modules/core/src/main/java/org/apache/ignite/DataRegionMetricsProvider.java

/*
 * 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;

/**
 * This interface provides calculated metrics for data region.
 */
public interface DataRegionMetricsProvider {
    /**
     * Calculates free space of partially filled pages for this data region. It does not include
     * empty data pages.
     *
     * @return free space in bytes.
     */
    public long partiallyFilledPagesFreeSpace();

    /**
     * Calculates empty data pages count for region. It counts only totally free pages that
     * can be reused (e. g. pages that are contained in reuse bucket of free list).
     *
     * @return empty data pages count.
     */
    public long emptyDataPages();
}