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<html>
<head>
<title>OSCache -
Statistics
</title>
<link rel="stylesheet" href="styles/site.css" type="text/css" />
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<body>
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<h3><a name="Statistics-Description"></a>Description</h3>
<p>With the <a href="http://www.opensymphony.com/oscache/api/com/opensymphony/oscache/base/events/package-summary.html" title="Visit page outside Confluence">cache event handlers</a> a listerner can be implemented to provide cache hits and misses information. You can copy and paste the following code to get a statistic of your OSCache integration. Just change the used logger and the sample helps you to improve the cache key creation and to decide which scope to use. The <em>SimpleStatisticListenerImpl</em> should be <a href="Configuration.html" title="Configuration">configured</a> via the <em>cache.event.listeners</em> in the <em>oscache.properties</em>.</p>
<h3><a name="Statistics-SampleCode"></a>Sample Code</h3>
<div class="code" style="border-style: solid; "><div class="codeHeader" style="border-bottom-style: solid; "><b>SimpleStatisticListenerImpl.java</b></div><div class="codeContent">
<pre class="code-java">/*
* Copyright (c) 2002-2007 by OpenSymphony
* All rights reserved.
*/
<span class="code-keyword">package</span> com.opensymphony.oscache.extra;
<span class="code-keyword">import</span> org.apache.commons.logging.Log;
<span class="code-keyword">import</span> org.apache.commons.logging.LogFactory;
<span class="code-keyword">import</span> com.opensymphony.oscache.base.Cache;
<span class="code-keyword">import</span> com.opensymphony.oscache.base.events.*;
/**
* A simple implementation of a statistic reporter which uses the
* CacheMapAccessEventListener, CacheEntryEventListener and ScopeEventListener.
* It uses the events to count the cache hit and misses and of course the
* flushes.
* <p>
* We are not using any <span class="code-keyword">synchronized</span> so that <span class="code-keyword">this</span> does not become a bottleneck.
* The consequence is that on retrieving values, the operations that are
* currently being done won't be counted.
*/
<span class="code-keyword">public</span> class SimpleStatisticListenerImpl <span class="code-keyword">implements</span> CacheMapAccessEventListener, CacheEntryEventListener, ScopeEventListener {
<span class="code-keyword">private</span> <span class="code-keyword">static</span> <span class="code-keyword">transient</span> <span class="code-keyword">final</span> Log log = LogFactory.getLog(SimpleStatisticListenerImpl.class);
/**
* Hit counter
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> hitCount = 0;
/**
* Miss counter
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> missCount = 0;
/**
* Stale hit counter
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> staleHitCount = 0;
/**
* Hit counter sum
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> hitCountSum = 0;
/**
* Miss counter sum
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> missCountSum = 0;
/**
* Stale hit counter
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> staleHitCountSum = 0;
/**
* Flush hit counter
*/
<span class="code-keyword">private</span> <span class="code-object">int</span> flushCount = 0;
/**
* Constructor, empty <span class="code-keyword">for</span> us
*/
<span class="code-keyword">public</span> SimpleStatisticListenerImpl() {
log.info(<span class="code-quote">"Creation of SimpleStatisticListenerImpl"</span>);
}
/**
* This method handles an event each time the cache is accessed
*
* @param event The event triggered when the cache was accessed
* @see com.opensymphony.oscache.base.events.CacheMapAccessEventListener#accessed(CacheMapAccessEvent)
*/
<span class="code-keyword">public</span> void accessed(CacheMapAccessEvent event) {
<span class="code-object">String</span> result = <span class="code-quote">"N/A"</span>;
<span class="code-comment">// Retrieve the event type and update the counters
</span> CacheMapAccessEventType type = event.getEventType();
<span class="code-comment">// Handles a hit event
</span> <span class="code-keyword">if</span> (type == CacheMapAccessEventType.HIT) {
hitCount++;
result = <span class="code-quote">"HIT"</span>;
}
<span class="code-comment">// Handles a stale hit event
</span> <span class="code-keyword">else</span> <span class="code-keyword">if</span> (type == CacheMapAccessEventType.STALE_HIT) {
staleHitCount++;
result = <span class="code-quote">"STALE HIT"</span>;
}
<span class="code-comment">// Handles a miss event
</span> <span class="code-keyword">else</span> <span class="code-keyword">if</span> (type == CacheMapAccessEventType.MISS) {
missCount++;
result = <span class="code-quote">"MISS"</span>;
}
<span class="code-keyword">if</span> (log.isDebugEnabled()) {
log.debug(<span class="code-quote">"ACCESS : "</span> + result + <span class="code-quote">": "</span> + event.getCacheEntryKey());
log.debug(<span class="code-quote">"STATISTIC : Hit = "</span> + hitCount + <span class="code-quote">", stale hit ="</span>
+ staleHitCount + <span class="code-quote">", miss = "</span> + missCount);
}
}
/**
* Logs the flush of the cache.
*
* @param info the string to be logged.
*/
<span class="code-keyword">private</span> void flushed(<span class="code-object">String</span> info) {
flushCount++;
hitCountSum += hitCount;
staleHitCountSum += staleHitCount;
missCountSum += missCount;
<span class="code-keyword">if</span> (log.isInfoEnabled()) {
log.info(<span class="code-quote">"FLUSH : "</span> + info);
log.info(<span class="code-quote">"STATISTIC SUM : "</span> + <span class="code-quote">"Hit = "</span> + hitCountSum
+ <span class="code-quote">", stale hit = "</span> + staleHitCountSum + <span class="code-quote">", miss = "</span>
+ missCountSum + <span class="code-quote">", flush = "</span> + flushCount);
}
hitCount = 0;
staleHitCount = 0;
missCount = 0;
}
/**
* Event fired when a specific or all scopes are flushed.
*
* @param event ScopeEvent
* @see com.opensymphony.oscache.base.events.ScopeEventListener#scopeFlushed(ScopeEvent)
*/
<span class="code-keyword">public</span> void scopeFlushed(ScopeEvent event) {
flushed(<span class="code-quote">"scope "</span> + ScopeEventListenerImpl.SCOPE_NAMES[event.getScope()]);
}
/**
* Event fired when an entry is added to the cache.
*
* @param event CacheEntryEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheEntryAdded(CacheEntryEvent)
*/
<span class="code-keyword">public</span> void cacheEntryAdded(CacheEntryEvent event) {
<span class="code-comment">// <span class="code-keyword">do</span> nothing
</span> }
/**
* Event fired when an entry is flushed from the cache.
*
* @param event CacheEntryEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheEntryFlushed(CacheEntryEvent)
*/
<span class="code-keyword">public</span> void cacheEntryFlushed(CacheEntryEvent event) {
<span class="code-comment">// <span class="code-keyword">do</span> nothing, because a group or other flush is coming
</span> <span class="code-keyword">if</span> (!Cache.NESTED_EVENT.equals(event.getOrigin())) {
flushed(<span class="code-quote">"entry "</span> + event.getKey() + <span class="code-quote">" / "</span> + event.getOrigin());
}
}
/**
* Event fired when an entry is removed from the cache.
*
* @param event CacheEntryEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheEntryRemoved(CacheEntryEvent)
*/
<span class="code-keyword">public</span> void cacheEntryRemoved(CacheEntryEvent event) {
<span class="code-comment">// <span class="code-keyword">do</span> nothing
</span> }
/**
* Event fired when an entry is updated in the cache.
*
* @param event CacheEntryEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheEntryUpdated(CacheEntryEvent)
*/
<span class="code-keyword">public</span> void cacheEntryUpdated(CacheEntryEvent event) {
<span class="code-comment">// <span class="code-keyword">do</span> nothing
</span> }
/**
* Event fired when a group is flushed from the cache.
*
* @param event CacheGroupEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheGroupFlushed(CacheGroupEvent)
*/
<span class="code-keyword">public</span> void cacheGroupFlushed(CacheGroupEvent event) {
flushed(<span class="code-quote">"group "</span> + event.getGroup());
}
/**
* Event fired when a key pattern is flushed from the cache.
*
* @param event CachePatternEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cachePatternFlushed(CachePatternEvent)
*/
<span class="code-keyword">public</span> void cachePatternFlushed(CachePatternEvent event) {
flushed(<span class="code-quote">"pattern "</span> + event.getPattern());
}
/**
* An event that is fired when an entire cache gets flushed.
*
* @param event CachewideEvent
* @see com.opensymphony.oscache.base.events.CacheEntryEventListener#cacheFlushed(CachewideEvent)
*/
<span class="code-keyword">public</span> void cacheFlushed(CachewideEvent event) {
flushed(<span class="code-quote">"wide "</span> + event.getDate());
}
/**
* Return the counters in a string form
*
* @<span class="code-keyword">return</span> <span class="code-object">String</span>
*/
<span class="code-keyword">public</span> <span class="code-object">String</span> toString() {
<span class="code-keyword">return</span> <span class="code-quote">"SimpleStatisticListenerImpl: Hit = "</span> + hitCount + <span class="code-quote">" / "</span> + hitCountSum
+ <span class="code-quote">", stale hit = "</span> + staleHitCount + <span class="code-quote">" / "</span> + staleHitCountSum
+ <span class="code-quote">", miss = "</span> + missCount + <span class="code-quote">" / "</span> + missCountSum
+ <span class="code-quote">", flush = "</span> + flushCount;
}
}</pre>
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