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# This program is copyright 2010-2011 Percona Inc.
# Feedback and improvements are welcome.
#
# THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
# WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
# MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, version 2; OR the Perl Artistic License. On UNIX and similar
# systems, you can issue `man perlgpl' or `man perlartistic' to read these
# licenses.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 59 Temple
# Place, Suite 330, Boston, MA 02111-1307 USA.
# ###########################################################################
# Retry package
# ###########################################################################
{
# Package: Retry
# Retry retries code that may die and handles those deaths nicely.
package Retry;
use strict;
use warnings FATAL => 'all';
use English qw(-no_match_vars);
use constant PTDEBUG => $ENV{PTDEBUG} || 0;
sub new {
my ( $class, %args ) = @_;
my $self = {
%args,
};
return bless $self, $class;
}
# Sub: retry
# Retry a code block that may die several times.
#
# Required Arguments:
# try - Callback to try.
# fail - Callback when try dies.
# final_fail - Callback when try dies for the last time.
#
# Optional arguments:
# tries - Number of try attempts (default 3)
# wait - Callback after fail if tries remain (default sleep 1s)
#
# Returns:
# Return value of try code when it doesn't die.
sub retry {
my ( $self, %args ) = @_;
my @required_args = qw(try fail final_fail);
foreach my $arg ( @required_args ) {
die "I need a $arg argument" unless $args{$arg};
};
my ($try, $fail, $final_fail) = @args{@required_args};
my $wait = $args{wait} || sub { sleep 1; };
my $tries = $args{tries} || 3;
my $last_error;
my $tryno = 0;
TRY:
while ( ++$tryno <= $tries ) {
PTDEBUG && _d("Try", $tryno, "of", $tries);
my $result;
eval {
$result = $try->(tryno=>$tryno);
};
if ( $EVAL_ERROR ) {
PTDEBUG && _d("Try code failed:", $EVAL_ERROR);
$last_error = $EVAL_ERROR;
if ( $tryno < $tries ) { # more retries
my $retry = $fail->(tryno=>$tryno, error=>$last_error);
last TRY unless $retry;
PTDEBUG && _d("Calling wait code");
$wait->(tryno=>$tryno);
}
}
else {
PTDEBUG && _d("Try code succeeded");
return $result;
}
}
PTDEBUG && _d('Try code did not succeed');
return $final_fail->(error=>$last_error);
}
sub _d {
my ($package, undef, $line) = caller 0;
@_ = map { (my $temp = $_) =~ s/\n/\n# /g; $temp; }
map { defined $_ ? $_ : 'undef' }
@_;
print STDERR "# $package:$line $PID ", join(' ', @_), "\n";
}
1;
}
# ###########################################################################
# End Retry package
# ###########################################################################
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