| /* |
| * 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.pig.data; |
| |
| import java.lang.Class; |
| import java.lang.ClassLoader; |
| import java.net.URL; |
| import java.net.URLClassLoader; |
| import java.util.Comparator; |
| import java.util.List; |
| |
| import org.apache.pig.classification.InterfaceAudience; |
| import org.apache.pig.classification.InterfaceStability; |
| import org.apache.pig.impl.util.SpillableMemoryManager; |
| |
| /** |
| * Factory for constructing different types of bags. |
| * This class is abstract so that users can |
| * override the bag factory if they desire to provide their own that |
| * returns their implementation of a bag. If the property |
| * pig.data.bag.factory.name is set to a class name and |
| * pig.data.bag.factory.jar is set to a URL pointing to a jar that |
| * contains the above named class, then getInstance() will create |
| * an instance of the named class using the indicated jar. Otherwise, it |
| * will create an instance of DefaultBagFactory. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public abstract class BagFactory { |
| private static BagFactory gSelf = null; |
| private static SpillableMemoryManager gMemMgr; |
| |
| /** |
| * Get a reference to the singleton factory. |
| * @return BagFactory |
| */ |
| public static BagFactory getInstance() { |
| if (gSelf == null) { |
| String factoryName = |
| System.getProperty("pig.data.bag.factory.name"); |
| String factoryJar = |
| System.getProperty("pig.data.bag.factory.jar"); |
| if (factoryName != null && factoryJar != null) { |
| try { |
| URL[] urls = new URL[1]; |
| urls[0] = new URL(factoryJar); |
| ClassLoader loader = new URLClassLoader(urls, |
| BagFactory.class.getClassLoader()); |
| Class c = Class.forName(factoryName, true, loader); |
| Object o = c.newInstance(); |
| if (!(o instanceof BagFactory)) { |
| throw new RuntimeException("Provided factory " + |
| factoryName + " does not extend BagFactory!"); |
| } |
| gSelf = (BagFactory)o; |
| } catch (Exception e) { |
| if (e instanceof RuntimeException) { |
| // We just threw this |
| RuntimeException re = (RuntimeException)e; |
| throw re; |
| } |
| throw new RuntimeException("Unable to instantiate " |
| + "bag factory " + factoryName, e); |
| } |
| } else { |
| gSelf = new DefaultBagFactory(); |
| } |
| } |
| return gSelf; |
| } |
| |
| /** |
| * Get a default (unordered, not distinct) data bag. |
| * @return default data bag. |
| */ |
| public abstract DataBag newDefaultBag(); |
| |
| /** |
| * Get a default (unordered, not distinct) data bag with |
| * an existing list of tuples inserted into the bag. |
| * @param listOfTuples list of tuples to be placed in the bag. This list may not be |
| * copied, it may be used directly by the created bag. |
| * @return default data bag. |
| */ |
| public abstract DataBag newDefaultBag(List<Tuple> listOfTuples); |
| |
| /** |
| * Get a sorted data bag. Sorted bags guarantee that when an iterator |
| * is opened on the bag the tuples will be returned in sorted order. |
| * @param comp Comparator that controls how the data is sorted. |
| * If null, default comparator will be used. |
| * @return a sorted data bag |
| */ |
| public abstract DataBag newSortedBag(Comparator<Tuple> comp); |
| |
| /** |
| * Get a distinct data bag. Distinct bags guarantee that when an |
| * iterator is opened on the bag, no two tuples returned from the |
| * iterator will be equal. |
| * @return distinct data bag |
| */ |
| public abstract DataBag newDistinctBag(); |
| |
| /** |
| * Construct a new BagFactory |
| */ |
| protected BagFactory() { |
| gMemMgr = SpillableMemoryManager.getInstance(); |
| } |
| |
| /** |
| * @deprecated As of Pig 0.11, bags register with the {@link SpillableMemoryManager} themselves. |
| * Register a bag with the |
| * {@link org.apache.pig.impl.util.SpillableMemoryManager}. |
| * If the bags created by an implementation of BagFactory are managed by |
| * the {@link org.apache.pig.impl.util.SpillableMemoryManager} then this |
| * method should be called each time a new bag is created. |
| * @param b bag to be registered. |
| */ |
| @Deprecated |
| protected void registerBag(DataBag b) { |
| gMemMgr.registerSpillable(b); |
| } |
| |
| /** |
| * Provided for testing purposes only. This function should never be |
| * called by anybody but the unit tests. |
| */ |
| public static void resetSelf() { |
| gSelf = null; |
| } |
| |
| } |
| |