Update to handle newer endian autoconf components.
[awesomized/libmemcached] / docs / memcached_behavior.rst
1 ================================
2 Modifying how the driver behaves
3 ================================
4
5
6 Manipulate the behavior of a memcached_st structure.
7
8 .. index:: object: memcached_st
9
10
11 --------
12 SYNOPSIS
13 --------
14
15
16 #include <libmemcached/memcached.h>
17
18 .. c:type:: memcached_behavior_t
19
20 .. c:function:: uint64_t memcached_behavior_get (memcached_st *ptr, memcached_behavior_t flag)
21
22 .. c:function:: memcached_return_t memcached_behavior_set (memcached_st *ptr, memcached_behavior_t flag, uint64_t data)
23
24 Compile and link with -lmemcached
25
26
27 -----------
28 DESCRIPTION
29 -----------
30
31 :manpage:`libmemcached(3)` behavior can be modified by using :c:func:`memcached_behavior_set`. Default behavior is the library strives to be quick and
32 accurate. Some behavior, while being faster, can also result in not entirely
33 accurate behavior (for instance, :c:func:`memcached_set` will always respond
34 with :c:type:`MEMCACHED_SUCCESS`).
35
36 :c:func:`memcached_behavior_get` takes a behavior flag and returns whether or not that behavior is currently enabled in the client.
37
38 :c:func:`memcached_behavior_set` changes the value of a particular option
39 of the client. It takes both a flag (listed below) and a value. For simple
40 on or off options you just need to pass in a value of 1. Calls to
41 :c:func:`memcached_behavior_set` will flush and reset all connections.
42
43
44 .. c:type:: MEMCACHED_BEHAVIOR_USE_UDP
45
46 Causes :manpage:`libmemcached(3)` to use the UDP transport when communicating
47 with a memcached server. Not all I/O operations are testsed
48 when this behavior is enababled. The following operations will return
49 :c:type:`MEMCACHED_NOT_SUPPORTED` when executed with the
50 :c:type:`MEMCACHED_BEHAVIOR_USE_UDP` enabled: :c:func:`memcached_version`,
51 :c:func:`memcached_stat`, :c:func:`memcached_get`,
52 :c:func:`memcached_get_by_key`, :c:func:`memcached_mget`,
53 :c:func:`memcached_mget_by_key`, :c:func:`memcached_fetch`,
54 :c:func:`memcached_fetch_result`, :c:func:`memcached_fetch_execute`.
55
56 All other operations are testsed but are executed in a 'fire-and-forget'
57 mode, in which once the client has executed the operation, no attempt
58 will be made to ensure the operation has been received and acted on by the
59 server.
60
61 :manpage:`libmemcached(3)` does not allow TCP and UDP servers to be shared
62 within the same libmemached(3) client 'instance'. An attempt to add a TCP
63 server when this behavior is enabled will result in a :c:type:`MEMCACHED_INVALID_HOST_PROTOCOL`, as will attempting to add a UDP server when this behavior has
64 not been enabled.
65
66
67
68 .. c:type:: MEMCACHED_BEHAVIOR_NO_BLOCK
69
70 Causes :manpage:`libmemcached(3)` to use asychronous IO. This is the fastest
71 transport available for storage functions.
72
73
74 .. c:type:: MEMCACHED_BEHAVIOR_SND_TIMEOUT
75
76 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.
77
78
79 .. c:type:: MEMCACHED_BEHAVIOR_RCV_TIMEOUT
80
81 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
82
83 In cases where you cannot use non-blocking IO this will allow you to still have timeouts on the reading of data.
84
85
86
87 .. c:type:: MEMCACHED_BEHAVIOR_TCP_NODELAY
88
89 Turns on the no-delay feature for connecting sockets (may be faster in some
90 environments).
91
92
93
94 .. c:type:: MEMCACHED_BEHAVIOR_HASH
95
96 Makes the default hashing algorithm for keys use MD5. The value can be set to either :c:type:`MEMCACHED_HASH_DEFAULT`, :c:type:`MEMCACHED_HASH_MD5`, :c:type:`MEMCACHED_HASH_CRC`, :c:type:`MEMCACHED_HASH_FNV1_64`, :c:type:`MEMCACHED_HASH_FNV1A_64`, :c:type:`MEMCACHED_HASH_FNV1_32`, :c:type:`MEMCACHED_HASH_FNV1A_32`, :c:type:`MEMCACHED_HASH_JENKINS`, :c:type:`MEMCACHED_HASH_HSIEH`, and :c:type:`MEMCACHED_HASH_MURMUR`.
97
98 Each hash has it's advantages and it's weaknesses. If you don't know or don't
99 care, just go with the default.
100
101 Support for :c:type:`MEMCACHED_HASH_HSIEH` 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.
102
103
104
105 .. c:type:: MEMCACHED_BEHAVIOR_DISTRIBUTION
106
107 Using this you can enable different means of distributing values to servers.
108
109 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.
110
111 .. c:type:: MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
112 .. deprecated:: 0.46(?)
113 DNS lookups are now always cached until an error occurs with the server.
114
115 Memcached can cache named lookups so that DNS lookups are made only once.
116
117 .. c:type:: MEMCACHED_BEHAVIOR_SUPPORT_CAS
118
119 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
120
121
122 .. c:type:: MEMCACHED_BEHAVIOR_KETAMA
123
124 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA and
125 the hash to :c:type:`MEMCACHED_HASH_MD5`.
126
127
128 .. c:type:: MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
129
130 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted tests. and the hash to MEMCACHED_HASH_MD5.
131
132 .. c:type:: MEMCACHED_BEHAVIOR_KETAMA_HASH
133
134 Sets the hashing algorithm for host mapping on continuum. The value can be set
135 to either :c:type:`MEMCACHED_HASH_DEFAULT`, :c:type:`MEMCACHED_HASH_MD5`,
136 :c:type:`MEMCACHED_HASH_CRC`, :c:type:`MEMCACHED_HASH_FNV1_64`,
137 :c:type:`MEMCACHED_HASH_FNV1A_64`, :c:type:`MEMCACHED_HASH_FNV1_32`, and
138 :c:type:`MEMCACHED_HASH_FNV1A_32`.
139
140 .. c:type:: MEMCACHED_BEHAVIOR_KETAMA_COMPAT
141
142 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.
143
144 .. c:type:: MEMCACHED_BEHAVIOR_POLL_TIMEOUT
145
146 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.
147
148 .. c:type:: MEMCACHED_BEHAVIOR_USER_DATA
149 .. deprecated:: < 0.30
150
151 .. c:type:: MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
152
153 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.
154
155
156 .. c:type:: MEMCACHED_BEHAVIOR_VERIFY_KEY
157
158 Enabling this will cause :manpage:`libmemcached(3)` to test all keys to verify that they are valid keys.
159
160
161
162 .. c:type:: MEMCACHED_BEHAVIOR_SORT_HOSTS
163
164 Enabling this will cause hosts that are added to be placed in the host list in sorted order. This will defeat consisten hashing.
165
166
167
168 .. c:type:: MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
169
170 In non-blocking mode this changes the value of the timeout during socket connection.
171
172
173
174 .. c:type:: MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
175
176 Enable the use of the binary protocol. Please note that you cannot toggle this flag on an open connection.
177
178
179
180 .. c:type:: MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
181
182 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT times connection failure.
183
184
185
186 .. c:type:: MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
187
188 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).
189
190
191
192 .. c:type:: MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
193
194 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).
195
196
197
198 .. c:type:: MEMCACHED_BEHAVIOR_IO_KEY_PREFETCH
199
200 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.
201
202
203
204 .. c:type:: MEMCACHED_BEHAVIOR_NOREPLY
205
206 Set this value to specify that you really don't care about the result from your storage commands (set, add, replace, append, prepend).
207
208
209
210 .. c:type:: MEMCACHED_BEHAVIOR_NUMBER_OF_REPLICAS
211
212 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 'n' next servers specified in your server list).
213
214
215
216 .. c:type:: MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ
217
218 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 'n' 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.
219
220
221
222 .. c:type:: MEMCACHED_BEHAVIOR_CORK
223
224 This open has been deprecated with the behavior now built and used appropriately on selected platforms.
225
226
227 .. c:type:: MEMCACHED_BEHAVIOR_KEEPALIVE
228
229 Enable TCP_KEEPALIVE behavior.
230
231
232
233 .. c:type:: MEMCACHED_BEHAVIOR_KEEPALIVE_IDLE
234
235 Specify time, in seconds, to mark a connection as idle. This is only available as an option Linux.
236
237
238 .. c:type:: MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE
239
240 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.
241
242
243 .. c:type:: MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE
244
245 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.
246
247
248 .. c:type:: MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
249 .. deprecated:: 0.48
250 See :c:type:`MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS`
251
252 This number of times a host can have an error before it is disabled.
253
254
255 .. c:type:: MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS
256 .. deprecated:: 0.48
257 See :c:type:`MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS`
258
259 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.
260
261 .. c:type:: MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS
262
263 If enabled any hosts which have been flagged as disabled will be removed from the list of servers in the memcached_st structure.
264
265 .. c:type:: MEMCACHED_BEHAVIOR_RETRY_TIMEOUT
266
267 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.
268
269
270 .. c:type:: MEMCACHED_BEHAVIOR_HASH_WITH_PREFIX_KEY
271
272 When enabled the prefix key will be added to the key when determining server
273 by hash. See :c:type:`MEMCACHED_CALLBACK_NAMESPACE` for additional
274 information.
275
276
277
278
279 ------
280 RETURN
281 ------
282
283
284 memcached_behavior_get returns either the current value of the get, or 0
285 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set
286 returns failure or success.
287
288
289 -----
290 NOTES
291 -----
292
293
294 memcached_behavior_set in version .17 was changed from taking a pointer
295 to data value, to taking a uin64_t.
296
297
298 ----
299 HOME
300 ----
301
302
303 To find out more information please check:
304 `http://libmemcached.org/ <http://libmemcached.org/>`_
305
306
307
308 --------
309 SEE ALSO
310 --------
311
312
313 :manpage:`memcached(1)` :manpage:`libmemcached(3)` :manpage:`memcached_strerror(3)`