The Memcached package provides the client interface API to a Memcached server. The major functionalities offered in the Memcached Package are the following:

  • Init() and AddServer() initializes the client and sets up the list of Memcached servers. Must be called before calling any other features.
  • Add(), Set(), Get(), Delete() and Replace() are the basic functions for manipulating Memcached values.
  • MultiGet() retrieves multiple values from Memcached.
  • Increment() and Decrement() increments and decrements a Memcached value respectively.
  • Stats() and Version() returns information for a server.
    •

    Class Attributes Index

    o ERROR
    Generic error constant.
    o INIT_ERROR
    Error initializing Memcached.
    o KEYALREADYEXIST
    Specified key already exists in cache.
    o KEYNOTFOUND
    Specified key was not found in the cache.
    o NOMEMORY
    Out of memory error constant.
    o NOTINITIALIZED
    Memcached not initialized. Call Init() to initialize Memcached.
    o SERVERNOTFOUND_ERROR
    The specified server could not be found in the server list.
    o SUCCESS
    Return code for a successful operation.

    Class Methods Index

    o Add( String key, String value, Integer valueLength, Integer timeout, Integer flags )
    Add a key/value pair to the cache
    o AddServer( String host, Integer port, Integer min, Integer smax, Integer max, Integer ttl )
    Add a server to the client server list.
    o Decrement( String key, Integer num )
    Decrement the value corresponding to key by num.
    o Delete( String key, Integer timeout )
    Delete the key entry in the cache.
    o Get( String key )
    Retrieve the value corresponding to key.
    o Increment( String key, Integer value )
    Increment the value corresponding to key.
    o Init( Integer max_servers )
    Initialize the Memcached client.
    o MultiGet( List keyList )
    Retrieve multiple values corresponding to the keys in keyList.
    o Replace( String key, String newValue, Integer newValueLength, Integer timeout, Integer flags )
    Replace the value corresponding to key with newValue.
    o Set( String key, String value, Integer valueLength, Integer timeout, Integer flags )
    Set a key/value pair to the cache
    o Stats( String host, Integer port )
    Return a set of statistics for the specified server.
    o Version( String host, Integer port )
    Return the version number for the specified server.

    Class Attributes

    o ERROR 
     Error ERROR

    Generic error constant.

    o INIT_ERROR 
     Error INIT_ERROR

    Server failed to initialize.

    o KEYALREADYEXIST 
     Error KEYALREADYEXIST

    Key already exists in cache.

    o KEYNOTFOUND 
     Error KEYNOTFOUND

    Key not found.

    o NOMEMORY 
     Error NOMEMORY

    Not enough memory.

    o NOTINITIALIZED 
     Error NOTINITIALIZED

    Memcached not initialized. Call Init() to intialize before calling any other features.

    o SERVERNOTFOUND_ERROR 
     Error SERVERNOTFOUND_ERROR

    Server not found.

    o SUCCESS 
     Integer SUCCESS

    Return code for an successful operation.

    Class Methods

    o Add 
     Integer Add(
            String key,
            String value,
            Integer valueLength,
            Integer timeout,
            Integer flags )

    Add a key/value pair to the cache.

    Parameters:
    key  -  String containing the key to be added to the cache.
    value  -  String containing the value to be added to the cache.
    valueLength  -  Length of value to be added.
    timeout  -  Time, in seconds, for the data to live on the server. Enter 0 for indefinite timeout.
    flags  -  Any flags set by the client for this key.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    KEYALREADYEXIST key already exists in the cache
    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o AddServer 
     Integer AddServer(
            String host,
            Integer port,
            Integer min,
            Integer smax,
            Integer max,
            Integer ttl )

    Add a server to the Memcached client server list.

    Parameters:
    host  -  hostname of the server.
    port  -  port of the server.
    min  -  minimum number of client sockets to open.
    smax  -  soft maximum number of client connections to open.
    max  -  hard maximum number of client connections to open.
    ttl  -  time to live, in seconds, of a client connection.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    NOMEMORY Not enough memory to add server.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Decrement 
     Integer Decrement(
            String key,
            Integer num )

    Decrement the value corresponding to key by num.

    Parameters:
    key  -  key to the value being decremented.
    num  -  number to decrement by.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Delete 
     Integer Delete(
            String key,
            Integer timeout )

    Delete key from the cache.

    Parameters:
    key  -  The key to delete.
    timeout  -  time for the delete to stop other clients from adding.
    Returns:
    An Integer indicating the return status. Possible values are:

    SUCCESS Operation was successful
    SERVERNOTFOUND_ERROR No servers were found
    KEYNOTFOUND The key was not found in the cache.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Get 
     String Get(
            String key )

    Get the value corresponding to key from the cache..

    Parameters:
    key  -  The key to get.
    Returns:
    A string containing the retrieved value if successful else an error code. Possible error codes are:

    KEYNOTFOUND The key was not found in the cache.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Increment 
     Integer Increment(
            String key,
            Integer num )

    Increment the value corresponding to key by num.

    Parameters:
    key  -  key to the value being incremented.
    num  -  number to increment by.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Init 
     Integer Init(
            Integer maxServers )

    Initialize the Memcached client with a maximum of maxServers servers.

    Parameters:
    maxServers  -  Maximum number of servers that can be added to this client.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    INIT_ERROR Server failed to initialize.
    o MultiGet 
     Assoc MultiGet(
            List keyList )

    Get a list of values, corresponding to the list of keys in keyList, from the cache..

    Parameters:
    keyList  -  A list keys to get from the cache.
    Returns:
    An Assoc containing the retrieved key/value pairs if successful else an error code. Possible error codes are:

    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Replace 
     Integer Replace(
            String key,
            String newValue,
            Integer newValueLength,
            Integer timeout,
            Integer flags )

    Add a key/value pair to the cache.

    Parameters:
    key  -  String containing the key to be replaced in the cache.
    newValue  -  String containing the new value to replace the current value corresponding to key in the cache.
    newValueLength  -  Length of the newValue.
    timeout  -  Time, in seconds, for the data to live on the server. Enter 0 for indefinite timeout.
    flags  -  Any flags set by the client for this key.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    KEYNOTFOUND key not found in the cache
    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Set 
     Integer Set(
            String key,
            String value,
            Integer valueLength,
            Integer timeout,
            Integer flags )

    Set a key/value pair to the cache.

    Parameters:
    key  -  String containing the key to be added to the cache.
    value  -  String containing the value to be added to the cache.
    valueLength  -  Length of value to be added.
    timeout  -  Time, in seconds, for the data to live on the server. Enter 0 for indefinite timeout.
    flags  -  Any flags set by the client for this key.
    Returns:
    A return code indicating the operation status. Possible values are:

    SUCCESS Operation was successful
    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Stats 
     Assoc Stats(
            String host,
            Integer port )

    Retrieves statistics for the specified server.

    Parameters:
    host  -  hostname of the server.
    port  -  port of the server.
    Returns:
    Returns an Assoc containing various statistics for the specified server. The Assoc contains the following keys:

    version  -  Version string of this server
    pid  -  Process id of this server process
    uptime  -  Number of seconds this server has been running
    time  -  current UNIX time according to the server
    pointer_size  -  The size of a pointer on the current machine
    rusage_user  -  Accumulated user time for this process
    rusage_system  -  Accumulated system time for this process
    curr_items  -  Current number of items stored by the server
    total_items  -  Total number of items stored by this server
    bytes  -  Current number of bytes used by this server to store items
    curr_connections  -  Number of open connections
    total_connections  -  Total number of connections opened since the server started running
    connection_structures  -  Number of connection structures allocated by the server
    cmd_get  -  Cumulative number of retrieval requests
    cmd_set  -  Cumulative number of storage requests
    get_hits  -  Number of keys that have been requested and found present
    get_misses  -  Number of items that have been requested and not found
    evictions  -  Number of items removed from cache because they passed their expiration time
    bytes_read  -  Total number of bytes read by this server
    bytes_written  -  Total number of bytes sent by this server
    limit_maxbytes  -  Number of bytes this server is allowed to use for storage
    threads  -  Number of threads the server is running (if built with threading)

    If unsuccessful the following error codes may be returned:

    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors
    o Version 
     String Version(
            String host,
            Integer port )

    Retrieves the version number for the specified server.

    Parameters:
    host  -  hostname of the server.
    port  -  port of the server.
    Returns:
    Returns a string containing the version number for the specified server if successful else returns an error code. Possible error codes are:

    SERVERNOTFOUND_ERROR No servers were found.
    NOTINITIALIZED Memcached not initialized. Call Init() before calling any other features.
    ERROR any other errors