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| <div class="sub-title"><span class="package-label-in-type">Package</span> <a href="package-summary.html">org.apache.storm.metricstore.rocksdb</a></div> |
| <h1 title="Class RocksDbMetricsWriter" class="title">Class RocksDbMetricsWriter</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.RocksDbMetricsWriter</div> |
| </div> |
| <section class="class-description" id="class-description"> |
| <dl class="notes"> |
| <dt>All Implemented Interfaces:</dt> |
| <dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/AutoCloseable.html" title="class or interface in java.lang" class="external-link">AutoCloseable</a></code>, <code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Runnable.html" title="class or interface in java.lang" class="external-link">Runnable</a></code></dd> |
| </dl> |
| <hr> |
| <div class="type-signature"><span class="modifiers">public class </span><span class="element-name type-name-label">RocksDbMetricsWriter</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="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Runnable.html" title="class or interface in java.lang" class="external-link">Runnable</a>, <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/AutoCloseable.html" title="class or interface in java.lang" class="external-link">AutoCloseable</a></span></div> |
| <div class="block">Class designed to perform all metrics inserts into RocksDB. Metrics are processed from a blocking queue. Inserts |
| to RocksDB are done using a single thread to simplify design (such as looking up existing metric data for aggregation, |
| and fetching/evicting metadata from the cache). This class is not thread safe. |
| </P> |
| A writable LRU StringMetadataCache is used to minimize looking up metadata string Ids. As entries are added to the full cache, older |
| entries are evicted from the cache and need to be written to the database. This happens as the handleEvictedMetadata() |
| method callback. |
| </P> |
| The following issues would need to be addressed to implement a multithreaded metrics writer: |
| <ul> |
| <li>Generation of unique unused IDs for new metadata strings needs to be thread safe.</li> |
| <li>Ensuring newly created metadata strings are seen by all threads.</li> |
| <li>Maintaining a properly cached state of metadata for multiple writers. The current LRU cache |
| evicts data as new metadata is added.</li> |
| <li>Processing the aggregation of a metric requires fetching and updating previous aggregates. A multithreaded |
| design would need to ensure two metrics were not updating an aggregated metric at the same time.</li> |
| <li>Investigate performance of multiple threads inserting into RocksDB versus a single ordered insert.</li> |
| </ul></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"> |
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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>void</code></div> |
| <div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#close()" class="member-name-link">close</a>()</code></div> |
| <div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"> </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="#run()" class="member-name-link">run</a>()</code></div> |
| <div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"> |
| <div class="block">Run routine to wait for metrics on a queue and insert into RocksDB.</div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="inherited-list"> |
| <h3 id="methods-inherited-from-class-java.lang.Object">Methods inherited from class 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="run()"> |
| <h3>run</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="return-type">void</span> <span class="element-name">run</span>()</div> |
| <div class="block">Run routine to wait for metrics on a queue and insert into RocksDB.</div> |
| <dl class="notes"> |
| <dt>Specified by:</dt> |
| <dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Runnable.html#run()" title="class or interface in java.lang" class="external-link">run</a></code> in interface <code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Runnable.html" title="class or interface in java.lang" class="external-link">Runnable</a></code></dd> |
| </dl> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="close()"> |
| <h3>close</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="return-type">void</span> <span class="element-name">close</span>()</div> |
| <dl class="notes"> |
| <dt>Specified by:</dt> |
| <dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/AutoCloseable.html#close()" title="class or interface in java.lang" class="external-link">close</a></code> in interface <code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/AutoCloseable.html" title="class or interface in java.lang" class="external-link">AutoCloseable</a></code></dd> |
| </dl> |
| </section> |
| </li> |
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