stream_select
When you use fwrite() on a non-blocking stream, data isn't discarded silently as t dot starling said.
Remember that fwrite() returns an int, and this int represents the amount of data really written to the stream. So, if you see that fwrite() returns less than the amount of written data, it means you'll have to call fwrite() again in the future to write the remaining amount of data.
You can use stream_select() to wait for the stream to be available for writing, then continue writing data to the stream.
Non-blocking streams are useful as you can have more than one non-blocking stream, and wait for them to be available for writing.
stream_set_blocking
(PHP 4 >= 4.3.0, PHP 5)
stream_set_blocking — Establecer el modo bloqueo/no-bloqueo en un flujo
Descripción
bool stream_set_blocking
( resource
$stream
, int $mode
)
Establece el modo de bloqueo o no-bloqueo en un stream.
Esta función funciona con cualquier flujo que soporte el modo de no bloqueo (actualmente, archivos normales y flujos de socket).
Parámetros
-
stream -
El flujo.
-
mode -
Si
modees 0, el flujo dado será cambiado al modo de no-bloqueo, y si es 1, será cambiado al modo de bloqueo. Esto afecta a las llamadas a, por ejemplo, fgets() y fread() que leen desde un flujo. En el modo de no-bloquo una llamada a fgets() devolverá siempre inmediatamente mientras que en el modo de bloqueo esperará a que la información esté disponible en el flujo.
Valores devueltos
Devuelve TRUE en caso de éxito o FALSE en caso de error.
Historial de cambios
| Versión | Descripción |
|---|---|
| 4.3.0 | Antes de PHP 4.3.0 esta función sólo funcionaba con flujos basados en sockets. |
Notas
Nota:
Esta función se llamaba anteriormente set_socket_blocking() y después socket_set_blocking() pero este uso está obsoleto.
Ver también
- stream_select() - Ejecuta el equivalente de la llamada al sistema select() sobre las matrices de flujos dadas con un tiempo de espera especificado por tv_sec y tv_usec
add a note
User Contributed Notes
stream_set_blocking - [4 notes]
MagicalTux at ookoo dot org ¶
6 years ago
Anonymous ¶
4 months ago
On Windows this function does not work with pipes opened with proc_open (https://bugs.php.net/bug.php?id=47918, https://bugs.php.net/bug.php?id=34972, https://bugs.php.net/bug.php?id=51800)
t dot starling at physics dot unimelb dot edu dot au ¶
7 years ago
Warning: if you write too much data to a stream in non-blocking mode and fill the buffer, the excess will be silently discarded. Observed in PHP 4.4.0 under linux.
nmmm at nmmm dot nu ¶
5 months ago
It took me long time to "compile" this code,
thanks to set blocking, we can write and read at the same time in proc_open().
Notice how the output from child begins after we feed several lines into it.
Also notice that end lines are output *after* we do
fclose($pipes[0]);
Then we need to continue read until feof(), because fgets() may return false even there are more data to read.
For educational reasons, I suggest you to try feeding small file (1-2 KB), medium file (4-5 MB) and huge file ( GB++ ).
#!/usr/bin/php
<?php
$max_buffer = 16 * 1024;
$prog = 'cat';
$descr = array(
0 => array("pipe", "r"), // stdin
1 => array("pipe", "w"), // stdout
2 => array("file", "/dev/null", "a") // stderr
);
$process = proc_open($prog, $descr, $pipes);
foreach($pipes as $f)
stream_set_blocking($f, 0);
//stream_set_write_buffer($pipes[0], 1*1024*1024);
$br = 0;
while ( ($line = fgets(STDIN, $max_buffer)) !== false){
$br = $br + strlen($line);
$ret = fwrite($pipes[0], $line);
if ($ret == false){
echo "error, buffer full?\n";
}
$s = fgets($pipes[1], $max_buffer);
printf("%12.3f | ", $br / 1024);
process_output($s);
}
//stream_set_blocking($pipes[1], 1);
fclose($pipes[0]);
while (! feof($pipes[1]) ){
$s = fgets($pipes[1], $max_buffer);
if ($s === false)
continue;
printf("%12s |", "end");
process_output($s);
}
fclose($pipes[1]);
function process_output($s){
$s = trim($s);
if (strlen($s) > 50)
$s = substr($s, 0, 50) . " [crop]";
printf("%s\n", $s ? $s : "--none--");
}
?>