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181 <li>Generating hash values directly
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198 <div class=
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"generating-hash-values-directly">
199 <h1>Generating hash values directly
<a class=
"headerlink" href=
"#generating-hash-values-directly" title=
"Permalink to this headline">¶
</a></h1>
200 <p>Hash a key value
</p>
201 <div class=
"section" id=
"synopsis">
202 <h2>SYNOPSIS
<a class=
"headerlink" href=
"#synopsis" title=
"Permalink to this headline">¶
</a></h2>
203 <dl class=
"docutils">
204 <dt>#include
<libmemcached/memcached.h
></dt>
205 <dd>Compile and link with -lmemcachedutil -lmemcached
</dd>
207 <dl class=
"function">
208 <dt id=
"_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t">
209 <span id=
"_CPPv329memcached_generate_hash_valuePKc6size_t16memcached_hash_t"></span><span id=
"_CPPv229memcached_generate_hash_valuePKc6size_t16memcached_hash_t"></span><span id=
"memcached_generate_hash_value__cCP.s.memcached_hash_t"></span>uint32_t
<code class=
"descname">memcached_generate_hash_value
</code><span class=
"sig-paren">(
</span><em class=
"property">const
</em> char *
<em>key
</em>, size_t
<em>key_length
</em>,
<a class=
"reference internal" href=
"#_CPPv416memcached_hash_t" title=
"memcached_hash_t">memcached_hash_t
</a> <em>hash_algorithm
</em><span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title=
"Permalink to this definition">¶
</a><br /></dt>
210 <dd><table class=
"docutils field-list" frame=
"void" rules=
"none">
211 <col class=
"field-name" />
212 <col class=
"field-body" />
214 <tr class=
"field-odd field"><th class=
"field-name">Parameters:
</th><td class=
"field-body"><ul class=
"first simple">
215 <li><strong>key
</strong> -- the key to generate a hash of
</li>
216 <li><strong>key_length
</strong> -- the length of the
<a class=
"reference internal" href=
"#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title=
"memcached_generate_hash_value::key"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">key
</span></code></a> without any terminating zero
</li>
217 <li><strong>hash_algorithm
</strong> --
<a class=
"reference internal" href=
"#_CPPv416memcached_hash_t" title=
"memcached_hash_t"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">memcached_hash_t
</span></code></a>, the algorithm to use
</li>
221 <tr class=
"field-even field"><th class=
"field-name">Returns:
</th><td class=
"field-body"><p class=
"first last">a
32 bit hash value
</p>
228 <dl class=
"function">
229 <dt id=
"_CPPv423memcached_generate_hashP12memcached_stPKc6size_t">
230 <span id=
"_CPPv323memcached_generate_hashP12memcached_stPKc6size_t"></span><span id=
"_CPPv223memcached_generate_hashP12memcached_stPKc6size_t"></span><span id=
"memcached_generate_hash__memcached_stP.cCP.s"></span>uint32_t
<code class=
"descname">memcached_generate_hash
</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>,
<em class=
"property">const
</em> char *
<em>key
</em>, size_t
<em>key_length
</em><span class=
"sig-paren">)
</span><a class=
"headerlink" href=
"#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title=
"Permalink to this definition">¶
</a><br /></dt>
231 <dd><table class=
"docutils field-list" frame=
"void" rules=
"none">
232 <col class=
"field-name" />
233 <col class=
"field-body" />
235 <tr class=
"field-odd field"><th class=
"field-name">Parameters:
</th><td class=
"field-body"><ul class=
"first simple">
236 <li><strong>ptr
</strong> -- pointer to an 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
</li>
237 <li><strong>key
</strong> -- the key to generate a hash of
</li>
238 <li><strong>key_length
</strong> -- the length of the
<a class=
"reference internal" href=
"#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title=
"memcached_generate_hash::key"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">key
</span></code></a> without any terminating zero
</li>
242 <tr class=
"field-even field"><th class=
"field-name">Returns:
</th><td class=
"field-body"><p class=
"first last">a
32 bit hash value
</p>
250 <dt id=
"c.memcached_hash_t">
251 enum
<a class=
"reference internal" href=
"#c.memcached_hash_t" title=
"memcached_hash_t">memcached_hash_t
</a> <code class=
"descname">memcached_hash_t
</code><a class=
"headerlink" href=
"#c.memcached_hash_t" title=
"Permalink to this definition">¶
</a></dt>
255 <dt id=
"_CPPv416memcached_hash_t">
256 <span id=
"_CPPv316memcached_hash_t"></span><span id=
"_CPPv216memcached_hash_t"></span><em class=
"property">enum
</em><code class=
"descname">memcached_hash_t
</code><a class=
"headerlink" href=
"#_CPPv416memcached_hash_t" title=
"Permalink to this definition">¶
</a><br /></dt>
257 <dd><dl class=
"enumerator">
258 <dt id=
"_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE">
259 <span id=
"_CPPv3N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><span id=
"_CPPv2N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_DEFAULT
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE" title=
"Permalink to this definition">¶
</a><br /></dt>
262 <dl class=
"enumerator">
263 <dt id=
"_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E">
264 <span id=
"_CPPv3N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><span id=
"_CPPv2N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_MD5
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E" title=
"Permalink to this definition">¶
</a><br /></dt>
267 <dl class=
"enumerator">
268 <dt id=
"_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE">
269 <span id=
"_CPPv3N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><span id=
"_CPPv2N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_CRC
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE" title=
"Permalink to this definition">¶
</a><br /></dt>
272 <dl class=
"enumerator">
273 <dt id=
"_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E">
274 <span id=
"_CPPv3N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E"></span><span id=
"_CPPv2N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_FNV1_64
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E" title=
"Permalink to this definition">¶
</a><br /></dt>
277 <dl class=
"enumerator">
278 <dt id=
"_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E">
279 <span id=
"_CPPv3N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E"></span><span id=
"_CPPv2N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_FNV1A_64
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E" title=
"Permalink to this definition">¶
</a><br /></dt>
282 <dl class=
"enumerator">
283 <dt id=
"_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E">
284 <span id=
"_CPPv3N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E"></span><span id=
"_CPPv2N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_FNV1_32
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E" title=
"Permalink to this definition">¶
</a><br /></dt>
287 <dl class=
"enumerator">
288 <dt id=
"_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E">
289 <span id=
"_CPPv3N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E"></span><span id=
"_CPPv2N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_FNV1A_32
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E" title=
"Permalink to this definition">¶
</a><br /></dt>
292 <dl class=
"enumerator">
293 <dt id=
"_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE">
294 <span id=
"_CPPv3N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><span id=
"_CPPv2N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_HSIEH
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE" title=
"Permalink to this definition">¶
</a><br /></dt>
297 <dl class=
"enumerator">
298 <dt id=
"_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE">
299 <span id=
"_CPPv3N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><span id=
"_CPPv2N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_MURMUR
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE" title=
"Permalink to this definition">¶
</a><br /></dt>
302 <dl class=
"enumerator">
303 <dt id=
"_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE">
304 <span id=
"_CPPv3N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><span id=
"_CPPv2N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_JENKINS
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE" title=
"Permalink to this definition">¶
</a><br /></dt>
307 <dl class=
"enumerator">
308 <dt id=
"_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E">
309 <span id=
"_CPPv3N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><span id=
"_CPPv2N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_MURMUR3
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E" title=
"Permalink to this definition">¶
</a><br /></dt>
312 <dl class=
"enumerator">
313 <dt id=
"_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME">
314 <span id=
"_CPPv3N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><span id=
"_CPPv2N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><em class=
"property">enumerator
</em><code class=
"descname">MEMCACHED_HASH_CUSTOM
</code><a class=
"headerlink" href=
"#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME" title=
"Permalink to this definition">¶
</a><br /></dt>
320 <div class=
"section" id=
"description">
321 <h2>DESCRIPTION
<a class=
"headerlink" href=
"#description" title=
"Permalink to this headline">¶
</a></h2>
322 <p><a class=
"reference internal" href=
"#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title=
"memcached_generate_hash_value"><code class=
"xref cpp cpp-func docutils literal notranslate"><span class=
"pre">memcached_generate_hash_value()
</span></code></a> allows you to hash a key using one of
323 the hash functions defined in the library. This method is provided for
324 the convenience of higher-level language bindings and is not necessary
325 for normal memcache operations.
</p>
326 <p>Support for
<a class=
"reference internal" href=
"#_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE" title=
"MEMCACHED_HASH_HSIEH"><code class=
"xref cpp cpp-any docutils literal notranslate"><span class=
"pre">MEMCACHED_HASH_HSIEH
</span></code></a> is a compile time option that is
327 disabled by default. To enable tests for this hashing algorithm,
328 configure and build libmemcached with the Hsieh hash enabled.
</p>
329 <p><a class=
"reference internal" href=
"#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title=
"memcached_generate_hash"><code class=
"xref cpp cpp-func docutils literal notranslate"><span class=
"pre">memcached_generate_hash()
</span></code></a> takes a
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-type docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a> structure
330 and produces the hash value that would have been generated based on the
331 defaults of
<a class=
"reference internal" href=
"memcached_create.html#_CPPv412memcached_st" title=
"memcached_st"><code class=
"xref cpp cpp-type docutils literal notranslate"><span class=
"pre">memcached_st
</span></code></a>.
</p>
332 <p>As of version
0.36 all hash methods have been placed into the library
333 libhashkit(
3) which is linked with libmemcached(
3). For more information please see its documentation.
</p>
335 <div class=
"section" id=
"return-value">
336 <h2>RETURN VALUE
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337 <p>A
32-bit integer which is the result of hashing the given key.
338 For
64-bit hash algorithms, only the least-significant
32 bits are
341 <div class=
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342 <h2>SEE ALSO
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