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189
190 <div class="section" id="generating-hash-values-directly">
191 <h1>Generating hash values directly<a class="headerlink" href="#generating-hash-values-directly" title="Permalink to this headline"></a></h1>
192 <p>Hash a key value</p>
193 <div class="section" id="synopsis">
194 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline"></a></h2>
195 <dl class="docutils">
196 <dt>#include &lt;libmemcached/memcached.h&gt;</dt>
197 <dd>Compile and link with -lmemcachedutil -lmemcached</dd>
198 </dl>
199 <dl class="function">
200 <dt id="_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t">
201 <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>
202 <dd><table class="docutils field-list" frame="void" rules="none">
203 <col class="field-name" />
204 <col class="field-body" />
205 <tbody valign="top">
206 <tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
207 <li><strong>key</strong> -- the key to generate a hash of</li>
208 <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>
209 <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>
210 </ul>
211 </td>
212 </tr>
213 <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>
214 </td>
215 </tr>
216 </tbody>
217 </table>
218 </dd></dl>
219
220 <dl class="function">
221 <dt id="_CPPv423memcached_generate_hashP12memcached_stPKc6size_t">
222 <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>
223 <dd><table class="docutils field-list" frame="void" rules="none">
224 <col class="field-name" />
225 <col class="field-body" />
226 <tbody valign="top">
227 <tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
228 <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>
229 <li><strong>key</strong> -- the key to generate a hash of</li>
230 <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>
231 </ul>
232 </td>
233 </tr>
234 <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>
235 </td>
236 </tr>
237 </tbody>
238 </table>
239 </dd></dl>
240
241 <dl class="type">
242 <dt id="c.memcached_hash_t">
243 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>
244 <dd></dd></dl>
245
246 <dl class="enum">
247 <dt id="_CPPv416memcached_hash_t">
248 <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>
249 <dd><dl class="enumerator">
250 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE">
251 <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>
252 <dd></dd></dl>
253
254 <dl class="enumerator">
255 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E">
256 <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>
257 <dd></dd></dl>
258
259 <dl class="enumerator">
260 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE">
261 <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>
262 <dd></dd></dl>
263
264 <dl class="enumerator">
265 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E">
266 <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>
267 <dd></dd></dl>
268
269 <dl class="enumerator">
270 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E">
271 <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>
272 <dd></dd></dl>
273
274 <dl class="enumerator">
275 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E">
276 <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>
277 <dd></dd></dl>
278
279 <dl class="enumerator">
280 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E">
281 <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>
282 <dd></dd></dl>
283
284 <dl class="enumerator">
285 <dt id="_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE">
286 <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>
287 <dd></dd></dl>
288
289 <dl class="enumerator">
290 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE">
291 <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>
292 <dd></dd></dl>
293
294 <dl class="enumerator">
295 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE">
296 <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>
297 <dd></dd></dl>
298
299 <dl class="enumerator">
300 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E">
301 <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>
302 <dd></dd></dl>
303
304 <dl class="enumerator">
305 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME">
306 <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>
307 <dd></dd></dl>
308
309 </dd></dl>
310
311 </div>
312 <div class="section" id="description">
313 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
314 <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
315 the hash functions defined in the library. This method is provided for
316 the convenience of higher-level language bindings and is not necessary
317 for normal memcache operations.</p>
318 <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
319 disabled by default. To enable tests for this hashing algorithm,
320 configure and build libmemcached with the Hsieh hash enabled.</p>
321 <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
322 and produces the hash value that would have been generated based on the
323 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>
324 <p>As of version 0.36 all hash methods have been placed into the library
325 libhashkit(3) which is linked with libmemcached(3). For more information please see its documentation.</p>
326 </div>
327 <div class="section" id="return-value">
328 <h2>RETURN VALUE<a class="headerlink" href="#return-value" title="Permalink to this headline"></a></h2>
329 <p>A 32-bit integer which is the result of hashing the given key.
330 For 64-bit hash algorithms, only the least-significant 32 bits are
331 returned.</p>
332 </div>
333 <div class="section" id="see-also">
334 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline"></a></h2>
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