shm_detach
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, $mutex_key, FALSE); ?>)
It would be nice to have a completely air-tight solution, though. D'oh!
shm_get_var
(PHP 4, PHP 5)
shm_get_var — Returns a variable from shared memory
Описание
shm_get_var() returns the variable with a given variable_key , in the given shared memory segment. The variable is still present in the shared memory.
Список параметров
- shm_identifier
-
Shared memory segment, obtained from shm_attach().
- variable_key
-
The variable key.
Возвращаемые значения
Returns the variable with the given key.
add a note
User Contributed Notesshm_get_var
JM
15-May-2005 12:50
15-May-2005 12:50
06-May-2005 11:01
You will still receive a notice use @:
if(!defined(@shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}
Bob Van Zant
18-Feb-2005 09:05
18-Feb-2005 09:05
This seems to work fine to detect the lack of presence of a key in shared memory and then init it to 0 when found:
if(!defined(shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}
chris at free-source dot com
05-Dec-2004 11:47
05-Dec-2004 11:47
if the variable_key asked for does not exist php generates a warning and shm_get_var() will return bool(false). there doesn't seem to be a clean way to test if a key exists.