6d155df4184c1599a3a236f2bb91949f9ac45a44
3 * @defgroup LockManager Lock management
8 * Resource locking handling.
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
23 * http://www.gnu.org/copyleft/gpl.html
26 * @ingroup LockManager
27 * @author Aaron Schulz
31 * @brief Class for handling resource locking.
33 * Locks on resource keys can either be shared or exclusive.
35 * Implementations must keep track of what is locked by this proccess
36 * in-memory and support nested locking calls (using reference counting).
37 * At least LOCK_UW and LOCK_EX must be implemented. LOCK_SH can be a no-op.
38 * Locks should either be non-blocking or have low wait timeouts.
40 * Subclasses should avoid throwing exceptions at all costs.
42 * @ingroup LockManager
45 abstract class LockManager
{
46 /** @var Array Mapping of lock types to the type actually used */
47 protected $lockTypeMap = array(
48 self
::LOCK_SH
=> self
::LOCK_SH
,
49 self
::LOCK_UW
=> self
::LOCK_EX
, // subclasses may use self::LOCK_SH
50 self
::LOCK_EX
=> self
::LOCK_EX
53 /** @var Array Map of (resource path => lock type => count) */
54 protected $locksHeld = array();
56 protected $domain; // string; domain (usually wiki ID)
58 /* Lock types; stronger locks have higher values */
59 const LOCK_SH
= 1; // shared lock (for reads)
60 const LOCK_UW
= 2; // shared lock (for reads used to write elsewhere)
61 const LOCK_EX
= 3; // exclusive lock (for writes)
64 * Construct a new instance from configuration
66 * $config paramaters include:
67 * - domain : Domain (usually wiki ID) that all resources are relative to [optional]
69 * @param $config Array
71 public function __construct( array $config ) {
72 $this->domain
= isset( $config['domain'] ) ?
$config['domain'] : wfWikiID();
76 * Lock the resources at the given abstract paths
78 * @param array $paths List of resource names
79 * @param $type integer LockManager::LOCK_* constant
82 final public function lock( array $paths, $type = self
::LOCK_EX
) {
83 wfProfileIn( __METHOD__
);
84 $status = $this->doLock( array_unique( $paths ), $this->lockTypeMap
[$type] );
85 wfProfileOut( __METHOD__
);
90 * Unlock the resources at the given abstract paths
92 * @param array $paths List of storage paths
93 * @param $type integer LockManager::LOCK_* constant
96 final public function unlock( array $paths, $type = self
::LOCK_EX
) {
97 wfProfileIn( __METHOD__
);
98 $status = $this->doUnlock( array_unique( $paths ), $this->lockTypeMap
[$type] );
99 wfProfileOut( __METHOD__
);
104 * Get the base 36 SHA-1 of a string, padded to 31 digits.
105 * Before hashing, the path will be prefixed with the domain ID.
106 * This should be used interally for lock key or file names.
108 * @param $path string
111 final protected function sha1Base36Absolute( $path ) {
112 return wfBaseConvert( sha1( "{$this->domain}:{$path}" ), 16, 36, 31 );
116 * Get the base 16 SHA-1 of a string, padded to 31 digits.
117 * Before hashing, the path will be prefixed with the domain ID.
118 * This should be used interally for lock key or file names.
120 * @param $path string
123 final protected function sha1Base16Absolute( $path ) {
124 return sha1( "{$this->domain}:{$path}" );
128 * Lock resources with the given keys and lock type
130 * @param array $paths List of storage paths
131 * @param $type integer LockManager::LOCK_* constant
134 abstract protected function doLock( array $paths, $type );
137 * Unlock resources with the given keys and lock type
139 * @param array $paths List of storage paths
140 * @param $type integer LockManager::LOCK_* constant
143 abstract protected function doUnlock( array $paths, $type );
147 * Simple version of LockManager that does nothing
150 class NullLockManager
extends LockManager
{
152 * @see LockManager::doLock()
153 * @param $paths array
157 protected function doLock( array $paths, $type ) {
158 return Status
::newGood();
162 * @see LockManager::doUnlock()
163 * @param $paths array
167 protected function doUnlock( array $paths, $type ) {
168 return Status
::newGood();