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JCR-5161: NamespaceHelper - get NamespaceRegistry only once #259

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Merged
reschke merged 2 commits into from
Jul 8, 2025
Merged

JCR-5161: NamespaceHelper - get NamespaceRegistry only once #259

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JCR-5161: NamespaceHelper - get NamespaceRegistry only once
reschke Jul 7, 2025
84a5487
JCR-5161: NamespaceHelper - get NamespaceRegistry only once
reschke Jul 7, 2025
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21 changes: 19 additions & 2 deletions jackrabbit-jcr-commons/src/main/java/org/apache/jackrabbit/commons/NamespaceHelper.java
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Original file line number Diff line number Diff line change
Expand Up @@ -53,13 +53,31 @@ public class NamespaceHelper {
*/
private final Session session;

/**
* Current namespace registry.
*/
private NamespaceRegistry namespaceRegistry;

/**
* Creates a namespace helper for the given session.
*
* @param session current session
*/
public NamespaceHelper(Session session) {
this.session = session;
// will be set on lazily
this.namespaceRegistry = null;
}

/**
Get the namespace registry; needs to be done on-demand because the constructor
does not allow RepositoryException
*/
private NamespaceRegistry getNamespaceRegistry() throws RepositoryException {
if (namespaceRegistry == null) {
namespaceRegistry = session.getWorkspace().getNamespaceRegistry();
}
return namespaceRegistry;
}

/**
Expand Down Expand Up @@ -197,8 +215,7 @@ public String getJcrName(String name)
*/
public String registerNamespace(String prefix, String uri)
throws RepositoryException {
NamespaceRegistry registry =
session.getWorkspace().getNamespaceRegistry();
NamespaceRegistry registry = getNamespaceRegistry();
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@kwin kwin Jul 7, 2025

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Any pointers on how much overhead this call is? I was assuming this is not leading to complex and expensive object creations

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@reschke reschke Jul 7, 2025

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apparently it does in Oak - see https://issues.apache.org/jira/browse/OAK-11784 - it's of course a good question why it is expensive in Oak. @mbaedke - any idea?

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@joerghoh joerghoh Jul 8, 2025

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I don't think that this is is an expensive operation by itself. It's rather a problem if there are a lot of registered prefixes (see the excerpt of the stacktrace in https://issues.apache.org/jira/browse/OAK-11784), which leads to many invocations of this method.

try {
// Check if the namespace is registered
registry.getPrefix(uri);
Expand Down
3 changes: 3 additions & 0 deletions jackrabbit-jcr-commons/src/test/java/org/apache/jackrabbit/commons/NamespaceHelperTest.java
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Expand Up @@ -233,5 +233,8 @@ public void testRegisterNamespace() throws RepositoryException {
assertEquals("test1", nsReg.getPrefix("test1:"));
assertEquals("test2", nsReg.getPrefix("test2"));
assertEquals("ns6", nsReg.getPrefix("test3:"));

// check invocation count for getNamespaceRegistry (JCR-5161)
Mockito.verify(workspace, Mockito.times(1)).getNamespaceRegistry();
}
}