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| <div class="sub-title"><span class="package-label-in-type">Package</span> <a href="package-summary.html">org.apache.sis.util.collection</a></div> |
| <h1 title="Interface Cache.Handler" class="title">Interface Cache.Handler<V></h1> |
| </div> |
| <section class="class-description" id="class-description"> |
| <dl class="notes"> |
| <dt>Type Parameters:</dt> |
| <dd><code>V</code> - the type of value objects.</dd> |
| </dl> |
| <dl class="notes"> |
| <dt>Enclosing class:</dt> |
| <dd><code><a href="Cache.html" title="class in org.apache.sis.util.collection">Cache</a><<a href="Cache.html" title="type parameter in Cache">K</a>,<wbr><a href="Cache.html" title="type parameter in Cache">V</a>></code></dd> |
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| <hr> |
| <div class="type-signature"><span class="modifiers">public static interface </span><span class="element-name type-name-label">Cache.Handler<V></span></div> |
| <div class="block">The handler returned by <a href="Cache.html#lock(K)"><code>Cache.lock(K)</code></a>, to be used for unlocking and storing the result. |
| This handler should be used as below (the <code>try</code> … <code>finally</code> statements are important): |
| |
| <blockquote><pre>Value V = <font color="green">null</font>; |
| Cache.Handler<V> handler = cache.<b>lock</b>(key); |
| <font color="green">try</font> { |
| value = handler.<b>peek</b>(); |
| <font color="green">if</font> (value == <font color="green">null</font>) { |
| value = <b>createMyObject</b>(key); |
| } |
| } <font color="green">finally</font> { |
| handler.<b>putAndUnlock</b>(value); |
| }</pre></blockquote> |
| |
| See the <a href="Cache.html" title="class in org.apache.sis.util.collection"><code>Cache</code></a> javadoc for a more complete example.</div> |
| <dl class="notes"> |
| <dt>Since:</dt> |
| <dd>0.3</dd> |
| |
| <p><font size="-1">Defined in the <code>sis-utility</code> module</font></p> |
| </dl> |
| </section> |
| <section class="summary"> |
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| <!-- ========== METHOD SUMMARY =========== --> |
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| <section class="method-summary" id="method-summary"> |
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| <div class="table-header col-first">Modifier and Type</div> |
| <div class="table-header col-second">Method</div> |
| <div class="table-header col-last">Description</div> |
| <div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="Cache.Handler.html" title="type parameter in Cache.Handler">V</a></code></div> |
| <div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#peek()" class="member-name-link">peek</a>()</code></div> |
| <div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"> |
| <div class="block">If the value is already in the cache, returns it.</div> |
| </div> |
| <div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>void</code></div> |
| <div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#putAndUnlock(V)" class="member-name-link">putAndUnlock</a><wbr>(<a href="Cache.Handler.html" title="type parameter in Cache.Handler">V</a> result)</code></div> |
| <div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"> |
| <div class="block">Stores the given value in the cache and release the lock.</div> |
| </div> |
| </div> |
| </div> |
| </div> |
| </section> |
| </li> |
| </ul> |
| </section> |
| <section class="details"> |
| <ul class="details-list"> |
| <!-- ============ METHOD DETAIL ========== --> |
| <li> |
| <section class="method-details" id="method-detail"> |
| <h2>Method Details</h2> |
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| <li> |
| <section class="detail" id="peek()"> |
| <h3>peek</h3> |
| <div class="member-signature"><span class="return-type"><a href="Cache.Handler.html" title="type parameter in Cache.Handler">V</a></span> <span class="element-name">peek</span>()</div> |
| <div class="block">If the value is already in the cache, returns it. Otherwise returns <code>null</code>. |
| This method should be invoked after the <code>Handler</code> creation in case a value |
| has been computed in another thread.</div> |
| <dl class="notes"> |
| <dt>Returns:</dt> |
| <dd>the value from the cache, or <code>null</code> if none.</dd> |
| </dl> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="putAndUnlock(V)"> |
| <h3 id="putAndUnlock(java.lang.Object)">putAndUnlock</h3> |
| <div class="member-signature"><span class="return-type">void</span> <span class="element-name">putAndUnlock</span><wbr><span class="parameters">(<a href="Cache.Handler.html" title="type parameter in Cache.Handler">V</a> result)</span> |
| throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/IllegalStateException.html" title="class or interface in java.lang" class="external-link">IllegalStateException</a></span></div> |
| <div class="block">Stores the given value in the cache and release the lock. This method |
| <strong>must</strong> be invoked in a <code>finally</code> block, no matter |
| what the result is.</div> |
| <dl class="notes"> |
| <dt>Parameters:</dt> |
| <dd><code>result</code> - the result to store in the cache, or <code>null</code> for removing |
| the entry from the cache. If an entry is removed, a new computation |
| will be attempted the next time a handler is created for the same key.</dd> |
| <dt>Throws:</dt> |
| <dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/IllegalStateException.html" title="class or interface in java.lang" class="external-link">IllegalStateException</a></code> - may be thrown if this method is not invoked in |
| the pattern described in class javadoc, or if a key collision occurs.</dd> |
| </dl> |
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