Author: hlship
Date: Thu Sep 11 07:25:11 2008
New Revision: 694274
URL: http://svn.apache.org/viewvc?rev=694274&view=rev
Log:
TAPESTRY-2561: Rapidly refreshing a page, even the same page, can cause a
deadlock related to class loading
Modified:
tapestry/tapestry5/trunk/tapestry-ioc/src/main/java/org/apache/tapestry5/ioc/internal/ModuleImpl.java
Modified:
tapestry/tapestry5/trunk/tapestry-ioc/src/main/java/org/apache/tapestry5/ioc/internal/ModuleImpl.java
URL:
http://svn.apache.org/viewvc/tapestry/tapestry5/trunk/tapestry-ioc/src/main/java/org/apache/tapestry5/ioc/internal/ModuleImpl.java?rev=694274&r1=694273&r2=694274&view=diff
==============================================================================
---
tapestry/tapestry5/trunk/tapestry-ioc/src/main/java/org/apache/tapestry5/ioc/internal/ModuleImpl.java
(original)
+++
tapestry/tapestry5/trunk/tapestry-ioc/src/main/java/org/apache/tapestry5/ioc/internal/ModuleImpl.java
Thu Sep 11 07:25:11 2008
@@ -44,6 +44,9 @@
private final Logger logger;
+ /**
+ * Lazily instantiated. Access is guarded by BARRIER.
+ */
private Object moduleBuilder;
// Set to true when invoking the module constructor. Used to
@@ -52,11 +55,15 @@
private boolean insideConstructor;
/**
- * Keyed on fully qualified service id; values are instantiated services
(proxies).
+ * Keyed on fully qualified service id; values are instantiated services
(proxies). Guarded by BARRIER.
*/
private final Map<String, Object> services =
CollectionFactory.newCaseInsensitiveMap();
- private final ConcurrentBarrier barrier = new ConcurrentBarrier();
+ /**
+ * The barrier is shared by all modules, which means that creation of
*any* service for any module is single
+ * threaded.
+ */
+ private final static ConcurrentBarrier BARRIER = new ConcurrentBarrier();
public ModuleImpl(InternalRegistry registry, ServiceActivityTracker
tracker, ModuleDef moduleDef,
ClassFactory classFactory, Logger logger)
@@ -148,9 +155,20 @@
{
public Object invoke()
{
- Object result = create(def, eagerLoadProxies);
+ // In a race condition, two threads may try to create the same
service simulatenously.
+ // The second will block until after the first creates the
service.
+
+ Object result = services.get(key);
- services.put(key, result);
+ // Normally, result is null, unless some other thread slipped
in and created the service
+ // proxy.
+
+ if (result == null)
+ {
+ result = create(def, eagerLoadProxies);
+
+ services.put(key, result);
+ }
return result;
}
@@ -164,14 +182,14 @@
if (result == null)
{
- result = barrier.withWrite(create);
+ result = BARRIER.withWrite(create);
}
return result;
}
};
- return barrier.withRead(find);
+ return BARRIER.withRead(find);
}
public void collectEagerLoadServices(Collection<EagerLoadServiceProxy>
proxies)
@@ -261,7 +279,7 @@
{
public Object invoke()
{
- if (moduleBuilder == null)
barrier.withWrite(instantiateModuleBuilder);
+ if (moduleBuilder == null)
BARRIER.withWrite(instantiateModuleBuilder);
return moduleBuilder;
}
@@ -269,7 +287,7 @@
public Object getModuleBuilder()
{
- return barrier.withRead(provideModuleBuilder);
+ return BARRIER.withRead(provideModuleBuilder);
}
private Object constructModuleBuilder()
