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| | # Copyright (C) 2018-2021 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
# Base class for per-inbox locking
package PublicInbox::Lock;
use strict;
use v5.10.1;
use Fcntl qw(:flock :DEFAULT);
use Carp qw(croak);
use PublicInbox::OnDestroy;
# we only acquire the flock if creating or reindexing;
# PublicInbox::Import already has the lock on its own.
sub lock_acquire {
my ($self) = @_;
my $lock_path = $self->{lock_path};
croak 'already locked '.($lock_path // '(undef)') if $self->{lockfh};
return unless defined($lock_path);
sysopen(my $lockfh, $lock_path, O_RDWR|O_CREAT) or
croak "failed to open $lock_path: $!\n";
flock($lockfh, LOCK_EX) or croak "lock $lock_path failed: $!\n";
$self->{lockfh} = $lockfh;
}
sub lock_release {
my ($self, $wake) = @_;
defined(my $lock_path = $self->{lock_path}) or return;
my $lockfh = delete $self->{lockfh} or croak "not locked: $lock_path";
syswrite($lockfh, '.') if $wake;
flock($lockfh, LOCK_UN) or croak "unlock $lock_path failed: $!\n";
close $lockfh or croak "close $lock_path failed: $!\n";
}
# caller must use return value
sub lock_for_scope {
my ($self, @single_pid) = @_;
lock_acquire($self) or return; # lock_path not set
PublicInbox::OnDestroy->new(@single_pid, \&lock_release, $self);
}
sub lock_acquire_fast {
$_[0]->{lockfh} or return lock_acquire($_[0]);
flock($_[0]->{lockfh}, LOCK_EX) or croak "lock (fast) failed: $!";
}
sub lock_release_fast {
flock($_[0]->{lockfh} // return, LOCK_UN) or
croak "unlock (fast) $_[0]->{lock_path}: $!";
}
# caller must use return value
sub lock_for_scope_fast {
my ($self, @single_pid) = @_;
lock_acquire_fast($self) or return; # lock_path not set
PublicInbox::OnDestroy->new(@single_pid, \&lock_release_fast, $self);
}
1;
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