/*
 * 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.ignite.internal.processors.cache.persistence.partstate;

import org.apache.ignite.internal.util.typedef.internal.S;

/**
 * Range of pages allocated.
 * Contains currently allocated page count and previously observed page count.
 * May be used for tracking history of recent allocation for partition <code>[partition, cacheId]</code>
 */
public class PagesAllocationRange {
    /**
     * Previously observed total number of allocated pages. May be stored using PageMetaIO.
     * Used to separate newly allocated pages with previously observed state
     * Minimum value is 0. Can't be greater than {@link #currAllocatedPageCnt}
     */
    private final int lastAllocatedPageCnt;

    /** Total current number of pages allocated, minimum value is 0. */
    private final int currAllocatedPageCnt;

    /**
     * Creates pages range
     *
     * @param lastAllocatedPageCnt Last allocated pages count.
     * @param currAllocatedPageCnt Currently allocated pages count.
     */
    public PagesAllocationRange(final int lastAllocatedPageCnt, final int currAllocatedPageCnt) {
        this.lastAllocatedPageCnt = lastAllocatedPageCnt;
        this.currAllocatedPageCnt = currAllocatedPageCnt;
    }

    /**
     * @return Total current number of pages allocated, minimum value is 0.
     */
    public int getCurrAllocatedPageCnt() {
        return currAllocatedPageCnt;
    }

    /**
     * @return Previously observed total number of allocated pages.
     */
    public int getLastAllocatedPageCnt() {
        return lastAllocatedPageCnt;
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(PagesAllocationRange.class, this);
    }
}