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| <li>Summary: </li> |
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| <div class="sub-title"><span class="package-label-in-type">Package</span> <a href="package-summary.html">org.apache.kafka.common.metrics.stats</a></div> |
| <h1 title="Class TokenBucket" class="title">Class TokenBucket</h1> |
| </div> |
| <div class="inheritance" title="Inheritance Tree"><a href="https://docs.oracle.com/en/java/javase/17/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.kafka.common.metrics.stats.TokenBucket</div> |
| </div> |
| <section class="class-description" id="class-description"> |
| <dl class="notes"> |
| <dt>All Implemented Interfaces:</dt> |
| <dd><code><a href="../Measurable.html" title="interface in org.apache.kafka.common.metrics">Measurable</a></code>, <code><a href="../MeasurableStat.html" title="interface in org.apache.kafka.common.metrics">MeasurableStat</a></code>, <code><a href="../MetricValueProvider.html" title="interface in org.apache.kafka.common.metrics">MetricValueProvider</a><<a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Double.html" title="class or interface in java.lang" class="external-link">Double</a>></code>, <code><a href="../Stat.html" title="interface in org.apache.kafka.common.metrics">Stat</a></code></dd> |
| </dl> |
| <hr> |
| <div class="type-signature"><span class="modifiers">public class </span><span class="element-name type-name-label">TokenBucket</span> |
| <span class="extends-implements">extends <a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html" title="class or interface in java.lang" class="external-link">Object</a> |
| implements <a href="../MeasurableStat.html" title="interface in org.apache.kafka.common.metrics">MeasurableStat</a></span></div> |
| <div class="block">The <a href="TokenBucket.html" title="class in org.apache.kafka.common.metrics.stats"><code>TokenBucket</code></a> is a <a href="../MeasurableStat.html" title="interface in org.apache.kafka.common.metrics"><code>MeasurableStat</code></a> implementing a token bucket algorithm |
| that is usable within a <a href="../Sensor.html" title="class in org.apache.kafka.common.metrics"><code>Sensor</code></a>. |
| |
| The <a href="../Quota.html#bound()"><code>Quota.bound()</code></a> defined the refill rate of the bucket while the maximum burst or |
| the maximum number of credits of the bucket is defined by |
| <a href="../MetricConfig.html#samples()"><code>* MetricConfig#timeWindowMs() * Quota#bound()</code></a>. |
| |
| The quota is considered as exhausted when the amount of remaining credits in the bucket |
| is below zero. The enforcement is done by the <a href="../Sensor.html" title="class in org.apache.kafka.common.metrics"><code>Sensor</code></a>. |
| |
| Token Bucket vs Rate based Quota: |
| The current sampled rate based quota does not cope well with bursty workloads. The issue is |
| that a unique and large sample can hold the average above the quota until it is discarded. |
| Practically, when this happens, one must wait until the sample is expired to bring the rate |
| below the quota even though less time would be theoretically required. As an example, let's |
| imagine that we have: |
| - Quota (Q) = 5 |
| - Samples (S) = 100 |
| - Window (W) = 1s |
| A burst of 560 brings the average rate (R) to 5.6 (560 / 100). The expected throttle time is |
| computed as follow: ((R - Q / Q * S * W)) = ((5.6 - 5) / 5 * 100 * 1) = 12 secs. In practice, |
| the average rate won't go below the quota before the burst is dropped from the samples so one |
| must wait 100s (S * W). |
| |
| The token bucket relies on continuously updated amount of credits. Therefore, it does not |
| suffers from the above issue. The same example would work as follow: |
| - Quota (Q) = 5 |
| - Burst (B) = 5 * 1 * 100 = 500 (Q * S * W) |
| A burst of 560 brings the amount of credits to -60. One must wait 12s (-(-60)/5) to refill the |
| bucket to zero.</div> |
| </section> |
| <section class="summary"> |
| <ul class="summary-list"> |
| <!-- ======== CONSTRUCTOR SUMMARY ======== --> |
| <li> |
| <section class="constructor-summary" id="constructor-summary"> |
| <h2>Constructor Summary</h2> |
| <div class="caption"><span>Constructors</span></div> |
| <div class="summary-table two-column-summary"> |
| <div class="table-header col-first">Constructor</div> |
| <div class="table-header col-last">Description</div> |
| <div class="col-constructor-name even-row-color"><code><a href="#%3Cinit%3E()" class="member-name-link">TokenBucket</a>()</code></div> |
| <div class="col-last even-row-color"> </div> |
| <div class="col-constructor-name odd-row-color"><code><a href="#%3Cinit%3E(java.util.concurrent.TimeUnit)" class="member-name-link">TokenBucket</a><wbr>(<a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/TimeUnit.html" title="class or interface in java.util.concurrent" class="external-link">TimeUnit</a> unit)</code></div> |
| <div class="col-last odd-row-color"> </div> |
| </div> |
| </section> |
| </li> |
| <!-- ========== 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>double</code></div> |
| <div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"><code><a href="#measure(org.apache.kafka.common.metrics.MetricConfig,long)" class="member-name-link">measure</a><wbr>(<a href="../MetricConfig.html" title="class in org.apache.kafka.common.metrics">MetricConfig</a> config, |
| long timeMs)</code></div> |
| <div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"> |
| <div class="block">Measure this quantity and return the result as a double</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="#record(org.apache.kafka.common.metrics.MetricConfig,double,long)" class="member-name-link">record</a><wbr>(<a href="../MetricConfig.html" title="class in org.apache.kafka.common.metrics">MetricConfig</a> config, |
| double value, |
| long timeMs)</code></div> |
| <div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"> |
| <div class="block">Record the given value</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/17/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="#toString()" class="member-name-link">toString</a>()</code></div> |
| <div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab4"> </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/17/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/17/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/17/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/17/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/17/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/17/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/17/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/17/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/17/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/17/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/17/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"> |
| <!-- ========= CONSTRUCTOR DETAIL ======== --> |
| <li> |
| <section class="constructor-details" id="constructor-detail"> |
| <h2>Constructor Details</h2> |
| <ul class="member-list"> |
| <li> |
| <section class="detail" id="<init>()"> |
| <h3>TokenBucket</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="element-name">TokenBucket</span>()</div> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="<init>(java.util.concurrent.TimeUnit)"> |
| <h3>TokenBucket</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="element-name">TokenBucket</span><wbr><span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/TimeUnit.html" title="class or interface in java.util.concurrent" class="external-link">TimeUnit</a> unit)</span></div> |
| </section> |
| </li> |
| </ul> |
| </section> |
| </li> |
| <!-- ============ METHOD DETAIL ========== --> |
| <li> |
| <section class="method-details" id="method-detail"> |
| <h2>Method Details</h2> |
| <ul class="member-list"> |
| <li> |
| <section class="detail" id="measure(org.apache.kafka.common.metrics.MetricConfig,long)"> |
| <h3>measure</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="return-type">double</span> <span class="element-name">measure</span><wbr><span class="parameters">(<a href="../MetricConfig.html" title="class in org.apache.kafka.common.metrics">MetricConfig</a> config, |
| long timeMs)</span></div> |
| <div class="block"><span class="descfrm-type-label">Description copied from interface: <code><a href="../Measurable.html#measure(org.apache.kafka.common.metrics.MetricConfig,long)">Measurable</a></code></span></div> |
| <div class="block">Measure this quantity and return the result as a double</div> |
| <dl class="notes"> |
| <dt>Specified by:</dt> |
| <dd><code><a href="../Measurable.html#measure(org.apache.kafka.common.metrics.MetricConfig,long)">measure</a></code> in interface <code><a href="../Measurable.html" title="interface in org.apache.kafka.common.metrics">Measurable</a></code></dd> |
| <dt>Parameters:</dt> |
| <dd><code>config</code> - The configuration for this metric</dd> |
| <dd><code>timeMs</code> - The POSIX time in milliseconds the measurement is being taken</dd> |
| <dt>Returns:</dt> |
| <dd>The measured value</dd> |
| </dl> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="record(org.apache.kafka.common.metrics.MetricConfig,double,long)"> |
| <h3>record</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="return-type">void</span> <span class="element-name">record</span><wbr><span class="parameters">(<a href="../MetricConfig.html" title="class in org.apache.kafka.common.metrics">MetricConfig</a> config, |
| double value, |
| long timeMs)</span></div> |
| <div class="block"><span class="descfrm-type-label">Description copied from interface: <code><a href="../Stat.html#record(org.apache.kafka.common.metrics.MetricConfig,double,long)">Stat</a></code></span></div> |
| <div class="block">Record the given value</div> |
| <dl class="notes"> |
| <dt>Specified by:</dt> |
| <dd><code><a href="../Stat.html#record(org.apache.kafka.common.metrics.MetricConfig,double,long)">record</a></code> in interface <code><a href="../Stat.html" title="interface in org.apache.kafka.common.metrics">Stat</a></code></dd> |
| <dt>Parameters:</dt> |
| <dd><code>config</code> - The configuration to use for this metric</dd> |
| <dd><code>value</code> - The value to record</dd> |
| <dd><code>timeMs</code> - The POSIX time in milliseconds this value occurred</dd> |
| </dl> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="toString()"> |
| <h3>toString</h3> |
| <div class="member-signature"><span class="modifiers">public</span> <span class="return-type"><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a></span> <span class="element-name">toString</span>()</div> |
| <dl class="notes"> |
| <dt>Overrides:</dt> |
| <dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html#toString()" title="class or interface in java.lang" class="external-link">toString</a></code> in class <code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html" title="class or interface in java.lang" class="external-link">Object</a></code></dd> |
| </dl> |
| </section> |
| </li> |
| </ul> |
| </section> |
| </li> |
| </ul> |
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