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Additional thread safety around filter creation - old code could create duplicate CachingWrapperFilter if thread1 gets cache miss and thread 2 has a cache miss before thread1 populates cache with new CachingWrapperFilter. 

Synchronization cost around whole method is OK here because Filter object construction should be a lightweight call. 
Note: CachingWrapperFilter currently has a similar bug in bits() method but adding "synchronized" around that whole method would not be a solution there because of the cost of evaluating filter.bits and the unnecessary blocking effect this would have on threads using different readers to the thread with the lock.

 

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@628921 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Mark Harwood 2008-02-18 23:39:12 +00:00
parent caed55ef5e
commit 37a060c15c
1 changed files with 7 additions and 15 deletions
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14
contrib/xml-query-parser/src/java/org/apache/lucene/xmlparser/builders/CachedFilterBuilder.java
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@ -66,7 +66,7 @@ public class CachedFilterBuilder implements FilterBuilder {
this.cacheSize=cacheSize;
}
public Filter getFilter(Element e) throws ParserException
public synchronized Filter getFilter(Element e) throws ParserException
{
Element childElement = DOMUtils.getFirstChildOrFail(e);
@ -78,8 +78,7 @@ public class CachedFilterBuilder implements FilterBuilder {
// Test to see if child Element is a query or filter that needs to be
// cached
QueryBuilder qb = queryFactory.getQueryBuilder(childElement
.getNodeName());
QueryBuilder qb = queryFactory.getQueryBuilder(childElement.getNodeName());
Object cacheKey = null;
Query q = null;
Filter f = null;
@ -92,15 +91,11 @@ public class CachedFilterBuilder implements FilterBuilder {
f = filterFactory.getFilter(childElement);
cacheKey = f;
}
Filter cachedFilter = null;
synchronized (filterCache)
{ // check cache
cachedFilter = (Filter) filterCache.get(cacheKey);
Filter cachedFilter = (Filter) filterCache.get(cacheKey);
if (cachedFilter != null)
{
return cachedFilter; // cache hit
}
}
//cache miss
if (qb != null)
@ -111,10 +106,7 @@ public class CachedFilterBuilder implements FilterBuilder {
cachedFilter = new CachingWrapperFilter(f);
}
synchronized (filterCache)
{ // update cache
filterCache.put(cacheKey, cachedFilter);
}
return cachedFilter;
}