[FIXED JENKINS-21780] Revised fix to make cache work properly without...

[FIXED JENKINS-21780] Revised fix to make cache work properly without introducing a new remote call to find hash codes.

changelog.html

@@ -58,6 +58,9 @@ Upcoming changes</a>
   <li class=bug>
     Archiving of symlinks as artifacts did not work in some cases.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21958">issue 21958</a>)
+  <li class=bug>
+    Slow rendering of directories with many entries in remote workspaces.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21780">issue 21780</a>)
 </ul>
 </div><!--=TRUNK-END=-->
 
@@ -98,9 +101,6 @@ Upcoming changes</a>
   <li class=bug>
     Expensive symlink-related calls on Windows can be simplified.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20534">issue 20534</a>)
-  <li class=bug>
-    Slow rendering of directories with many entries in remote workspaces.
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21780">issue 21780</a>)
 </ul>
 <h3><a name=v1.551>What's new in 1.551</a> (2014/02/14)</h3>
 <ul class=image>

core/src/main/java/hudson/model/DirectoryBrowserSupport.java

@@ -34,7 +34,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.HashMap;
+import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -431,7 +431,7 @@ public final class DirectoryBrowserSupport implements HttpResponse {
 
     private static final class FileComparator implements Comparator<VirtualFile> {
         private Collator collator;
-        private final Map<VirtualFile,Boolean> isDirCache = new HashMap<VirtualFile,Boolean>();
+        private final Map<VirtualFile,Boolean> isDirCache = new IdentityHashMap<VirtualFile,Boolean>();
 
         FileComparator(Locale locale) {
             this.collator = Collator.getInstance(locale);