Php reads the memory sequence number to generate a unique ID.

This code is google for tens of millions. Please do not add it to favorites or use it. Thank you for your cooperation. The author only makes a record. Note: You need to enable extended extensionphp_shmop.dll without ** semaphores (Semaphore ). * This is a packaging class used to solve different implementation methods of the "semaphore" on different platforms. * Currently, this class is symbolic.

This code is google for tens of millions. Please do not add it to favorites or use it. Thank you for your cooperation. The author only makes a record. Note: You need to enable extended extension = php_shmop.dll without/** semaphores (Semaphore ). * This is a packaging class used to solve different implementation methods of the "semaphore" on different platforms. * Currently, this class is symbolic.

This code is google for tens of millions. Please do not add it to favorites or use it. Thank you for your cooperation.
The author only makes a record.
Note: Extended extension = php_shmop.dll must be enabled. <无>

/** Semaphore ). * This is a packaging class used to solve different implementation methods of the "semaphore" on different platforms. * Currently, this class is symbolic. It is actually a dry run on Windows platforms (and does not actually implement mutual exclusion ). */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 ;}}

/** Sequence number generator. */Class SeqGenerator {const SHM_KEY = 1;/*** initialize the sequence number generator. * This method is valid only when it is called for the first time after the server is started. * @ Param int $ start generates the starting value of the sequence number. * @ Return boolean true indicates success. */Static public function init ($ start = 1) {// mutex is implemented through semaphores to avoid access conflicts to shared memory $ sw = new SemWrapper; if (! $ Sw-> acquire () {return false;} // open the shared memory $ shm_id = shmop_open (self: SHM_KEY, 'n', 0644, 4 ); if (empty ($ shm_id) {// because the 'N' mode is used, if the shared memory cannot be enabled, you can think that the shared memory has been created, no need to initialize $ sw-> release (); return true;} // write the initial value $ size = shmop_write ($ shm_id, pack ('l ', $ start), 0); if ($ size! = 4) {shmop_close ($ shm_id); $ sw-> release (); return false;} // close the shared memory and release the semaphores shmop_close ($ shm_id ); $ sw-> release (); return true;}/*** generates the next sequence number. * @ Return int the sequence number */static public function next () {// mutex through semaphores to avoid access conflicts to shared memory $ sw = new SemWrapper; if (! $ Sw-> acquire () {return 0;} // open the shared memory $ shm_id = shmop_open (self: SHM_KEY, 'w', 0, 0 ); if (empty ($ shm_id) {$ sw-> release (); return 0;} // read the sequence number $ 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 to the shared memory $ size = shmop_write ($ shm_id, pack ('l', $ seq + 1), 0 ); if ($ size! = 4) {$ sw-> release (); return 0 ;}// close the shared memory and release the semaphores shmop_close ($ shm_id); $ sw-> release (); return $ seq ;}}

// Usage method $ seq = SeqGenerator: next (); var_dump ($ seq );