LocationMap should use HashMap for better performance

The TreeMap data retrieval is slower compared to HashMap and it seems
that TreeMap.subMap used in matchingPrefixDo() only needed on moving /
deleting resources. So it seems that at least for startup / refresh /
build case we can save lot of time.

Fixes #2251

Author: iloveeclipse

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/AliasManager.java

@@ -24,6 +24,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.SortedMap;
@@ -134,7 +135,7 @@ class LocationMap {
 		/**
 		 * Map of FileStore->IResource OR FileStore->ArrayList of (IResource)
 		 */
-		private final SortedMap<IFileStore, Object> map = new TreeMap<>(IFileStore::compareTo);
+		private Map<IFileStore, Object> map = new HashMap<>(10_000); // new TreeMap<>(IFileStore::compareTo);
 
 		/**
 		 * Adds the given resource to the map, keyed by the given location.
@@ -177,13 +178,20 @@ public void clear() {
 		 * given location as a prefix.
 		 */
 		public void matchingPrefixDo(IFileStore prefix, Consumer<IResource> doit) {
-			SortedMap<IFileStore, Object> matching;
+			Map<IFileStore, Object> matching;
 			IFileStore prefixParent = prefix.getParent();
 			if (prefixParent != null) {
 				//endPoint is the smallest possible path greater than the prefix that doesn't
 				//match the prefix
 				IFileStore endPoint = prefixParent.getChild(prefix.getName() + "\0"); //$NON-NLS-1$
-				matching = map.subMap(prefix, endPoint);
+				if (map instanceof SortedMap<IFileStore, Object> sorted) {
+					matching = sorted.subMap(prefix, endPoint);
+				} else {
+					TreeMap<IFileStore, Object> newMap = new TreeMap<>(IFileStore::compareTo);
+					newMap.putAll(map);
+					map = newMap;
+					matching = newMap.subMap(prefix, endPoint);
+				}
 			} else {
 				matching = map;
 			}