1memcached_behavior_get.pop(3)memcached_behavior_getmemcached_behavior_get.pop(3)
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6 memcached_behavior_get, memcached_behavior_set - Manipulate behavior
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9 C Client Library for memcached (libmemcached, -lmemcached)
10
12 #include <memcached.h>
13 uint64_t
15 memcached_behavior_get (memcached_st *ptr,
16 memcached_behavior flag);
17 memcached_return_t
19 memcached_behavior_set (memcached_st *ptr,
20 memcached_behavior flag,
21 uint64_t data);
22
24 libmemcached(3) behavior can be modified by use
25 memcached_behavior_set(). Default behavior is the library strives to
26 be quick and accurate. Some behavior, while being faster, can also
27 result in not entirely accurate behavior (for instance, memcached_set()
28 will always respond with "MEMCACHED_SUCCESS").
29 memcached_behavior_get() takes a behavior flag and returns whether or
31 not that behavior is currently enabled in the client.
32 memcached_behavior_set() changes the value of a particular option of
34 the client. It takes both a flag (listed below) and a value. For simple
35 on or 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 MEMCACHED_BEHAVIOR_USE_UDP
39 Causes libmemcached(3) to use the UDP transport when communicating
40 with a memcached server. Not all I/O operations are supported when
41 this behavior is enababled. The following operations will return
42 "MEMCACHED_NOT_SUPPORTED" when executed with the
43 MEMCACHED_BEHAVIOR_USE_UDP enabled: memcached_version(),
44 memcached_stat(), memcached_get(), memcached_get_by_key(),
45 memcached_mget(), memcached_mget_by_key(), memcached_fetch(),
46 memcached_fetch_result(), memcached_value_fetch().
47 All other operations are supported but are executed in a
49 'fire-and-forget' mode, in which once the client has executed the
50 operation, no attempt will be made to ensure the operation has been
51 received and acted on by the server.
52 libmemcached(3) does not allow TCP and UDP servers to be shared
54 within the same libmemached(3) client 'instance'. An attempt to add
55 a TCP server when this behavior is enabled will result in a
56 "MEMCACHED_INVALID_HOST_PROTOCOL", as will attempting to add a UDP
57 server when this behavior has not been enabled.
58 MEMCACHED_BEHAVIOR_NO_BLOCK
60 Causes libmemcached(3) to use asychronous IO. This is the fastest
61 transport available for storage functions.
62 MEMCACHED_BEHAVIOR_SND_TIMEOUT
64 This sets the microsecond behavior of the socket against the
65 SO_SNDTIMEO flag. In cases where you cannot use non-blocking IO
66 this will allow you to still have timeouts on the sending of data.
67 MEMCACHED_BEHAVIOR_RCV_TIMEOUT
69 This sets the microsecond behavior of the socket against the
70 SO_RCVTIMEO flag. In cases where you cannot use non-blocking IO
71 this will allow you to still have timeouts on the reading of data.
72 MEMCACHED_BEHAVIOR_TCP_NODELAY
74 Turns on the no-delay feature for connecting sockets (may be faster
75 in some environments).
76 MEMCACHED_BEHAVIOR_HASH
78 Makes the default hashing algorithm for keys use MD5. The value can
79 be set to either MEMCACHED_HASH_DEFAULT, MEMCACHED_HASH_MD5,
80 MEMCACHED_HASH_CRC, MEMCACHED_HASH_FNV1_64,
81 MEMCACHED_HASH_FNV1A_64, MEMCACHED_HASH_FNV1_32,
82 MEMCACHED_HASH_FNV1A_32, MEMCACHED_HASH_JENKINS,
83 MEMCACHED_HASH_HSIEH, and MEMCACHED_HASH_MURMUR. Each hash has
84 it's advantages and it's weaknesses. If you don't know or don't
85 care, just go with the default. Support for MEMCACHED_HASH_HSIEH
86 is a compile time option that is disabled by default. To enable
87 support for this hashing algorithm, configure and build
88 libmemcached with the --enable-hash_hsieh.
89 MEMCACHED_BEHAVIOR_DISTRIBUTION
91 Using this you can enable different means of distributing values to
92 servers. The default method is MEMCACHED_DISTRIBUTION_MODULA. You
93 can enable consistent hashing by setting
94 MEMCACHED_DISTRIBUTION_CONSISTENT. Consistent hashing delivers
95 better distribution and allows servers to be added to the cluster
96 with minimal cache losses. Currently
97 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
98 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
99 MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
101 Memcached can cache named lookups so that DNS lookups are made only
102 once.
103 MEMCACHED_BEHAVIOR_SUPPORT_CAS
105 Support CAS operations (this is not enabled by default at this
106 point in the server since it imposes a slight performance penalty).
107 MEMCACHED_BEHAVIOR_KETAMA
109 Sets the default distribution to
110 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA and the hash to
111 MEMCACHED_HASH_MD5.
112 MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
114 Sets the default distribution to
115 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
116 and the hash to MEMCACHED_HASH_MD5.
117 MEMCACHED_BEHAVIOR_KETAMA_HASH
119 Sets the hashing algorithm for host mapping on continuum. The value
120 can be set to either MEMCACHED_HASH_DEFAULT, MEMCACHED_HASH_MD5,
121 MEMCACHED_HASH_CRC, MEMCACHED_HASH_FNV1_64,
122 MEMCACHED_HASH_FNV1A_64, MEMCACHED_HASH_FNV1_32, and
123 MEMCACHED_HASH_FNV1A_32.
124 MEMCACHED_BEHAVIOR_KETAMA_COMPAT
126 Sets the compatibility mode. The value can be set to either
127 MEMCACHED_KETAMA_COMPAT_LIBMEMCACHED (this is the default) or
128 MEMCACHED_KETAMA_COMPAT_SPY to be compatible with the SPY Memcached
129 client for Java.
130 MEMCACHED_BEHAVIOR_POLL_TIMEOUT
132 Modify the timeout value that is used by poll(). The default value
133 is -1. An signed int pointer must be passed to
134 memcached_behavior_set() to change this value. For
135 memcached_behavior_get() a signed int value will be cast and
136 returned as the unsigned long long.
137 MEMCACHED_BEHAVIOR_USER_DATA
139 This allows you to store a pointer to a specifc piece of data. This
140 can be retrieved from inside of memcached_fetch_execute(). Cloning
141 a memcached_st
142 will copy the pointer to the clone. This was deprecated in 0.14 in
144 favor of memcached_callback_set(3). This will be removed in 0.15.
145 MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
147 Enabling buffered IO causes commands to "buffer" instead of being
148 sent. Any action that gets data causes this buffer to be be sent to
149 the remote connection. Quiting the connection or closing down the
150 connection will also cause the buffered data to be pushed to the
151 remote connection.
152 MEMCACHED_BEHAVIOR_VERIFY_KEY
154 Enabling this will cause libmemcached(3) to test all keys to verify
155 that they are valid keys.
156 MEMCACHED_BEHAVIOR_SORT_HOSTS
158 Enabling this will cause hosts that are added to be placed in the
159 host list in sorted order. This will defeat consisten hashing.
160 MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
162 In non-blocking mode this changes the value of the timeout during
163 socket connection.
164 MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
166 Enable the use of the binary protocol. Please note that you cannot
167 toggle this flag on an open connection.
168 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
170 Set this value to enable the server be removed after continuous
171 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT times connection failure.
172 MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
174 Set this value to tune the number of messages that may be sent
175 before libmemcached should start to automatically drain the input
176 queue. Setting this value to high, may cause libmemcached to
177 deadlock (trying to send data, but the send will block because the
178 input buffer in the kernel is full).
179 MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
181 Set this value to tune the number of bytes that may be sent before
182 libmemcached should start to automatically drain the input queue
183 (need at least 10 IO requests sent without reading the input
184 buffer). Setting this value to high, may cause libmemcached to
185 deadlock (trying to send data, but the send will block because the
186 input buffer in the kernel is full).
187 MEMCACHED_BEHAVIOR_IO_KEY_PREFETCH
189 The binary protocol works a bit different than the textual protocol
190 in that a multiget is implemented as a pipe of single get-
191 operations which are sent to the server in a chunk. If you are
192 using large multigets from your application, you may improve the
193 latency of the gets by setting this value so you send out the first
194 chunk of requests when you hit the specified limit. It allows the
195 servers to start processing the requests to send the data back
196 while the rest of the requests are created and sent to the server.
197 MEMCACHED_BEHAVIOR_NOREPLY
199 Set this value to specify that you really don't care about the
200 result from your storage commands (set, add, replace, append,
201 prepend).
202 MEMCACHED_BEHAVIOR_NUMBER_OF_REPLICAS
204 If you just want "a poor mans HA", you may specify the numbers of
205 replicas libmemcached should store of each item (on different
206 servers). This replication does not dedicate certain memcached
207 servers to store the replicas in, but instead it will store the
208 replicas together with all of the other objects (on the 'n' next
209 servers specified in your server list).
210 MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ
212 Allows randomizing the replica reads starting point. Normally the
213 read is done from primary server and in case of miss the read is
214 done from primary + 1, then primary + 2 all the way to 'n'
215 replicas. If this option is set on the starting point of the
216 replica reads is randomized between the servers. This allows
217 distributing read load to multiple servers with the expense of more
218 write traffic.
219 MEMCACHED_BEHAVIOR_CORK
221 Enable TCP_CORK behavior. This is only available as an option
222 Linux. MEMCACHED_NO_SERVERS is returned if no servers are
223 available to test with. MEMCACHED_NOT_SUPPORTED is returned if we
224 were not able to determine if support was available. All other
225 responses then MEMCACHED_SUCCESS report an error of some sort. This
226 behavior also enables MEMCACHED_BEHAVIOR_TCP_NODELAY when set.
227 MEMCACHED_BEHAVIOR_KEEPALIVE
229 Enable TCP_KEEPALIVE behavior.
230 MEMCACHED_BEHAVIOR_KEEPALIVE_IDLE
232 Specify time, in seconds, to mark a connection as idle. This is
233 only available as an option Linux.
234 MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE
236 Find the current size of SO_SNDBUF. A value of 0 means either an
237 error occured or no hosts were available. It is safe to assume
238 system default if this occurs.
239 MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE
241 Find the current size of SO_RCVBUF. A value of 0 means either an
242 error occured or no hosts were available. It is safe to assume
243 system default if this occurs.
244 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
246 This number of times a host can have an error before it is
247 disabled.
248 MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS
250 If enabled any hosts which have been flagged as disabled will be
251 removed from the list of servers in the memcached_st structure.
252 This must be used in combination with
253 MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT.
254 MEMCACHED_BEHAVIOR_RETRY_TIMEOUT
256 When enabled a host which is problematic will only be checked for
257 usage based on the amount of time set by this behavior.
258
260 memcached_behavior_get() returns either the current value of the get,
261 or 0 or 1 on simple flag behaviors (1 being enabled).
262 memcached_behavior_set() returns failure or success.
263
265 memcached_behavior_set() in version .17 was changed from taking a
266 pointer to data value, to taking a uin64_t.
267
269 To find out more information please check:
270 <https://launchpad.net/libmemcached>
271
273 Brian Aker, <brian@tangent.org>
274
276 memcached(1) libmemcached(3) memcached_strerror(3)
277 2010-06-28 memcached_behavior_get.pop(3)