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

   1 .TH "MEMCACHED_BEHAVIOR" "3" "April 08, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_behavior \- libmemcached Documentation
   4 .
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  32 .
  33 .sp
  34 Manipulate behavior
  35 .SH LIBRARY
  36 .sp
  37 C Client Library for memcached (libmemcached, \-lmemcached)
  38 .SH SYNOPSIS
  39 .sp
  40 .nf
  41 .ft C
  42 #include <libmemcached/memcached.h>
  43
  44 uint64_t
  45   memcached_behavior_get (memcached_st *ptr,
  46                           memcached_behavior flag);
  47
  48 memcached_return_t
  49   memcached_behavior_set (memcached_st *ptr,
  50                           memcached_behavior flag,
  51                           uint64_t data);
  52 .ft P
  53 .fi
  54 .SH DESCRIPTION
  55 .sp
  56 libmemcached(3) behavior can be modified by use memcached_behavior_set().
  57 Default behavior is the library strives to be quick and accurate. Some
  58 behavior, while being faster, can also result in not entirely accurate
  59 behavior (for instance, memcached_set() will always respond with
  60 \fBMEMCACHED_SUCCESS\fP).
  61 .sp
  62 memcached_behavior_get() takes a behavior flag and returns whether or not
  63 that behavior is currently enabled in the client.
  64 .sp
  65 memcached_behavior_set() changes the value of a particular option of the
  66 client. It takes both a flag (listed below) and a value. For simple on or
  67 off options you just need to pass in a value of 1. Calls to
  68 memcached_behavior_set() will flush and reset all connections.
  69 .sp
  70 MEMCACHED_BEHAVIOR_USE_UDP
  71 .INDENT 0.0
  72 .INDENT 3.5
  73 .sp
  74 Causes libmemcached(3) to use the UDP transport when communicating
  75 with a memcached server. Not all I/O operations are supported
  76 when this behavior is enababled. The following operations will return
  77 \fBMEMCACHED_NOT_SUPPORTED\fP when executed with the MEMCACHED_BEHAVIOR_USE_UDP
  78 enabled: memcached_version(), memcached_stat(), memcached_get(),
  79 memcached_get_by_key(), memcached_mget(), memcached_mget_by_key(),
  80 memcached_fetch(), memcached_fetch_result(), memcached_value_fetch().
  81 .sp
  82 All other operations are supported but are executed in a \(aqfire\-and\-forget\(aq
  83 mode, in which once the client has executed the operation, no attempt
  84 will be made to ensure the operation has been received and acted on by the
  85 server.
  86 .sp
  87 libmemcached(3) does not allow TCP and UDP servers to be shared within
  88 the same libmemached(3) client \(aqinstance\(aq. An attempt to add a TCP server
  89 when this behavior is enabled will result in a \fBMEMCACHED_INVALID_HOST_PROTOCOL\fP,
  90 as will attempting to add a UDP server when this behavior has not been enabled.
  91 .UNINDENT
  92 .UNINDENT
  93 .sp
  94 MEMCACHED_BEHAVIOR_NO_BLOCK
  95 .INDENT 0.0
  96 .INDENT 3.5
  97 .sp
  98 Causes libmemcached(3) to use asychronous IO. This is the fastest transport
  99 available for storage functions.
 100 .UNINDENT
 101 .UNINDENT
 102 .sp
 103 MEMCACHED_BEHAVIOR_SND_TIMEOUT
 104 .INDENT 0.0
 105 .INDENT 3.5
 106 .sp
 107 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.
 108 In cases where you cannot use non\-blocking IO this will allow you to still have
 109 timeouts on the sending of data.
 110 .UNINDENT
 111 .UNINDENT
 112 .sp
 113 MEMCACHED_BEHAVIOR_RCV_TIMEOUT
 114 .INDENT 0.0
 115 .INDENT 3.5
 116 .sp
 117 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
 118 In cases where you cannot use non\-blocking IO this will allow you to still have
 119 timeouts on the reading of data.
 120 .UNINDENT
 121 .UNINDENT
 122 .sp
 123 MEMCACHED_BEHAVIOR_TCP_NODELAY
 124 .INDENT 0.0
 125 .INDENT 3.5
 126 .sp
 127 Turns on the no\-delay feature for connecting sockets (may be faster in some
 128 environments).
 129 .UNINDENT
 130 .UNINDENT
 131 .sp
 132 MEMCACHED_BEHAVIOR_HASH
 133 .INDENT 0.0
 134 .INDENT 3.5
 135 .sp
 136 Makes the default hashing algorithm for keys use MD5. The value can be set
 137 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.
 138 Each hash has it\(aqs advantages and it\(aqs weaknesses. If you don\(aqt know or don\(aqt care, just go with the default.
 139 Support for MEMCACHED_HASH_HSIEH is a compile time option that is disabled by default. To enable support for this hashing algorithm, configure and build libmemcached with the \-\-enable\-hash_hsieh.
 140 .UNINDENT
 141 .UNINDENT
 142 .sp
 143 MEMCACHED_BEHAVIOR_DISTRIBUTION
 144 .INDENT 0.0
 145 .INDENT 3.5
 146 .sp
 147 Using this you can enable different means of distributing values to servers.
 148 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable
 149 consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.
 150 Consistent hashing delivers better distribution and allows servers to be
 151 added to the cluster with minimal cache losses. Currently
 152 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
 153 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
 154 .UNINDENT
 155 .UNINDENT
 156 .sp
 157 MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
 158 .INDENT 0.0
 159 .INDENT 3.5
 160 .sp
 161 Memcached can cache named lookups so that DNS lookups are made only once.
 162 .UNINDENT
 163 .UNINDENT
 164 .sp
 165 MEMCACHED_BEHAVIOR_SUPPORT_CAS
 166 .INDENT 0.0
 167 .INDENT 3.5
 168 .sp
 169 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
 170 .UNINDENT
 171 .UNINDENT
 172 .sp
 173 MEMCACHED_BEHAVIOR_KETAMA
 174 .INDENT 0.0
 175 .INDENT 3.5
 176 .sp
 177 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
 178 and the hash to MEMCACHED_HASH_MD5.
 179 .UNINDENT
 180 .UNINDENT
 181 .sp
 182 MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
 183 .INDENT 0.0
 184 .INDENT 3.5
 185 .sp
 186 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
 187 and the hash to MEMCACHED_HASH_MD5.
 188 .UNINDENT
 189 .UNINDENT
 190 .sp
 191 MEMCACHED_BEHAVIOR_KETAMA_HASH
 192 .INDENT 0.0
 193 .INDENT 3.5
 194 .sp
 195 Sets the hashing algorithm for host mapping on continuum. The value can be set
 196 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.
 197 .UNINDENT
 198 .UNINDENT
 199 .sp
 200 MEMCACHED_BEHAVIOR_KETAMA_COMPAT
 201 .INDENT 0.0
 202 .INDENT 3.5
 203 .sp
 204 Sets the compatibility mode. The value can be set to either
 205 MEMCACHED_KETAMA_COMPAT_LIBMEMCACHED (this is the default) or
 206 MEMCACHED_KETAMA_COMPAT_SPY to be compatible with the SPY Memcached client
 207 for Java.
 208 .UNINDENT
 209 .UNINDENT
 210 .sp
 211 MEMCACHED_BEHAVIOR_POLL_TIMEOUT
 212 .INDENT 0.0
 213 .INDENT 3.5
 214 .sp
 215 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.
 216 .UNINDENT
 217 .UNINDENT
 218 .sp
 219 MEMCACHED_BEHAVIOR_USER_DATA
 220 .INDENT 0.0
 221 .INDENT 3.5
 222 .sp
 223 This allows you to store a pointer to a specifc piece of data. This can be
 224 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
 225 .sp
 226 will copy the pointer to the clone. This was deprecated in 0.14 in favor
 227 of memcached_callback_set(3). This will be removed in 0.15.
 228 .UNINDENT
 229 .UNINDENT
 230 .sp
 231 MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
 232 .INDENT 0.0
 233 .INDENT 3.5
 234 .sp
 235 Enabling buffered IO causes commands to "buffer" instead of being sent. Any
 236 action that gets data causes this buffer to be be sent to the remote
 237 connection. Quiting the connection or closing down the connection will also
 238 cause the buffered data to be pushed to the remote connection.
 239 .UNINDENT
 240 .UNINDENT
 241 .sp
 242 MEMCACHED_BEHAVIOR_VERIFY_KEY
 243 .INDENT 0.0
 244 .INDENT 3.5
 245 .sp
 246 Enabling this will cause libmemcached(3) to test all keys to verify that they
 247 are valid keys.
 248 .UNINDENT
 249 .UNINDENT
 250 .sp
 251 MEMCACHED_BEHAVIOR_SORT_HOSTS
 252 .INDENT 0.0
 253 .INDENT 3.5
 254 .sp
 255 Enabling this will cause hosts that are added to be placed in the host list in
 256 sorted order. This will defeat consisten hashing.
 257 .UNINDENT
 258 .UNINDENT
 259 .sp
 260 MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
 261 .INDENT 0.0
 262 .INDENT 3.5
 263 .sp
 264 In non\-blocking mode this changes the value of the timeout during socket
 265 connection.
 266 .UNINDENT
 267 .UNINDENT
 268 .sp
 269 MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
 270 .INDENT 0.0
 271 .INDENT 3.5
 272 .sp
 273 Enable the use of the binary protocol. Please note that you cannot toggle
 274 this flag on an open connection.
 275 .UNINDENT
 276 .UNINDENT
 277 .sp
 278 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 279 .INDENT 0.0
 280 .INDENT 3.5
 281 .sp
 282 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 283 times connection failure.
 284 .UNINDENT
 285 .UNINDENT
 286 .sp
 287 MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
 288 .INDENT 0.0
 289 .INDENT 3.5
 290 .sp
 291 Set this value to tune the number of messages that may be sent before
 292 libmemcached should start to automatically drain the input queue. Setting
 293 this value to high, may cause libmemcached to deadlock (trying to send data,
 294 but the send will block because the input buffer in the kernel is full).
 295 .UNINDENT
 296 .UNINDENT
 297 .sp
 298 MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
 299 .INDENT 0.0
 300 .INDENT 3.5
 301 .sp
 302 Set this value to tune the number of bytes that may be sent before
 303 libmemcached should start to automatically drain the input queue (need
 304 at least 10 IO requests sent without reading the input buffer). Setting
 305 this value to high, may cause libmemcached to deadlock (trying to send
 306 data, but the send will block because the input buffer in the kernel is full).
 307 .UNINDENT
 308 .UNINDENT
 309 .sp
 310 MEMCACHED_BEHAVIOR_IO_KEY_PREFETCH
 311 .INDENT 0.0
 312 .INDENT 3.5
 313 .sp
 314 The binary protocol works a bit different than the textual protocol in
 315 that a multiget is implemented as a pipe of single get\-operations which
 316 are sent to the server in a chunk. If you are using large multigets from
 317 your application, you may improve the latency of the gets by setting
 318 this value so you send out the first chunk of requests when you hit the
 319 specified limit.  It allows the servers to start processing the requests
 320 to send the data back while the rest of the requests are created and
 321 sent to the server.
 322 .UNINDENT
 323 .UNINDENT
 324 .sp
 325 MEMCACHED_BEHAVIOR_NOREPLY
 326 .INDENT 0.0
 327 .INDENT 3.5
 328 .sp
 329 Set this value to specify that you really don\(aqt care about the result
 330 from your storage commands (set, add, replace, append, prepend).
 331 .UNINDENT
 332 .UNINDENT
 333 .sp
 334 MEMCACHED_BEHAVIOR_NUMBER_OF_REPLICAS
 335 .INDENT 0.0
 336 .INDENT 3.5
 337 .sp
 338 If you just want "a poor mans HA", you may specify the numbers of
 339 replicas libmemcached should store of each item (on different servers).
 340 This replication does not dedicate certain memcached servers to store the
 341 replicas in, but instead it will store the replicas together with all of the
 342 other objects (on the \(aqn\(aq next servers specified in your server list).
 343 .UNINDENT
 344 .UNINDENT
 345 .sp
 346 MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ
 347 .INDENT 0.0
 348 .INDENT 3.5
 349 .sp
 350 Allows randomizing the replica reads starting point. Normally the read is
 351 done from primary server and in case of miss the read is done from primary
 352 + 1, then primary + 2 all the way to \(aqn\(aq replicas. If this option is set
 353 on the starting point of the replica reads is randomized between the servers.
 354 This allows distributing read load to multiple servers with the expense of
 355 more write traffic.
 356 .UNINDENT
 357 .UNINDENT
 358 .sp
 359 MEMCACHED_BEHAVIOR_CORK
 360 .INDENT 0.0
 361 .INDENT 3.5
 362 .sp
 363 Enable TCP_CORK behavior. This is only available as an option Linux.
 364 MEMCACHED_NO_SERVERS is returned if no servers are available to test with.
 365 MEMCACHED_NOT_SUPPORTED is returned if we were not able to determine
 366 if support was available. All other responses then MEMCACHED_SUCCESS
 367 report an error of some sort. This behavior also enables
 368 MEMCACHED_BEHAVIOR_TCP_NODELAY when set.
 369 .UNINDENT
 370 .UNINDENT
 371 .sp
 372 MEMCACHED_BEHAVIOR_KEEPALIVE
 373 .INDENT 0.0
 374 .INDENT 3.5
 375 .sp
 376 Enable TCP_KEEPALIVE behavior.
 377 .UNINDENT
 378 .UNINDENT
 379 .sp
 380 MEMCACHED_BEHAVIOR_KEEPALIVE_IDLE
 381 .INDENT 0.0
 382 .INDENT 3.5
 383 .sp
 384 Specify time, in seconds, to mark a connection as idle. This is only available as an option Linux.
 385 .UNINDENT
 386 .UNINDENT
 387 .sp
 388 MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE
 389 .INDENT 0.0
 390 .INDENT 3.5
 391 .sp
 392 Find the current size of SO_SNDBUF. A value of 0 means either an error
 393 occured or no hosts were available. It is safe to assume system default
 394 if this occurs. If an error occurs you can checked the last cached errno statement to find the specific error.
 395 .UNINDENT
 396 .UNINDENT
 397 .sp
 398 MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE
 399 .INDENT 0.0
 400 .INDENT 3.5
 401 .sp
 402 Find the current size of SO_RCVBUF. A value of 0 means either an error
 403 occured or no hosts were available. It is safe to assume system default
 404 if this occurs. If an error occurs you can checked the last cached errno statement to find the specific error.
 405 .UNINDENT
 406 .UNINDENT
 407 .sp
 408 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
 409 .INDENT 0.0
 410 .INDENT 3.5
 411 .sp
 412 This number of times a host can have an error before it is disabled.
 413 .UNINDENT
 414 .UNINDENT
 415 .sp
 416 MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS
 417 .INDENT 0.0
 418 .INDENT 3.5
 419 .sp
 420 If enabled any hosts which have been flagged as disabled will be removed
 421 from the list of servers in the memcached_st structure. This must be used
 422 in combination with MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT.
 423 .UNINDENT
 424 .UNINDENT
 425 .sp
 426 MEMCACHED_BEHAVIOR_RETRY_TIMEOUT
 427 .INDENT 0.0
 428 .INDENT 3.5
 429 .sp
 430 When enabled a host which is problematic will only be checked for usage
 431 based on the amount of time set by this behavior.
 432 .UNINDENT
 433 .UNINDENT
 434 .sp
 435 MEMCACHED_BEHAVIOR_HASH_WITH_PREFIX_KEY
 436 .INDENT 0.0
 437 .INDENT 3.5
 438 .sp
 439 When enabled the prefix key will be added to the key when determining
 440 server by hash.
 441 .UNINDENT
 442 .UNINDENT
 443 .SH RETURN
 444 .sp
 445 memcached_behavior_get() returns either the current value of the get, or 0
 446 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set()
 447 returns failure or success.
 448 .SH NOTES
 449 .sp
 450 memcached_behavior_set() in version .17 was changed from taking a pointer
 451 to data value, to taking a uin64_t.
 452 .SH HOME
 453 .sp
 454 To find out more information please check:
 455 \fI\%https://launchpad.net/libmemcached\fP
 456 .SH AUTHOR
 457 .sp
 458 Brian Aker, <\fI\%brian@tangent.org\fP>
 459 .SH SEE ALSO
 460 .sp
 461 memcached(1) libmemcached(3) memcached_strerror(3)
 462 .SH AUTHOR
 463 Brian Aker
 464 .SH COPYRIGHT
 465 2011, Brian Aker
 466 .\" Generated by docutils manpage writer.
 467 .\"
 468 .