Bug 575932 - cache existence of parent directoriesI20211103-1800I20211103-0020I20211102-1800I20211102-1020

For dependent and registered buddy policy it is possible that a large
number of dependent and/or registered bundles can be queried for classes
for a single hosting class loader.  This results in many bundle files
getting searched.  For DirBundleFile this can be expensive because it
involves checking for the existence of each file.  This solution caches
if the parent path of the entry lookup exists.  The idea is that in most
cases where an entry lookup doesn't exists the parent directory also
doesn't exists.  We cache a smaller number of existence checks and can
do a faster lookup if files in an non-existing parent exist or not.


Change-Id: Ibc4b48800335288bb0d2a770786c612c5d5eb6dc
Signed-off-by: Thomas Watson <tjwatson@us.ibm.com>
Reviewed-on: https://git.eclipse.org/r/c/equinox/rt.equinox.framework/+/186979
Tested-by: Equinox Bot <equinox-bot@eclipse.org>

1 files changed, 21 insertions, 1 deletions

diff --git a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/storage/bundlefile/DirBundleFile.java b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/storage/bundlefile/DirBundleFile.java
index 366c82b47..42483984f 100644
--- a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/storage/bundlefile/DirBundleFile.java
+++ b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/storage/bundlefile/DirBundleFile.java
@@ -16,7 +16,11 @@ package org.eclipse.osgi.storage.bundlefile;
 
 import java.io.File;
 import java.io.IOException;
-import java.util.*;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import org.eclipse.osgi.internal.messages.Msg;
 import org.eclipse.osgi.util.NLS;
 
@@ -30,6 +34,7 @@ public class DirBundleFile extends BundleFile {
 	private static final String POINTER_UPPER_DIRECTORY = "..";//$NON-NLS-1$
 
 	private final boolean enableStrictBundleEntryPath;
+	private final Map<File, Boolean> doesNotExistCache = new ConcurrentHashMap<>();
 
 	/**
 	 * Constructs a DirBundleFile
@@ -52,7 +57,12 @@ public class DirBundleFile extends BundleFile {
 	public File getFile(String path, boolean nativeCode) {
 		final boolean checkInBundle = path != null && path.indexOf(POINTER_UPPER_DIRECTORY) >= 0;
 		File file = new File(this.basefile, path);
+		File parentFile = file.getParentFile();
+		if (!parentExists(parentFile)) {
+			return null;
+		}
 		if (!BundleFile.secureAction.exists(file)) {
+			cacheIfParentExists(parentFile);
 			return null;
 		}
 
@@ -106,6 +116,16 @@ public class DirBundleFile extends BundleFile {
 		return file;
 	}
 
+
+	private void cacheIfParentExists(File parentFile) {
+		doesNotExistCache.computeIfAbsent(parentFile, secureAction::isDirectory);
+	}
+
+	private boolean parentExists(File parentFile) {
+		Boolean exists = doesNotExistCache.get(parentFile);
+		return exists == null || exists.booleanValue();
+	}
+
 	@Override
 	public BundleEntry getEntry(String path) {
 		File filePath = getFile(path, false);