Add a base Inmplementation for StageContext
-------------------------------------------
Key: SANDBOX-249
URL: https://issues.apache.org/jira/browse/SANDBOX-249
Project: Commons Sandbox
Issue Type: Improvement
Components: Pipeline
Reporter: Sheldon Robinson
/*
* 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.commons.pipeline;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EventObject;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* This class provide an instance inmplementation of StageContext and maybe
* extended to provided additional functionality of included in other classes
* wishing to in the StageContext Interface
*
* @author sheldon
*
*/
public class BaseContext implements StageContext {
// Map of DownstreamFeeder having the Stage as key
private final Map<Stage, Feeder> feeders;
// Map of pipeline branches where the keys are branch names.
private final Map<String,Pipeline> branches;
// The list of listeners registered with the pipeline.
private final List<StageEventListener> listeners;
// Global environment variables
private Map<String,Object> env = Collections.synchronizedMap(new
HashMap<String,Object>());
public BaseContext(){
this.feeders = new HashMap<Stage, Feeder>();
this.branches = new HashMap<String,Pipeline>();
this.listeners = Collections.synchronizedList(new
ArrayList<StageEventListener>());
}
@Override
public Feeder getBranchFeeder(String branch) {
return branches.get(branch).getSourceFeeder();
}
/**
* Add a branch [EMAIL PROTECTED] Pipeline} to the Stage
* @param key a string allowing the look-up of a branch
* @param branch a Pipeline added to Stage
* @return Pipeline The prior Pipeline corresponding to the key
*/
public Pipeline addBranch(String key, Pipeline branch){
return branches.put(key,branch);
}
@Override
public Feeder getDownstreamFeeder(Stage stage) {
return feeders.get(stage)!= null?feeders.get(stage):Feeder.VOID;
}
public Feeder addDownstreamFeeder(Stage stage, Feeder feeder) throws
IllegalArgumentException{
if(stage != null)
return feeders.put(stage, feeder);
else
throw new IllegalArgumentException("Attempted insert of
null stage");
}
@Override
public Object getEnv(String key) {
return env.get(key);
}
/**
* Sets a global environment variable for the stage.
* @param key a string to look-up the an environment variable
* @param value The Object to set for the variable
* @return Object The prior object corresponding to the key
*/
public Object setEnv(String key, Object value){
return env.put(key, value);
}
@Override
public Collection<StageEventListener> getRegisteredListeners() {
return listeners;
}
@Override
public void raise(final EventObject ev) {
for (final StageEventListener listener : listeners) {
new Thread() {
public void run() {
listener.notify(ev);
}
}.start();
}
}
@Override
public void registerListener(StageEventListener listener) {
listeners.add(listener);
}
}
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