A simple wrapper around PHP shm_* functions with semaphores. Any data structure that supports serialisation can be stored in shared memory and accessed across two or more processes.

SharedMemory.php

<?php 
class SharedMemory {
	private $shmID;
	private $semaphoreID;

	public function __construct($token, $memSize=10000){
		$this->shmID = shm_attach($token, $memSize);
		$this->semaphoreID = sem_get($token);
		if($this->shmID === false){
			error_log("Failed to create shared memory segment");
		}		
	}

	public function __destruct(){
		if($this->shmID) shm_detach($this->shmID);
		// sem_release($this->semaphoreID);
	}

	public function getVar($key){
		sem_acquire($this->semaphoreID);
		$var = shm_has_var($this->shmID, $key) ? shm_get_var($this->shmID, $key) : false;
		sem_release($this->semaphoreID);
		return $var;
	}

	public function putVar($key, $val){
		sem_acquire($this->semaphoreID);
		$success = shm_put_var($this->shmID, $key, $val);
		sem_release($this->semaphoreID);
		return $success;
	}

	public function delVar($key){
		sem_acquire($this->semaphoreID);
		$success = shm_has_var($this->shmID, $key) && shm_remove_var($this->shmID, $key);
		sem_release($this->semaphoreID);
		return $success;
	}

	public function delSegment(){
		sem_acquire($this->semaphoreID);
		// shm_detach($this->shmID);	// not required
		$success = shm_remove($this->shmID);
		sem_release($this->semaphoreID);
		sem_remove($this->semaphoreID);
		$this->shmID = null;
		$this->semaphoreID = null;
		return $success;
	}
}


// $memory = new SharedMemory($token=1001);
// $memory->putVar(1, 1000);
// echo $memory->getVar(1);
// $memory->delVar(1);
// $memory->delSegment();