f4246556f7a43c701c8adee8d6eec7348da17af1
[m6w6/libmemcached] / docs / memcached_behavior.pod
1 =head1 NAME
2
3 memcached_behavior_get memcached_behavior_set
4
5 =head1 LIBRARY
6
7 C Client Library for memcached (libmemcached, -lmemcached)
8
9 =head1 SYNOPSIS
10
11 #include <memcached.h>
12
13 uint64_t
14 memcached_behavior_get (memcached_st *ptr,
15 memcached_behavior flag);
16
17 memcached_return
18 memcached_behavior_set (memcached_st *ptr,
19 memcached_behavior flag,
20 uint64_t data);
21
22 =head1 DESCRIPTION
23
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>).
29
30 memcached_behavior_get() takes a behavior flag and returns whether or not
31 that behavior is currently enabled in the client.
32
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.
37
38 =over 4
39
40 =item MEMCACHED_BEHAVIOR_NO_BLOCK
41
42 Causes libmemcached(3) to use asychronous IO. This is the fastest transport
43 available for storage functions. For read operations it is currently
44 similar in performance to the non-blocking method (this is being
45 looked into).
46
47 =item MEMCACHED_BEHAVIOR_SND_TIMEOUT
48
49 This sets the microsecond behavior of the socket against the SO_SNDTIMEO flag.
50 In cases where you cannot use non-blocking IO this will allow you to still have
51 timeouts on the sending of data.
52
53 =item MEMCACHED_BEHAVIOR_RCV_TIMEOUT
54
55 This sets the microsecond behavior of the socket against the SO_RCVTIMEO flag.
56 In cases where you cannot use non-blocking IO this will allow you to still have
57 timeouts on the reading of data.
58
59 =item MEMCACHED_BEHAVIOR_TCP_NODELAY
60
61 Turns on the no-delay feature for connecting sockets (may be faster in some
62 environments).
63
64 =item MEMCACHED_BEHAVIOR_HASH
65
66 Makes the default hashing algorithm for keys use MD5. The value can be set
67 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.
68 Each hash has it's advantages and it's weaknesses. If you dont know or dont care, just go with the default.
69
70 =item MEMCACHED_BEHAVIOR_DISTRIBUTION
71
72 Using this you can enable different means of distributing values to servers.
73 The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable
74 consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT.
75 Consistent hashing delivers better distribution and allows servers to be
76 added to the cluster with minimal cache losses. Currently
77 MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value
78 MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.
79
80 =item MEMCACHED_BEHAVIOR_CACHE_LOOKUPS
81
82 Memcached can cache named lookups so that DNS lookups are made only once.
83
84 =item MEMCACHED_BEHAVIOR_SUPPORT_CAS
85
86 Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).
87
88 =item MEMCACHED_BEHAVIOR_KETAMA
89
90 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA
91 and the hash to MEMCACHED_HASH_MD5.
92
93 =item MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED
94
95 Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted support.
96 and the hash to MEMCACHED_HASH_MD5.
97
98 =item MEMCACHED_BEHAVIOR_KETAMA_HASH
99
100 Sets the hashing algorithm for host mapping on continuum. The value can be set
101 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.
102
103 =item MEMCACHED_BEHAVIOR_POLL_TIMEOUT
104
105 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.
106
107 =item MEMCACHED_BEHAVIOR_USER_DATA
108
109 This allows you to store a pointer to a specifc piece of data. This can be
110 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
111
112 will copy the pointer to the clone. This was deprecated in 0.14 in favor
113 of memcached_callback_set(3). This will be removed in 0.15.
114
115 =item MEMCACHED_BEHAVIOR_BUFFER_REQUESTS
116
117 Enabling buffered IO causes commands to "buffer" instead of being sent. Any
118 action that gets data causes this buffer to be be sent to the remote
119 connection. Quiting the connection or closing down the connection will also
120 cause the buffered data to be pushed to the remote connection.
121
122 =item MEMCACHED_BEHAVIOR_VERIFY_KEY
123
124 Enabling this will cause libmemcached(3) to test all keys to verify that they
125 are valid keys.
126
127 =item MEMCACHED_BEHAVIOR_SORT_HOSTS
128
129 Enabling this will cause hosts that are added to be placed in the host list in
130 sorted order. This will defeat consisten hashing.
131
132 =item MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT
133
134 In non-blocking mode this changes the value of the timeout during socket
135 connection.
136
137 =item MEMCACHED_BEHAVIOR_BINARY_PROTOCOL
138
139 Enable the use of the binary protocol. Please note that you cannot toggle
140 this flag on an open connection.
141
142 =item MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
143
144 Set this value to enable the server be removed after continuous MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT
145 times connection failure.
146
147 =item MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK
148
149 Set this value to tune the number of messages that may be sent before
150 libmemcached should start to automatically drain the input queue. Setting
151 this value to high, may cause libmemcached to deadlock (trying to send data,
152 but the send will block because the input buffer in the kernel is full).
153
154 =item MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK
155
156 Set this value to tune the number of bytes that may be sent before
157 libmemcached should start to automatically drain the input queue (need
158 at least 10 IO requests sent without reading the input buffer). Setting
159 this value to high, may cause libmemcached to deadlock (trying to send
160 data, but the send will block because the input buffer in the kernel is full).
161
162 =item MEMCACHED_BEHAVIOR_NOREPLY
163
164 Set this value to specify that you really don't care about the result
165 from your storage commands (set, add, replace, append, prepend). With
166 this flag enabled, each storage request will be sent immediately to the
167 server overriding any setting of MEMCACHED_BEHAVIOR_BUFFER_REQUESTS.
168
169 =back
170
171 =head1 RETURN
172
173 memcached_behavior_get() returns either the current value of the get, or 0
174 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set()
175 returns failure or success.
176
177 =head1 NOTES
178
179 memcached_behavior_set() in version .17 was changed from taking a pointer
180 to data value, to taking a uin64_t.
181
182 =head1 HOME
183
184 To find out more information please check:
185 L<http://tangent.org/552/libmemcached.html>
186
187 =head1 AUTHOR
188
189 Brian Aker, E<lt>brian@tangent.orgE<gt>
190
191 =head1 SEE ALSO
192
193 memcached(1) libmemcached(3) memcached_strerror(3)
194
195 =cut
196