git.m6w6.name Git - awesomized/libmemcached/blob - docs/memcached_behavior.pod

   1 =head1 NAME
   2
   3 memcached_behavior_get memcached_behavior_set
   4
   5 =head1 LIBRARY
   6
   7 C Client Library for memcached (libmemcached, -lmemcached)
   8
   9 =head1 SYNOPSIS
  10
  11   #include <memcached.h>
  12
  13   uint64_t
  14     memcached_behavior_get (memcached_st *ptr,
  15                             memcached_behavior flag);
  16
  17   memcached_return
  18     memcached_behavior_set (memcached_st *ptr,
  19                             memcached_behavior flag,
  20                             uint64_t data);
  21
  22 =head1 DESCRIPTION
  23
  24 libmemcached(3) behavior can be modified by use memcached_behavior_set().
  25 Default behavior is the library strives to be quick and accurate. Some
  26 behavior, while being faster, can also result in not entirely accurate
  27 behavior (for instance, memcached_set() will always respond with
  28 C<MEMCACHED_SUCCESS>).
  29
  30 memcached_behavior_get() takes a behavior flag and returns whether or not
  31 that behavior is currently enabled in the client.
  32
  33 memcached_behavior_set() changes the value of a particular option of the
  34 client. It takes both a flag (listed below) and a value. For simple on or
  35 off options you just need to pass in a value of 1. Calls to
  36 memcached_behavior_set() will flush and reset all connections.
  37
  38 =over 4
  39
  40 =item MEMCACHED_BEHAVIOR_USE_UDP
  41
  42 Causes libmemcached(3) to use the UDP transport when communicating
  43 with a memcached server. Not all I/O operations are supported
  44 when this behavior is enababled. The following operations will return
  45 C<MEMCACHED_NOT_SUPPORTED> when executed with the MEMCACHED_BEHAVIOR_USE_UDP
  46 enabled: memcached_version(), memcached_stat(), memcached_get(),
  47 memcached_get_by_key(), memcached_mget(), memcached_mget_by_key(),
  48 memcached_fetch(), memcached_fetch_result(), memcached_value_fetch().
  49
  50 All other operations are supported but are executed in a 'fire-and-forget'
  51 mode, in which once the client has executed the operation, no attempt
  52 will be made to ensure the operation has been received and acted on by the
  53 server.
  54
  55 libmemcached(3) does not allow TCP and UDP servers to be shared within
  56 the same libmemached(3) client 'instance'. An attempt to add a TCP server
  57 when this behavior is enabled will result in a C<MEMCACHED_INVALID_HOST_PROTOCOL>,
  58 as will attempting to add a UDP server when this behavior has not been enabled.
  59
  60 =item MEMCACHED_BEHAVIOR_NO_BLOCK
  61
  62 Causes libmemcached(3) to use asychronous IO. This is the fastest transport
  63 available for storage functions.
  64
  65 =item MEMCACHED_BEHAVIOR_SND_TIMEOUT
  66
  67 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.
  68 In cases where you cannot use non-blocking IO this will allow you to still have
  69 timeouts on the sending of data.
  70
  71 =item MEMCACHED_BEHAVIOR_RCV_TIMEOUT
  72
  73 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
  74 In cases where you cannot use non-blocking IO this will allow you to still have
  75 timeouts on the reading of data.
  76
  77 =item MEMCACHED_BEHAVIOR_TCP_NODELAY
  78
  79 Turns on the no-delay feature for connecting sockets (may be faster in some
  80 environments).
  81
  82 =item MEMCACHED_BEHAVIOR_HASH
  83
  84 Makes the default hashing algorithm for keys use MD5. The value can be set
  85 to either MEMCACHED_HASH_DEFAULT, MEMCACHED_HASH_MD5, MEMCACHED_HASH_CRC, MEMCACHED_HASH_FNV1_64, MEMCACHED_HASH_FNV1A_64, MEMCACHED_HASH_FNV1_32, MEMCACHED_HASH_FNV1A_32, MEMCACHED_HASH_JENKINS, MEMCACHED_HASH_HSIEH, and MEMCACHED_HASH_MURMUR.
  86 Each hash has it's advantages and it's weaknesses. If you dont know or dont care, just go with the default.
  87
  88 =item MEMCACHED_BEHAVIOR_DISTRIBUTION
  89
  90 Using this you can enable different means of distributing values to servers.
  91 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable
  92 consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.
  93 Consistent hashing delivers better distribution and allows servers to be
  94 added to the cluster with minimal cache losses. Currently
  95 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
  96 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
  97
  98 =item MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
  99
 100 Memcached can cache named lookups so that DNS lookups are made only once.
 101
 102 =item MEMCACHED_BEHAVIOR_SUPPORT_CAS
 103
 104 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
 105
 106 =item MEMCACHED_BEHAVIOR_KETAMA
 107
 108 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
 109 and the hash to MEMCACHED_HASH_MD5.
 110
 111 =item MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
 112
 113 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
 114 and the hash to MEMCACHED_HASH_MD5.
 115
 116 =item MEMCACHED_BEHAVIOR_KETAMA_HASH
 117
 118 Sets the hashing algorithm for host mapping on continuum. The value can be set
 119 to either MEMCACHED_HASH_DEFAULT, MEMCACHED_HASH_MD5, MEMCACHED_HASH_CRC, MEMCACHED_HASH_FNV1_64, MEMCACHED_HASH_FNV1A_64, MEMCACHED_HASH_FNV1_32, and MEMCACHED_HASH_FNV1A_32.
 120
 121 =item MEMCACHED_BEHAVIOR_POLL_TIMEOUT
 122
 123 Modify the timeout value that is used by poll(). The default value is -1. An signed int pointer must be passed to memcached_behavior_set() to change this value. For memcached_behavior_get() a signed int value will be cast and returned as the unsigned long long.
 124
 125 =item MEMCACHED_BEHAVIOR_USER_DATA
 126
 127 This allows you to store a pointer to a specifc piece of data. This can be
 128 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
 129
 130 will copy the pointer to the clone. This was deprecated in 0.14 in favor
 131 of memcached_callback_set(3). This will be removed in 0.15.
 132
 133 =item MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
 134
 135 Enabling buffered IO causes commands to "buffer" instead of being sent. Any
 136 action that gets data causes this buffer to be be sent to the remote
 137 connection. Quiting the connection or closing down the connection will also
 138 cause the buffered data to be pushed to the remote connection.
 139
 140 =item MEMCACHED_BEHAVIOR_VERIFY_KEY
 141
 142 Enabling this will cause libmemcached(3) to test all keys to verify that they
 143 are valid keys.
 144
 145 =item MEMCACHED_BEHAVIOR_SORT_HOSTS
 146
 147 Enabling this will cause hosts that are added to be placed in the host list in
 148 sorted order. This will defeat consisten hashing.
 149
 150 =item MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
 151
 152 In non-blocking mode this changes the value of the timeout during socket
 153 connection.
 154
 155 =item MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
 156
 157 Enable the use of the binary protocol. Please note that you cannot toggle
 158 this flag on an open connection.
 159
 160 =item MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 161
 162 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 163 times connection failure.
 164
 165 =item MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
 166
 167 Set this value to tune the number of messages that may be sent before
 168 libmemcached should start to automatically drain the input queue. Setting
 169 this value to high, may cause libmemcached to deadlock (trying to send data,
 170 but the send will block because the input buffer in the kernel is full).
 171
 172 =item MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
 173
 174 Set this value to tune the number of bytes that may be sent before
 175 libmemcached should start to automatically drain the input queue (need
 176 at least 10 IO requests sent without reading the input buffer). Setting
 177 this value to high, may cause libmemcached to deadlock (trying to send
 178 data, but the send will block because the input buffer in the kernel is full).
 179
 180 =item MEMCACHED_BEHAVIOR_NOREPLY
 181
 182 Set this value to specify that you really don't care about the result
 183 from your storage commands (set, add, replace, append, prepend).
 184
 185 =back
 186
 187 =head1 RETURN
 188
 189 memcached_behavior_get() returns either the current value of the get, or 0
 190 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set()
 191 returns failure or success.
 192
 193 =head1 NOTES
 194
 195 memcached_behavior_set() in version .17 was changed from taking a pointer
 196 to data value, to taking a uin64_t.
 197
 198 =head1 HOME
 199
 200 To find out more information please check:
 201 L<http://tangent.org/552/libmemcached.html>
 202
 203 =head1 AUTHOR
 204
 205 Brian Aker, E<lt>brian@tangent.orgE<gt>
 206
 207 =head1 SEE ALSO
 208
 209 memcached(1) libmemcached(3) memcached_strerror(3)
 210
 211 =cut
 212