cassandra-server
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A thin Javascript wrapper around Apache Cassandra to provide out of the box server support
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<div class="subTitle">org.apache.cassandra.metrics</div>
<h2 title="Class RestorableMeter" class="title">Class RestorableMeter</h2>
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<li>java.lang.Object</li>
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<pre>public class <span class="strong">RestorableMeter</span>
extends java.lang.Object</pre>
<div class="block">A meter metric which measures mean throughput as well as fifteen-minute and two-hour
exponentially-weighted moving average throughputs.
This is based heavily on the Meter and EWMA classes from codahale/yammer metrics.</div>
<dl><dt><span class="strong">See Also:</span></dt><dd><a href="http://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average">EMA</a></dd></dl>
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<th class="colOne" scope="col">Constructor and Description</th>
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<td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#RestorableMeter()">RestorableMeter</a></strong>()</code>
<div class="block">Creates a new, uninitialized RestorableMeter.</div>
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<td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#RestorableMeter(double,%20double)">RestorableMeter</a></strong>(double lastM15Rate,
double lastM120Rate)</code>
<div class="block">Restores a RestorableMeter from the last seen 15m and 2h rates.</div>
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<td class="colFirst"><code>long</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#count()">count</a></strong>()</code>
<div class="block">The total number of events that have occurred since this object was created.</div>
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<td class="colFirst"><code>double</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#fifteenMinuteRate()">fifteenMinuteRate</a></strong>()</code>
<div class="block">Returns the 15-minute rate in terms of events per second.</div>
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<td class="colFirst"><code>void</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#mark()">mark</a></strong>()</code>
<div class="block">Mark the occurrence of an event.</div>
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<td class="colFirst"><code>void</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#mark(long)">mark</a></strong>(long n)</code>
<div class="block">Mark the occurrence of a given number of events.</div>
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<td class="colFirst"><code>double</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#meanRate()">meanRate</a></strong>()</code>
<div class="block">Returns the mean rate of events per second since this object was created.</div>
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<td class="colFirst"><code>double</code></td>
<td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/metrics/RestorableMeter.html#twoHourRate()">twoHourRate</a></strong>()</code>
<div class="block">Returns the two-hour rate in terms of events per second.</div>
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<h4>RestorableMeter</h4>
<pre>public RestorableMeter()</pre>
<div class="block">Creates a new, uninitialized RestorableMeter.</div>
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<pre>public RestorableMeter(double lastM15Rate,
double lastM120Rate)</pre>
<div class="block">Restores a RestorableMeter from the last seen 15m and 2h rates.</div>
<dl><dt><span class="strong">Parameters:</span></dt><dd><code>lastM15Rate</code> - the last-seen 15m rate, in terms of events per second</dd><dd><code>lastM120Rate</code> - the last seen 2h rate, in terms of events per second</dd></dl>
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<h4>mark</h4>
<pre>public void mark()</pre>
<div class="block">Mark the occurrence of an event.</div>
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<pre>public void mark(long n)</pre>
<div class="block">Mark the occurrence of a given number of events.</div>
<dl><dt><span class="strong">Parameters:</span></dt><dd><code>n</code> - the number of events</dd></dl>
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<pre>public double fifteenMinuteRate()</pre>
<div class="block">Returns the 15-minute rate in terms of events per second. This carries the previous rate when restored.</div>
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<pre>public double twoHourRate()</pre>
<div class="block">Returns the two-hour rate in terms of events per second. This carries the previous rate when restored.</div>
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<h4>count</h4>
<pre>public long count()</pre>
<div class="block">The total number of events that have occurred since this object was created. Note that the previous count
is *not* carried over when a RestorableMeter is restored.</div>
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<pre>public double meanRate()</pre>
<div class="block">Returns the mean rate of events per second since this object was created. Note that the mean rate
does *not* carry over when a RestorableMeter is restored, so the mean rate is only a measure since
this object was created.</div>
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