In cases where you cannot
use non-blocking I/O this will allow you to still have timeouts on the
reading of data.
Type: int, default: 0
.
Memcached::OPT_POLL_TIMEOUT
-
Timeout for connection polling, in milliseconds.
Type: int, default: 1000
.
Memcached::OPT_CACHE_LOOKUPS
-
Enables or disables caching of DNS lookups.
Type: bool, default: false
.
Memcached::OPT_SERVER_FAILURE_LIMIT
-
Specifies the failure limit for server connection attempts.
The server will be removed after this many continuous connection failures.
Type: int, default: 5
.
Memcached::OPT_SERVER_TIMEOUT_LIMIT
-
Specifies the timeout limit for server connection attempts.
The server will be removed after this many continuous connection timeouts.
Type: int, default: 0
.
Memcached::OPT_AUTO_EJECT_HOSTS
-
Removes disabled servers from the list. Use together with
Memcached::OPT_SERVER_FAILURE_LIMIT
and
Memcached::OPT_SERVER_TIMEOUT_LIMIT
.
Note:
This option is replaced by
Memcached::OPT_REMOVE_FAILED_SERVERS
.
Type: bool, default: false
.
Memcached::OPT_VERIFY_KEY
-
Enables verification of keys by memcached.
Type: bool, default: false
.
Memcached::OPT_USE_UDP
-
Uses UDP instead of TCP.
Type: bool, default: false
.
Memcached::OPT_NUMBER_OF_REPLICAS
-
Stores this many replicas of each item on different servers.
Type: int, default: 0
.
Memcached::OPT_RANDOMIZE_REPLICA_READS
-
Randomizes replica read server.
Type: bool, default: false
.
Memcached::OPT_REMOVE_FAILED_SERVERS
-
Removes disabled servers from the list. Use together with
Memcached::OPT_SERVER_FAILURE_LIMIT
and
Memcached::OPT_SERVER_TIMEOUT_LIMIT
.
Type: bool, default: false
.
Memcached::HAVE_IGBINARY
-
Indicates whether igbinary serializer support is available.
Type: bool.
Memcached::HAVE_JSON
-
Indicates whether JSON serializer support is available.
Type: bool.
Memcached::HAVE_MSGPACK
-
Indicates whether MessagePack serializer support is available.
Type: bool.
Available as of Memcached 3.0.0.
Memcached::HAVE_ZSTD
-
Indicates whether ZSTD compression support is available.
Type: bool.
Available as of Memcached 3.3.0.
Memcached::HAVE_ENCODING
-
Indicates whether data encryption using
Memcached::setEncodingKey is supported.
Type: bool.
Available as of Memcached 3.1.0.
Memcached::HAVE_SESSION
-
Type: bool.
Available as of Memcached 3.0.0.
Memcached::HAVE_SASL
-
Type: bool.
Available as of Memcached 3.0.0.
Memcached::GET_EXTENDED
-
A flag for Memcached::get, Memcached::getMulti and
Memcached::getMultiByKey to ensure that the CAS token values
are returned as well.
Available as of Memcached 3.0.0.
Memcached::GET_PRESERVE_ORDER
-
A flag for Memcached::getMulti and
Memcached::getMultiByKey to ensure that the keys are
returned in the same order as they were requested in. Non-existing keys
get a default value of null
.
Memcached::RES_SUCCESS
-
The operation was successful.
Memcached::RES_FAILURE
-
The operation failed in some fashion.
Memcached::RES_HOST_LOOKUP_FAILURE
-
DNS lookup failed.
Memcached::RES_UNKNOWN_READ_FAILURE
-
Failed to read network data.
Memcached::RES_PROTOCOL_ERROR
-
Bad command in memcached protocol.
Memcached::RES_CLIENT_ERROR
-
Error on the client side.
Memcached::RES_SERVER_ERROR
-
Error on the server side.
Memcached::RES_WRITE_FAILURE
-
Failed to write network data.
Memcached::RES_DATA_EXISTS
-
Failed to do compare-and-swap: item you are trying to store has been
modified since you last fetched it.
Memcached::RES_NOTSTORED
-
Item was not stored: but not because of an error. This normally
means that either the condition for an "add" or a "replace" command
wasn't met, or that the item is in a delete queue.
Memcached::RES_NOTFOUND
-
Item with this key was not found (with "get" operation or "cas"
operations).
Memcached::RES_PARTIAL_READ
-
Partial network data read error.
Memcached::RES_SOME_ERRORS
-
Some errors occurred during multi-get.
Memcached::RES_NO_SERVERS
-
Server list is empty.
Memcached::RES_END
-
End of result set.
Memcached::RES_ERRNO
-
System error.
Memcached::RES_BUFFERED
-
The operation was buffered.
Memcached::RES_TIMEOUT
-
The operation timed out.
Memcached::RES_BAD_KEY_PROVIDED
-
Bad key.
Memcached::RES_STORED
-
Item stored.
Memcached::RES_DELETED
-
Item deleted.
Memcached::RES_STAT
-
Statistics.
Memcached::RES_ITEM
-
Item.
Memcached::RES_NOT_SUPPORTED
-
Not supported.
Memcached::RES_FETCH_NOTFINISHED
-
Fetch not finished.
Memcached::RES_SERVER_MARKED_DEAD
-
Server marked dead.
Memcached::RES_UNKNOWN_STAT_KEY
-
Unknown stat key.
Memcached::RES_INVALID_HOST_PROTOCOL
-
Invalid host protocol.
Memcached::RES_MEMORY_ALLOCATION_FAILURE
-
Memory allocation failure.
Memcached::RES_CONNECTION_SOCKET_CREATE_FAILURE
-
Failed to create network socket.
Memcached::RES_PAYLOAD_FAILURE
-
Payload failure: could not compress/decompress or serialize/unserialize the value.
Memcached::RES_AUTH_PROBLEM
-
Available as of Memcached 3.0.0.
Memcached::RES_AUTH_FAILURE
-
Available as of Memcached 3.0.0.
Memcached::RES_AUTH_CONTINUE
-
Available as of Memcached 3.0.0.
Memcached::RES_E2BIG
-
Available as of Memcached 3.0.0.
Memcached::RES_KEY_TOO_BIG
-
Available as of Memcached 3.0.0.
Memcached::RES_SERVER_TEMPORARILY_DISABLED
-
Available as of Memcached 3.0.0.
Memcached::RES_SERVER_MEMORY_ALLOCATION_FAILURE
-
Available as of Memcached 3.0.0.