/*
 * Copyright Terracotta, Inc.
 *
 * 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 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.ehcache.core.statistics;

import org.terracotta.statistics.ValueStatistic;

import java.util.Map;

All statistics relative to a tier
/**
 * All statistics relative to a tier
 */
public interface TierStatistics {

  
List of statistics tracked on this cache
Returns:
a map of statistics per name/**
   * List of statistics tracked on this cache
   *
   * @return a map of statistics per name
   */
  Map<String, ValueStatistic<?>> getKnownStatistics();

  
Reset the values for this tier. However, note that mapping, allocatedMemory, occupiedMemory won't be reset since it doesn't make sense. 

Implementation note: Calling clear doesn't really clear the data. It freezes the actual values and compensate
for them when returning a result.
/**
   * Reset the values for this tier. However, note that {@code mapping, allocatedMemory, occupiedMemory}
   * won't be reset since it doesn't make sense.
   * <p>
   * <b>Implementation note:</b> Calling clear doesn't really clear the data. It freezes the actual values and compensate
   * for them when returning a result.
   */
  void clear();

  
How many hits occurred on the tier since its creation or the latest clear() 
Returns:
hit count/**
   * How many hits occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return hit count
   */
  long getHits();

  
How many misses occurred on the tier since its creation or the latest clear() 
Returns:
miss count/**
   * How many misses occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return miss count
   */
  long getMisses();

  
How many puts occurred on the tier since its creation or the latest clear() 
Returns:
put count/**
   * How many puts occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return put count
   */
  long getPuts();

  
How many removals occurred on the tier since its creation or the latest clear() 
Returns:
removal count/**
   * How many removals occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return removal count
   */
  long getRemovals();

  
How many evictions occurred on the tier since its creation or the latest clear() 
Returns:
eviction count/**
   * How many evictions occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return eviction count
   */
  long getEvictions();

  
How many expirations occurred on the tier since its creation or the latest clear() 
Returns:
expiration count/**
   * How many expirations occurred on the tier since its creation or the latest {@link #clear()}
   *
   * @return expiration count
   */
  long getExpirations();

  
Number of entries currently in this tier
Returns:
number of entries/**
   * Number of entries currently in this tier
   *
   * @return number of entries
   */
  long getMappings();

  
How many bytes are currently allocated (occupied or not) for this tier
Returns:
number of bytes allocated/**
   * How many bytes are currently allocated (occupied or not) for this tier
   *
   * @return number of bytes allocated
   */
  long getAllocatedByteSize();

  
How many bytes are currently occupied for this tier
Returns:
number of bytes occupied/**
   * How many bytes are currently occupied for this tier
   *
   * @return number of bytes occupied
   */
  long getOccupiedByteSize();
}