shmop_open
You should always serialize data written in shared memory.
And when you are reading data you should always unserialize.
<?php
$data = 'test';
$shm_bytes_written = shmop_write($shm_id, serialize($data), 0);
$shm_data = unserialize(shmop_read($shm_id, 0, $shm_bytes_written));
?>
shmop_read
(PHP 4 >= 4.0.4, PHP 5)
shmop_read — Leer datos desde un segmento de memoria compartida
Descripción
string shmop_read
( int
$shmid
, int $start
, int $count
)shmop_read() leerá una cadena desde un segmento de memoria compartida.
Parámetros
-
shmid -
El identificador del segmento de memoria compartida creado por shmop_open()
-
start -
Offset desde el que comenzar a leer
-
count -
El número de bytes a leer
Valores devueltos
Devuelve los datos o FALSE en caso de error.
Ejemplos
Ejemplo #1 Lectura de un segmento de memoria compartida
<?php
$shm_data = shmop_read($shm_id, 0, 50);
?>
Este ejemplo, leerá los 50 primeros bytes del segmento de memoria compartida y almacenará los datos en la variable $shm_data.
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User Contributed Notes
shmop_read - [4 notes]
Milan Cvejic ¶
4 years ago
Craig Manley ¶
8 years ago
shmop_read() reads and returns the whole memory segment's data. This is not useful if you're just working with strings. If you need to read a string from shared memory, call str_from_mem() on the result of shmop_read(). Similarly when writing strings to memory (instead of binary data), null terminate your strings with str_to_nts() before passing the value on to shmop_write().
function str_to_nts($value) {
return "$value\0";
}
function str_from_mem(&$value) {
$i = strpos($value, "\0");
if ($i === false) {
return $value;
}
$result = substr($value, 0, $i);
return $result;
}
slavapl at mailandnews dot com ¶
12 years ago
Also you can use the shmop_size() function to determine the block size.
macmaster at pobox dot com ¶
12 years ago
When i need to read the whole string at that shm pointer, setting the count parameter to zero (0) seems work for me.