Cancel a query when user leaves a web page

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Hi all,

I have a small problem. Is it possible to cancel a running query when a
person leave or pressed the stop button in my web page.

I've been thinking about mixing php and javascript. Is this the best way
to go about it?

basic out line of my code:
<html><head>....stuff....</head>
<body>...stuff
<?php
$connection = pg_connect(host, dbname, user);

pg_send_query($connection, "SELECT * FROM blah");

// collect the results and display etc..
?>
</body></html>
The query can take some time.
And when the page is left the query is still running on postmaster.

Have tried
<?php
include "functions.php";
$connection = pg_connect(host, dbname, user);
?>
<html><body onunload(<?close_connection($connection)?>)>
<?php
echo $connection;
pg_send_query($connection, "SELECT * FROM blah");

// collect the results and display etc..
?>
</body></html>

The function, close_connection($connection), is defined in the include
file, which is the connection is busy, cancels the query and closes the
connection.

This gives the following error:

Resource id #1
Warning: pg_send_query(): 1 is not a valid PostgreSQL link resource in
/home/fauxn/public_html/singleAArepeats/test.php on line 11

Any suggestions welcome.

Many thanks

--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia

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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1">
<title></title>
</head>
<body text="#000000" bgcolor="#ffffff">
Hi all, 
 
I have a small problem. Is it possible to cancel a running query when a
person leave or pressed the stop button in my web page. 
 
I've been thinking about mixing php and javascript. Is this the best
way to go about it? 
 
basic out line of my code: 
<html><head>....stuff....</head> 
<body>...stuff 
<?php 
 $connection = pg_connect(host, dbname, user); 
 
 pg_send_query($connection, "SELECT * FROM blah"); 
 
 // collect the results and display etc.. 
?> 
</body></html> 
The query can take some time. 
And when the page is left the query is still running on postmaster. 
 
Have tried 
<?php 
 include "functions.php"; 
 $connection = pg_connect(host, dbname, user); 
?> 
<html><body
onunload(<?close_connection($connection)?>)> 
<?php 
 echo $connection; 
 pg_send_query($connection, "SELECT * FROM blah"); 
 
 // collect the results and display etc.. 
?> 
</body></html> 
 
The function, close_connection($connection), is defined in the include
file, which is the connection is busy, cancels the query and closes the
connection. 
 
This gives the following error: 
 
Resource id #1 
Warning: pg_send_query(): 1 is not a valid PostgreSQL link
resource in /home/fauxn/public_html/singleAArepeats/test.php on
line 11 
 
Any suggestions welcome. 
 
Many thanks 

<pre class="moz-signature" cols="72">--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia
</pre>
</body>
</html>

--Boundary_(ID_HmeUQXJ/q/MVS8FcWBpQCw)--

Noel [ Di, 18 November 2003 03:33 ] [ ID #141491 ]

Re: Cancel a query when user leaves a web page

noel.faux [at] med.monash.edu.au wrote:
> I have a small problem. Is it possible to cancel a running query when a
> person leave or pressed the stop button in my web page.
> ...
> Have tried
> <?php
> include "functions.php";
> $connection = pg_connect(host, dbname, user);
> ?>
> <html><body onunload(<?close_connection($connection)?>)>
....

This will never work, as you found. The Javascript action is client-side
and PHP is server-side.

Try using register_shutdown_function() to register a function which will
call pg_cancel_query(). As long as PHP isn't ignoring user aborts (see
ignore_user_abort()), your query will be cancelled when the user hits STOP.
Another way is to ignore user aborts, and while waiting for the
asynchronous query to finish, keep calling connection_aborted() to see if
you are still connected to the user; if not you cancel the query and exit.

---------------------------(end of broadcast)---------------------------
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ljb [ Mi, 19 November 2003 03:05 ] [ ID #141492 ]

Re: Cancel a query when user leaves a web page

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------=_NextPart_000_009D_01C3AF07.CA3727B0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<body onunload(<?close_connection($connection)?>)>

onunload above can't call function from PHP, but it called from javascript,=
you can create javascript function to call PHP function/file that you wann=
a PHP do

<?php
// close_connection.php
include('connection.php');
global $connection;

function close_connection($connection){
// close_connection here
// .....
// .....
// .....

}

close_connection($connection);
echo "<SCRIPT>window.close();</SCRIPT>";
?>

---------

<html>

<SCRIPT LANGUAGE=3D"JavaScript">

</SCRIPT>

<body onunload =3D "leave()">

</body>
</html>

----- Original Message -----
From: Noel
To: pgsql-php [at] postgresql.org
Sent: Tuesday, November 18, 2003 10:33 AM
Subject: [PHP] Cancel a query when user leaves a web page

Hi all,

I have a small problem. Is it possible to cancel a running query when a p=
erson leave or pressed the stop button in my web page.

I've been thinking about mixing php and javascript. Is this the best way =
to go about it?

basic out line of my code:
<html><head>....stuff....</head>
<body>...stuff
<?php
$connection =3D pg_connect(host, dbname, user);

pg_send_query($connection, "SELECT * FROM blah");

// collect the results and display etc..
?>
</body></html>
The query can take some time.
And when the page is left the query is still running on postmaster.

Have tried
<?php
include "functions.php";
$connection =3D pg_connect(host, dbname, user);
?>
<html><body onunload(<?close_connection($connection)?>)>
<?php
echo $connection;
pg_send_query($connection, "SELECT * FROM blah");

// collect the results and display etc..
?>
</body></html>

The function, close_connection($connection), is defined in the include fi=
le, which is the connection is busy, cancels the query and closes the conne=
ction.

This gives the following error:

Resource id #1
Warning: pg_send_query(): 1 is not a valid PostgreSQL link resource in /h=
ome/fauxn/public_html/singleAArepeats/test.php on line 11

Any suggestions welcome.

Many thanks

--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia

------=_NextPart_000_009D_01C3AF07.CA3727B0
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE></TITLE>
<META http-equiv=3DContent-Type content=3Dtext/html;charset=3DISO-8859-1>
<META content=3D"MSHTML 6.00.2800.1170" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY text=3D#000000 bgColor=3D#ffffff>
<DIV>
<DIV>
<body
onunload(<?close_connection($connection)?>)>
onunload above can't call fu=
nction from
PHP, but it called from javascript, you can create javascript fun=
ction
to call PHP function/file that you wanna PHP do <FONT=

face=3D"Courier New" color=3D#ff0000 size=3D1>
<?php <FONT=

face=3D"Courier New" color=3D#ff8000 size=3D1>// close_connection.php</=
FONT> include('connection.php'); global $connection; function close_connection($connection){ //
close_connection here =
//
...... // ..... // ..... <FO=
NT
color=3D#000000>} close_connection($connection); echo "<SCRIPT>window.close();</SCRIPT>"; ?>
<FONT=

face=3D"Courier New" color=3D#0000ff size=3D1>---------
<html</FON=
T>> <=
;SCRIPT LANGUAGE=3D"JavaScript"> =
 </SCRIPT> <FON=
T
face=3D"Courier New" color=3D#0000ff size=3D1><body
onunload<=
FONT
face=3D"Courier New" color=3D#008080 size=3D1> =3D
"leave()"> </=
FONT></body> </html></DIV></DIV>
<BLOCKQUOTE dir=3Dltr
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LE=
FT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">Fro=
m:
<A title=3Dnoel.faux [at] med.monash.edu.au
href=3D"mailto:noel.faux [at] med.monash.edu.au">Noel</A> </DIV>
<DIV style=3D"FONT: 10pt arial">To: <A title=3Dpgsql-php [at] postgresq=
l.org
href=3D"mailto:pgsql-php [at] postgresql.org">pgsql-php [at] postgresq l.org</A> </D=
IV>
<DIV style=3D"FONT: 10pt arial">Sent: Tuesday, November 18, 2003 1=
0:33
AM</DIV>
<DIV style=3D"FONT: 10pt arial">Subject: [PHP] Cancel a query when=
user
leaves a web page</DIV>
<DIV> </DIV>Hi all, I have a small problem. Is it possible to c=
ancel
a running query when a person leave or pressed the stop button in my web=

page. I've been thinking about mixing php and javascript. Is this =
the
best way to go about it? basic out line of my
code: <html><head>....stuff....</head> <body&g=
t;...stuff <?php 
$connection =3D pg_connect(host, dbname, user); =

pg_send_query($connection, "SELECT * FROM blah"); &nbs=
p; //
collect the results and display
etc.. ?> </body></html> The query can take some=

time. And when the page is left the query is still running on
postmaster. Have tried <?php include=

"functions.php"; $connection =3D pg_connect(host, d=
bname,
user); ?> <html><body
onunload(<?close_connection($connection)?>)> <?php &nbs=
p;
echo $connection; pg_send_query($connection, "SELEC=
T *
FROM blah"); // collect the results and display=

etc.. ?> </body></html> The function,
close_connection($connection), is defined in the include file, which is t=
he
connection is busy, cancels the query and closes the connection. T=
his
gives the following error: Resource id #1 Warning:
pg_send_query(): 1 is not a valid PostgreSQL link resource in
/home/fauxn/public_html/singleAArepeats/test.php on line
11 Any suggestions welcome. Many thanks <P=
RE class=3Dmoz-signature cols=3D"72">--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia
</PRE></BLOCKQUOTE></BODY></HTML>

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middink [ Mi, 19 November 2003 18:44 ] [ ID #141493 ]

Re: Cancel a query when user leaves a web page

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Hi all,
Sorry for the delayed response, I've added both Hayat's and ljb220's
suggestions.

I've tried both, but still having problems.
Code:
//----------------------
test.php
<html>
<script language="JavaScript">

</script>
<body onunload = 'leave()'>
<?php include "functions.php";
global $connection;
$connection = pg_connect("host=localhost dbname=test user=test");
echo $connection." connection ";
echo pg_connection_status($connection)." status ";
pg_send_query($connection, "SELECT COUNT(id) FROM test"); //
expected to take ~2min enough time to press stop
echo pg_connection_busy($connection)." busy ";
$res = pg_get_result($connection);
echo pg_num_rows($res)." # rows ";
echo $GLOBALS["connection"]." GLOBALS ";
?>
</body></html>

//--------------------------------------
close.php
<?php include "functions.php";
echo "closing connection ";
$f = fopen("/home/xxx/log","w"); // log file to trace the code etc...
fwrite($f,"new page\n");
fclose($f);
close_con();
echo "closed";
echo "<script>window.close();</script>";
?>

//--------------------------------
functions.php
<?php
/* when the page is exited, if the connection is not null, cancel and
sql statements and
close the database connection */
function close_con() {
$f = fopen("/home/xxx/log","w"); // log file to trace the code
etc...
$connection = $GLOBALS["connection"];
fwrite($f,"Closing connection\n");
$status = pg_connection_status($connection);
fwrite($f, $status." status\n");
if($status == 0){// connected
fwrite($f, "connected\n");
if(pg_connection_busy($connection)) {// busy so cancel last
query
fwrite($f, "connection busy\n");
pg_cancel_query($connection);
fwrite($f, "query killed\n");
}
// close connection
pg_close($connection);
fwrite($f, "connection closed");
}
else {
fwrite($f, "not connected\n");
}
fclose($f);
}
?>

With this set up, the user enters test.php. Stops before the query
finishes. It should call leave(). However, this dose not happen. I
believe it is because the script has not finished and passed the page
text to the browser (pls correct me if I'm wrong), until php has
finished processing it.

I've tried using register_shutdown_function() as:
test.php
<html>
<body>
<?php include "functions.php";
global $connection;
$connection = pg_connect("host=localhost dbname=test user=test");
register_shutdown_function("close_con");
echo $connection." connection ";
echo pg_connection_status($connection)." status ";
pg_send_query($connection, "SELECT COUNT(id) FROM test");
echo pg_connection_busy($connection)." busy ";
$res = pg_get_result($connection);
echo pg_num_rows($res)." # rows ";
echo $GLOBALS["connection"]." GLOBALS ";
?>
</body></html>

The functions.php as above.

This also dose not work as, " The registered shutdown functions are
called after the request has been completed" (from
http://au2.php.net/manual/en/function.register-shutdown-func tion.php ).
I'm interpreting that as, any functions in the list will not be
called until the pg_send_query() or the pg_get_result(), not sure which,
returns. Then close_con() from functions.php is called via
register_shutdown_function(). Thus I'm unable to cancel the query :(

Any comments, suggestions or work arounds would be greatly appreciated.

I'm using PHP 4.2.3

Cheers
Noel

//---------------------------------------------------------- -------------------
Muhyiddin A.M Hayat wrote:

> <body onunload(<?close_connection($connection)?>)>
>
> onunload above can't call function from PHP, but it called from
> javascript, you can create javascript function to call PHP
> function/file that you wanna PHP do
>
> <?php
> // close_connection.php
> include('connection.php');
> global $connection;
>
> function close_connection($connection){
> // close_connection here
> // .....
> // .....
> // .....
>
> }
>
> close_connection($connection);
> echo "<SCRIPT>window.close();</SCRIPT>";
> ?>
>
> ---------
>
> <html>
>
> <SCRIPT LANGUAGE="JavaScript">
> 
> </SCRIPT>
>
> <body onunload = "leave()">
>
> </body>
> </html>
>
//----------------------------------------
ljb wrote:

noel.faux [at] med.monash.edu.au wrote:

>I have a small problem. Is it possible to cancel a running query when a
>person leave or pressed the stop button in my web page.
>...
>Have tried
><?php
> include "functions.php";
> $connection = pg_connect(host, dbname, user);
>?>
><html><body onunload(<?close_connection($connection)?>)>
>
>
> ...
>
> This will never work, as you found. The Javascript action is client-side
> and PHP is server-side.
>
> Try using register_shutdown_function() to register a function which will
> call pg_cancel_query(). As long as PHP isn't ignoring user aborts (see
> ignore_user_abort()), your query will be cancelled when the user hits STOP.
> Another way is to ignore user aborts, and while waiting for the
> asynchronous query to finish, keep calling connection_aborted() to see if
> you are still connected to the user; if not you cancel the query and exit.

--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia

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Content-type: text/html; charset=us-ascii
Content-transfer-encoding: 7BIT

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1">
<title></title>
</head>
<body text="#000000" bgcolor="#ffffff">
Hi all, 
Sorry for the delayed response, I've added both Hayat's and ljb220's
suggestions. 
 
I've tried both, but still having problems. 
Code: 
//---------------------- 
test.php 
<html> 
<script language="JavaScript"> 
 
</script> 
<body onunload = 'leave()'> 
<?php include "functions.php"; 
 global $connection; 
 $connection = pg_connect("host=localhost dbname=test user=test"); 
 echo $connection." connection "; 
 echo pg_connection_status($connection)." status "; 
 pg_send_query($connection, "SELECT COUNT(id) FROM test"); //
expected to take ~2min enough time to press stop 
 echo pg_connection_busy($connection)." busy "; 
 $res = pg_get_result($connection); 
 echo pg_num_rows($res)." # rows "; 
 echo $GLOBALS["connection"]." GLOBALS "; 
?> 
</body></html> 
 
//-------------------------------------- 
close.php 
<?php include "functions.php"; 
 echo "closing connection "; 
 $f = fopen("/home/xxx/log","w"); // log file to trace the code
etc... 
 fwrite($f,"new page\n"); 
 fclose($f); 
 close_con(); 
 echo "closed"; 
 echo "<script>window.close();</script>"; 
?> 
 
//-------------------------------- 
functions.php 
<?php 
/* when the page is exited, if the connection is not null, cancel and
sql statements and 
 close the database connection */ 
 function close_con() { 
 $f = fopen("/home/xxx/log","w"); // log file to trace the code
etc... 
 $connection = $GLOBALS["connection"]; 
 fwrite($f,"Closing connection\n"); 
 $status = pg_connection_status($connection); 
 fwrite($f, $status." status\n"); 
 if($status == 0){// connected 
 fwrite($f, "connected\n"); 
 if(pg_connection_busy($connection)) {// busy so cancel last
query 
 fwrite($f, "connection busy\n"); 
 pg_cancel_query($connection); 
 fwrite($f, "query killed\n"); 
 } 
 // close connection 
 pg_close($connection); 
 fwrite($f, "connection closed"); 
 } 
 else { 
 fwrite($f, "not connected\n"); 
 } 
 fclose($f); 
 } 
?> 
 
With this set up, the user enters test.php. Stops before the query
finishes. It should call leave(). However, this dose not happen. I
believe it is because the script has not finished and passed the page
text to the browser (pls correct me if I'm wrong), until php has
finished processing it. 
 
I've tried using register_shutdown_function() as: 
test.php 
<html> 
<body> 
<?php include "functions.php"; 
 global $connection; 
 $connection = pg_connect("host=localhost dbname=test user=test"); 
 register_shutdown_function("close_con"); 
 echo $connection." connection "; 
 echo pg_connection_status($connection)." status "; 
 pg_send_query($connection, "SELECT COUNT(id) FROM test"); 
 echo pg_connection_busy($connection)." busy "; 
 $res = pg_get_result($connection); 
 echo pg_num_rows($res)." # rows "; 
 echo $GLOBALS["connection"]." GLOBALS "; 
?> 
</body></html> 
 
The functions.php as above. 
 
This also dose not work as, " The registered shutdown functions are
called after the request has been completed" (from
<a class="moz-txt-link-freetext" href="http://au2.php.net/manual/en/function.register-shutdown-function.php"> http://au2.php.net/manual/en/function.register-shutdown-func tion.php</a> ).
I'm interpreting that as, any functions in the list will not be 
called until the pg_send_query() or the pg_get_result(), not sure
which, returns. Then close_con() from functions.php is called via
register_shutdown_function(). Thus I'm unable to cancel the query :( 
 
Any comments, suggestions or work arounds would be greatly appreciated. 
 
I'm using PHP 4.2.3 
 
Cheers 
Noel 
 
//---------------------------------------------------------- ------------------- 
Muhyiddin A.M Hayat wrote: 
<blockquote type="cite"
cite="mid00aa01c3aec5$3fb5df60$2b179fca [at] middinkcomp">
<title></title>
<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1">
<meta content="MSHTML 6.00.2800.1170" name="GENERATOR">
<style></style>
<div>
<div>
<body
onunload(<?close_connection($connection)?>)>
onunload
above can't call function from PHP, but it called from javascript, you
can create javascript function to call PHP function/file that you wanna
PHP do 

<?php 
//
close_connection.php 
include('connection.php'); 
global $connection; 
 
function close_connection($connection){ 
//
close_connection here 
// ..... 
// ..... 
// ..... 
 
} 
 
close_connection($connection); 
echo "<SCRIPT>window.close();</SCRIPT>"; 
?>
---------
<html> 
 
<SCRIPT LANGUAGE="JavaScript"> 
 
</SCRIPT> 
 
<body onunload = "leave()"> 
 
</body> 
</html>
</div>
</div>
</blockquote>
//---------------------------------------- 
ljb wrote: 
<pre wrap=""><a class="moz-txt-link-abbreviated" href="mailto:noel.faux [at] med.monash.edu.au">noel.faux [at] med.monash.edu.au</a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I have a small problem. Is it possible to cancel a running query when a
person leave or pressed the stop button in my web page.
....
Have tried
<?php
include "functions.php";
$connection = pg_connect(host, dbname, user);
?>
<html><body onunload(<?close_connection($connection)?>)>
</pre>
</blockquote>
<pre wrap="">> ...
>
> This will never work, as you found. The Javascript action is client-side
> and PHP is server-side.
>
> Try using register_shutdown_function() to register a function which will
> call pg_cancel_query(). As long as PHP isn't ignoring user aborts (see
> ignore_user_abort()), your query will be cancelled when the user hits STOP.
> Another way is to ignore user aborts, and while waiting for the
> asynchronous query to finish, keep calling connection_aborted() to see if
> you are still connected to the user; if not you cancel the query and exit.</pre>
 
 
<pre class="moz-signature" cols="72">--
Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia
</pre>
</body>
</html>

--Boundary_(ID_guCDxg5vhcnlCQv3p5oAOw)--

Noel [ Di, 16 Dezember 2003 08:58 ] [ ID #141546 ]