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java/org/apache/tomcat/websocket/FutureToSendHandler.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You 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.apache.tomcat.websocket;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicReference;
+
+import javax.websocket.SendHandler;
+import javax.websocket.SendResult;
+
+import org.apache.tomcat.util.res.StringManager;
+
+
+/**
+ * Converts a Future to a SendHandler.
+ */
+class FutureToSendHandler implements Future<Void>, SendHandler {
+
+    private static final StringManager sm = StringManager.getManager(FutureToSendHandler.class);
+
+    private final CountDownLatch latch = new CountDownLatch(1);
+    private final WsSession wsSession;
+    private volatile AtomicReference<SendResult> result = new AtomicReference<>(null);
+
+    public FutureToSendHandler(WsSession wsSession) {
+        this.wsSession = wsSession;
+    }
+
+
+    // --------------------------------------------------------- SendHandler
+
+    @Override
+    public void onResult(SendResult result) {
+        this.result.compareAndSet(null, result);
+        latch.countDown();
+    }
+
+
+    // -------------------------------------------------------------- Future
+
+    @Override
+    public boolean cancel(boolean mayInterruptIfRunning) {
+        // Cancelling the task is not supported
+        return false;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        // Cancelling the task is not supported
+        return false;
+    }
+
+    @Override
+    public boolean isDone() {
+        return latch.getCount() == 0;
+    }
+
+    @Override
+    public Void get() throws InterruptedException,
+            ExecutionException {
+        try {
+            wsSession.registerFuture(this);
+            latch.await();
+        } finally {
+            wsSession.unregisterFuture(this);
+        }
+        if (result.get().getException() != null) {
+            throw new ExecutionException(result.get().getException());
+        }
+        return null;
+    }
+
+    @Override
+    public Void get(long timeout, TimeUnit unit)
+            throws InterruptedException, ExecutionException,
+            TimeoutException {
+        boolean retval = false;
+        try {
+            wsSession.registerFuture(this);
+            retval = latch.await(timeout, unit);
+        } finally {
+            wsSession.unregisterFuture(this);
+
+        }
+        if (retval == false) {
+            throw new TimeoutException(sm.getString("futureToSendHandler.timeout",
+                    Long.valueOf(timeout), unit.toString().toLowerCase()));
+        }
+        if (result.get().getException() != null) {
+            throw new ExecutionException(result.get().getException());
+        }
+        return null;
+    }
+}