Author: johnh
Date: Mon Sep 8 17:54:41 2008
New Revision: 693329
URL: http://svn.apache.org/viewvc?rev=693329&view=rev
Log:
Using TtlCache in CachingWebRetrievalFactory. With this change, the remaining
code there is small enough that we should be able to get rid of its templatized
confusion.
Modified:
incubator/shindig/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/CachingWebRetrievalFactory.java
Modified:
incubator/shindig/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/CachingWebRetrievalFactory.java
URL:
http://svn.apache.org/viewvc/incubator/shindig/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/CachingWebRetrievalFactory.java?rev=693329&r1=693328&r2=693329&view=diff
==============================================================================
---
incubator/shindig/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/CachingWebRetrievalFactory.java
(original)
+++
incubator/shindig/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/CachingWebRetrievalFactory.java
Mon Sep 8 17:54:41 2008
@@ -20,8 +20,8 @@
import java.util.logging.Logger;
-import org.apache.shindig.common.cache.Cache;
import org.apache.shindig.common.cache.CacheProvider;
+import org.apache.shindig.common.cache.TtlCache;
import org.apache.shindig.gadgets.GadgetException;
/**
@@ -54,14 +54,11 @@
protected abstract K getCacheKeyFromQueryObj(Q queryObj);
protected abstract Logger getLogger();
- private final Cache<K, TimeoutPair<T>> cache;
- private final long minTtl, maxTtl;
+ private final TtlCache<K, T> ttlCache;
protected CachingWebRetrievalFactory(CacheProvider cacheProvider,
int capacity, long minTtl, long maxTtl) {
- this.cache = cacheProvider.createCache(capacity);
- this.minTtl = minTtl;
- this.maxTtl = maxTtl;
+ this.ttlCache = new TtlCache<K, T>(cacheProvider, capacity, minTtl,
maxTtl);
}
protected T doCachedFetch(Q queryObj, boolean ignoreCache) throws
GadgetException {
@@ -69,49 +66,34 @@
return fetchObjectAndCache(queryObj, ignoreCache);
}
- T resultObj = null;
- long expiration = -1;
+ TtlCache.CachedObject<T> cached = null;
K cacheKey = getCacheKeyFromQueryObj(queryObj);
- synchronized(cache) {
- TimeoutPair<T> cachedEntry = cache.getElement(cacheKey);
- if (cachedEntry != null) {
- resultObj = cachedEntry.cachedObj;
- expiration = cachedEntry.timeout;
- }
+ synchronized(ttlCache) {
+ cached = ttlCache.getElementWithExpiration(cacheKey);
}
- // If the obj is not in the cache or has expired, fetch it from its URI.
- long now = System.currentTimeMillis();
-
- if (resultObj == null || expiration < now) {
+ if (cached.obj == null || cached.isExpired) {
try {
return fetchObjectAndCache(queryObj, false);
} catch (GadgetException e) {
- if (resultObj == null) {
+ // Failed to re-fetch raw object. Use cached object if it exists.
+ if (cached.obj == null) {
throw e;
} else {
- getLogger().info("Object fetch failed for " + cacheKey + " - using
cached ");
- // Try again later...
- synchronized (cache) {
- cache.addElement(cacheKey, new TimeoutPair<T>(resultObj, now +
minTtl));
- }
+ getLogger().info("Object fetch failed for " + cacheKey + " - using
cached.");
}
}
}
- return resultObj;
+ return cached.obj;
}
private T fetchObjectAndCache(Q queryObj, boolean ignoreCache) throws
GadgetException {
FetchedObject<T> fetched = retrieveRawObject(queryObj, ignoreCache);
- long now = System.currentTimeMillis();
- long expiration = fetched.expirationTime;
- expiration = Math.max(now + minTtl, Math.min(now + maxTtl, expiration));
- synchronized (cache) {
- cache.addElement(getCacheKeyFromQueryObj(queryObj),
- new TimeoutPair<T>(fetched.fetchedObj, expiration));
+ synchronized(ttlCache) {
+ ttlCache.addElement(getCacheKeyFromQueryObj(queryObj),
fetched.fetchedObj, fetched.expirationTime);
}
return fetched.fetchedObj;
@@ -126,14 +108,4 @@
this.expirationTime = expirationTime;
}
}
-
- private static class TimeoutPair<T> {
- private T cachedObj;
- private long timeout;
-
- private TimeoutPair(T cachedObj, long timeout) {
- this.cachedObj = cachedObj;
- this.timeout = timeout;
- }
- }
}
