# Copyright 2017-2019, Paul Johnson (paul@pjcj.net)

# This software is free.  It is licensed under the same terms as Perl itself.

# The latest version of this software should be available from my homepage:
# http://www.pjcj.net

package Devel::Cover::DB::IO::Base;

use strict;
use warnings;

use Fcntl ":flock";

our $VERSION = '1.36'; # VERSION

sub new {
    my $class = shift;
    bless { @_ }, $class
}

sub _lock {
    my $self = shift;
    my ($file, $type) = @_;
    my $lock = "$file.lock";
    open my $fh, "+>>", $lock or die "Can't open $lock: $!\n";
    flock $fh, $type          or die "Can't lock $lock: $!\n";
    $fh
}

sub _read {
    my $self   = shift;
    my ($file, $reader) = @_;
    my $lock_fh = $self->_lock($file, LOCK_SH);
    $reader->()
}

sub _write {
    my $self = shift;
    my ($file, $writer) = @_;
    my $lock_fh = $self->_lock($file, LOCK_EX);
    unlink $file;
    $writer->();
    $self
}

sub _read_fh {
    my $self   = shift;
    my ($file, $reader) = @_;
    $self->_read($file, sub {
        open my $fh, "<", $file or die "Can't open $file: $!\n";
        my $data = $reader->($fh);
        close $fh or die "Can't close $file: $!\n";
        $data
    })
}

sub _write_fh {
    my $self = shift;
    my ($file, $writer) = @_;
    $self->_write($file, sub {
        open my $fh, ">", $file or die "Can't open $file: $!\n";
        $writer->($fh);
        close $fh or die "Can't close $file: $!\n";
    })
}

"
Green trees call to me
I am free but life is so cheap
"

__END__

=head1 NAME

Devel::Cover::DB::IO::Base - Base class for IO routines for Devel::Cover::DB

=head1 VERSION

version 1.36

=head1 SYNOPSIS

 use parent "Devel::Cover::DB::IO::Base";

=head1 DESCRIPTION

This module is a base class for IO routines for Devel::Cover::DB.

=head1 SEE ALSO

L<Devel::Cover>

=head1 METHODS

=head1 BUGS

Huh?

=head1 LICENCE

Copyright 2017-2019, Paul Johnson (paul@pjcj.net)

This software is free.  It is licensed under the same terms as Perl itself.

The latest version of this software should be available from my homepage:
http://www.pjcj.net

=cut
