83 lines
3.1 KiB
Java
83 lines
3.1 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* $Header:$
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*/
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package org.apache.beehive.controls.api.context;
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import java.util.Stack;
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/**
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* The ControlThreadContext class manages the association between ControlContainerContexts
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* and threads of execution. For a given thread of execution, the beginning and ending of
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* contexts will always be nested (never interleaved), so each thread will maintain its own
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* stack of currently executing contexts. This can be used to reassociate with the current
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* active context.
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*/
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public class ControlThreadContext
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{
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/**
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* This thread local maintains a per-thread stack of ControlContainerContext instances.
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*/
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private static ThreadLocal<Stack<ControlContainerContext>> _threadContexts =
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new ThreadLocal<Stack<ControlContainerContext>>();
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/**
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* Returns the active ControlContainerContext for the current thread, or null if no
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* context is currently active.
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* @return the current active ControlContainerContext
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*/
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public static ControlContainerContext getContext()
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{
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Stack<ControlContainerContext> contextStack = _threadContexts.get();
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if (contextStack == null || contextStack.size() == 0)
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return null;
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return contextStack.peek();
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}
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/**
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* Defines the beginning of a new control container execution context.
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*/
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public static void beginContext(ControlContainerContext context)
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{
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Stack<ControlContainerContext> contextStack = _threadContexts.get();
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if (contextStack == null)
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{
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contextStack = new Stack<ControlContainerContext>();
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_threadContexts.set(contextStack);
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}
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contextStack.push(context);
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}
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/**
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* Ends the current control container execution context
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* @throws IllegalStateException if there is not current active context or it is not
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* the requested context.
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*/
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public static void endContext(ControlContainerContext context)
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{
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Stack<ControlContainerContext> contextStack = _threadContexts.get();
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if (contextStack == null || contextStack.size() == 0)
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throw new IllegalStateException("No context started for current thread");
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if (contextStack.peek() != context)
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throw new IllegalStateException("Context is not the current active context");
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contextStack.pop();
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}
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}
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