Cache DirCache instance in DecoratableResourceHelper

DirCache instances are reused in DecoratableResourceAdapter and
DecoratableResourceHelper to improve decoration performance.
Depends on jgit change http://egit.eclipse.org/r/2467

Change-Id: I222c5880167c99dee1c3a5c018fb329688720472
Signed-off-by: Jens Baumgart <jens.baumgart@sap.com>
Signed-off-by: Philipp Thun <philipp.thun@sap.com>

2 files changed, 19 insertions, 2 deletions

diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceAdapter.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceAdapter.java
index 3424c23348..5eddaf7b67 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceAdapter.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceAdapter.java
@@ -349,10 +349,11 @@ class DecoratableResourceAdapter extends DecoratableResource {
 			treeWalk.addTree(new EmptyTreeIterator());
 
 		// Index
-		treeWalk.addTree(new DirCacheIterator(repository.readDirCache()));
+		treeWalk.addTree(new DirCacheIterator(DecoratableResourceHelper.getDirCache(repository)));
 
 		// Working directory
 		treeWalk.addTree(IteratorService.createInitialIterator(repository));
 		return treeWalk;
 	}
+
 }
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceHelper.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceHelper.java
index 22b7734188..816def25e3 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceHelper.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/decorators/DecoratableResourceHelper.java
@@ -10,6 +10,8 @@ package org.eclipse.egit.ui.internal.decorators;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.eclipse.core.resources.IResource;
 import org.eclipse.egit.core.ContainerTreeIterator;
@@ -17,6 +19,7 @@ import org.eclipse.egit.core.ContainerTreeIterator.ResourceEntry;
 import org.eclipse.egit.core.IteratorService;
 import org.eclipse.egit.core.project.RepositoryMapping;
 import org.eclipse.egit.ui.internal.decorators.IDecoratableResource.Staged;
+import org.eclipse.jgit.dircache.DirCache;
 import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.dircache.DirCacheIterator;
 import org.eclipse.jgit.lib.Constants;
@@ -42,6 +45,8 @@ class DecoratableResourceHelper {
 
 	static final int T_WORKSPACE = 2;
 
+	private static final Map<Repository, DirCache> repoToDirCache = new WeakHashMap<Repository, DirCache>();
+
 	static IDecoratableResource[] createDecoratableResources(
 			final IResource[] resources) throws IOException {
 		// Use first (available) resource to get repository mapping
@@ -112,6 +117,17 @@ class DecoratableResourceHelper {
 		return decoratableResources;
 	}
 
+	static DirCache getDirCache(Repository repository) throws IOException {
+		synchronized(repoToDirCache) {
+			DirCache dirCache = repoToDirCache.get(repository);
+			if (dirCache != null && !dirCache.isOutdated())
+				return dirCache;
+			dirCache = repository.readDirCache();
+			repoToDirCache.put(repository, dirCache);
+			return dirCache;
+		}
+	}
+
 	private static TreeWalk createThreeWayTreeWalk(
 			final RepositoryMapping mapping,
 			final ArrayList<String> resourcePaths) throws IOException {
@@ -136,7 +152,7 @@ class DecoratableResourceHelper {
 			treeWalk.addTree(new EmptyTreeIterator());
 
 		// Index
-		treeWalk.addTree(new DirCacheIterator(repository.readDirCache()));
+		treeWalk.addTree(new DirCacheIterator(getDirCache(repository)));
 
 		// Working directory
 		treeWalk.addTree(IteratorService.createInitialIterator(repository));