includes/libs/objectcache/IExpiringStore.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  * @ingroup Cache
  20  */
  21
  22 /**
  23  * Generic interface for lightweight expiring object stores.
  24  *
  25  * Provides convenient TTL constants.
  26  *
  27  * @ingroup Cache
  28  * @since 1.27
  29  */
  30 interface IExpiringStore {
  31         // Constants for TTL values, in seconds
  32         const TTL_SECOND = 1;
  33         const TTL_MINUTE = 60;
  34         const TTL_HOUR = 3600;
  35         const TTL_DAY = 86400; // 24 * 3600
  36         const TTL_WEEK = 604800; // 7 * 24 * 3600
  37         const TTL_MONTH = 2592000; // 30 * 24 * 3600
  38         const TTL_YEAR = 31536000; // 365 * 24 * 3600
  39
  40         // Shorthand process cache TTLs (useful for web requests and CLI mode)
  41         const TTL_PROC_SHORT = 3; // reasonably strict cache time that last the life of quick requests
  42         const TTL_PROC_LONG = 30; // loose cache time that can survive slow web requests
  43
  44         const TTL_INDEFINITE = 0;
  45
  46         // Emulation/fallback medium attribute (e.g. SQLBagOStuff)
  47         const ATTR_EMULATION = 1;
  48         // Quality of service constants for ATTR_EMULATION (higher means faster)
  49         const QOS_EMULATION_SQL = 1;
  50
  51         // Replica synchronization/consistency attribute of medium when SYNC_WRITES is used
  52         const ATTR_SYNCWRITES = 2;
  53         // Quality of service constants for ATTR_SYNCWRITES (higher means more consistent)
  54         const QOS_SYNCWRITES_NONE = 1; // replication only supports eventual consistency or less
  55         const QOS_SYNCWRITES_BE = 2; // best effort synchronous with limited retries
  56         const QOS_SYNCWRITES_QC = 3; // write quorum applied directly to state machines where R+W > N
  57         const QOS_SYNCWRITES_SS = 4; // strict-serializable, nodes refuse reads if possible stale
  58
  59         // Generic "unknown" value that is useful for comparisons (e.g. always good enough)
  60         const QOS_UNKNOWN = INF;
  61
  62         const ERR_NONE = 0; // no error
  63         const ERR_NO_RESPONSE = 1; // no response
  64         const ERR_UNREACHABLE = 2; // can't connect
  65         const ERR_UNEXPECTED = 3; // response gave some error
  66 }