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.TH "MEMCACHED_CALLBACK_SET" "3" "February 09, 2014" "1.0.18" "libmemcached"
.SH NAME
memcached_callback_set \- libmemcached Documentation
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Get and set a callback
.SH SYNOPSIS
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#include <libmemcached/memcached.h>
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.TP
.B memcached_callback_t
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.B memcached_return_t memcached_callback_set(memcached_st\fI\ *ptr\fP, \fI\%memcached_callback_t\fP\fI\ flag\fP, const void\fI\ *data\fP)
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.B void * memcached_callback_get(memcached_st\fI\ *ptr\fP, \fI\%memcached_callback_t\fP\fI\ flag\fP, memcached_return_t\fI\ *error\fP)
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Compile and link with \-lmemcached
.SH DESCRIPTION
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libmemcached(3) can have callbacks set key execution points. These either
provide function calls at points in the code, or return pointers to
structures for particular usages.
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\fI\%memcached_callback_get()\fP takes a callback flag and returns the
structure or function set by \fI\%memcached_callback_set()\fP\&.
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\fI\%memcached_callback_set()\fP changes the function/structure assigned by a
callback flag. No connections are reset.
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You can use \fI\%MEMCACHED_CALLBACK_USER_DATA\fP to provide custom context
if required for any of the callbacks.
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.B MEMCACHED_CALLBACK_CLEANUP_FUNCTION
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When \fBmemcached_delete()\fP is called this function will be excuted. At
the point of its execution all connections are closed.
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.B MEMCACHED_CALLBACK_CLONE_FUNCTION
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When \fBmemcached_delete()\fP is called this function will be excuted.
At the point of its execution all connections are closed.
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.B MEMCACHED_CALLBACK_PREFIX_KEY
See \fI\%MEMCACHED_CALLBACK_NAMESPACE\fP
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.B MEMCACHED_CALLBACK_NAMESPACE
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You can set a value which will be used to create a domain for your keys.
The value specified here will be prefixed to each of your keys. The value can
not be greater then \fBMEMCACHED_PREFIX_KEY_MAX_SIZE\fP \- 1 and will
reduce \fBMEMCACHED_MAX_KEY\fP by the value of your key.
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The prefix key is only applied to the primary key, not the master key.
\fBMEMCACHED_FAILURE\fP will be returned if no key is set. In the case of
a key which is too long, \fBMEMCACHED_BAD_KEY_PROVIDED\fP will be returned.
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If you set a value with the value being NULL then the prefix key is disabled.
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.B MEMCACHED_CALLBACK_USER_DATA
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This allows you to store a pointer to a specifc piece of data. This can be
retrieved from inside of \fBmemcached_fetch_execute()\fP\&. Cloning a
\fBmemcached_st\fP will copy the pointer to the clone.
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.B MEMCACHED_CALLBACK_MALLOC_FUNCTION
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Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
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.B MEMCACHED_CALLBACK_REALLOC_FUNCTION
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Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
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.B MEMCACHED_CALLBACK_FREE_FUNCTION
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Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
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.B MEMCACHED_CALLBACK_GET_FAILURE
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This function implements the read through cache behavior. On failure of retrieval this callback will be called.
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You are responsible for populating the result object provided. This result object will then be stored in the server and returned to the calling process.
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You must clone the \fBmemcached_st\fP in order to
make use of it. The value will be stored only if you return
\fBMEMCACHED_SUCCESS\fP or \fBMEMCACHED_BUFFERED\fP\&. Returning
\fBMEMCACHED_BUFFERED\fP will cause the object to be buffered and not sent
immediatly (if this is the default behavior based on your connection setup
this will happen automatically).
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The prototype for this is:
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.B memcached_return_t (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
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.B MEMCACHED_CALLBACK_DELETE_TRIGGER
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This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned in order to make use of it.
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The prototype for this is:
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.B typedef memcached_return_t (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
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.SH RETURN
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\fI\%memcached_callback_get()\fP return the function or structure that was
provided. Upon error, nothing is set, null is returned, and the
\fBmemcached_return_t\fP argument is set to \fBMEMCACHED_FAILURE\fP\&.
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\fI\%memcached_callback_set()\fP returns \fBMEMCACHED_SUCCESS\fP upon
successful setting, otherwise \fBMEMCACHED_FAILURE\fP on error.
.SH HOME
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To find out more information please check:
\fI\%http://libmemcached.org/\fP
.SH AUTHOR
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Brian Aker, <\fI\%brian@tangent.org\fP>
.SH SEE ALSO
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\fImemcached(1)\fP \fIlibmemcached(3)\fP \fImemcached_strerror(3)\fP
.SH AUTHOR
Brian Aker
.SH COPYRIGHT
2011-2013, Brian Aker DataDifferential, http://datadifferential.com/
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