git.m6w6.name Git - m6w6/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_NO_BLOCK
  41
  42 Causes libmemcached(3) to use asychronous IO. This is the fastest transport
  43 available for storage functions. For read operations it is currently
  44 similar in performance to the non-blocking method (this is being
  45 looked into).
  46
  47 =item MEMCACHED_BEHAVIOR_SND_TIMEOUT
  48
  49 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.
  50 In cases where you cannot use non-blocking IO this will allow you to still have
  51 timeouts on the sending of data.
  52
  53 =item MEMCACHED_BEHAVIOR_RCV_TIMEOUT
  54
  55 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
  56 In cases where you cannot use non-blocking IO this will allow you to still have
  57 timeouts on the reading of data.
  58
  59 =item MEMCACHED_BEHAVIOR_TCP_NODELAY
  60
  61 Turns on the no-delay feature for connecting sockets (may be faster in some
  62 environments).
  63
  64 =item MEMCACHED_BEHAVIOR_HASH
  65
  66 Makes the default hashing algorithm for keys use MD5. The value can be set
  67 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.
  68 Each hash has it's advantages and it's weaknesses. If you dont know or dont care, just go with the default.
  69
  70 =item MEMCACHED_BEHAVIOR_DISTRIBUTION
  71
  72 Using this you can enable different means of distributing values to servers.
  73 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable
  74 consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.
  75 Consistent hashing delivers better distribution and allows servers to be
  76 added to the cluster with minimal cache losses. Currently
  77 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
  78 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
  79
  80 =item MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
  81
  82 Memcached can cache named lookups so that DNS lookups are made only once.
  83
  84 =item MEMCACHED_BEHAVIOR_SUPPORT_CAS
  85
  86 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
  87
  88 =item MEMCACHED_BEHAVIOR_KETAMA
  89
  90 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
  91 and the hash to MEMCACHED_HASH_MD5.
  92
  93 =item MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
  94
  95 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
  96 and the hash to MEMCACHED_HASH_MD5.
  97
  98 =item MEMCACHED_BEHAVIOR_KETAMA_HASH
  99
 100 Sets the hashing algorithm for host mapping on continuum. The value can be set
 101 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.
 102
 103 =item MEMCACHED_BEHAVIOR_POLL_TIMEOUT
 104
 105 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.
 106
 107 =item MEMCACHED_BEHAVIOR_USER_DATA
 108
 109 This allows you to store a pointer to a specifc piece of data. This can be
 110 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
 111
 112 will copy the pointer to the clone. This was deprecated in 0.14 in favor
 113 of memcached_callback_set(3). This will be removed in 0.15.
 114
 115 =item MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
 116
 117 Enabling buffered IO causes commands to "buffer" instead of being sent. Any
 118 action that gets data causes this buffer to be be sent to the remote
 119 connection. Quiting the connection or closing down the connection will also
 120 cause the buffered data to be pushed to the remote connection.
 121
 122 =item MEMCACHED_BEHAVIOR_VERIFY_KEY
 123
 124 Enabling this will cause libmemcached(3) to test all keys to verify that they
 125 are valid keys.
 126
 127 =item MEMCACHED_BEHAVIOR_SORT_HOSTS
 128
 129 Enabling this will cause hosts that are added to be placed in the host list in
 130 sorted order. This will defeat consisten hashing.
 131
 132 =item MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
 133
 134 In non-blocking mode this changes the value of the timeout during socket
 135 connection.
 136
 137 =item MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
 138
 139 Enable the use of the binary protocol. Please note that you cannot toggle
 140 this flag on an open connection.
 141
 142 =item MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 143
 144 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 145 times connection failure.
 146
 147 =item MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
 148
 149 Set this value to tune the number of messages that may be sent before
 150 libmemcached should start to automatically drain the input queue. Setting
 151 this value to high, may cause libmemcached to deadlock (trying to send data,
 152 but the send will block because the input buffer in the kernel is full).
 153
 154 =item MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
 155
 156 Set this value to tune the number of bytes that may be sent before
 157 libmemcached should start to automatically drain the input queue (need
 158 at least 10 IO requests sent without reading the input buffer). Setting
 159 this value to high, may cause libmemcached to deadlock (trying to send
 160 data, but the send will block because the input buffer in the kernel is full).
 161
 162 =item MEMCACHED_BEHAVIOR_NOREPLY
 163
 164 Set this value to specify that you really don't care about the result
 165 from your storage commands (set, add, replace, append, prepend). With
 166 this flag enabled, each storage request will be sent immediately to the
 167 server overriding any setting of MEMCACHED_BEHAVIOR_BUFFER_REQUESTS.
 168
 169 =back
 170
 171 =head1 RETURN
 172
 173 memcached_behavior_get() returns either the current value of the get, or 0
 174 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set()
 175 returns failure or success.
 176
 177 =head1 NOTES
 178
 179 memcached_behavior_set() in version .17 was changed from taking a pointer
 180 to data value, to taking a uin64_t.
 181
 182 =head1 HOME
 183
 184 To find out more information please check:
 185 L<http://tangent.org/552/libmemcached.html>
 186
 187 =head1 AUTHOR
 188
 189 Brian Aker, E<lt>brian@tangent.orgE<gt>
 190
 191 =head1 SEE ALSO
 192
 193 memcached(1) libmemcached(3) memcached_strerror(3)
 194
 195 =cut
 196