e1505ff742
App servers should not lower the redis structure TTL of locks set from CLI scripts, which is what would typically happen before if they touched the same keys. Instead, keep a high lock record TTL and rely on the logical TTLs for expiry semantics. Change-Id: I2948369845c47d2682a85dd0564673f3b813be83
276 lines
8.3 KiB
PHP
276 lines
8.3 KiB
PHP
<?php
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/**
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* Version of LockManager based on using redis servers.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup LockManager
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*/
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/**
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* Manage locks using redis servers.
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*
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* Version of LockManager based on using redis servers.
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* This is meant for multi-wiki systems that may share files.
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* All locks are non-blocking, which avoids deadlocks.
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*
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* All lock requests for a resource, identified by a hash string, will map to one
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* bucket. Each bucket maps to one or several peer servers, each running redis.
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* A majority of peers must agree for a lock to be acquired.
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*
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* This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
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*
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* @ingroup LockManager
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* @since 1.22
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*/
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class RedisLockManager extends QuorumLockManager {
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/** @var array Mapping of lock types to the type actually used */
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protected $lockTypeMap = [
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self::LOCK_SH => self::LOCK_SH,
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self::LOCK_UW => self::LOCK_SH,
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self::LOCK_EX => self::LOCK_EX
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];
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/** @var RedisConnectionPool */
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protected $redisPool;
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/** @var array Map server names to hostname/IP and port numbers */
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protected $lockServers = [];
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/**
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* Construct a new instance from configuration.
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*
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* @param array $config Parameters include:
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* - lockServers : Associative array of server names to "<IP>:<port>" strings.
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* - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
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* each having an odd-numbered list of server names (peers) as values.
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* - redisConfig : Configuration for RedisConnectionPool::__construct().
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* @throws Exception
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*/
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public function __construct( array $config ) {
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parent::__construct( $config );
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$this->lockServers = $config['lockServers'];
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// Sanitize srvsByBucket config to prevent PHP errors
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$this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
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$this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
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$config['redisConfig']['serializer'] = 'none';
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$this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] );
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}
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protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
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$status = StatusValue::newGood();
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$pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
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$server = $this->lockServers[$lockSrv];
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$conn = $this->redisPool->getConnection( $server, $this->logger );
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if ( !$conn ) {
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foreach ( $pathList as $path ) {
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$status->fatal( 'lockmanager-fail-acquirelock', $path );
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}
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return $status;
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}
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$pathsByKey = []; // (type:hash => path) map
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foreach ( $pathsByType as $type => $paths ) {
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$typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
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foreach ( $paths as $path ) {
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$pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
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}
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}
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try {
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static $script =
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/** @lang Lua */
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<<<LUA
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local failed = {}
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-- Load input params (e.g. session, ttl, time of request)
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local rSession, rTTL, rMaxTTL, rTime = unpack(ARGV)
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-- Check that all the locks can be acquired
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for i,requestKey in ipairs(KEYS) do
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local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
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local keyIsFree = true
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local currentLocks = redis.call('hKeys',resourceKey)
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for i,lockKey in ipairs(currentLocks) do
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-- Get the type and session of this lock
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local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
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-- Check any locks that are not owned by this session
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if session ~= rSession then
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local lockExpiry = redis.call('hGet',resourceKey,lockKey)
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if 1*lockExpiry < 1*rTime then
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-- Lock is stale, so just prune it out
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redis.call('hDel',resourceKey,lockKey)
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elseif rType == 'EX' or type == 'EX' then
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keyIsFree = false
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break
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end
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end
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end
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if not keyIsFree then
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failed[#failed+1] = requestKey
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end
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end
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-- If all locks could be acquired, then do so
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if #failed == 0 then
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for i,requestKey in ipairs(KEYS) do
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local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
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redis.call('hSet',resourceKey,rType .. ':' .. rSession,rTime + rTTL)
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-- In addition to invalidation logic, be sure to garbage collect
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redis.call('expire',resourceKey,rMaxTTL)
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end
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end
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return failed
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LUA;
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$res = $conn->luaEval( $script,
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array_merge(
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array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
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[
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$this->session, // ARGV[1]
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$this->lockTTL, // ARGV[2]
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self::MAX_LOCK_TTL, // ARGV[3]
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time() // ARGV[4]
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]
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),
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count( $pathsByKey ) # number of first argument(s) that are keys
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);
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} catch ( RedisException $e ) {
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$res = false;
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$this->redisPool->handleError( $conn, $e );
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}
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if ( $res === false ) {
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foreach ( $pathList as $path ) {
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$status->fatal( 'lockmanager-fail-acquirelock', $path );
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}
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} else {
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foreach ( $res as $key ) {
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$status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
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}
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}
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return $status;
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}
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protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
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$status = StatusValue::newGood();
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$pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
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$server = $this->lockServers[$lockSrv];
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$conn = $this->redisPool->getConnection( $server, $this->logger );
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if ( !$conn ) {
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foreach ( $pathList as $path ) {
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$status->fatal( 'lockmanager-fail-releaselock', $path );
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}
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return $status;
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}
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$pathsByKey = []; // (type:hash => path) map
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foreach ( $pathsByType as $type => $paths ) {
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$typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
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foreach ( $paths as $path ) {
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$pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
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}
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}
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try {
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static $script =
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/** @lang Lua */
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<<<LUA
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local failed = {}
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-- Load input params (e.g. session)
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local rSession = unpack(ARGV)
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for i,requestKey in ipairs(KEYS) do
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local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
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local released = redis.call('hDel',resourceKey,rType .. ':' .. rSession)
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if released > 0 then
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-- Remove the whole structure if it is now empty
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if redis.call('hLen',resourceKey) == 0 then
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redis.call('del',resourceKey)
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end
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else
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failed[#failed+1] = requestKey
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end
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end
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return failed
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LUA;
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$res = $conn->luaEval( $script,
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array_merge(
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array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
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[
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$this->session, // ARGV[1]
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]
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),
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count( $pathsByKey ) # number of first argument(s) that are keys
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);
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} catch ( RedisException $e ) {
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$res = false;
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$this->redisPool->handleError( $conn, $e );
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}
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if ( $res === false ) {
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foreach ( $pathList as $path ) {
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$status->fatal( 'lockmanager-fail-releaselock', $path );
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}
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} else {
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foreach ( $res as $key ) {
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$status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
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}
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}
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return $status;
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}
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protected function releaseAllLocks() {
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return StatusValue::newGood(); // not supported
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}
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protected function isServerUp( $lockSrv ) {
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$conn = $this->redisPool->getConnection( $this->lockServers[$lockSrv], $this->logger );
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return (bool)$conn;
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}
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/**
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* @param string $path
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* @param string $type One of (EX,SH)
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* @return string
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*/
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protected function recordKeyForPath( $path, $type ) {
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return implode( ':',
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[ __CLASS__, 'locks', "$type:" . $this->sha1Base36Absolute( $path ) ] );
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}
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/**
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* Make sure remaining locks get cleared for sanity
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*/
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function __destruct() {
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while ( count( $this->locksHeld ) ) {
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$pathsByType = [];
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foreach ( $this->locksHeld as $path => $locks ) {
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foreach ( $locks as $type => $count ) {
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$pathsByType[$type][] = $path;
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}
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}
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$this->unlockByType( $pathsByType );
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}
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}
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}
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