File Coverage

blib/lib/Server/Starter.pm

Criterion	Covered	Total	%
statement	281	330	85.1
branch	112	186	60.2
condition	29	52	55.7
subroutine	29	32	90.6
pod	2	4	50.0
total	453	604	75.0

package Server::Starter;

use 5.008;
use strict;
use warnings;
use Carp;
use Fcntl;
use IO::Handle;
use IO::Socket::UNIX;
use POSIX qw(:sys_wait_h);
use Socket ();
use Server::Starter::Guard;
use Fcntl qw(:flock);

use Exporter qw(import);

our $VERSION = '0.33';
our @EXPORT_OK = qw(start_server restart_server stop_server server_ports);

my @signals_received;

sub start_server {
    my $opts = {
        (@_ == 1 ? @$_[0] : @_),
    };
    $opts->{interval} = 1
        if not defined $opts->{interval};
    $opts->{signal_on_hup}  ||= 'TERM';
    $opts->{signal_on_term} ||= 'TERM';
    $opts->{backlog} ||= Socket::SOMAXCONN();
    for ($opts->{signal_on_hup}, $opts->{signal_on_term}) {
        # normalize to the one that can be passed to kill
        tr/a-z/A-Z/;
        s/^SIG//i;
    }

    # prepare args
    my $ports = $opts->{port};
    my $paths = $opts->{path};
    croak "either of ``port'' or ``path'' option is mandatory\n"
        unless $ports || $paths;
    $ports = [ $ports ]
        if ! ref $ports && defined $ports;
    $paths = [ $paths ]
        if ! ref $paths && defined $paths;
    croak "mandatory option ``exec'' is missing or is not an arrayref\n"
        unless $opts->{exec} && ref $opts->{exec} eq 'ARRAY';

    # set envs
    $ENV{ENVDIR} = $opts->{envdir}
        if defined $opts->{envdir};
    $ENV{ENABLE_AUTO_RESTART} = $opts->{enable_auto_restart}
        if defined $opts->{enable_auto_restart};
    $ENV{KILL_OLD_DELAY} = $opts->{kill_old_delay}
        if defined $opts->{kill_old_delay};
    $ENV{AUTO_RESTART_INTERVAL} = $opts->{auto_restart_interval}
        if defined $opts->{auto_restart_interval};

    # open log file
    my $logfh;
    if ($opts->{log_file}) {
        if ($opts->{log_file} =~ /^\s*\|\s*/s) {
            my $cmd = $';
            open $logfh, '|-', $cmd
                or die "failed to open pipe:$opts->{log_file}: $!";
        } else {
            open $logfh, '>>', $opts->{log_file}
                or die "failed to open log file:$opts->{log_file}: $!";
        }
        $logfh->autoflush(1);
    }

    # create guard that removes the status file
    my $status_file_created;
    my $status_file_guard = $opts->{status_file} && Server::Starter::Guard->new(
        sub {
            if ($status_file_created) {
                unlink $opts->{status_file};
            }
        },
    );

    print STDERR "start_server (pid:$$) starting now...\n";

    # start listening, setup envvar
    my @sock;
    my @sockenv;
    for my $hostport (@$ports) {
        my ($domain, $sa);
        my $fd;
        my $sockopts = sub {};
        if ($hostport =~ /^\s*(\d+)(?:\s*=(\d+))?\s*$/) {
            # by default, only bind to IPv4 (for compatibility)
            $hostport = $1;
            $fd = $2;
            $domain = Socket::PF_INET;
            $sa = pack_sockaddr_in $1, Socket::inet_aton("0.0.0.0");
        } elsif ($hostport =~ /^\s*(?:\[\s*|)([^\]]*)\s*(?:\]\s*|):\s*(\d+)(?:\s*=(\d+))?\s*$/) {
            my ($host, $port) = ($1, $2);
            $fd = $3;
            if ($host =~ /:/) {
                # IPv6
                local $@;
                eval {
                    $hostport = "[$host]:$port";
                    my $addr = Socket::inet_pton(Socket::AF_INET6(), $host)
                        or die "failed to resolve host:$host:$!";
                    $sa = Socket::pack_sockaddr_in6($port, $addr);
                    $domain = Socket::PF_INET6();
                };
                if ($@) {
                    die "No support for IPv6. Please update Perl (or Perl modules)";
                }
                $sockopts = sub {
                    my $sock = shift;
                    local $@;
                    eval {
                        setsockopt $sock, Socket::IPPROTO_IPV6(), Socket::IPV6_V6ONLY(), 1;
                    };
                };
            } else {
                # IPv4
                $domain = Socket::PF_INET;
                $hostport = "$host:$port";
                my $addr = gethostbyname $host
                    or die "failed to resolve host:$host:$!";
                $sa = Socket::pack_sockaddr_in($port, $addr);
            }
        } else {
            croak "invalid ``port'' value:$hostport\n"
        }
        socket my $sock, $domain, Socket::SOCK_STREAM(), 0
            or die "failed to create socket:$!";
        setsockopt $sock, Socket::SOL_SOCKET, Socket::SO_REUSEADDR(), pack("l", 1);
        $sockopts->($sock);
        bind $sock, $sa
            or die "failed to bind to $hostport:$!";
        listen $sock, $opts->{backlog}
            or die "listen(2) failed:$!";
        fcntl($sock, F_SETFD, my $flags = '')
                or die "fcntl(F_SETFD, 0) failed:$!";
        if (defined $fd) {
            POSIX::dup2($sock->fileno, $fd)
                or die "dup2(2) failed(${fd}): $!";
            print STDERR "socket is duplicated to file descriptor ${fd}\n";
            close $sock;
            push @sockenv, "$hostport=$fd";
        } else {
            push @sockenv, "$hostport=" . $sock->fileno;
        }
        push @sock, $sock;
    }
    my $path_remove_guard = Server::Starter::Guard->new(
        sub {
            -S $_ and unlink $_
                for @$paths;
        },
    );
    for my $path (@$paths) {
        if (-S $path) {
            warn "removing existing socket file:$path";
            unlink $path
                or die "failed to remove existing socket file:$path:$!";
        }
        unlink $path;
        my $saved_umask = umask(0);
        my $sock = IO::Socket::UNIX->new(
            Listen => $opts->{backlog},
            Local  => $path,
        ) or die "failed to listen to file $path:$!";
        umask($saved_umask);
        fcntl($sock, F_SETFD, my $flags = '')
            or die "fcntl(F_SETFD, 0) failed:$!";
        push @sockenv, "$path=" . $sock->fileno;
        push @sock, $sock;
    }
    $ENV{SERVER_STARTER_PORT} = join ";", @sockenv;
    $ENV{SERVER_STARTER_GENERATION} = 0;

    # setup signal handlers
    _set_sighandler($_, sub {
        push @signals_received, $_[0];
    }) for (qw/INT TERM HUP ALRM/);
    $SIG{PIPE} = 'IGNORE';

    # setup status monitor
    my ($current_worker, %old_workers, $last_restart_time);
    my $update_status = $opts->{status_file}
        ? sub {
            my $tmpfn = "$opts->{status_file}.$$";
            open my $tmpfh, '>', $tmpfn
                or die "failed to create temporary file:$tmpfn:$!";
            $status_file_created = 1;
            my %gen_pid = (
                ($current_worker
                 ? ($ENV{SERVER_STARTER_GENERATION} => $current_worker)
                 : ()),
                map { $old_workers{$_} => $_ } keys %old_workers,
            );
            print $tmpfh "$_:$gen_pid{$_}\n"
                for sort keys %gen_pid;
            close $tmpfh;
            rename $tmpfn, $opts->{status_file}
                or die "failed to rename $tmpfn to $opts->{status_file}:$!";
        } : sub {
        };

    # now that setup is complete, redirect outputs to the log file (if specified)
    if ($logfh) {
        STDOUT->flush;
        STDERR->flush;
        open STDOUT, '>&=', $logfh
            or die "failed to dup STDOUT to file: $!";
        open STDERR, '>&=', $logfh
            or die "failed to dup STDERR to file: $!";
        close $logfh;
        undef $logfh;
    }

    # daemonize
    if ($opts->{daemonize}) {
        my $pid = fork;
        die "fork failed:$!"
            unless defined $pid;
        if ($pid != 0) {
            $path_remove_guard->dismiss;
            exit 0;
        }
        # in child process
        POSIX::setsid();
        $pid = fork;
        die "fork failed:$!"
            unless defined $pid;
        if ($pid != 0) {
            $path_remove_guard->dismiss;
            exit 0;
        }
        # do not close STDIN if `--port=n=0`.
        unless (grep /=0$/, @sockenv) {
            close STDIN;
            open STDIN, '<', '/dev/null'
                or die "reopen failed: $!";
        }
    }

    # open pid file
    my $pid_file_guard = sub {
        return unless $opts->{pid_file};
        open my $fh, '>', $opts->{pid_file}
            or die "failed to open file:$opts->{pid_file}: $!";
        flock($fh, LOCK_EX)
            or die "flock failed($opts->{pid_file}): $!";
        print $fh "$$\n";
        $fh->flush();
        return Server::Starter::Guard->new(
            sub {
                unlink $opts->{pid_file}
                    or warn "failed to unlink file:$opts->{pid_file}:$!";
                close $fh;
            },
        );
    }->();

    # setup the start_worker function
    my $start_worker = sub {
        my $pid;
        while (1) {
            $ENV{SERVER_STARTER_GENERATION}++;
            $pid = fork;
            die "fork(2) failed:$!"
                unless defined $pid;
            if ($pid == 0) {
                my @args = @{$opts->{exec}};
                # child process
                if (defined $opts->{dir}) {
                    chdir $opts->{dir} or die "failed to chdir:$opts->{dir}:$!";
                }
                { exec { $args[0] } @args };
                print STDERR "failed to exec $args[0]$!";
                exit(255);
            }
            print STDERR "starting new worker $pid\n";
            sleep $opts->{interval};
            if ((grep { $_ ne 'HUP' } @signals_received)
                    || waitpid($pid, WNOHANG) <= 0) {
                last;
            }
            print STDERR "new worker $pid seems to have failed to start, exit status:$?\n";
        }
        # ready, update the environment
        $current_worker = $pid;
        $last_restart_time = time;
        $update_status->();
    };

    # setup the wait function
    my $wait = sub {
        my $block = @signals_received == 0;
        my @r;
        if ($block && $ENV{ENABLE_AUTO_RESTART}) {
            alarm(1);
            @r = _wait3($block);
            alarm(0);
        } else {
            @r = _wait3($block);
        }
        return @r;
    };

    # setup the cleanup function
    my $cleanup = sub {
        my $sig = shift;
        my $term_signal = $sig eq 'TERM' ? $opts->{signal_on_term} : 'TERM';
        $old_workers{$current_worker} = $ENV{SERVER_STARTER_GENERATION};
        undef $current_worker;
        print STDERR "received $sig, sending $term_signal to all workers:",
            join(',', sort keys %old_workers), "\n";
        kill $term_signal, $_
            for sort keys %old_workers;
        while (%old_workers) {
            if (my @r = _wait3(1)) {
                my ($died_worker, $status) = @r;
                print STDERR "worker $died_worker died, status:$status\n";
                delete $old_workers{$died_worker};
                $update_status->();
            }
        }
        print STDERR "exiting\n";
    };

    # the main loop
    $start_worker->();
    while (1) {
        # wait for next signal (or when auto-restart becomes necessary)
        my @r = $wait->();
        # reload env if necessary
        my %loaded_env = _reload_env();
        my @loaded_env_keys = keys %loaded_env;
        local @ENV{@loaded_env_keys} = map { $loaded_env{$_} } (@loaded_env_keys);
        $ENV{AUTO_RESTART_INTERVAL} ||= 360
            if $ENV{ENABLE_AUTO_RESTART};
        # restart if worker died
        if (@r) {
            my ($died_worker, $status) = @r;
            if ($died_worker == $current_worker) {
                print STDERR "worker $died_worker died unexpectedly with status:$status, restarting\n";
                $start_worker->();
            } else {
                print STDERR "old worker $died_worker died, status:$status\n";
                delete $old_workers{$died_worker};
                $update_status->();
            }
        }
        # handle signals
        my $restart;
        while (@signals_received) {
            my $sig = shift @signals_received;
            if ($sig eq 'HUP') {
                print STDERR "received HUP, spawning a new worker\n";
                $restart = 1;
                last;
            } elsif ($sig eq 'ALRM') {
                # skip
            } else {
                return $cleanup->($sig);
            }
        }
        if (! $restart && $ENV{ENABLE_AUTO_RESTART}) {
            my $auto_restart_interval = $ENV{AUTO_RESTART_INTERVAL};
            my $elapsed_since_restart = time - $last_restart_time;
            if ($elapsed_since_restart >= $auto_restart_interval && ! %old_workers) {
                print STDERR "autorestart triggered (interval=$auto_restart_interval)\n";
                $restart = 1;
            } elsif ($elapsed_since_restart >= $auto_restart_interval * 2) {
                print STDERR "autorestart triggered (forced, interval=$auto_restart_interval)\n";
                $restart = 1;
            }
        }
        # restart if requested
        if ($restart) {
            $old_workers{$current_worker} = $ENV{SERVER_STARTER_GENERATION};
            $start_worker->();
            print STDERR "new worker is now running, sending $opts->{signal_on_hup} to old workers:";
            if (%old_workers) {
                print STDERR join(',', sort keys %old_workers), "\n";
            } else {
                print STDERR "none\n";
            }
            my $kill_old_delay = defined $ENV{KILL_OLD_DELAY} ? $ENV{KILL_OLD_DELAY} : $ENV{ENABLE_AUTO_RESTART} ? 5 : 0;
            if ($kill_old_delay != 0) {
                print STDERR "sleeping $kill_old_delay secs before killing old workers\n";
                while ($kill_old_delay > 0) {
                    $kill_old_delay -= sleep $kill_old_delay || 1;
                }
            }
            print STDERR "killing old workers\n";
            kill $opts->{signal_on_hup}, $_
                for sort keys %old_workers;
        }
    }

    die "unreachable";
}

sub restart_server {
    my $opts = {
        (@_ == 1 ? @$_[0] : @_),
    };
    die "--restart option requires --pid-file and --status-file to be set as well\n"
        unless $opts->{pid_file} && $opts->{status_file};

    # get pid
    my $pid = do {
        open my $fh, '<', $opts->{pid_file}
            or die "failed to open file:$opts->{pid_file}:$!";
        my $line = <$fh>;
        chomp $line;
        $line;
    };

    # function that returns a list of active generations in sorted order
    my $get_generations = sub {
        open my $fh, '<', $opts->{status_file}
            or die "failed to open file:$opts->{status_file}:$!";
        my %gen;
        while (my $line = <$fh>) {
            if ($line =~ /^(\d+):/) {
                $gen{$1} = 1;
            }
        }
        sort { $a <=> $b } keys %gen;
    };

    # wait for this generation
    my $wait_for = do {
        my @gens = $get_generations->()
            or die "no active process found in the status file";
        pop(@gens) + 1;
    };

    # send HUP
    kill 'HUP', $pid
        or die "failed to send SIGHUP to the server process:$!";

    # wait for the generation
    while (1) {
        my @gens = $get_generations->();
        last if scalar(@gens) == 1 && $gens[0] == $wait_for;
        sleep 1;
    }
}

sub stop_server {
    my $opts = {
        (@_ == 1 ? @$_[0] : @_),
    };
    die "--stop option requires --pid-file to be set as well\n"
        unless $opts->{pid_file};

    # get pid
    open my $fh, '+<', $opts->{pid_file}
        or die "failed to open file:$opts->{pid_file}:$!";
    my $pid = do {
        my $line = <$fh>;
        chomp $line;
        $line;
    };

    print STDERR "stop_server (pid:$$) stopping now (pid:$pid)...\n";

    # send TERM
    kill 'TERM', $pid
        or die "failed to send SIGTERM to the server process:$!";

    # wait process
    flock($fh, LOCK_EX)
        or die "flock failed($opts->{pid_file}): $!";
    close $fh;
}

sub server_ports {
    die "no environment variable SERVER_STARTER_PORT. Did you start the process using server_starter?",
        unless $ENV{SERVER_STARTER_PORT};
    my %ports = map {
        +(split /=/, $_, 2)
    } split /;/, $ENV{SERVER_STARTER_PORT};
    \%ports;
}

sub _reload_env {
    my $dn = $ENV{ENVDIR};
    return if !defined $dn or !-d $dn;
    my $d;
    opendir($d, $dn) or return;
    my %env;
    while (my $n = readdir($d)) {
        next if $n =~ /^\./;
        open my $fh, '<', "$dn/$n" or next;
        chomp(my $v = <$fh>);
        $env{$n} = $v if defined $v;
    }
    return %env;
}

our $sighandler_should_die;
my $sighandler_got_sig;

sub _set_sighandler {
    my ($sig, $proc) = @_;
    $SIG{$sig} = sub {
        $proc->(@_);
        $sighandler_got_sig = 1;
        die "got signal"
            if $sighandler_should_die;
    };
}

sub _wait3 {
    my $block = shift;
    my $pid = -1;
    if ($block) {
        local $@;
        eval {
            $sighandler_got_sig = 0;
            local $sighandler_should_die = 1;
            die "exit from eval"
                if $sighandler_got_sig;
            $pid = wait();
        };
        if ($pid == -1 && $@) {
            $! = Errno::EINTR;
        }
    } else {
        $pid = waitpid(-1, WNOHANG);
    }
    return $pid > 0 ? ($pid, $?) : ();
}

1;
__END__