[LockManager] Split QuorumLockManager into its own file.
Change-Id: Ib487a39b04ac9de3449695ac388c95ae45933469
This commit is contained in:
Aaron Schulz
parent
7875479757
commit
7224c402ca
3 changed files with 233 additions and 211 deletions
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@ -573,7 +573,7 @@ $wgAutoloadLocalClasses = array(
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'DBLockManager' => 'includes/filebackend/lockmanager/DBLockManager.php',
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'LSLockManager' => 'includes/filebackend/lockmanager/LSLockManager.php',
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'MemcLockManager' => 'includes/filebackend/lockmanager/MemcLockManager.php',
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'QuorumLockManager' => 'includes/filebackend/lockmanager/LockManager.php',
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'QuorumLockManager' => 'includes/filebackend/lockmanager/QuorumLockManager.php',
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'MySqlLockManager'=> 'includes/filebackend/lockmanager/DBLockManager.php',
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'NullLockManager' => 'includes/filebackend/lockmanager/LockManager.php',
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'FileOp' => 'includes/filebackend/FileOp.php',
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@ -131,216 +131,6 @@ abstract class LockManager {
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abstract protected function doUnlock( array $paths, $type );
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}
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/**
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* Version of LockManager that uses a quorum from peer servers for locks.
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* The resource space can also be sharded into separate peer groups.
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*
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* @ingroup LockManager
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* @since 1.20
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*/
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abstract class QuorumLockManager extends LockManager {
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/** @var Array Map of bucket indexes to peer server lists */
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protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...))
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/**
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* @see LockManager::doLock()
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* @param $paths array
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* @param $type int
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* @return Status
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*/
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final protected function doLock( array $paths, $type ) {
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$status = Status::newGood();
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$pathsToLock = array(); // (bucket => paths)
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// Get locks that need to be acquired (buckets => locks)...
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foreach ( $paths as $path ) {
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if ( isset( $this->locksHeld[$path][$type] ) ) {
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++$this->locksHeld[$path][$type];
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} elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
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$this->locksHeld[$path][$type] = 1;
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} else {
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$bucket = $this->getBucketFromKey( $path );
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$pathsToLock[$bucket][] = $path;
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}
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}
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$lockedPaths = array(); // files locked in this attempt
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// Attempt to acquire these locks...
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foreach ( $pathsToLock as $bucket => $paths ) {
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// Try to acquire the locks for this bucket
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$status->merge( $this->doLockingRequestBucket( $bucket, $paths, $type ) );
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if ( !$status->isOK() ) {
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$status->merge( $this->doUnlock( $lockedPaths, $type ) );
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return $status;
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}
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// Record these locks as active
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foreach ( $paths as $path ) {
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$this->locksHeld[$path][$type] = 1; // locked
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}
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// Keep track of what locks were made in this attempt
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$lockedPaths = array_merge( $lockedPaths, $paths );
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}
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return $status;
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}
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/**
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* @see LockManager::doUnlock()
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* @param $paths array
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* @param $type int
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* @return Status
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*/
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final protected function doUnlock( array $paths, $type ) {
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$status = Status::newGood();
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$pathsToUnlock = array();
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foreach ( $paths as $path ) {
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if ( !isset( $this->locksHeld[$path][$type] ) ) {
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$status->warning( 'lockmanager-notlocked', $path );
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} else {
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--$this->locksHeld[$path][$type];
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// Reference count the locks held and release locks when zero
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if ( $this->locksHeld[$path][$type] <= 0 ) {
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unset( $this->locksHeld[$path][$type] );
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$bucket = $this->getBucketFromKey( $path );
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$pathsToUnlock[$bucket][] = $path;
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}
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if ( !count( $this->locksHeld[$path] ) ) {
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unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
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}
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}
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}
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// Remove these specific locks if possible, or at least release
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// all locks once this process is currently not holding any locks.
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foreach ( $pathsToUnlock as $bucket => $paths ) {
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$status->merge( $this->doUnlockingRequestBucket( $bucket, $paths, $type ) );
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}
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if ( !count( $this->locksHeld ) ) {
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$status->merge( $this->releaseAllLocks() );
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}
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return $status;
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}
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/**
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* Attempt to acquire locks with the peers for a bucket.
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* This is all or nothing; if any key is locked then this totally fails.
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*
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* @param $bucket integer
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* @param $paths Array List of resource keys to lock
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* @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
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* @return Status
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*/
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final protected function doLockingRequestBucket( $bucket, array $paths, $type ) {
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$status = Status::newGood();
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$yesVotes = 0; // locks made on trustable servers
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$votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers
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$quorum = floor( $votesLeft/2 + 1 ); // simple majority
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// Get votes for each peer, in order, until we have enough...
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foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
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if ( !$this->isServerUp( $lockSrv ) ) {
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--$votesLeft;
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$status->warning( 'lockmanager-fail-svr-acquire', $lockSrv );
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continue; // server down?
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}
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// Attempt to acquire the lock on this peer
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$status->merge( $this->getLocksOnServer( $lockSrv, $paths, $type ) );
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if ( !$status->isOK() ) {
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return $status; // vetoed; resource locked
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}
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++$yesVotes; // success for this peer
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if ( $yesVotes >= $quorum ) {
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return $status; // lock obtained
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}
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--$votesLeft;
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$votesNeeded = $quorum - $yesVotes;
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if ( $votesNeeded > $votesLeft ) {
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break; // short-circuit
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}
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}
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// At this point, we must not have met the quorum
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$status->setResult( false );
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return $status;
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}
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/**
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* Attempt to release locks with the peers for a bucket
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*
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* @param $bucket integer
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* @param $paths Array List of resource keys to lock
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* @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
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* @return Status
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*/
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final protected function doUnlockingRequestBucket( $bucket, array $paths, $type ) {
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$status = Status::newGood();
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foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
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if ( !$this->isServerUp( $lockSrv ) ) {
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$status->fatal( 'lockmanager-fail-svr-release', $lockSrv );
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// Attempt to release the lock on this peer
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} else {
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$status->merge( $this->freeLocksOnServer( $lockSrv, $paths, $type ) );
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}
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}
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return $status;
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}
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/**
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* Get the bucket for resource path.
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* This should avoid throwing any exceptions.
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*
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* @param $path string
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* @return integer
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*/
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protected function getBucketFromKey( $path ) {
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$prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
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return (int)base_convert( $prefix, 16, 10 ) % count( $this->srvsByBucket );
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}
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/**
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* Check if a lock server is up
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*
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* @param $lockSrv string
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* @return bool
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*/
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abstract protected function isServerUp( $lockSrv );
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/**
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* Get a connection to a lock server and acquire locks on $paths
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*
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* @param $lockSrv string
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* @param $paths array
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* @param $type integer
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* @return Status
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*/
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abstract protected function getLocksOnServer( $lockSrv, array $paths, $type );
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/**
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* Get a connection to a lock server and release locks on $paths.
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*
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* Subclasses must effectively implement this or releaseAllLocks().
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*
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* @param $lockSrv string
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* @param $paths array
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* @param $type integer
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* @return Status
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*/
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abstract protected function freeLocksOnServer( $lockSrv, array $paths, $type );
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/**
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* Release all locks that this session is holding.
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*
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* Subclasses must effectively implement this or freeLocksOnServer().
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*
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* @return Status
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*/
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abstract protected function releaseAllLocks();
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}
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/**
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* Simple version of LockManager that does nothing
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* @since 1.19
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232
includes/filebackend/lockmanager/QuorumLockManager.php
Normal file
232
includes/filebackend/lockmanager/QuorumLockManager.php
Normal file
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@ -0,0 +1,232 @@
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<?php
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/**
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* Version of LockManager that uses a quorum from peer servers for locks.
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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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* Version of LockManager that uses a quorum from peer servers for locks.
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* The resource space can also be sharded into separate peer groups.
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*
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* @ingroup LockManager
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* @since 1.20
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*/
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abstract class QuorumLockManager extends LockManager {
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/** @var Array Map of bucket indexes to peer server lists */
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protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...))
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/**
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* @see LockManager::doLock()
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* @param $paths array
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* @param $type int
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* @return Status
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*/
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final protected function doLock( array $paths, $type ) {
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$status = Status::newGood();
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$pathsToLock = array(); // (bucket => paths)
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// Get locks that need to be acquired (buckets => locks)...
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foreach ( $paths as $path ) {
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if ( isset( $this->locksHeld[$path][$type] ) ) {
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++$this->locksHeld[$path][$type];
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} elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
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$this->locksHeld[$path][$type] = 1;
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} else {
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$bucket = $this->getBucketFromKey( $path );
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$pathsToLock[$bucket][] = $path;
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}
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}
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$lockedPaths = array(); // files locked in this attempt
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// Attempt to acquire these locks...
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foreach ( $pathsToLock as $bucket => $paths ) {
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// Try to acquire the locks for this bucket
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$status->merge( $this->doLockingRequestBucket( $bucket, $paths, $type ) );
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if ( !$status->isOK() ) {
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$status->merge( $this->doUnlock( $lockedPaths, $type ) );
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return $status;
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}
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// Record these locks as active
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foreach ( $paths as $path ) {
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$this->locksHeld[$path][$type] = 1; // locked
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}
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// Keep track of what locks were made in this attempt
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$lockedPaths = array_merge( $lockedPaths, $paths );
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}
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return $status;
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}
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/**
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* @see LockManager::doUnlock()
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* @param $paths array
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* @param $type int
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* @return Status
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*/
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final protected function doUnlock( array $paths, $type ) {
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$status = Status::newGood();
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$pathsToUnlock = array();
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foreach ( $paths as $path ) {
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if ( !isset( $this->locksHeld[$path][$type] ) ) {
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$status->warning( 'lockmanager-notlocked', $path );
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} else {
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--$this->locksHeld[$path][$type];
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// Reference count the locks held and release locks when zero
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if ( $this->locksHeld[$path][$type] <= 0 ) {
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unset( $this->locksHeld[$path][$type] );
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$bucket = $this->getBucketFromKey( $path );
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$pathsToUnlock[$bucket][] = $path;
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}
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if ( !count( $this->locksHeld[$path] ) ) {
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unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
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}
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}
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}
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// Remove these specific locks if possible, or at least release
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// all locks once this process is currently not holding any locks.
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foreach ( $pathsToUnlock as $bucket => $paths ) {
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$status->merge( $this->doUnlockingRequestBucket( $bucket, $paths, $type ) );
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}
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if ( !count( $this->locksHeld ) ) {
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$status->merge( $this->releaseAllLocks() );
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}
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return $status;
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}
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/**
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* Attempt to acquire locks with the peers for a bucket.
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* This is all or nothing; if any key is locked then this totally fails.
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*
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* @param $bucket integer
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* @param $paths Array List of resource keys to lock
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* @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
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* @return Status
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*/
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final protected function doLockingRequestBucket( $bucket, array $paths, $type ) {
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$status = Status::newGood();
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$yesVotes = 0; // locks made on trustable servers
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$votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers
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$quorum = floor( $votesLeft/2 + 1 ); // simple majority
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// Get votes for each peer, in order, until we have enough...
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foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
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if ( !$this->isServerUp( $lockSrv ) ) {
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--$votesLeft;
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$status->warning( 'lockmanager-fail-svr-acquire', $lockSrv );
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continue; // server down?
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}
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// Attempt to acquire the lock on this peer
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$status->merge( $this->getLocksOnServer( $lockSrv, $paths, $type ) );
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if ( !$status->isOK() ) {
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return $status; // vetoed; resource locked
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}
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++$yesVotes; // success for this peer
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if ( $yesVotes >= $quorum ) {
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return $status; // lock obtained
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}
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--$votesLeft;
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$votesNeeded = $quorum - $yesVotes;
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if ( $votesNeeded > $votesLeft ) {
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break; // short-circuit
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}
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}
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// At this point, we must not have met the quorum
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$status->setResult( false );
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return $status;
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}
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/**
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* Attempt to release locks with the peers for a bucket
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*
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* @param $bucket integer
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* @param $paths Array List of resource keys to lock
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* @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
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* @return Status
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*/
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final protected function doUnlockingRequestBucket( $bucket, array $paths, $type ) {
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$status = Status::newGood();
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foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
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if ( !$this->isServerUp( $lockSrv ) ) {
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$status->fatal( 'lockmanager-fail-svr-release', $lockSrv );
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// Attempt to release the lock on this peer
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} else {
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$status->merge( $this->freeLocksOnServer( $lockSrv, $paths, $type ) );
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}
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}
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return $status;
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}
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/**
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* Get the bucket for resource path.
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* This should avoid throwing any exceptions.
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*
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* @param $path string
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* @return integer
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*/
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protected function getBucketFromKey( $path ) {
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$prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
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return (int)base_convert( $prefix, 16, 10 ) % count( $this->srvsByBucket );
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}
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/**
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* Check if a lock server is up
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*
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* @param $lockSrv string
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* @return bool
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*/
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abstract protected function isServerUp( $lockSrv );
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/**
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* Get a connection to a lock server and acquire locks on $paths
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*
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* @param $lockSrv string
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* @param $paths array
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* @param $type integer
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* @return Status
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*/
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abstract protected function getLocksOnServer( $lockSrv, array $paths, $type );
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/**
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* Get a connection to a lock server and release locks on $paths.
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*
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* Subclasses must effectively implement this or releaseAllLocks().
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*
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* @param $lockSrv string
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* @param $paths array
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* @param $type integer
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* @return Status
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*/
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abstract protected function freeLocksOnServer( $lockSrv, array $paths, $type );
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/**
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* Release all locks that this session is holding.
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*
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* Subclasses must effectively implement this or freeLocksOnServer().
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*
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* @return Status
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*/
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abstract protected function releaseAllLocks();
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}
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