/*
 * 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.hyracks.storage.am.lsm.common.impls;

import java.util.concurrent.atomic.AtomicInteger;

import org.apache.hyracks.api.exceptions.HyracksDataException;
import org.apache.hyracks.storage.am.common.impls.NoOpIndexAccessParameters;
import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndex;
import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
import org.apache.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
import org.apache.hyracks.storage.am.lsm.common.api.LSMOperationType;
import org.apache.hyracks.storage.common.IModificationOperationCallback;
import org.apache.hyracks.storage.common.ISearchOperationCallback;

public class ThreadCountingTracker implements ILSMOperationTracker {
    private final AtomicInteger threadRefCount;

    public ThreadCountingTracker() {
        this.threadRefCount = new AtomicInteger();
    }

    @Override
    public void beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
            IModificationOperationCallback modificationCallback) throws HyracksDataException {
        if (opType == LSMOperationType.MODIFICATION) {
            threadRefCount.incrementAndGet();
        }
    }

    @Override
    public void afterOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
            IModificationOperationCallback modificationCallback) throws HyracksDataException {
        // The operation is considered inactive, immediately after leaving the index.
        completeOperation(index, opType, searchCallback, modificationCallback);
    }

    @Override
    public void completeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
            IModificationOperationCallback modificationCallback) throws HyracksDataException {
        // Flush will only be handled by last exiting thread.
        if (opType == LSMOperationType.MODIFICATION && threadRefCount.decrementAndGet() == 0
                && index.hasFlushRequestForCurrentMutableComponent()) {
            ILSMIndexAccessor accessor = index.createAccessor(NoOpIndexAccessParameters.INSTANCE);
            accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(index));
        }
    }
}
