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 — Configure le mode bloquant d'un flux
Description
bool stream_set_blocking
( resource
$stream
, int $mode
)
stream_set_blocking() configure le mode bloquant
du flux stream.
Cette fonction fonctionne pour tous les flux qui supportent le mode non-bloquant (actuellement, les fichiers et les flux de sockets).
Liste de paramètres
-
stream -
Le flux.
-
mode -
Si
modevaut 0,streamsera configuré en mode non-bloquant, et s'il vaut 1,streamsera configuré en mode bloquant. Cet appel affecte les fonctions telles que fgets() et fread() qui lisent dans des flux. En mode non-bloquant, la fonction fgets() s'exécute juste après son appel, alors qu'en mode bloquant, elle attendra des données.
Valeurs de retour
Cette fonction retourne TRUE en cas de
succès ou FALSE si une erreur survient.
Historique
| Version | Description |
|---|---|
| 4.3.0 | Avant PHP 4.3, cette fonction ne fonctionnait que sur les flux utilisant des sockets. |
Notes
Note:
Cette fonction s'appelait jadis set_socket_blocking() puis socket_set_blocking() mais leur usage est déconseillé.
Voir aussi
- stream_select() - Surveille la modification d'un ou plusieurs flux
add a note
User Contributed Notes
stream_set_blocking - [4 notes]
MagicalTux at ookoo dot org ¶
6 years ago
Anonymous ¶
5 months ago
On Windows this function does not work with pipes opened with proc_open (https://bugs.php.net/bug.php?id=47918, https://bugs.php.net/bug.php?id=34972, https://bugs.php.net/bug.php?id=51800)
t dot starling at physics dot unimelb dot edu dot au ¶
7 years ago
Warning: if you write too much data to a stream in non-blocking mode and fill the buffer, the excess will be silently discarded. Observed in PHP 4.4.0 under linux.
nmmm at nmmm dot nu ¶
6 months ago
It took me long time to "compile" this code,
thanks to set blocking, we can write and read at the same time in proc_open().
Notice how the output from child begins after we feed several lines into it.
Also notice that end lines are output *after* we do
fclose($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--");
}
?>