| 1 | 2 | simandl | <?php |
| 2 | | | |
| 3 | | | namespace Phem\Core; |
| 4 | | | |
| 5 | | | /* |
| 6 | | | CLASS ExclusiveLock |
| 7 | | | Description |
| 8 | | | ================================================================== |
| 9 | | | This is a pseudo implementation of mutex since php does not have |
| 10 | | | any thread synchronization objects |
| 11 | | | This class uses flock() as a base to provide locking functionality. |
| 12 | | | Lock will be released in following cases |
| 13 | | | 1 - user calls unlock |
| 14 | | | 2 - when this lock object gets deleted |
| 15 | | | 3 - when request or script ends |
| 16 | | | ================================================================== |
| 17 | | | Usage: |
| 18 | | | |
| 19 | | | //get the lock |
| 20 | | | $lock = new ExclusiveLock( "mylock", FALSE); |
| 21 | | | |
| 22 | | | //lock |
| 23 | | | if( $lock->lock( ) == FALSE ) |
| 24 | | | error("Locking failed"); |
| 25 | | | //-- |
| 26 | | | //Do your work here |
| 27 | | | //-- |
| 28 | | | |
| 29 | | | //unlock |
| 30 | | | $lock->unlock(); |
| 31 | | | =================================================================== |
| 32 | | | */ |
| 33 | | | class ExclusiveLock |
| 34 | | | { |
| 35 | | | protected $key = null; //user given value |
| 36 | | | protected $file = null; //resource to lock |
| 37 | | | protected $own = FALSE; //have we locked resource |
| 38 | | | |
| 39 | | | function __construct( $key ) |
| 40 | | | { |
| 41 | | | $this->key = $key; |
| 42 | | | //create a new resource or get exisitng with same key |
| 43 | | | $this->file = fopen(RUN_DIR.DS."Lock".DS."$key.lockfile", 'w+'); |
| 44 | | | } |
| 45 | | | |
| 46 | | | |
| 47 | | | function __destruct() |
| 48 | | | { |
| 49 | | | if( $this->own == TRUE ) |
| 50 | | | $this->unlock( ); |
| 51 | | | } |
| 52 | | | |
| 53 | | | |
| 54 | | | function lock( ) |
| 55 | | | { |
| 56 | | | if( !flock($this->file, LOCK_EX)) |
| 57 | | | { //failed |
| 58 | | | $key = $this->key; |
| 59 | | | error_log("ExclusiveLock::acquire_lock FAILED to acquire lock [$key]"); |
| 60 | | | return FALSE; |
| 61 | | | } |
| 62 | | | ftruncate($this->file, 0); // truncate file |
| 63 | | | //write something to just help debugging |
| 64 | | | fwrite( $this->file, "Locked\n"); |
| 65 | | | fflush( $this->file ); |
| 66 | | | |
| 67 | | | $this->own = TRUE; |
| 68 | | | return $this->own; |
| 69 | | | } |
| 70 | | | |
| 71 | | | |
| 72 | | | function unlock( ) |
| 73 | | | { |
| 74 | | | $key = $this->key; |
| 75 | | | if( $this->own == TRUE ) |
| 76 | | | { |
| 77 | | | if( !flock($this->file, LOCK_UN) ) |
| 78 | | | { //failed |
| 79 | | | error_log("ExclusiveLock::lock FAILED to release lock [$key]"); |
| 80 | | | return FALSE; |
| 81 | | | } |
| 82 | | | ftruncate($this->file, 0); // truncate file |
| 83 | | | //write something to just help debugging |
| 84 | | | fwrite( $this->file, "Unlocked\n"); |
| 85 | | | fflush( $this->file ); |
| 86 | | | } |
| 87 | | | else |
| 88 | | | { |
| 89 | | | error_log("ExclusiveLock::unlock called on [$key] but its not acquired by caller"); |
| 90 | | | } |
| 91 | | | $this->own = FALSE; |
| 92 | | | return $this->own; |
| 93 | | | } |
| 94 | | | } |
