/usr/share/perl5/DBIx/Class/Storage/BlockRunner.pm is in libdbix-class-perl 0.082840-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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DBIx::Class::Storage::BlockRunner;
use warnings;
use strict;
use DBIx::Class::Exception;
use DBIx::Class::Carp;
use Context::Preserve 'preserve_context';
use DBIx::Class::_Util qw(is_exception qsub);
use Scalar::Util qw(weaken blessed reftype);
use Try::Tiny;
use Moo;
use namespace::clean;
=head1 NAME
DBIx::Class::Storage::BlockRunner - Try running a block of code until success with a configurable retry logic
=head1 DESCRIPTION
=head1 METHODS
=cut
has storage => (
is => 'ro',
required => 1,
);
has wrap_txn => (
is => 'ro',
required => 1,
);
# true - retry, false - rethrow, or you can throw your own (not catching)
has retry_handler => (
is => 'ro',
required => 1,
isa => qsub q{
(Scalar::Util::reftype($_[0])||'') eq 'CODE'
or DBIx::Class::Exception->throw('retry_handler must be a CODE reference')
},
);
has retry_debug => (
is => 'rw',
# use a sub - to be evaluated on the spot lazily
default => qsub '$ENV{DBIC_STORAGE_RETRY_DEBUG}',
lazy => 1,
);
has max_attempts => (
is => 'ro',
default => 20,
);
has failed_attempt_count => (
is => 'ro',
init_arg => undef, # ensures one can't pass the value in
writer => '_set_failed_attempt_count',
default => 0,
lazy => 1,
trigger => qsub q{
$_[0]->throw_exception( sprintf (
'Reached max_attempts amount of %d, latest exception: %s',
$_[0]->max_attempts, $_[0]->last_exception
)) if $_[0]->max_attempts <= ($_[1]||0);
},
);
has exception_stack => (
is => 'ro',
init_arg => undef,
clearer => '_reset_exception_stack',
default => qsub q{ [] },
lazy => 1,
);
sub last_exception { shift->exception_stack->[-1] }
sub throw_exception { shift->storage->throw_exception (@_) }
sub run {
my $self = shift;
$self->_reset_exception_stack;
$self->_set_failed_attempt_count(0);
my $cref = shift;
$self->throw_exception('run() requires a coderef to execute as its first argument')
if ( reftype($cref)||'' ) ne 'CODE';
my $storage = $self->storage;
return $cref->( @_ ) if (
$storage->{_in_do_block}
and
! $self->wrap_txn
);
local $storage->{_in_do_block} = 1 unless $storage->{_in_do_block};
return $self->_run($cref, @_);
}
# this is the actual recursing worker
sub _run {
# internal method - we know that both refs are strong-held by the
# calling scope of run(), hence safe to weaken everything
weaken( my $self = shift );
weaken( my $cref = shift );
my $args = @_ ? \@_ : [];
# from this point on (defined $txn_init_depth) is an indicator for wrap_txn
# save a bit on method calls
my $txn_init_depth = $self->wrap_txn ? $self->storage->transaction_depth : undef;
my $txn_begin_ok;
my $run_err = '';
return preserve_context {
try {
if (defined $txn_init_depth) {
$self->storage->txn_begin;
$txn_begin_ok = 1;
}
$cref->( @$args );
} catch {
$run_err = $_;
(); # important, affects @_ below
};
} replace => sub {
my @res = @_;
my $storage = $self->storage;
my $cur_depth = $storage->transaction_depth;
if (defined $txn_init_depth and ! is_exception $run_err) {
my $delta_txn = (1 + $txn_init_depth) - $cur_depth;
if ($delta_txn) {
# a rollback in a top-level txn_do is valid-ish (seen in the wild and our own tests)
carp (sprintf
'Unexpected reduction of transaction depth by %d after execution of '
. '%s, skipping txn_commit()',
$delta_txn,
$cref,
) unless $delta_txn == 1 and $cur_depth == 0;
}
else {
$run_err = eval { $storage->txn_commit; 1 } ? '' : $@;
}
}
# something above threw an error (could be the begin, the code or the commit)
if ( is_exception $run_err ) {
# attempt a rollback if we did begin in the first place
if ($txn_begin_ok) {
# some DBDs go crazy if there is nothing to roll back on, perform a soft-check
my $rollback_exception = $storage->_seems_connected
? (! eval { $storage->txn_rollback; 1 }) ? $@ : ''
: 'lost connection to storage'
;
if ( $rollback_exception and (
! defined blessed $rollback_exception
or
! $rollback_exception->isa('DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION')
) ) {
$run_err = "Transaction aborted: $run_err. Rollback failed: $rollback_exception";
}
}
push @{ $self->exception_stack }, $run_err;
# this will throw if max_attempts is reached
$self->_set_failed_attempt_count($self->failed_attempt_count + 1);
# init depth of > 0 ( > 1 with AC) implies nesting - no retry attempt queries
$storage->throw_exception($run_err) if (
(
defined $txn_init_depth
and
# FIXME - we assume that $storage->{_dbh_autocommit} is there if
# txn_init_depth is there, but this is a DBI-ism
$txn_init_depth > ( $storage->{_dbh_autocommit} ? 0 : 1 )
) or ! $self->retry_handler->($self)
);
# we got that far - let's retry
carp( sprintf 'Retrying %s (attempt %d) after caught exception: %s',
$cref,
$self->failed_attempt_count + 1,
$run_err,
) if $self->retry_debug;
$storage->ensure_connected;
# if txn_depth is > 1 this means something was done to the
# original $dbh, otherwise we would not get past the preceding if()
$storage->throw_exception(sprintf
'Unexpected transaction depth of %d on freshly connected handle',
$storage->transaction_depth,
) if (defined $txn_init_depth and $storage->transaction_depth);
return $self->_run($cref, @$args);
}
return wantarray ? @res : $res[0];
};
}
=head1 FURTHER QUESTIONS?
Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
=head1 COPYRIGHT AND LICENSE
This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
redistribute it and/or modify it under the same terms as the
L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.
=cut
1;
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