/*

 * Copyright (c) 2020 Red Hat, Inc.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 * 

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA. 

 *

 * $Id: //eng/uds-releases/jasper/src/uds/cacheCounters.h#1 $

 */

#ifndef CACHE_COUNTERS_H

#define CACHE_COUNTERS_H

#include "typeDefs.h"

/**

 * Basic counts of hits and misses for a given type of cache probe.

 **/

typedef struct cacheCountsByKind {

  /** Number of hits */

  uint64_t hits;

  /** Number of misses */

  uint64_t misses;

  /** Number of probes for data already queued for read */

  uint64_t queued;

} CacheCountsByKind;

/**

 * The various types of cache probes we care about.

 **/

typedef enum cacheProbeType {

  /** First attempt to look up an index page, for a given request. */

  CACHE_PROBE_INDEX_FIRST = 0,

  /** First attempt to look up a record page, for a given request. */

  CACHE_PROBE_RECORD_FIRST,

  /** Second or later attempt to look up an index page, for a given request. */

  CACHE_PROBE_INDEX_RETRY,

  /** Second or later attempt to look up a record page, for a given request. */

  CACHE_PROBE_RECORD_RETRY

} CacheProbeType;

enum {

  /** Flag bit to indicate that failures shouldn't be recorded.  */

  CACHE_PROBE_IGNORE_FAILURE = 128

};

/**

 * Result-type counts for both kinds of data pages in the page cache.

 **/

typedef struct cacheCountsByPageType {

  /** His/miss counts for index pages. */

  CacheCountsByKind indexPage;

  /** Hit/miss counts for record pages. */

  CacheCountsByKind recordPage;

} CacheCountsByPageType;

/**

 * All the counters used for an entry cache.

 **/

typedef struct cacheCounters {

  // counters for the page cache

  /** Hit/miss counts for the first attempt per request */

  CacheCountsByPageType firstTime;

  /** Hit/miss counts when a second (or later) attempt is needed */

  CacheCountsByPageType retried;

  /** Number of cache entry invalidations due to single-entry eviction */

  uint64_t              evictions;

  /** Number of cache entry invalidations due to chapter expiration */

  uint64_t              expirations;

  // counters for the sparse chapter index cache

  /** Hit/miss counts for the sparse cache chapter probes */

  CacheCountsByKind     sparseChapters;

  /** Hit/miss counts for the sparce cache name searches */

  CacheCountsByKind     sparseSearches;

} CacheCounters;

/**

 * Success/failure assessment of cache probe result.

 **/

typedef enum cacheResultKind {

  /** The requested entry was found in the cache */

  CACHE_RESULT_HIT,

  /** The requested entry was not found in the cache */

  CACHE_RESULT_MISS,

  /** The requested entry wasn't found in the cache but is queued for read */

  CACHE_RESULT_QUEUED

} CacheResultKind;

/**

 * Increment one of the cache counters.

 *

 * @param counters    pointer to the counters

 * @param probeType   type of access done

 * @param kind        result of probe

 **/

void incrementCacheCounter(CacheCounters   *counters,

                           int              probeType,

                           CacheResultKind  kind);

#endif /* CACHE_COUNTERS_H */