3 memcached_behavior_get memcached_behavior_set
7 C Client Library for memcached (libmemcached, -lmemcached)
11 #include <memcached.h>
14 memcached_behavior_get (memcached_st *ptr,
15 memcached_behavior flag);
18 memcached_behavior_set (memcached_st *ptr,
19 memcached_behavior flag,
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>).
30 memcached_behavior_get() takes a behavior flag and returns whether or not
31 that behavior is currently enabled in the client.
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.
40 =item MEMCACHED_BEHAVIOR_USE_UDP
42 Causes libmemcached(3) to use the UDP transport when communicating
43 with a memcached server. Not all I/O operations are supported
44 when this behavior is enababled. The following operations will return
45 C<MEMCACHED_NOT_SUPPORTED> when executed with the MEMCACHED_BEHAVIOR_USE_UDP
46 enabled: memcached_version(), memcached_stat(), memcached_get(),
47 memcached_get_by_key(), memcached_mget(), memcached_mget_by_key(),
48 memcached_fetch(), memcached_fetch_result(), memcached_value_fetch().
50 All other operations are supported but are executed in a 'fire-and-forget'
51 mode, in which once the client has executed the operation, no attempt
52 will be made to ensure the operation has been received and acted on by the
55 libmemcached(3) does not allow TCP and UDP servers to be shared within
56 the same libmemached(3) client 'instance'. An attempt to add a TCP server
57 when this behavior is enabled will result in a C<MEMCACHED_INVALID_HOST_PROTOCOL>,
58 as will attempting to add a UDP server when this behavior has not been enabled.
60 =item MEMCACHED_BEHAVIOR_NO_BLOCK
62 Causes libmemcached(3) to use asychronous IO. This is the fastest transport
63 available for storage functions. For read operations it is currently
64 similar in performance to the non-blocking method (this is being
67 =item MEMCACHED_BEHAVIOR_SND_TIMEOUT
69 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.
70 In cases where you cannot use non-blocking IO this will allow you to still have
71 timeouts on the sending of data.
73 =item MEMCACHED_BEHAVIOR_RCV_TIMEOUT
75 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
76 In cases where you cannot use non-blocking IO this will allow you to still have
77 timeouts on the reading of data.
79 =item MEMCACHED_BEHAVIOR_TCP_NODELAY
81 Turns on the no-delay feature for connecting sockets (may be faster in some
84 =item MEMCACHED_BEHAVIOR_HASH
86 Makes the default hashing algorithm for keys use MD5. The value can be set
87 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.
88 Each hash has it's advantages and it's weaknesses. If you dont know or dont care, just go with the default.
90 =item MEMCACHED_BEHAVIOR_DISTRIBUTION
92 Using this you can enable different means of distributing values to servers.
93 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable
94 consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.
95 Consistent hashing delivers better distribution and allows servers to be
96 added to the cluster with minimal cache losses. Currently
97 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
98 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
100 =item MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
102 Memcached can cache named lookups so that DNS lookups are made only once.
104 =item MEMCACHED_BEHAVIOR_SUPPORT_CAS
106 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
108 =item MEMCACHED_BEHAVIOR_KETAMA
110 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
111 and the hash to MEMCACHED_HASH_MD5.
113 =item MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
115 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
116 and the hash to MEMCACHED_HASH_MD5.
118 =item MEMCACHED_BEHAVIOR_KETAMA_HASH
120 Sets the hashing algorithm for host mapping on continuum. The value can be set
121 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.
123 =item MEMCACHED_BEHAVIOR_POLL_TIMEOUT
125 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.
127 =item MEMCACHED_BEHAVIOR_USER_DATA
129 This allows you to store a pointer to a specifc piece of data. This can be
130 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
132 will copy the pointer to the clone. This was deprecated in 0.14 in favor
133 of memcached_callback_set(3). This will be removed in 0.15.
135 =item MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
137 Enabling buffered IO causes commands to "buffer" instead of being sent. Any
138 action that gets data causes this buffer to be be sent to the remote
139 connection. Quiting the connection or closing down the connection will also
140 cause the buffered data to be pushed to the remote connection.
142 =item MEMCACHED_BEHAVIOR_VERIFY_KEY
144 Enabling this will cause libmemcached(3) to test all keys to verify that they
147 =item MEMCACHED_BEHAVIOR_SORT_HOSTS
149 Enabling this will cause hosts that are added to be placed in the host list in
150 sorted order. This will defeat consisten hashing.
152 =item MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
154 In non-blocking mode this changes the value of the timeout during socket
157 =item MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
159 Enable the use of the binary protocol. Please note that you cannot toggle
160 this flag on an open connection.
162 =item MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
164 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
165 times connection failure.
167 =item MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
169 Set this value to tune the number of messages that may be sent before
170 libmemcached should start to automatically drain the input queue. Setting
171 this value to high, may cause libmemcached to deadlock (trying to send data,
172 but the send will block because the input buffer in the kernel is full).
174 =item MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
176 Set this value to tune the number of bytes that may be sent before
177 libmemcached should start to automatically drain the input queue (need
178 at least 10 IO requests sent without reading the input buffer). Setting
179 this value to high, may cause libmemcached to deadlock (trying to send
180 data, but the send will block because the input buffer in the kernel is full).
182 =item MEMCACHED_BEHAVIOR_NOREPLY
184 Set this value to specify that you really don't care about the result
185 from your storage commands (set, add, replace, append, prepend).
191 memcached_behavior_get() returns either the current value of the get, or 0
192 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set()
193 returns failure or success.
197 memcached_behavior_set() in version .17 was changed from taking a pointer
198 to data value, to taking a uin64_t.
202 To find out more information please check:
203 L<http://tangent.org/552/libmemcached.html>
207 Brian Aker, E<lt>brian@tangent.orgE<gt>
211 memcached(1) libmemcached(3) memcached_strerror(3)