how to do a non-blocking fgets? – PHP

  php

Q(Question):

Hello,

I need to read a result of the first script (that takes some time to
run) from the second script so that the first script doesn’t block the
second. Here is a short example. do_smth_else() should be called
during test.php’s sleep, instead the first fgets blocks the processing
of the parent script and do_smth_else is called only once. How can I
do a non-blocking fgets()? I use php 4.3.4 on windows xp

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
do {
$line = fgets($process);
print $line;
do_smth_else();
if ($line === false) break;
} while(true);
pclose($process);

contents of the test.php:
<?php echo ‘Hello’;sleep(2); echo ‘ World!’; ?>

A(Answer):

"Tanel" <ri****@hot.ee> wrote in message
news:99**************************@posting.google.c om…

Hello,

I need to read a result of the first script (that takes some time to
run) from the second script so that the first script doesn’t block the
second. Here is a short example. do_smth_else() should be called
during test.php’s sleep, instead the first fgets blocks the processing
of the parent script and do_smth_else is called only once. How can I
do a non-blocking fgets()? I use php 4.3.4 on windows xp

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
do {
$line = fgets($process);
print $line;
do_smth_else();
if ($line === false) break;
} while(true);
pclose($process);

contents of the test.php:
<?php echo ‘Hello’;sleep(2); echo ‘ World!’; ?>

sounds like you are a VB programmer looking for doevents() or you want to
spawn a background thread.

To the best of my knowlendge there is no *simple* way of doing multithreads
*within* a php script.

my advice, rethink what you are trying to acomplish, and shell out of the
script and launch a new proccess in the background: `php -q script.php &`;

Mike Bradley
http://www.gzentools.com — free online php tools

A(Answer):

ri****@hot.ee (Tanel) wrote in message news:<99**************************@posting.google. com>…

Hello,

I need to read a result of the first script (that takes some time to
run) from the second script so that the first script doesn’t block the
second. Here is a short example. do_smth_else() should be called
during test.php’s sleep, instead the first fgets blocks the processing
of the parent script and do_smth_else is called only once. How can I
do a non-blocking fgets()? I use php 4.3.4 on windows xp

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
do {
$line = fgets($process);
print $line;
do_smth_else();
if ($line === false) break;
} while(true);
pclose($process);

contents of the test.php:
<?php echo ‘Hello’;sleep(2); echo ‘ World!’; ?>

Are you sure it’s blocking and not just looping once? I get
do_smth_else() being called once, but also no "Hello World" and
with fgets() returning "false" the first time, as expected. It
works for me without the "if ($line == false) break;" line and
with "while(!feof($process))" instead of "while(true)"

A(Answer):

mc*******@earthlink.net (martin) wrote in message >

Are you sure it’s blocking and not just looping once? I get
do_smth_else() being called once, but also no "Hello World" and
with fgets() returning "false" the first time, as expected. It
works for me without the "if ($line == false) break;" line and
with "while(!feof($process))" instead of "while(true)"

Notice the three = in ($line === false). Here is maybe a better
example to show what I mean. The first fgets waits until the test.php
has finished, and second fgets has nothing. Desired behavior should be
1st fgets:Hello, 2nd fgets World!

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
print "\n 1st fgets:".fgets($process);
sleep(3);
print "\n 2nd fgets:".fgets($process);
pclose($process);

A(Answer):

"CountScubula" <me@scantek.hotmail.com> wrote in message news:<6HXOb.13433

To the best of my knowlendge there is no *simple* way of doing multithreads
*within* a php script.

my advice, rethink what you are trying to acomplish, and shell out of the
script and launch a new proccess in the background: `php -q script.php &`;

I am trying to make a php-gtk utility which uses curl to get some web
content. So far the curl_exec blocks the whole script (until download
is finished) and gui freezes. I also need to start to download a
second page before the first is finished, so I have multiple streams I
need to check for arriving data. All that time the gui should be
responsive. It seams that its not an easy task in php..

A(Answer):

"Tanel" <ri****@hot.ee> wrote in message
news:<99**************************@posting.google. com>…

"CountScubula" <me@scantek.hotmail.com> wrote in message news:<6HXOb.13433

To the best of my knowlendge there is no *simple* way of doing
multithreads *within* a php script.

my advice, rethink what you are trying to acomplish, and shell out of
the script and launch a new proccess in the background: `php -q script.php

&`;
I am trying to make a php-gtk utility which uses curl to get some web
content. So far the curl_exec blocks the whole script (until download
is finished) and gui freezes. I also need to start to download a
second page before the first is finished, so I have multiple streams I
need to check for arriving data. All that time the gui should be
responsive. It seams that its not an easy task in php..

if this is a shell script with gui front, then it might be easier to launch
other proccesses instead of trying to multithread. launch your get php
script with
`php -q script.php $url &`;
or
`wget $url &`;

both will run in background while your gui is active.


Mike Bradley
http://www.gzentools.com — free online php tools

A(Answer):

ri****@hot.ee (Tanel) wrote in message news:<99**************************@posting.google. com>…

mc*******@earthlink.net (martin) wrote in message >

Are you sure it’s blocking and not just looping once? I get
do_smth_else() being called once, but also no "Hello World" and
with fgets() returning "false" the first time, as expected. It
works for me without the "if ($line == false) break;" line and
with "while(!feof($process))" instead of "while(true)"
Notice the three = in ($line === false).

Same difference. "false" is the empty string. fgets() returns
an empty string when reading from a non-blocking file-descriptor
which has nothing to read. "if ($line === false) break;" will
surely break out of your loop when $line comes from such a read,
as it surely must for at least the first read. Fgets() will not
wait for anything when reading from a non-blocking file-descriptor.

If, as you said, you want to "read a result of the first script
(that takes some time to run) from the second script so that the
first script doesn’t block the second", and meanwhile be doing
something else, this will do that for you until the first script
is finished. (your example code modified):

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
do {
$line = fgets($process);
do_something_with_line($line);
do_something_else();
} while(!feof($process));
pclose($process);

Here is maybe a better
example to show what I mean. The first fgets waits until the test.php
has finished, and second fgets has nothing. Desired behavior should be
1st fgets:Hello, 2nd fgets World!

$process = popen("c:\php\php -f test.php", ‘r’);
stream_set_blocking($process, false);
print "\n 1st fgets:".fgets($process);
sleep(3);
print "\n 2nd fgets:".fgets($process);
pclose($process);

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