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<div class="sub-title"><span class="package-label-in-type">Package</span>&nbsp;<a href="package-summary.html">org.apache.storm.metricstore.rocksdb</a></div>
<h1 title="Class StringMetadataCache" class="title">Class StringMetadataCache</h1>
</div>
<div class="inheritance" title="Inheritance Tree"><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html" title="class or interface in java.lang" class="external-link">java.lang.Object</a>
<div class="inheritance">org.apache.storm.metricstore.rocksdb.StringMetadataCache</div>
</div>
<section class="class-description" id="class-description">
<dl class="notes">
<dt>All Implemented Interfaces:</dt>
<dd><code><a href="ReadOnlyStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">ReadOnlyStringMetadataCache</a></code>, <code><a href="WritableStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">WritableStringMetadataCache</a></code>, <code><a href="../../utils/LruMap.CacheEvictionCallback.html" title="interface in org.apache.storm.utils">LruMap.CacheEvictionCallback</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>,<wbr>org.apache.storm.metricstore.rocksdb.StringMetadata&gt;</code></dd>
</dl>
<hr>
<div class="type-signature"><span class="modifiers">public class </span><span class="element-name type-name-label">StringMetadataCache</span>
<span class="extends-implements">extends <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html" title="class or interface in java.lang" class="external-link">Object</a>
implements <a href="../../utils/LruMap.CacheEvictionCallback.html" title="interface in org.apache.storm.utils">LruMap.CacheEvictionCallback</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>,<wbr>org.apache.storm.metricstore.rocksdb.StringMetadata&gt;, <a href="WritableStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">WritableStringMetadataCache</a>, <a href="ReadOnlyStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">ReadOnlyStringMetadataCache</a></span></div>
<div class="block">Class to create a use a cache that stores Metadata string information in memory. It allows searching for a
Metadata string's unique id, or looking up the string by the unique id. The StringMetadata is stored in an
LRU map. When an entry is added to the cache, an older entry may be evicted, which then needs to be
immediately stored to the database to provide a consistent view of all the metadata strings.
<p>All write operations adding metadata to RocksDB are done by a single thread (a RocksDbMetricsWriter),
but multiple threads can read values from the cache. To clarify which permissions are accessible by various
threads, the ReadOnlyStringMetadataCache and WritableStringMetadataCache are provided to be used.</div>
</section>
<section class="summary">
<ul class="summary-list">
<!-- ========== METHOD SUMMARY =========== -->
<li>
<section class="method-summary" id="method-summary">
<h2>Method Summary</h2>
<div id="method-summary-table">
<div class="table-tabs" role="tablist" aria-orientation="horizontal"><button id="method-summary-table-tab0" role="tab" aria-selected="true" aria-controls="method-summary-table.tabpanel" tabindex="0" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table', 3)" class="active-table-tab">All Methods</button><button id="method-summary-table-tab2" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab2', 3)" class="table-tab">Instance Methods</button><button id="method-summary-table-tab4" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab4', 3)" class="table-tab">Concrete Methods</button></div>
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<div class="summary-table three-column-summary" aria-labelledby="method-summary-table-tab0">
<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-tab4"><code>boolean</code></div>
<div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#contains(java.lang.Integer)" class="member-name-link">contains</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Integer.html" title="class or interface in java.lang" class="external-link">Integer</a>&nbsp;stringId)</code></div>
<div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Determines if a string Id is contained in the cache.</div>
</div>
<div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Set.html" title="class or interface in java.util" class="external-link">Set</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Map.Entry.html" title="class or interface in java.util" class="external-link">Map.Entry</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>,<wbr>org.apache.storm.metricstore.rocksdb.StringMetadata&gt;&gt;</code></div>
<div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#entrySet()" class="member-name-link">entrySet</a>()</code></div>
<div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Get the map of the cache contents.</div>
</div>
<div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code>void</code></div>
<div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#evictionCallback(java.lang.String,org.apache.storm.metricstore.rocksdb.StringMetadata)" class="member-name-link">evictionCallback</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;key,
org.apache.storm.metricstore.rocksdb.StringMetadata&nbsp;val)</code></div>
<div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Callback when data is about to be removed from the cache.</div>
</div>
<div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code>org.apache.storm.metricstore.rocksdb.StringMetadata</code></div>
<div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#get(java.lang.String)" class="member-name-link">get</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;s)</code></div>
<div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Get the string metadata from the cache.</div>
</div>
<div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a></code></div>
<div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#getMetadataString(java.lang.Integer)" class="member-name-link">getMetadataString</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Integer.html" title="class or interface in java.lang" class="external-link">Integer</a>&nbsp;stringId)</code></div>
<div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Returns the string matching the string Id if in the cache.</div>
</div>
<div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code>void</code></div>
<div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#put(java.lang.String,org.apache.storm.metricstore.rocksdb.StringMetadata,boolean)" class="member-name-link">put</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;s,
org.apache.storm.metricstore.rocksdb.StringMetadata&nbsp;stringMetadata,
boolean&nbsp;newEntry)</code></div>
<div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4">
<div class="block">Add the string metadata to the cache.</div>
</div>
</div>
</div>
</div>
<div class="inherited-list">
<h3 id="methods-inherited-from-class-java.lang.Object">Methods inherited from class&nbsp;java.lang.<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html" title="class or interface in java.lang" class="external-link">Object</a></h3>
<code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#clone()" title="class or interface in java.lang" class="external-link">clone</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#equals(java.lang.Object)" title="class or interface in java.lang" class="external-link">equals</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#finalize()" title="class or interface in java.lang" class="external-link">finalize</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#getClass()" title="class or interface in java.lang" class="external-link">getClass</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#hashCode()" title="class or interface in java.lang" class="external-link">hashCode</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#notify()" title="class or interface in java.lang" class="external-link">notify</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#notifyAll()" title="class or interface in java.lang" class="external-link">notifyAll</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#toString()" title="class or interface in java.lang" class="external-link">toString</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#wait()" title="class or interface in java.lang" class="external-link">wait</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#wait(long)" title="class or interface in java.lang" class="external-link">wait</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#wait(long,int)" title="class or interface in java.lang" class="external-link">wait</a></code></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>
<ul class="member-list">
<li>
<section class="detail" id="get(java.lang.String)">
<h3>get</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type">org.apache.storm.metricstore.rocksdb.StringMetadata</span>&nbsp;<span class="element-name">get</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;s)</span></div>
<div class="block">Get the string metadata from the cache.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="ReadOnlyStringMetadataCache.html#get(java.lang.String)">get</a></code>&nbsp;in interface&nbsp;<code><a href="ReadOnlyStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">ReadOnlyStringMetadataCache</a></code></dd>
<dt>Parameters:</dt>
<dd><code>s</code> - The string to look for</dd>
<dt>Returns:</dt>
<dd>the metadata associated with the string or null if not found</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="put(java.lang.String,org.apache.storm.metricstore.rocksdb.StringMetadata,boolean)">
<h3>put</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type">void</span>&nbsp;<span class="element-name">put</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;s,
org.apache.storm.metricstore.rocksdb.StringMetadata&nbsp;stringMetadata,
boolean&nbsp;newEntry)</span>
throws <span class="exceptions"><a href="../MetricException.html" title="class in org.apache.storm.metricstore">MetricException</a></span></div>
<div class="block">Add the string metadata to the cache.
<p>NOTE: this can cause data to be evicted from the cache when full. When this occurs, the evictionCallback() method
is called to store the metadata back into the RocksDB database.
<p>This method is only exposed to the WritableStringMetadataCache interface.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="WritableStringMetadataCache.html#put(java.lang.String,org.apache.storm.metricstore.rocksdb.StringMetadata,boolean)">put</a></code>&nbsp;in interface&nbsp;<code><a href="WritableStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">WritableStringMetadataCache</a></code></dd>
<dt>Parameters:</dt>
<dd><code>s</code> - The string to add</dd>
<dd><code>stringMetadata</code> - The string's metadata</dd>
<dd><code>newEntry</code> - Indicates the metadata is being used for the first time and should be written to RocksDB immediately</dd>
<dt>Throws:</dt>
<dd><code><a href="../MetricException.html" title="class in org.apache.storm.metricstore">MetricException</a></code> - when evicted data fails to save to the database or when the database is shutdown</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="evictionCallback(java.lang.String,org.apache.storm.metricstore.rocksdb.StringMetadata)">
<h3>evictionCallback</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type">void</span>&nbsp;<span class="element-name">evictionCallback</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;key,
org.apache.storm.metricstore.rocksdb.StringMetadata&nbsp;val)</span></div>
<div class="block">Callback when data is about to be removed from the cache. This method then
immediately writes the metadata to RocksDB.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="../../utils/LruMap.CacheEvictionCallback.html#evictionCallback(K,V)">evictionCallback</a></code>&nbsp;in interface&nbsp;<code><a href="../../utils/LruMap.CacheEvictionCallback.html" title="interface in org.apache.storm.utils">LruMap.CacheEvictionCallback</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>,<wbr>org.apache.storm.metricstore.rocksdb.StringMetadata&gt;</code></dd>
<dt>Parameters:</dt>
<dd><code>key</code> - The evicted string</dd>
<dd><code>val</code> - The evicted string's metadata</dd>
<dt>Throws:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/RuntimeException.html" title="class or interface in java.lang" class="external-link">RuntimeException</a></code> - when evicted data fails to save to the database</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="contains(java.lang.Integer)">
<h3>contains</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type">boolean</span>&nbsp;<span class="element-name">contains</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Integer.html" title="class or interface in java.lang" class="external-link">Integer</a>&nbsp;stringId)</span></div>
<div class="block">Determines if a string Id is contained in the cache.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="ReadOnlyStringMetadataCache.html#contains(java.lang.Integer)">contains</a></code>&nbsp;in interface&nbsp;<code><a href="ReadOnlyStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">ReadOnlyStringMetadataCache</a></code></dd>
<dt>Parameters:</dt>
<dd><code>stringId</code> - The string Id to check</dd>
<dt>Returns:</dt>
<dd>true if the Id is in the cache, false otherwise</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="getMetadataString(java.lang.Integer)">
<h3>getMetadataString</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type"><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a></span>&nbsp;<span class="element-name">getMetadataString</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Integer.html" title="class or interface in java.lang" class="external-link">Integer</a>&nbsp;stringId)</span></div>
<div class="block">Returns the string matching the string Id if in the cache.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="ReadOnlyStringMetadataCache.html#getMetadataString(java.lang.Integer)">getMetadataString</a></code>&nbsp;in interface&nbsp;<code><a href="ReadOnlyStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">ReadOnlyStringMetadataCache</a></code></dd>
<dt>Parameters:</dt>
<dd><code>stringId</code> - The string Id to check</dd>
<dt>Returns:</dt>
<dd>the associated string if the Id is in the cache, null otherwise</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="entrySet()">
<h3>entrySet</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span class="return-type"><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Set.html" title="class or interface in java.util" class="external-link">Set</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Map.Entry.html" title="class or interface in java.util" class="external-link">Map.Entry</a>&lt;<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>,<wbr>org.apache.storm.metricstore.rocksdb.StringMetadata&gt;&gt;</span>&nbsp;<span class="element-name">entrySet</span>()</div>
<div class="block">Get the map of the cache contents. Provided to allow writing the data to RocksDB on shutdown.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="WritableStringMetadataCache.html#entrySet()">entrySet</a></code>&nbsp;in interface&nbsp;<code><a href="WritableStringMetadataCache.html" title="interface in org.apache.storm.metricstore.rocksdb">WritableStringMetadataCache</a></code></dd>
<dt>Returns:</dt>
<dd>the string metadata map entrySet</dd>
</dl>
</section>
</li>
</ul>
</section>
</li>
</ul>
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