Re: [PHP-DB] connection id mystery
Charles Whitaker wrote: Using persistant connections simply means that you will be given a connection from a pool of open connections rather than creating a new one each time. There is no guarantee you'll get the same connection from request to request. Right. I had assumed that I would get a connection previously initiated by me, and that there would therefore be only one, so I would always get the same connection. So much for assumptions. I would suggest you add another field to the table you are trying to lock. Put an ID in there that you can pass from request to request. Use the locking feature to lock the table, read that value for a record, if it's not set to something write your ID to it then unlock it. If it does already contain an ID you treat it as locked. you just need to make sure you unlock the row when you're done (probably by setting that value to NULL. If you're already using sessions I would strongly recommend using the session ID as the lock ID. If not you can easily generate one but you'll need to pass it manually from request to request. I did as you suggest, and it seems to work fine. I surrounded the lock code with get_lock() and release_lock(), to make it quasi-atomic. Thanks for the suggestion, and thanks to Charles Morris as well for his response. No problem, but please include the list when replying in future. -Stut -- http://stut.net/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] connection id mystery
Charles Whitaker wrote: Since I'm requesting persistent connections, why don't I get the same connection each time? Or, to ask it another way: I notice that the number of threads slowly increases as I continue to access records -- why would this happen if I'm using persistent connections? I assumed that the first time I did 'new PDO' I'd create a connection, and each time after that I'd get the same connection. At least that's how I read the documentation. Using persistant connections simply means that you will be given a connection from a pool of open connections rather than creating a new one each time. There is no guarantee you'll get the same connection from request to request. Can anyone point me in the right direction? Thanks. I would suggest you add another field to the table you are trying to lock. Put an ID in there that you can pass from request to request. Use the locking feature to lock the table, read that value for a record, if it's not set to something write your ID to it then unlock it. If it does already contain an ID you treat it as locked. you just need to make sure you unlock the row when you're done (probably by setting that value to NULL. If you're already using sessions I would strongly recommend using the session ID as the lock ID. If not you can easily generate one but you'll need to pass it manually from request to request. That may not be as clean as a pure SQL solution, but it will work. You may also want to add a timestamp row to allow for a timeout on the lock. -Stut -- http://stut.net/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP-DB] connection id mystery
Greetings,
I'm developing a tech support log using php and MySQL. Users will
add, delete and modify records. In fact, it's fully implemented
except for concurrency control. I'm trying to use get_lock and
release_lock to implement record-level locking, but when I go to
release the lock, the connection id doesn't match the id used to get
the lock, and so the release fails and the record stays, in effect,
locked.
When a user loads the edit page for a record, get_lock is called with
a unique id before the record is read. When the user saves changes,
the edit page is reloaded, and the record is modified. The lock is
released only after the user loads some other page.
It often works, but sometimes I see this in the log:
[25/Jul/2007:11:33:39] 192.168.2.102 InitSQL: new connection: pdo
client id = 279 // load the edit page, and ...
[25/Jul/2007:11:33:39] 192.168.2.102 Lock iss_23 gotten using
connection id 279 // lock the record.
[25/Jul/2007:11:33:42] 192.168.2.102 InitSQL: new connection: pdo
client id = 288 // load some other page, but get a different
connection id, and so ...
[25/Jul/2007:11:33:42] 192.168.2.102 Lock iss_23 was not gotten using
current connection id (288), not released // fail to
unlock the record.
Since I'm requesting persistent connections, why don't I get the same
connection each time? Or, to ask it another way: I notice that the
number of threads slowly increases as I continue to access records --
why would this happen if I'm using persistent connections? I assumed
that the first time I did 'new PDO' I'd create a connection, and each
time after that I'd get the same connection. At least that's how I
read the documentation.
Can anyone point me in the right direction? Thanks.
The gory details:
At the beginning of every page is a call to a function with this code:
$gSQL = new
PDO('mysql:unix_socket=/tmp/mysql.sock;dbname=operations',
$_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW'],
array(PDO::ATTR_PERSISTENT = true, PDO::ATTR_ERRMODE =
PDO::ERRMODE_EXCEPTION, PDO::ATTR_TIMEOUT = 86400));
// get connection id
$stmt = $sql-query('show processlist');
$therow = $stmt-fetch();
$pdoclientid = $therow['Id'];
elog('InitSQL: new connection: pdo client id = ' . $pdoclientid);
In the edit page I call to a function that does this:
// get the current connection id
$stmt = $gSQL-query('select connection_id()');
$therow = $stmt-fetch();
$connectionid = $therow[0];
// get the lock
$thelock = 'iss_' . $issueid;
foreach ($gSQL-query(select get_lock(' . $thelock . ', . 1 .
)) as $row) {
// check the result
$result = $row[0];
switch ($result) {
case 1:
eLog(Lock . $thelock . ' gotten using connection
id ' . $connectionid);
return true;
break;
case 0:
eLog(Getting lock . $thelock . ' timed out');
return false;
break;
case NULL:
eLog(Error getting lock . $thelock);
return false;
break;
default:
return false;
break;
}
}
On all other pages, I try to release the lock with this code:
// get the current connection id
$stmt = $gSQL-query('select connection_id()');
$therow = $stmt-fetch();
$connectionid = $therow[0];
// try to release the lock
foreach ($gSQL-query(select release_lock(' . $thelock . ')) as $row) {
$result = $row[0];
switch ($result) {
case 1:
eLog(Lock . $thelock . ' released');
break;
case 0:
eLog(Lock . $thelock . ' was not gotten
using current connection id (' . $connectionid . '), not released');
break;
case NULL:
eLog(Lock . $thelock . ' does not exist,
not released');
break;
default:
break;
}
}
--
Charles Whitaker
--
PHP Database Mailing List (http://www.php.net/)
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Re: [PHP-DB] connection id
Use persistent connections it's a matter of performance of your script. When you use persistent connections the next call to mysql_pconnect will catch a opened connection if available. The mysql_connect command always open a new connection which slower than get an opened one. Anyway you can't use the connection_id in other page. May be using PHP4 Sessions. HTH. Jayme. -Mensagem Original- De: andrie [EMAIL PROTECTED] Para: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Enviada em: sexta-feira, 23 de maro de 2001 20:38 Assunto: [PHP-DB] connection id Hello php mania, i was connecting into mysql using mysql_connect, and i just saved the return value from this funtion. now i want to use this connection id in the other page so i dont have to connect into mysql again. is it possible for me to do that ? anybody could tell me the different between persistence connection or not ? and how the implementation ? TIA -- Best regards, andrie mailto:[EMAIL PROTECTED] -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED] -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
[PHP-DB] connection id
Hello php mania, i was connecting into mysql using mysql_connect, and i just saved the return value from this funtion. now i want to use this connection id in the other page so i dont have to connect into mysql again. is it possible for me to do that ? anybody could tell me the different between persistence connection or not ? and how the implementation ? TIA -- Best regards, andrie mailto:[EMAIL PROTECTED] -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
[PHP-DB] connection id in mysql
Does any body know why the connection id in mysql will increase when you exit the mysql and login again? But I think the connection id should be cleared when user exit mysql. -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
