move to springloaded

springloaded/src/main/java/org/springsource/loaded/NameRegistry.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2010-2012 VMware and contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springsource.loaded;
+
+/**
+ * Manages a mapping of names to numbers. The same number anywhere means the same name. This means that if some type a/b/C has been
+ * loaded in two places (by different classloaders), it will have the same number in both. Only one of those a/b/C types will be
+ * visible at the location in question, the tricky part could be working out which one (if classloaders are being naughty) but in
+ * theory the first time we get confused (due to finding the name twice), we can work out which one is right and use that mapping
+ * from then on.
+ * 
+ * @author Andy Clement
+ * @since 0.8.1
+ */
+public class NameRegistry {
+
+	private static int nextTypeId = 0;
+	private static int size = 10;
+	private static String[] allocatedIds = new String[size];
+
+	private NameRegistry() {
+	}
+
+	/**
+	 * Typically used by tests to ensure it looks like a fresh NameRegistry is being used.
+	 */
+	public static void reset() {
+		nextTypeId = 0;
+		size = 10;
+		allocatedIds = new String[size];
+	}
+
+	/**
+	 * Return the id for a particular type. This method will not allocate a new id if the type is unknown, it will return -1
+	 * instead.
+	 * 
+	 * @param slashedClassName a type name like java/lang/String
+	 * @return the allocated ID for that type or -1 if unknown
+	 */
+	public static int getIdFor(String slashedClassName) {
+		assert Asserts.assertNotDotted(slashedClassName);
+		for (int i = 0; i < nextTypeId; i++) {
+			if (allocatedIds[i].equals(slashedClassName)) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	/**
+	 * Return the id for a particular type. This method will not allocate a new id if the type is unknown, it will return -1
+	 * instead.
+	 * 
+	 * @param slashedClassName a type name like java/lang/String
+	 * @return the allocated ID for that type or -1 if unknown
+	 */
+	public static int getIdOrAllocateFor(String slashedClassName) {
+		int id = getIdFor(slashedClassName);
+		if (id == -1) {
+			id = allocateId(slashedClassName);
+		}
+		return id;
+	}
+
+	private synchronized static int allocateId(String slashedClassName) {
+		// Check again, in case two threads passed the -1 check in the getIdOrAllocateFor method
+		int id = getIdFor(slashedClassName);
+		if (id == -1) {
+			id = nextTypeId;
+			if (nextTypeId >= allocatedIds.length) {
+				size = size + 10;
+				// need to make more room
+				String[] newAllocatedIds = new String[size];
+				System.arraycopy(allocatedIds, 0, newAllocatedIds, 0, allocatedIds.length);
+				allocatedIds = newAllocatedIds;
+			}
+			allocatedIds[id] = slashedClassName;
+			nextTypeId++; // increase at the end once the value has been set in the array
+		}
+		return id;
+	}
+
+	public static String getTypenameById(int typeId) {
+		if (typeId > size) {
+			return null;
+		}
+		return allocatedIds[typeId];
+	}
+}