Predefined Constants

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 100 bytes) will be compressed during storage and decompressed during retrieval transparently.

Type: bool, default: true.

Memcached::OPT_SERIALIZER

Specifies the serializer to use for serializing non-scalar values. The valid serializers are Memcached::SERIALIZER_PHP or Memcached::SERIALIZER_IGBINARY. The latter is supported only when memcached is configured with --enable-memcached-igbinary option and the igbinary extension is loaded.

Type: int, default: 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.

Memcached::SERIALIZER_JSON

The JSON serializer.

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::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_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: 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: 0.

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 msgpack serializer support is available.

Type: bool.

Available as of Memcached 3.0.0.

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_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.

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User Contributed Notes 5 notes

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10
tyliu2 at gmail dot com
14 years ago
RES_SUCCESS = 0
RES_FAILURE = 1
RES_HOST_LOOKUP_FAILURE = 2
RES_UNKNOWN_READ_FAILURE = 7
RES_PROTOCOL_ERROR = 8
RES_CLIENT_ERROR = 9
RES_SERVER_ERROR = 10
RES_WRITE_FAILURE = 5
RES_DATA_EXISTS = 12
RES_NOTSTORED = 14
RES_NOTFOUND = 16
RES_PARTIAL_READ = 18
RES_SOME_ERRORS = 19
RES_NO_SERVERS = 20
RES_END = 21
RES_ERRNO = 26
RES_BUFFERED = 32
RES_TIMEOUT = 31
RES_BAD_KEY_PROVIDED = 33
RES_CONNECTION_SOCKET_CREATE_FAILURE = 11
RES_PAYLOAD_FAILURE = -1001
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5
igorsantos07 no gmail
8 years ago
As per a StackOverflow answer (http://stackoverflow.com/a/9042985/102960, by @rid), this is the current list of Memcached Response constants:

00 = MEMCACHED_SUCCESS
01 = MEMCACHED_FAILURE
02 = MEMCACHED_HOST_LOOKUP_FAILURE // getaddrinfo() and getnameinfo() only
03 = MEMCACHED_CONNECTION_FAILURE
04 = MEMCACHED_CONNECTION_BIND_FAILURE // DEPRECATED see MEMCACHED_HOST_LOOKUP_FAILURE
05 = MEMCACHED_WRITE_FAILURE
06 = MEMCACHED_READ_FAILURE
07 = MEMCACHED_UNKNOWN_READ_FAILURE
08 = MEMCACHED_PROTOCOL_ERROR
09 = MEMCACHED_CLIENT_ERROR
10 = MEMCACHED_SERVER_ERROR // Server returns "SERVER_ERROR"
11 = MEMCACHED_ERROR // Server returns "ERROR"
12 = MEMCACHED_DATA_EXISTS
13 = MEMCACHED_DATA_DOES_NOT_EXIST
14 = MEMCACHED_NOTSTORED
15 = MEMCACHED_STORED
16 = MEMCACHED_NOTFOUND
17 = MEMCACHED_MEMORY_ALLOCATION_FAILURE
18 = MEMCACHED_PARTIAL_READ
19 = MEMCACHED_SOME_ERRORS
20 = MEMCACHED_NO_SERVERS
21 = MEMCACHED_END
22 = MEMCACHED_DELETED
23 = MEMCACHED_VALUE
24 = MEMCACHED_STAT
25 = MEMCACHED_ITEM
26 = MEMCACHED_ERRNO
27 = MEMCACHED_FAIL_UNIX_SOCKET // DEPRECATED
28 = MEMCACHED_NOT_SUPPORTED
29 = MEMCACHED_NO_KEY_PROVIDED /* Deprecated. Use MEMCACHED_BAD_KEY_PROVIDED! */
30 = MEMCACHED_FETCH_NOTFINISHED
31 = MEMCACHED_TIMEOUT
32 = MEMCACHED_BUFFERED
33 = MEMCACHED_BAD_KEY_PROVIDED
34 = MEMCACHED_INVALID_HOST_PROTOCOL
35 = MEMCACHED_SERVER_MARKED_DEAD
36 = MEMCACHED_UNKNOWN_STAT_KEY
37 = MEMCACHED_E2BIG
38 = MEMCACHED_INVALID_ARGUMENTS
39 = MEMCACHED_KEY_TOO_BIG
40 = MEMCACHED_AUTH_PROBLEM
41 = MEMCACHED_AUTH_FAILURE
42 = MEMCACHED_AUTH_CONTINUE
43 = MEMCACHED_PARSE_ERROR
44 = MEMCACHED_PARSE_USER_ERROR
45 = MEMCACHED_DEPRECATED
46 = MEMCACHED_IN_PROGRESS
47 = MEMCACHED_SERVER_TEMPORARILY_DISABLED
48 = MEMCACHED_SERVER_MEMORY_ALLOCATION_FAILURE
49 = MEMCACHED_MAXIMUM_RETURN /* Always add new error code before */
11 = MEMCACHED_CONNECTION_SOCKET_CREATE_FAILURE = MEMCACHED_ERROR
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1
Anonymous
7 years ago
Note that with Memcached::OPT_BINARY_PROTOCOL enabled there is some (possibly significant) size overhead added at the TCP level.

If you have a high volume of small values being get/set, you should analyze the effect of this option on your overall traffic size with a network tool (e.g. tcpdump) before enabling it, especially if you pay for traffic in/out of your memcache instance.
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1
akenney at onesite dot com
13 years ago
Apparently there is a bug in libmemcached where connect timeout does not work when OPT_NO_BLOCK is set as well.

The bug and related blocking bugs are discussed here:
https://bugs.launchpad.net/libmemcached/+bug/583031

We confirmed this in libmemcached version 0.43

Be sure to test some memcache servers in your pool being unavailable (no route to host and memcache service down) to ensure that timeout settings are working correctly.
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0
Allen Tsai
13 years ago
Memcached::OPT_SERVER_FAILURE_LIMIT - once a server has hit this limit, the client's getResultMessage() will return "SERVER IS MARKED DEAD." Further gets() for keys hashing to this server will continue returning this message, as will sets() hashing to the dead server.

Version 2.0.01b supports a constant Memcached::OPT_AUTO_EJECT_HOSTS which allows automatic rebalancing of the cluster/automatic failover handling.
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