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203 <h1>Library callbacks
<a class=
"headerlink" href=
"#library-callbacks" title=
"Permalink to this headline">¶
</a></h1>
204 <div class=
"section" id=
"synopsis">
205 <h2>SYNOPSIS
<a class=
"headerlink" href=
"#synopsis" title=
"Permalink to this headline">¶
</a></h2>
207 <dt>#include
<libmemcached/memcached.h
></dt><dd><p>Compile and link with -lmemcached
</p>
210 <dl class=
"cpp function">
211 <dt id=
"_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv">
212 <span id=
"_CPPv322memcached_callback_setP12memcached_st20memcached_callback_tPKv"></span><span id=
"_CPPv222memcached_callback_setP12memcached_st20memcached_callback_tPKv"></span><span id=
"memcached_callback_set__memcached_stP.memcached_callback_t.voidCP"></span><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> <code class=
"sig-name descname">memcached_callback_set
</code><span class=
"sig-paren">(
</span><a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *
<em>ptr
</em>,
<a class=
"reference internal" href=
"#_CPPv420memcached_callback_t" title=
"memcached_callback_t">memcached_callback_t
</a> <em>flag
</em>,
<em class=
"property">const
</em> void *
<em>data
</em><span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv" title=
"Permalink to this definition">¶
</a><br /></dt>
213 <dd><dl class=
"field-list simple">
214 <dt class=
"field-odd">Parameters
</dt>
215 <dd class=
"field-odd"><ul class=
"simple">
216 <li><p><strong>ptr
</strong> -- pointer to initialized
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> struct
</p></li>
217 <li><p><strong>flag
</strong> --
<a class=
"reference internal" href=
"#_CPPv420memcached_callback_t" title=
"memcached_callback_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_t
</span></code></a> flag to set
</p></li>
218 <li><p><strong>data
</strong> -- data corresponding to
<a class=
"reference internal" href=
"#_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv" title=
"memcached_callback_set::flag"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">flag
</span></code></a></p></li>
221 <dt class=
"field-even">Returns
</dt>
222 <dd class=
"field-even"><p><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_return_t
</span></code></a> indicating success
</p>
227 <dl class=
"cpp function">
228 <dt id=
"_CPPv422memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t">
229 <span id=
"_CPPv322memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t"></span><span id=
"_CPPv222memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t"></span><span id=
"memcached_callback_get__memcached_stP.memcached_callback_t.memcached_return_tP"></span>void *
<code class=
"sig-name descname">memcached_callback_get
</code><span class=
"sig-paren">(
</span><a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *
<em>ptr
</em>,
<a class=
"reference internal" href=
"#_CPPv420memcached_callback_t" title=
"memcached_callback_t">memcached_callback_t
</a> <em>flag
</em>,
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> *
<em>error
</em><span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv422memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t" title=
"Permalink to this definition">¶
</a><br /></dt>
230 <dd><dl class=
"field-list simple">
231 <dt class=
"field-odd">Parameters
</dt>
232 <dd class=
"field-odd"><ul class=
"simple">
233 <li><p><strong>ptr
</strong> -- pointer to initialized
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> struct
</p></li>
234 <li><p><strong>flag
</strong> --
<a class=
"reference internal" href=
"#_CPPv420memcached_callback_t" title=
"memcached_callback_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_t
</span></code></a> flag to query
</p></li>
235 <li><p><strong>error
</strong> -- pointer to
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_return_t
</span></code></a> indicating success
</p></li>
238 <dt class=
"field-even">Returns
</dt>
239 <dd class=
"field-even"><p>the
<code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">data
</span></code> previously set
</p>
245 <dt id=
"c.memcached_callback_t">
246 <em class=
"property">typedef
</em><em class=
"property">enum
</em> <a class=
"reference internal" href=
"#c.memcached_callback_t" title=
"memcached_callback_t">memcached_callback_t
</a> <code class=
"sig-name descname">memcached_callback_t
</code><a class=
"headerlink" href=
"#c.memcached_callback_t" title=
"Permalink to this definition">¶
</a><br /></dt>
249 <dl class=
"cpp enum">
250 <dt id=
"_CPPv420memcached_callback_t">
251 <span id=
"_CPPv320memcached_callback_t"></span><span id=
"_CPPv220memcached_callback_t"></span><em class=
"property">enum
</em><code class=
"sig-name descname">memcached_callback_t
</code><a class=
"headerlink" href=
"#_CPPv420memcached_callback_t" title=
"Permalink to this definition">¶
</a><br /></dt>
252 <dd><dl class=
"cpp enumerator">
253 <dt id=
"_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTIONE">
254 <span id=
"_CPPv3N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTIONE"></span><span id=
"_CPPv2N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTIONE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_CLEANUP_FUNCTION
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTIONE" title=
"Permalink to this definition">¶
</a><br /></dt>
255 <dd><p>When
<a class=
"reference internal" href=
"memcached_create.html#_CPPv414memcached_freeP12memcached_st" title=
"memcached_free"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_free()
</span></code></a> or
<code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_reset
</span></code> is called this function
256 will be executed. At the point of its execution all connections are closed.
</p>
257 <p>Its signature is:
</p>
258 <dl class=
"cpp type">
259 <dt id=
"_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTION20memcached_cleanup_fnE">
260 <span id=
"_CPPv3N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTION20memcached_cleanup_fnE"></span><span id=
"_CPPv2N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTION20memcached_cleanup_fnE"></span><span id=
"memcached_callback_t::MEMCACHED_CALLBACK_CLEANUP_FUNCTION::memcached_cleanup_fn"></span><em class=
"property">typedef
</em><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> (*
<code class=
"sig-name descname">memcached_cleanup_fn
</code>)
<span class=
"sig-paren">(
</span><em class=
"property">const
</em> <a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *ptr
<span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_CLEANUP_FUNCTION20memcached_cleanup_fnE" title=
"Permalink to this definition">¶
</a><br /></dt>
265 <dl class=
"cpp enumerator">
266 <dt id=
"_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTIONE">
267 <span id=
"_CPPv3N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTIONE"></span><span id=
"_CPPv2N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTIONE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_CLONE_FUNCTION
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTIONE" title=
"Permalink to this definition">¶
</a><br /></dt>
268 <dd><p>When
<a class=
"reference internal" href=
"memcached_create.html#_CPPv415memcached_cloneP12memcached_stP12memcached_st" title=
"memcached_clone"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_clone()
</span></code></a> is called this function will be executed.
</p>
269 <p>Its signature is:
</p>
270 <dl class=
"cpp type">
271 <dt id=
"_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTION18memcached_clone_fnE">
272 <span id=
"_CPPv3N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTION18memcached_clone_fnE"></span><span id=
"_CPPv2N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTION18memcached_clone_fnE"></span><span id=
"memcached_callback_t::MEMCACHED_CALLBACK_CLONE_FUNCTION::memcached_clone_fn"></span><em class=
"property">typedef
</em><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> (*
<code class=
"sig-name descname">memcached_clone_fn
</code>)
<span class=
"sig-paren">(
</span><a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *destination,
<em class=
"property">const
</em> <a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *source
<span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_CLONE_FUNCTION18memcached_clone_fnE" title=
"Permalink to this definition">¶
</a><br /></dt>
277 <dl class=
"cpp enumerator">
278 <dt id=
"_CPPv4N20memcached_callback_t29MEMCACHED_CALLBACK_PREFIX_KEYE">
279 <span id=
"_CPPv3N20memcached_callback_t29MEMCACHED_CALLBACK_PREFIX_KEYE"></span><span id=
"_CPPv2N20memcached_callback_t29MEMCACHED_CALLBACK_PREFIX_KEYE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_PREFIX_KEY
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t29MEMCACHED_CALLBACK_PREFIX_KEYE" title=
"Permalink to this definition">¶
</a><br /></dt>
280 <dd><p>See
<a class=
"reference internal" href=
"#_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_NAMESPACEE" title=
"memcached_callback_t::MEMCACHED_CALLBACK_NAMESPACE"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_CALLBACK_NAMESPACE
</span></code></a>.
</p>
283 <dl class=
"cpp enumerator">
284 <dt id=
"_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_NAMESPACEE">
285 <span id=
"_CPPv3N20memcached_callback_t28MEMCACHED_CALLBACK_NAMESPACEE"></span><span id=
"_CPPv2N20memcached_callback_t28MEMCACHED_CALLBACK_NAMESPACEE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_NAMESPACE
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_NAMESPACEE" title=
"Permalink to this definition">¶
</a><br /></dt>
286 <dd><p>You can set a value which will be used to create a domain for your keys.
287 The value specified here will be prefixed to each of your keys. The
288 value can not be greater then
<a class=
"reference internal" href=
"constants.html#c.MEMCACHED_MAX_NAMESPACE" title=
"MEMCACHED_MAX_NAMESPACE"><code class=
"xref c c-macro docutils literal notranslate"><span class=
"pre">MEMCACHED_MAX_NAMESPACE
</span></code></a> -
1 and
289 will reduce
<a class=
"reference internal" href=
"constants.html#c.MEMCACHED_MAX_KEY" title=
"MEMCACHED_MAX_KEY"><code class=
"xref c c-macro docutils literal notranslate"><span class=
"pre">MEMCACHED_MAX_KEY
</span></code></a> by the value of your key.
</p>
290 <p>The prefix key is only applied to the primary key, not the master key.
291 <a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_FAILUREE" title=
"MEMCACHED_FAILURE"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_FAILURE
</span></code></a> will be returned if no key is set. In the case of a
292 key which is too long,
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t26MEMCACHED_BAD_KEY_PROVIDEDE" title=
"MEMCACHED_BAD_KEY_PROVIDED"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_BAD_KEY_PROVIDED
</span></code></a> will be returned.
</p>
293 <p>If you set a value with the value being NULL then the prefix key is
297 <dl class=
"cpp enumerator">
298 <dt id=
"_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_USER_DATAE">
299 <span id=
"_CPPv3N20memcached_callback_t28MEMCACHED_CALLBACK_USER_DATAE"></span><span id=
"_CPPv2N20memcached_callback_t28MEMCACHED_CALLBACK_USER_DATAE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_USER_DATA
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_USER_DATAE" title=
"Permalink to this definition">¶
</a><br /></dt>
300 <dd><p>This allows you to store a pointer to a specific piece of data. This can
301 be retrieved from inside of
<a class=
"reference internal" href=
"memcached_get.html#_CPPv423memcached_fetch_executeP12memcached_stP20memcached_execute_fnPv8uint32_t" title=
"memcached_fetch_execute"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_fetch_execute()
</span></code></a>. Cloning a
302 <a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> will copy the pointer to the clone.
</p>
305 <dl class=
"cpp enumerator">
306 <dt id=
"_CPPv4N20memcached_callback_t34MEMCACHED_CALLBACK_MALLOC_FUNCTIONE">
307 <span id=
"_CPPv3N20memcached_callback_t34MEMCACHED_CALLBACK_MALLOC_FUNCTIONE"></span><span id=
"_CPPv2N20memcached_callback_t34MEMCACHED_CALLBACK_MALLOC_FUNCTIONE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_MALLOC_FUNCTION
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t34MEMCACHED_CALLBACK_MALLOC_FUNCTIONE" title=
"Permalink to this definition">¶
</a><br /></dt>
308 <dd><div class=
"deprecated">
309 <p><span class=
"versionmodified deprecated">Deprecated since version
<0.32:
</span>Use
<a class=
"reference internal" href=
"memcached_memory_allocators.html#_CPPv431memcached_set_memory_allocatorsP12memcached_st19memcached_malloc_fn17memcached_free_fn20memcached_realloc_fn19memcached_calloc_fnPv" title=
"memcached_set_memory_allocators"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_set_memory_allocators()
</span></code></a> instead.
</p>
313 <dl class=
"cpp enumerator">
314 <dt id=
"_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_REALLOC_FUNCTIONE">
315 <span id=
"_CPPv3N20memcached_callback_t35MEMCACHED_CALLBACK_REALLOC_FUNCTIONE"></span><span id=
"_CPPv2N20memcached_callback_t35MEMCACHED_CALLBACK_REALLOC_FUNCTIONE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_REALLOC_FUNCTION
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t35MEMCACHED_CALLBACK_REALLOC_FUNCTIONE" title=
"Permalink to this definition">¶
</a><br /></dt>
316 <dd><div class=
"deprecated">
317 <p><span class=
"versionmodified deprecated">Deprecated since version
<0.32:
</span>Use
<a class=
"reference internal" href=
"memcached_memory_allocators.html#_CPPv431memcached_set_memory_allocatorsP12memcached_st19memcached_malloc_fn17memcached_free_fn20memcached_realloc_fn19memcached_calloc_fnPv" title=
"memcached_set_memory_allocators"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_set_memory_allocators()
</span></code></a> instead.
</p>
321 <dl class=
"cpp enumerator">
322 <dt id=
"_CPPv4N20memcached_callback_t32MEMCACHED_CALLBACK_FREE_FUNCTIONE">
323 <span id=
"_CPPv3N20memcached_callback_t32MEMCACHED_CALLBACK_FREE_FUNCTIONE"></span><span id=
"_CPPv2N20memcached_callback_t32MEMCACHED_CALLBACK_FREE_FUNCTIONE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_FREE_FUNCTION
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t32MEMCACHED_CALLBACK_FREE_FUNCTIONE" title=
"Permalink to this definition">¶
</a><br /></dt>
324 <dd><div class=
"deprecated">
325 <p><span class=
"versionmodified deprecated">Deprecated since version
<0.32:
</span>Use
<a class=
"reference internal" href=
"memcached_memory_allocators.html#_CPPv431memcached_set_memory_allocatorsP12memcached_st19memcached_malloc_fn17memcached_free_fn20memcached_realloc_fn19memcached_calloc_fnPv" title=
"memcached_set_memory_allocators"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_set_memory_allocators()
</span></code></a> instead.
</p>
329 <dl class=
"cpp enumerator">
330 <dt id=
"_CPPv4N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILUREE">
331 <span id=
"_CPPv3N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILUREE"></span><span id=
"_CPPv2N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILUREE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_GET_FAILURE
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILUREE" title=
"Permalink to this definition">¶
</a><br /></dt>
332 <dd><p>This function implements the read through cache behavior. On failure of
333 retrieval this callback will be called.
</p>
334 <p>You are responsible for populating the result object provided. This
335 result object will then be stored in the server and returned to the
337 <p>You must clone the
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> in order to make use of it. The value
338 will be stored only if you return
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_SUCCESSE" title=
"MEMCACHED_SUCCESS"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_SUCCESS
</span></code></a> or
339 <a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t18MEMCACHED_BUFFEREDE" title=
"MEMCACHED_BUFFERED"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_BUFFERED
</span></code></a>. Returning
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t18MEMCACHED_BUFFEREDE" title=
"MEMCACHED_BUFFERED"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_BUFFERED
</span></code></a> will cause the
340 object to be buffered and not sent immediately (if this is the default
341 behavior based on your connection setup this will happen automatically).
</p>
342 <p>The prototype for this is:
</p>
343 <dl class=
"cpp type">
344 <dt id=
"_CPPv4N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILURE21memcached_trigger_keyE">
345 <span id=
"_CPPv3N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILURE21memcached_trigger_keyE"></span><span id=
"_CPPv2N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILURE21memcached_trigger_keyE"></span><span id=
"memcached_callback_t::MEMCACHED_CALLBACK_GET_FAILURE::memcached_trigger_key"></span><em class=
"property">typedef
</em><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> (*
<code class=
"sig-name descname">memcached_trigger_key
</code>)
<span class=
"sig-paren">(
</span><a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *ptr, char *key, size_t key_length,
<a class=
"reference internal" href=
"memcached_result_st.html#_CPPv419memcached_result_st" title=
"memcached_result_st">memcached_result_st
</a> *result
<span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t30MEMCACHED_CALLBACK_GET_FAILURE21memcached_trigger_keyE" title=
"Permalink to this definition">¶
</a><br /></dt>
350 <dl class=
"cpp enumerator">
351 <dt id=
"_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGERE">
352 <span id=
"_CPPv3N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGERE"></span><span id=
"_CPPv2N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGERE"></span><em class=
"property">enumerator
</em><code class=
"sig-name descname">MEMCACHED_CALLBACK_DELETE_TRIGGER
</code><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGERE" title=
"Permalink to this definition">¶
</a><br /></dt>
353 <dd><p>This function implements a trigger upon successful deletion of a key.
354 The
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> structure will need to be cloned in order to make use
356 <p>The prototype for this is:
</p>
357 <dl class=
"cpp type">
358 <dt id=
"_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGER28memcached_trigger_delete_keyE">
359 <span id=
"_CPPv3N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGER28memcached_trigger_delete_keyE"></span><span id=
"_CPPv2N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGER28memcached_trigger_delete_keyE"></span><span id=
"memcached_callback_t::MEMCACHED_CALLBACK_DELETE_TRIGGER::memcached_trigger_delete_key"></span><em class=
"property">typedef
</em><a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t">memcached_return_t
</a> (*
<code class=
"sig-name descname">memcached_trigger_delete_key
</code>)
<span class=
"sig-paren">(
</span><a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st">memcached_st
</a> *ptr, char *key, size_t key_length
<span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv4N20memcached_callback_t33MEMCACHED_CALLBACK_DELETE_TRIGGER28memcached_trigger_delete_keyE" title=
"Permalink to this definition">¶
</a><br /></dt>
367 <div class=
"section" id=
"description">
368 <h2>DESCRIPTION
<a class=
"headerlink" href=
"#description" title=
"Permalink to this headline">¶
</a></h2>
369 <p><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">libmemcached
</span></code> can have callbacks set key execution points. These either provide
370 function calls at points in the code, or return pointers to structures for
371 particular usages.
</p>
372 <p><a class=
"reference internal" href=
"#_CPPv422memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t" title=
"memcached_callback_get"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_get()
</span></code></a> takes a callback flag and returns the structure or
373 function set by
<a class=
"reference internal" href=
"#_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv" title=
"memcached_callback_set"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_set()
</span></code></a>.
</p>
374 <p><a class=
"reference internal" href=
"#_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv" title=
"memcached_callback_set"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_set()
</span></code></a> changes the function/structure assigned by a callback
375 flag. No connections are reset.
</p>
376 <p>You can use
<a class=
"reference internal" href=
"#_CPPv4N20memcached_callback_t28MEMCACHED_CALLBACK_USER_DATAE" title=
"MEMCACHED_CALLBACK_USER_DATA"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_CALLBACK_USER_DATA
</span></code></a> to provide custom context if required
377 for any of the callbacks.
</p>
379 <div class=
"section" id=
"return-value">
380 <h2>RETURN VALUE
<a class=
"headerlink" href=
"#return-value" title=
"Permalink to this headline">¶
</a></h2>
381 <p><a class=
"reference internal" href=
"#_CPPv422memcached_callback_getP12memcached_st20memcached_callback_tP18memcached_return_t" title=
"memcached_callback_get"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_get()
</span></code></a> returns the function or structure that was provided.
382 Upon error, nothing is set, NULL is returned, and the
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv418memcached_return_t" title=
"memcached_return_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_return_t
</span></code></a>
383 argument is set to
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_FAILUREE" title=
"MEMCACHED_FAILURE"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_FAILURE
</span></code></a>.
</p>
384 <p><a class=
"reference internal" href=
"#_CPPv422memcached_callback_setP12memcached_st20memcached_callback_tPKv" title=
"memcached_callback_set"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_callback_set()
</span></code></a> returns
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_SUCCESSE" title=
"MEMCACHED_SUCCESS"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_SUCCESS
</span></code></a> upon successful setting,
385 otherwise
<a class=
"reference internal" href=
"memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_FAILUREE" title=
"MEMCACHED_FAILURE"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_FAILURE
</span></code></a> on error.
</p>
387 <div class=
"section" id=
"see-also">
388 <h2>SEE ALSO
<a class=
"headerlink" href=
"#see-also" title=
"Permalink to this headline">¶
</a></h2>
390 <li><p><em class=
"manpage"><a class=
"manpage reference external" href=
"https://linux.die.net/man/1/memcached">memcached(
1)
</a></em></p></li>
391 <li><p><a class=
"reference internal" href=
"../libmemcached.html"><span class=
"doc">C/C++ Client Library for memcached
</span></a></p></li>
392 <li><p><a class=
"reference internal" href=
"memcached_strerror.html"><span class=
"doc">Converting Error Codes to Messages
</span></a></p></li>
403 <div class=
"rst-footer-buttons" role=
"navigation" aria-label=
"footer navigation">
405 <a href=
"memcached_memory_allocators.html" class=
"btn btn-neutral float-right" title=
"Use custom allocators for embedded usage" accesskey=
"n" rel=
"next">Next
<span class=
"fa fa-arrow-circle-right"></span></a>
408 <a href=
"memcached_behavior.html" class=
"btn btn-neutral float-left" title=
"Behaviors of the library" accesskey=
"p" rel=
"prev"><span class=
"fa fa-arrow-circle-left"></span> Previous
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