| /* |
| * 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.cocoon.components.flow.java; |
| |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * Continuation object to store the current execution. The continuation |
| * object can only used once. |
| * |
| * @author <a href="mailto:stephan@apache.org">Stephan Michels</a> |
| * @author <a href="mailto:tcurdt@apache.org">Torsten Curdt</a> |
| * @version CVS $Id$ |
| */ |
| public class Continuation { |
| |
| private static final Map continuations = Collections.synchronizedMap(new HashMap()); |
| |
| private final String functionName; |
| private final ContinuationStack stack; |
| private Object context; |
| |
| public boolean restoring = false; |
| public boolean capturing = false; |
| |
| /** |
| * Create new continuation. |
| */ |
| public Continuation(final String functionName, final Object context) { |
| this.functionName = functionName; |
| this.stack = new ContinuationStack(); |
| this.context = context; |
| } |
| |
| /** |
| * Create a new continuation, which continue a previous continuation. |
| */ |
| public Continuation(final Continuation parent, final Object context) { |
| if (parent == null) |
| throw new NullPointerException("Parent continuation is null"); |
| |
| this.functionName = parent.functionName; |
| this.stack = new ContinuationStack(parent.stack); |
| this.context = context; |
| this.restoring = true; |
| } |
| |
| public String getFunctionName() { |
| return functionName; |
| } |
| |
| /** |
| * Return the stack, which is used to store the frame information. |
| */ |
| public ContinuationStack getStack() { |
| return stack; |
| } |
| |
| /** |
| * Return context object, which is associated to this continuation. |
| */ |
| public Object getContext() { |
| return context; |
| } |
| |
| /** |
| * Suspend the running continuation or restore the suspended continuation. |
| * |
| * With the help of byte code manipulation this method is run twice, once at |
| * the end of request 1 to suspend the continuation and a second time at the |
| * beginning of the request 2. |
| */ |
| public static void suspend() { |
| Continuation continuation = Continuation.currentContinuation(); |
| |
| if (continuation == null) |
| throw new IllegalStateException("No continuation is running"); |
| |
| if (continuation.restoring) { |
| // restoring |
| continuation.capturing = false; |
| } else { |
| // suspending |
| continuation.context = null; |
| continuation.capturing = true; |
| } |
| continuation.restoring = false; |
| } |
| |
| /** |
| * True, if the continuation restores the previous stack trace to the |
| * last invocation of suspend(). |
| */ |
| public boolean isRestoring() { |
| return restoring; |
| } |
| |
| /** |
| * True, if the continuation freezes the stack trace, and stops the continuation. |
| */ |
| public boolean isCapturing() { |
| return capturing; |
| } |
| |
| /** |
| * Bind the continuation to running thread. |
| */ |
| public void registerThread() { |
| continuations.put(Thread.currentThread(), this); |
| } |
| |
| /** |
| * Unbind the continuation to running thread. |
| */ |
| public void deregisterThread() { |
| continuations.remove(Thread.currentThread()); |
| } |
| |
| /** |
| * Return the continuation, which is associated to the |
| * current thread. |
| */ |
| public static Continuation currentContinuation() { |
| Thread t = Thread.currentThread(); |
| return (Continuation) continuations.get(t); |
| } |
| |
| } |