hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/dataflow/IndexDataflowHelper.java

/*
 * Copyright 2009-2010 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.hyracks.storage.am.common.dataflow;

import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.api.io.FileReference;
import edu.uci.ics.hyracks.dataflow.std.file.IFileSplitProvider;
import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;

public abstract class IndexDataflowHelper {
    protected IIndex index;
    protected int indexFileId = -1;
    protected int partition;
    
    protected final IIndexOperatorDescriptor opDesc;
    protected final IHyracksTaskContext ctx;
    protected final boolean createIfNotExists;
    
    public IndexDataflowHelper(IIndexOperatorDescriptor opDesc, final IHyracksTaskContext ctx,
            int partition, boolean createIfNotExists) {
        this.opDesc = opDesc;
        this.ctx = ctx;        
        this.partition = partition;
        this.createIfNotExists = createIfNotExists;
    }

    public void init() throws HyracksDataException {
        IBufferCache bufferCache = opDesc.getStorageManager().getBufferCache(ctx);
        IFileMapProvider fileMapProvider = opDesc.getStorageManager().getFileMapProvider(ctx);        

        FileReference f = getFilereference();
        int fileId = -1;
        synchronized (fileMapProvider) {
            boolean fileIsMapped = fileMapProvider.isMapped(f);
            if (!fileIsMapped) {
                bufferCache.createFile(f);
            }
            fileId = fileMapProvider.lookupFileId(f);
            try {
                bufferCache.openFile(fileId);
            } catch (HyracksDataException e) {
                // Revert state of buffer cache since file failed to open.
                if (!fileIsMapped) {
                    bufferCache.deleteFile(fileId);
                }
                throw e;
            }
        }

        // Only set indexFileId member when openFile() succeeds,
        // otherwise deinit() will try to close the file that failed to open
        indexFileId = fileId;
        IndexRegistry<IIndex> indexRegistry = opDesc.getIndexRegistryProvider().getRegistry(ctx);
        // Create new index instance and register it.
        synchronized (indexRegistry) {
            // Check if the index has already been registered.
            index = indexRegistry.get(indexFileId);
            if (index != null) {
                return;
            }
            index = createIndexInstance();
            if (createIfNotExists) {
                index.create(indexFileId);                
            }
            index.open(indexFileId);
            indexRegistry.register(indexFileId, index);
        }
    }

    public abstract IIndex createIndexInstance() throws HyracksDataException;

    public FileReference getFilereference() {
        IFileSplitProvider fileSplitProvider = opDesc.getFileSplitProvider();
        return fileSplitProvider.getFileSplits()[partition].getLocalFile();
    }
    
    public void deinit() throws HyracksDataException {
        if (indexFileId != -1) {
            IBufferCache bufferCache = opDesc.getStorageManager().getBufferCache(ctx);
            bufferCache.closeFile(indexFileId);
        }
    }

    public IIndex getIndex() {
        return index;
    }

    public IHyracksTaskContext getHyracksTaskContext() {
        return ctx;
    }

    public IIndexOperatorDescriptor getOperatorDescriptor() {
        return opDesc;
    }

    public int getIndexFileId() {
        return indexFileId;
    }
}