git.m6w6.name Git - m6w6/libmemcached/blob - docs/man/memcached_behavior_get.3

   1 .TH "MEMCACHED_BEHAVIOR_GET" "3" "May 22, 2012" "1.0.8" "libmemcached"
   2 .SH NAME
   3 memcached_behavior_get \- libmemcached Documentation
   4 .
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  32 .
  33 .sp
  34 Manipulate the behavior of a memcached_st structure.
  35 .SH SYNOPSIS
  36 .sp
  37 #include <libmemcached/memcached.h>
  38 .INDENT 0.0
  39 .TP
  40 .B memcached_behavior_t
  41 .UNINDENT
  42 .INDENT 0.0
  43 .TP
  44 .B uint64_t memcached_behavior_get(memcached_st\fI\ *ptr\fP, \fI\%memcached_behavior_t\fP\fI\ flag\fP)
  45 .UNINDENT
  46 .INDENT 0.0
  47 .TP
  48 .B memcached_return_t memcached_behavior_set(memcached_st\fI\ *ptr\fP, \fI\%memcached_behavior_t\fP\fI\ flag\fP, uint64_t\fI\ data\fP)
  49 .UNINDENT
  50 .sp
  51 Compile and link with \-lmemcached
  52 .SH DESCRIPTION
  53 .sp
  54 \fIlibmemcached(3)\fP behavior can be modified by using \fI\%memcached_behavior_set()\fP. Default behavior is the library strives to be quick and
  55 accurate. Some behavior, while being faster, can also result in not entirely
  56 accurate behavior (for instance, \fBmemcached_set()\fP will always respond
  57 with \fBMEMCACHED_SUCCESS\fP).
  58 .sp
  59 \fI\%memcached_behavior_get()\fP takes a behavior flag and returns whether or not that behavior is currently enabled in the client.
  60 .sp
  61 \fI\%memcached_behavior_set()\fP changes the value of a particular option
  62 of the client. It takes both a flag (listed below) and a value. For simple
  63 on or off options you just need to pass in a value of 1. Calls to
  64 \fI\%memcached_behavior_set()\fP will flush and reset all connections.
  65 .INDENT 0.0
  66 .TP
  67 .B MEMCACHED_BEHAVIOR_USE_UDP
  68 .UNINDENT
  69 .sp
  70 Causes \fIlibmemcached(3)\fP to use the UDP transport when communicating
  71 with a memcached server. Not all I/O operations are testsed
  72 when this behavior is enababled. The following operations will return
  73 \fBMEMCACHED_NOT_SUPPORTED\fP when executed with the
  74 \fI\%MEMCACHED_BEHAVIOR_USE_UDP\fP enabled: \fBmemcached_version()\fP,
  75 \fBmemcached_stat()\fP, \fBmemcached_get()\fP,
  76 \fBmemcached_get_by_key()\fP, \fBmemcached_mget()\fP,
  77 \fBmemcached_mget_by_key()\fP, \fBmemcached_fetch()\fP,
  78 \fBmemcached_fetch_result()\fP, \fBmemcached_fetch_execute()\fP.
  79 .sp
  80 All other operations are testsed but are executed in a \(aqfire\-and\-forget\(aq
  81 mode, in which once the client has executed the operation, no attempt
  82 will be made to ensure the operation has been received and acted on by the
  83 server.
  84 .sp
  85 \fIlibmemcached(3)\fP does not allow TCP and UDP servers to be shared
  86 within the same libmemached(3) client \(aqinstance\(aq. An attempt to add a TCP
  87 server when this behavior is enabled will result in a \fBMEMCACHED_INVALID_HOST_PROTOCOL\fP, as will attempting to add a UDP server when this behavior has
  88 not been enabled.
  89 .INDENT 0.0
  90 .TP
  91 .B MEMCACHED_BEHAVIOR_NO_BLOCK
  92 .UNINDENT
  93 .sp
  94 Causes \fIlibmemcached(3)\fP to use asychronous IO. This is the fastest
  95 transport available for storage functions.
  96 .INDENT 0.0
  97 .TP
  98 .B MEMCACHED_BEHAVIOR_SND_TIMEOUT
  99 .UNINDENT
 100 .sp
 101 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.  In cases where you cannot use non\-blocking IO this will allow you to still have timeouts on the sending of data.
 102 .INDENT 0.0
 103 .TP
 104 .B MEMCACHED_BEHAVIOR_RCV_TIMEOUT
 105 .UNINDENT
 106 .sp
 107 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
 108 .sp
 109 In cases where you cannot use non\-blocking IO this will allow you to still have timeouts on the reading of data.
 110 .INDENT 0.0
 111 .TP
 112 .B MEMCACHED_BEHAVIOR_TCP_NODELAY
 113 .UNINDENT
 114 .sp
 115 Turns on the no\-delay feature for connecting sockets (may be faster in some
 116 environments).
 117 .INDENT 0.0
 118 .TP
 119 .B MEMCACHED_BEHAVIOR_HASH
 120 .UNINDENT
 121 .sp
 122 Makes the default hashing algorithm for keys use MD5. The value can be set to either \fBMEMCACHED_HASH_DEFAULT\fP, \fBMEMCACHED_HASH_MD5\fP, \fBMEMCACHED_HASH_CRC\fP, \fBMEMCACHED_HASH_FNV1_64\fP, \fBMEMCACHED_HASH_FNV1A_64\fP, \fBMEMCACHED_HASH_FNV1_32\fP, \fBMEMCACHED_HASH_FNV1A_32\fP, \fBMEMCACHED_HASH_JENKINS\fP, \fBMEMCACHED_HASH_HSIEH\fP, and \fBMEMCACHED_HASH_MURMUR\fP.
 123 .sp
 124 Each hash has it\(aqs advantages and it\(aqs weaknesses. If you don\(aqt know or don\(aqt
 125 care, just go with the default.
 126 .sp
 127 Support for \fBMEMCACHED_HASH_HSIEH\fP is a compile time option that is disabled by default. To enable tests for this hashing algorithm, configure and build libmemcached with the \-\-enable\-hash_hsieh.
 128 .INDENT 0.0
 129 .TP
 130 .B MEMCACHED_BEHAVIOR_DISTRIBUTION
 131 .UNINDENT
 132 .sp
 133 Using this you can enable different means of distributing values to servers.
 134 .sp
 135 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.  Consistent hashing delivers better distribution and allows servers to be added to the cluster with minimal cache losses. Currently MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
 136 .INDENT 0.0
 137 .TP
 138 .B MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
 139 .UNINDENT
 140 .sp
 141 Deprecated since version 0.46(?): DNS lookups are now always cached until an error occurs with the server.
 142 .sp
 143 Memcached can cache named lookups so that DNS lookups are made only once.
 144
 145 .INDENT 0.0
 146 .TP
 147 .B MEMCACHED_BEHAVIOR_SUPPORT_CAS
 148 .UNINDENT
 149 .sp
 150 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
 151 .INDENT 0.0
 152 .TP
 153 .B MEMCACHED_BEHAVIOR_KETAMA
 154 .UNINDENT
 155 .sp
 156 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA and
 157 the hash to \fBMEMCACHED_HASH_MD5\fP.
 158 .INDENT 0.0
 159 .TP
 160 .B MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
 161 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted tests.  and the hash to MEMCACHED_HASH_MD5.
 162 .UNINDENT
 163 .INDENT 0.0
 164 .TP
 165 .B MEMCACHED_BEHAVIOR_KETAMA_HASH
 166 .UNINDENT
 167 .sp
 168 Sets the hashing algorithm for host mapping on continuum. The value can be set
 169 to either \fBMEMCACHED_HASH_DEFAULT\fP, \fBMEMCACHED_HASH_MD5\fP,
 170 \fBMEMCACHED_HASH_CRC\fP, \fBMEMCACHED_HASH_FNV1_64\fP,
 171 \fBMEMCACHED_HASH_FNV1A_64\fP, \fBMEMCACHED_HASH_FNV1_32\fP, and
 172 \fBMEMCACHED_HASH_FNV1A_32\fP.
 173 .INDENT 0.0
 174 .TP
 175 .B MEMCACHED_BEHAVIOR_KETAMA_COMPAT
 176 .UNINDENT
 177 .sp
 178 Sets the compatibility mode. The value can be set to either MEMCACHED_KETAMA_COMPAT_LIBMEMCACHED (this is the default) or MEMCACHED_KETAMA_COMPAT_SPY to be compatible with the SPY Memcached client for Java.
 179 .INDENT 0.0
 180 .TP
 181 .B MEMCACHED_BEHAVIOR_POLL_TIMEOUT
 182 .UNINDENT
 183 .sp
 184 Modify the timeout value that is used by poll. The default value is \-1. An signed int must be passed to memcached_behavior_set to change this value (this requires casting). For memcached_behavior_get a signed int value will be cast and returned as the unsigned long long.
 185 .INDENT 0.0
 186 .TP
 187 .B MEMCACHED_BEHAVIOR_USER_DATA
 188 .UNINDENT
 189 .sp
 190 Deprecated since version <: 0.30
 191 .INDENT 0.0
 192 .TP
 193 .B MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
 194 .UNINDENT
 195 .sp
 196 Enabling buffered IO causes commands to "buffer" instead of being sent. Any action that gets data causes this buffer to be be sent to the remote connection. Quiting the connection or closing down the connection will also cause the buffered data to be pushed to the remote connection.
 197 .INDENT 0.0
 198 .TP
 199 .B MEMCACHED_BEHAVIOR_VERIFY_KEY
 200 .UNINDENT
 201 .sp
 202 Enabling this will cause \fIlibmemcached(3)\fP to test all keys to verify that they are valid keys.
 203 .INDENT 0.0
 204 .TP
 205 .B MEMCACHED_BEHAVIOR_SORT_HOSTS
 206 .UNINDENT
 207 .sp
 208 Enabling this will cause hosts that are added to be placed in the host list in sorted order. This will defeat consisten hashing.
 209 .INDENT 0.0
 210 .TP
 211 .B MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
 212 .UNINDENT
 213 .sp
 214 In non\-blocking mode this changes the value of the timeout during socket connection.
 215 .INDENT 0.0
 216 .TP
 217 .B MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
 218 .UNINDENT
 219 .sp
 220 Enable the use of the binary protocol. Please note that you cannot toggle this flag on an open connection.
 221 .INDENT 0.0
 222 .TP
 223 .B MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 224 .UNINDENT
 225 .sp
 226 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT times connection failure.
 227 .INDENT 0.0
 228 .TP
 229 .B MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
 230 .UNINDENT
 231 .sp
 232 Set this value to tune the number of messages that may be sent before libmemcached should start to automatically drain the input queue. Setting this value to high, may cause libmemcached to deadlock (trying to send data, but the send will block because the input buffer in the kernel is full).
 233 .INDENT 0.0
 234 .TP
 235 .B MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
 236 .UNINDENT
 237 .sp
 238 Set this value to tune the number of bytes that may be sent before libmemcached should start to automatically drain the input queue (need at least 10 IO requests sent without reading the input buffer). Setting this value to high, may cause libmemcached to deadlock (trying to send data, but the send will block because the input buffer in the kernel is full).
 239 .INDENT 0.0
 240 .TP
 241 .B MEMCACHED_BEHAVIOR_IO_KEY_PREFETCH
 242 .UNINDENT
 243 .sp
 244 The binary protocol works a bit different than the textual protocol in that a multiget is implemented as a pipe of single get\-operations which are sent to the server in a chunk. If you are using large multigets from your application, you may improve the latency of the gets by setting this value so you send out the first chunk of requests when you hit the specified limit.  It allows the servers to start processing the requests to send the data back while the rest of the requests are created and sent to the server.
 245 .INDENT 0.0
 246 .TP
 247 .B MEMCACHED_BEHAVIOR_NOREPLY
 248 .UNINDENT
 249 .sp
 250 Set this value to specify that you really don\(aqt care about the result from your storage commands (set, add, replace, append, prepend).
 251 .INDENT 0.0
 252 .TP
 253 .B MEMCACHED_BEHAVIOR_NUMBER_OF_REPLICAS
 254 .UNINDENT
 255 .sp
 256 If you just want "a poor mans HA", you may specify the numbers of replicas libmemcached should store of each item (on different servers).  This replication does not dedicate certain memcached servers to store the replicas in, but instead it will store the replicas together with all of the other objects (on the \(aqn\(aq next servers specified in your server list).
 257 .INDENT 0.0
 258 .TP
 259 .B MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ
 260 .UNINDENT
 261 .sp
 262 Allows randomizing the replica reads starting point. Normally the read is done from primary server and in case of miss the read is done from primary + 1, then primary + 2 all the way to \(aqn\(aq replicas. If this option is set on the starting point of the replica reads is randomized between the servers.  This allows distributing read load to multiple servers with the expense of more write traffic.
 263 .INDENT 0.0
 264 .TP
 265 .B MEMCACHED_BEHAVIOR_CORK
 266 .UNINDENT
 267 .sp
 268 This open has been deprecated with the behavior now built and used appropriately on selected platforms.
 269 .INDENT 0.0
 270 .TP
 271 .B MEMCACHED_BEHAVIOR_KEEPALIVE
 272 .UNINDENT
 273 .sp
 274 Enable TCP_KEEPALIVE behavior.
 275 .INDENT 0.0
 276 .TP
 277 .B MEMCACHED_BEHAVIOR_KEEPALIVE_IDLE
 278 .UNINDENT
 279 .sp
 280 Specify time, in seconds, to mark a connection as idle. This is only available as an option Linux.
 281 .INDENT 0.0
 282 .TP
 283 .B MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE
 284 .UNINDENT
 285 .sp
 286 Find the current size of SO_SNDBUF. A value of 0 means either an error occured or no hosts were available. It is safe to assume system default if this occurs. If an error occurs you can checked the last cached errno statement to find the specific error.
 287 .INDENT 0.0
 288 .TP
 289 .B MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE
 290 .UNINDENT
 291 .sp
 292 Find the current size of SO_RCVBUF. A value of 0 means either an error occured or no hosts were available. It is safe to assume system default if this occurs. If an error occurs you can checked the last cached errno statement to find the specific error.
 293 .INDENT 0.0
 294 .TP
 295 .B MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 296 .UNINDENT
 297 .sp
 298 Deprecated since version 0.48: See \fI\%MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS\fP
 299 .sp
 300 This number of times a host can have an error before it is disabled.
 301
 302 .INDENT 0.0
 303 .TP
 304 .B MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS
 305 .UNINDENT
 306 .sp
 307 Deprecated since version 0.48: See \fI\%MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS\fP
 308 .sp
 309 If enabled any hosts which have been flagged as disabled will be removed from the list of servers in the memcached_st structure. This must be used in combination with MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT.
 310
 311 .INDENT 0.0
 312 .TP
 313 .B MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS
 314 If enabled any hosts which have been flagged as disabled will be removed from the list of servers in the memcached_st structure.
 315 .UNINDENT
 316 .INDENT 0.0
 317 .TP
 318 .B MEMCACHED_BEHAVIOR_RETRY_TIMEOUT
 319 .UNINDENT
 320 .sp
 321 When enabled a host which is problematic will only be checked for usage based on the amount of time set by this behavior. The value is in seconds.
 322 .INDENT 0.0
 323 .TP
 324 .B MEMCACHED_BEHAVIOR_HASH_WITH_PREFIX_KEY
 325 .UNINDENT
 326 .sp
 327 When enabled the prefix key will be added to the key when determining server
 328 by hash. See \fBMEMCACHED_CALLBACK_NAMESPACE\fP for additional
 329 information.
 330 .SH RETURN
 331 .sp
 332 memcached_behavior_get returns either the current value of the get, or 0
 333 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set
 334 returns failure or success.
 335 .SH NOTES
 336 .sp
 337 memcached_behavior_set in version .17 was changed from taking a pointer
 338 to data value, to taking a uin64_t.
 339 .SH HOME
 340 .sp
 341 To find out more information please check:
 342 \fI\%http://libmemcached.org/\fP
 343 .SH SEE ALSO
 344 .sp
 345 \fImemcached(1)\fP \fIlibmemcached(3)\fP \fImemcached_strerror(3)\fP
 346 .SH AUTHOR
 347 Brian Aker
 348 .SH COPYRIGHT
 349 2011, Brian Aker DataDifferential, http://datadifferential.com/
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