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Add Cxn.pm. Make MasterSlave, NibbleIterator, and ReplicaLagWaiter use Cxn. Rewrite, simplify Retry.

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Daniel Nichter
2011-10-06 12:47:35 -06:00
parent bd900c5ab8
commit e2e40488c5
9 changed files with 310 additions and 203 deletions
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72
lib/Retry.pm
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@@ -19,7 +19,7 @@
# ###########################################################################
{
# Package: Retry
# Retry retries code until a condition succeeds.
# Retry retries code that may die and handles those deaths nicely.
package Retry;
use strict;
@@ -35,64 +35,58 @@ sub new {
return bless $self, $class;
}
# Required arguments:
# * try coderef: code to try; return true on success
# * wait coderef: code that waits in between tries
# 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 scalar: number of retries to attempt (default 3)
# * retry_on_die bool: retry try code if it dies (default no)
# * on_success coderef: code to call if try is successful
# * on_failure coderef: code to call if try does not succeed
# Retries the try code until either it returns true or we exhaust
# the number of retry attempts. The args are passed to the coderefs
# (try, wait, on_success, on_failure). If the try code dies, that's
# a final failure (no more retries) unless retry_on_die is true.
# Returns either whatever the try code returned or undef on failure.
# 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 wait);
my @required_args = qw(try fail final_fail);
foreach my $arg ( @required_args ) {
die "I need a $arg argument" unless $args{$arg};
};
my ($try, $wait) = @args{@required_args};
my ($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 ) {
MKDEBUG && _d("Retry", $tryno, "of", $tries);
MKDEBUG && _d("Try", $tryno, "of", $tries);
my $result;
eval {
$result = $try->(tryno=>$tryno);
};
if ( $EVAL_ERROR ) {
MKDEBUG && _d("Try code failed:", $EVAL_ERROR);
$last_error = $EVAL_ERROR;
if ( defined $result ) {
MKDEBUG && _d("Try code succeeded");
if ( my $on_success = $args{on_success} ) {
MKDEBUG && _d("Calling on_success code");
$on_success->(tryno=>$tryno, result=>$result);
if ( $tryno < $tries ) { # more retries
my $retry = $fail->(tryno=>$tryno, error=>$last_error);
last TRY unless $retry;
MKDEBUG && _d("Calling wait code");
$wait->(tryno=>$tryno);
}
}
else {
MKDEBUG && _d("Try code succeeded");
return $result;
}
if ( $EVAL_ERROR ) {
MKDEBUG && _d("Try code died:", $EVAL_ERROR);
die $EVAL_ERROR unless $args{retry_on_die};
}
# Wait if there's more retries, else end immediately.
if ( $tryno < $tries ) {
MKDEBUG && _d("Try code failed, calling wait code");
$wait->(tryno=>$tryno);
}
}
MKDEBUG && _d("Try code did not succeed");
if ( my $on_failure = $args{on_failure} ) {
MKDEBUG && _d("Calling on_failure code");
$on_failure->();
}
return;
MKDEBUG && _d('Try code did not succeed');
return $final_fail->(error=>$last_error);
}
sub _d {