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markt pushed a commit to branch 11.0.x
in repository https://gitbox.apache.org/repos/asf/tomcat.git
The following commit(s) were added to refs/heads/11.0.x by this push:
new d4e12aee16 Re-work the fix for BZ 69527
d4e12aee16 is described below
commit d4e12aee1636bee4a4e48b3ffd0408f4049e3425
Author: Mark Thomas <[email protected]>
AuthorDate: Tue Jan 14 07:22:20 2025 +0000
Re-work the fix for BZ 69527
Ensures that getSize() always returns the correct value which fixes both
BZ 69527 and the original cache size corruption issue (the original fix
for which caused BZ 69527(
---
.../catalina/webresources/CachedResource.java | 23 ++++++++++------------
1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/java/org/apache/catalina/webresources/CachedResource.java
b/java/org/apache/catalina/webresources/CachedResource.java
index 987cac39c0..c71807255d 100644
--- a/java/org/apache/catalina/webresources/CachedResource.java
+++ b/java/org/apache/catalina/webresources/CachedResource.java
@@ -75,7 +75,6 @@ public class CachedResource implements WebResource {
private volatile Boolean cachedExists = null;
private volatile Boolean cachedIsVirtual = null;
private volatile Long cachedContentLength = null;
- private final Object cachedContentLengthLock = new Object();
private volatile String cachedStrongETag = null;
@@ -248,28 +247,26 @@ public class CachedResource implements WebResource {
@Override
public long getContentLength() {
- if (webResource == null) {
- return 0;
- }
/*
* Cache the content length for two reasons.
*
* 1. It is relatively expensive to calculate, it shouldn't change and
this method is called multiple times
* during cache validation. Caching, therefore, offers a performance
benefit.
*
- * 2. There is a race condition if concurrent threads are trying to
PUT and DELETE the same resource. If the
- * DELETE thread removes the cache entry after the PUT thread has
created it but before validation is complete
- * the DELETE thread sees a content length for a non-existant resource
but the PUT thread sees the actual
- * content length. While that isn't an issue for the individual
requests it, does corrupt the cache size
- * tracking as the size used for the resource is different between
when it is added to the cache and when it is
- * removed. Caching combined with locking ensures that a consistent
content length is reported for the resource.
+ * 2. There is a race condition if concurrent threads are trying to
PUT and DELETE the same resource. See BZ
+ * 69527 (https://bz.apache.org/bugzilla/show_bug.cgi?id=69527#c14)
for full details. The short version is that
+ * getContentLength() must always return the same value for any one
CachedResource instance else the cache size
+ * will be corrupted.
*/
if (cachedContentLength == null) {
- synchronized (cachedContentLengthLock) {
- if (cachedContentLength == null) {
- cachedContentLength =
Long.valueOf(webResource.getContentLength());
+ if (webResource == null) {
+ synchronized (this) {
+ if (webResource == null) {
+ webResource = root.getResourceInternal(webAppPath,
usesClassLoaderResources);
+ }
}
}
+ cachedContentLength = Long.valueOf(webResource.getContentLength());
}
return cachedContentLength.longValue();
}
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