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Posted by Tim Hunt on 12/17/06 11:52
ImOk wrote:
> I just have a question about trapping and retrying errors especially
> file locking or database locks or duplicate key errors.
>
> Is there a way after you trap an error to retry the same line that
> cause the error?
>
> In many other languages you have the option of rertying certain errors.
> In effect, its like a return to the exact same line. You can then retry
> certain # of times and then produce an error if it keeps failing.
If you use set_error_handler to collect the errors and debug_backtrace
to see what caused the error it is possible to retry *some* errors.
I could only get it working if the error occured inside a function. If
you check the error message given to the event handler then you maybe
able to handle other errors, not sure if it can be done though.
Anyhoo the code below will try 3 times when a error occurs in any and
all functions.
<?php
error_reporting(0);
function retryErrorHandler($errNo, $errMsg ) {
static $attempts = 1;
$maxAttempts = 3;
$backTrace = debug_backtrace();
print "<br><br>Attempt $attempts<br>$errMsg<br>";
if ( $attempts >= $maxAttempts ) {
$attempts = 1;
} else if ( isset($backTrace[1]) &&
isset($backTrace[1]['function']) && isset($backTrace[1]['args']) ) {
// $backTrace[0] is info about the call to retryErrorHandler
// we need info about the previous function that triggered the
error
// so $backTrace[1] is used if a function + its arguments are
available
$attempts+=1;
$func = $backTrace[1]['function'];
$args = $backTrace[1]['args'];
print "Retry function $func <br>";
//Hmm..The error handler is only called the second time round if
the handler is reset
set_error_handler('retryErrorHandler');
call_user_func_array( $func, $args );
} else {
print "Can't retry error: $errMsg<br>";
$attempts = 1;
}
}
$old_error_handler = set_error_handler('retryErrorHandler');
// trigger a few errors...
// will not retry, not enough info returned by debug_backtrace to try
again
$i = UNDEFINED_THING;
// not enough info to try include() errors again - the dodgy filename
isn't in the backtrace details
// assume its because include is a language construct not a function
call
include('is not a file.php');
// will retry three times
fopen( 'no file', 'r' );
// will retry three times
mysql_connect( 'mysql wont connect' );
// will retry user functions as well as internal ones
testFunc();
function testFunc() {
$x = 3 / 0;
}
?>
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