Just for record keeping, there should be duplicates on osc site
semWrapper.class.php
?
|
/* * Semaphore. * This is a wrapper class used to solve the different implementations of "semaphores" on different platforms. * At present, this class is only symbolic, and it actually runs in vain on the Windows platform (mutual exclusion is not really implemented). */ class SemWrapper { private $hasSemSupport; private $sem; const SEM_KEY = 1; public function __construct() { $this->hasSemSupport = function_exists( 'sem_get' ); if ( $this->hasSemSupport ) { $this->sem = sem_get( self::SEM_KEY ); } } public function acquire() { if ( $this->hasSemSupport ) { return sem_acquire( $this->sem ); } return true; } public function release() { if ( $this->hasSemSupport ) { return sem_release( $this->sem ); } return true; } } |
SeqGenerator.class.php
?
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 |
/* * 顺序号发生器。 */ class SeqGenerator { const SHM_KEY = 1;
/** * Initialize the sequence number generator. * This method is only valid for the first call after the server is started. Calling this method after that has no practical effect. * @param int $start The starting value for generating sequence numbers. * @return boolean Returns true to indicate success. */ static public function init( $start = 1 ) { // 通过信号量实现互斥，避免对共享内存的访问冲突 $sw = new SemWrapper; if ( ! $sw->acquire() ) { return false; }
// 打开共享内存 $shm_id = shmop_open( self::SHM_KEY, 'n', 0644, 4 ); if ( empty($shm_id) ) { // 因使用了 'n' 模式，如果无法打开共享内存，可以认为该共享内存已经创建，无需再次初始化 $sw->release(); return true; }
// 在共享内存中写入初始值 $size = shmop_write( $shm_id, pack( 'L', $start ), 0 ); if ( $size != 4 ) { shmop_close( $shm_id ); $sw->release(); return false; }
// 关闭共享内存，释放信号量 shmop_close( $shm_id ); $sw->release(); return true; }
/** * Generates the next sequence number. * @return int generated sequence number */ static public function next() { // 通过信号量实现互斥，避免对共享内存的访问冲突 $sw = new SemWrapper; if ( ! $sw->acquire() ) { return 0; }
// 打开共享内存 $shm_id = shmop_open( self::SHM_KEY, 'w', 0, 0 ); if ( empty($shm_id) ) { $sw->release(); return 0; }
// 从共享内存中读出顺序号 $data = shmop_read( $shm_id, 0, 4 ); if ( empty($data) ) { $sw->release(); return 0; }
$arr = unpack( 'L', $data ); $seq = $arr[1];
//Write the next sequence number into the shared memory $size = shmop_write( $shm_id, pack( 'L', $seq 1 ), 0 ); if ( $size != 4 ) { $sw->release(); return 0; }
//Close shared memory and release the semaphore shmop_close( $shm_id ); $sw->release(); return $seq; } } |
page.php
?
3 4 5
|
