Initial import.

src/cz/cvut/keyczar/StreamCache.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2008 Google Inc.
+ *
+ * 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 cz.cvut.keyczar;
+
+import cz.cvut.keyczar.interfaces.Stream;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+/**
+ * Caches StreamQueue objects for KeyczarKeys so they can reused.
+ *
+ * @author steveweis@gmail.com (Steve Weis)
+ *
+ * @param <T>
+ */
+class StreamCache<T extends Stream> {
+  private final ConcurrentHashMap<KeyczarKey, StreamQueue<T>> cacheMap =
+    new ConcurrentHashMap<KeyczarKey, StreamQueue<T>>();
+
+  void put(KeyczarKey key, T s) {
+    getQueue(key).add(s);
+  }
+
+  T get(KeyczarKey key) {
+    return getQueue(key).poll();
+  }
+
+  StreamQueue<T> getQueue(KeyczarKey key) {
+    StreamQueue<T> queue = cacheMap.get(key);
+    if (queue != null) {
+      return queue;
+    }
+    StreamQueue<T> freshQueue = new StreamQueue<T>();
+    queue = cacheMap.putIfAbsent(key, freshQueue);
+    if (queue != null) {
+      // Another thread already inserted a fresh queue with this key.
+      return queue;
+    }
+    return freshQueue;
+  }
+}
+
+/**
+ * A thread-safe queue for Streams and their derived classes.
+ *
+ * @author steveweis@gmail.com (Steve Weis)
+ *
+ * @param <T>
+ */
+class StreamQueue<T extends Stream> extends ConcurrentLinkedQueue<T> {
+
+}