shm_get_var

(PHP 4, PHP 5)

shm_get_var — Returns a variable from shared memory

说明

mixed shm_get_var ( resource $shm_identifier , int $variable_key )

shm_get_var() returns the variable with a given variable_key, in the given shared memory segment. The variable is still present in the shared memory.

参数

shm_identifier: Shared memory segment, obtained from shm_attach() .
variable_key: The variable key.

返回值

Returns the variable with the given key.

参见

shm_has_var() - Check whether a specific entry exists
shm_put_var() - Inserts or updates a variable in shared memory

用户评论:

[#1] serg at red-sign dot ru [2013-02-28 14:38:29]

If any body has problem with shm_get_var();

this code correctly work with boolean-values^
<?php if(shm_has_var ($this->shm_mem_id, $_varno)){ $_value = shm_get_var($this->shm_mem_id, $_varno); }else{ $_value = NULL; } ?>

[#2] hackmac at nowhere dot com [2009-06-24 02:19:21]

hello everyone i came up with some sort of solution to the shm_get_var()
returns false on error/returns a boolean false variable problem.

test script

<?php error_reporting(E_ALL); ini_set('display_errors', '1'); echo '<pre>'; echo ini_get('sysvshm.init_mem'); require_once('ClassShmWrapper.php5'); $nKey = ftok(__FILE__,'x'); $myShm = new ClassShmWrapper($nKey); $myShm->attachToSegment(); #$mValue = range(1,rand(3,10)); #$myShm->nVarKey = count($mrValue); #$mValue = FALSE; #$myShm->nVarKey = 2; $myShm->nVarKey = 1; if ($myShm->getVarFromSegment()) { echo "found var in shm\n"; } else { echo "could NOT find var in shm\n"; } $myShm->detachFromSegment(); echo "\ndumping " . '$myShm->mVar' . "\n"; var_dump($myShm->mVar); ?>

class for using the shm_ functions & class for storing boolean values

<?php class ClassShmWrapper { public $nPermissions; public $nKey; public $nBytesMemorySize; public $nShmId; public $nVarKey; public $mVar; public function __construct($nKey,$nBytesMemorySize=50000,$nPermissions=0666) { $this->nKey = $nKey; $this->nBytesMemorySize = $nBytesMemorySize; $this->nPermissions = $nPermissions; } public function attachToSegment() { $this->nShmId = shm_attach($this->nKey,$this->nBytesMemorySize,$this->nPermissions); } public function detachFromSegment() { shm_detach($this->nShmId); } public function removeSegment() { shm_remove($this->nShmId); } public function getVarFromSegment() { $mVar = NULL; if (($mVar = @shm_get_var($this->nShmId,$this->nVarKey)) !== FALSE) { $this->mVar = $mVar; unset($mVar); if ($this->mVar instanceof ClassShmBooleanWrapper) { $this->mVar = $this->mVar->bVal; } return TRUE; } else { return FALSE; } } public function putVarToSegment() { // cmp -> comment getVarFromSegment() if (is_bool($this->mVar)) { return shm_put_var($this->nShmId,$this->nVarKey,new ClassShmBooleanWrapper($this->mVar)); } else { return shm_put_var($this->nShmId,$this->nVarKey,$this->mVar); } } public function removeVarFromSgement() { shm_remove_var($this->nShmId,$this->nVarKey); } } // end class class ClassShmBooleanWrapper { public $bVal; public function __construct($bVal) { $this->bVal = $bVal; } } // end class ?>

[#3] php at pharse dot com [2008-12-03 12:05:26]

I was annoyed by this warning when using shm_get_var():

Warning: shm_get_var() [function.shm-get-var]: variable key 2 doesn't exist in PATH_TO_FILE on line 64.

You can suppress the warning by changing the error reporting level. To do this for just the page in question, include the following line:

<?php error_reporting(E_ERROR); ?>

For more info: http://us.php.net/error_reporting

[#4] ricardophp at yahoo dot com dot br [2008-09-27 14:18:13]

A fully functional sample ...

<?php echo "<PRE>\n"; define("FOPEN_RESOURCE", 1); $shm_id = shm_attach(FOPEN_RESOURCE); if ($shm_id === false) { exit("Fail to attach shared memory.\n"); } $fopen_resource = fopen("/tmp/phpSharedMemory.bin", "w"); $a = array("Teste1", 1); if (!shm_put_var($shm_id, $a, $a)) { exit("Failed to put var 1 in shared memory $shm_id.\n"); } echo "F: ".$a[0].":".$a[1]."\n"; $pid = pcntl_fork(); if($pid == -1) { die("could not fork\n"); } else if ($pid) { $a = array("Teste2", 3); if (!shm_put_var($shm_id, $a, $a)) { exit("Failed to put var 1 in shared memory $shm_id.\n"); } echo "P1: ".$a[0].":".$a[1]."\n"; } else { sleep(2); $a = shm_get_var($shm_id, $a); echo "P2: ".$a[0].":".$a[1]."\n"; } pcntl_wait($status); exit(); ?>

[#5] JM [2005-05-14 15:50:17]

To follow up on the posts by anonymous, Bob Van Zant and chris at free-source dot com below (or, as must people inexplicably write, above) regarding the PHP warning and FALSE that shm_get_var returns if the variable key doesn't exist:

My tests (with PHP4.3.4) show that defined() is useless here. Because the function defined(string) checks whether the constant whose name is string exists, the code
<?php if ( defined(@shm_get_var($mutex, $mutex_key)) {    ... } ?>
acts the same ("..." does not get executed) whether the variable is defined or not--unless $mutex_key happens to identify a valid string that happens to be the name of a constant. :)

Rather,
<?php if ( @shm_get_var($mutex, $mutex_key) === FALSE ) {    ... } ?>
works, provided the object that was stored isn't actually FALSE (via <?php shm_put_var($mutex, $mutex_key, FALSE); ?>)

It would be nice to have a completely air-tight solution, though.  D'oh!

[#6] [2005-05-06 02:01:57]

You will still receive a notice use @:

if(!defined(@shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}

[#7] Bob Van Zant [2005-02-18 00:05:17]

This seems to work fine to detect the lack of presence of a key in shared memory and then init it to 0 when found:

if(!defined(shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}