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=head1 NAME |
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AnyEvent::Watchdog - generic watchdog/program restarter |
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=head1 SYNOPSIS |
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# MUST be use'd as the very first thing in the main program, |
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# as it clones/forks the program before it returns. |
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use AnyEvent::Watchdog; |
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|
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=head1 DESCRIPTION |
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|
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This module implements a watchdog that can repeatedly fork the program and |
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thus effectively restart it - as soon as the module is use'd, it will fork |
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the program (if possible) and continue to run it normally in the child, |
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while the parent becomes a supervisor. |
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|
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The child can then ask the supervisor to restart itself instead of |
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exiting, or ask the supervisor to restart it gracefully or forcefully. |
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|
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B<NOTE:> This module B<< I<MUST> >> be used as the first thing in the main |
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program. It will cause weird effects when used from another module, as |
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perl does not expect to be forked inside C<BEGIN> blocks. |
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|
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=head1 RECIPES |
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|
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Use AnyEvent::Watchdog solely as a convenient on-demand-restarter: |
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|
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use AnyEvent::Watchdog; |
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|
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# and whenever you want to restart (e.g. to upgrade code): |
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use AnyEvent::Watchdog::Util; |
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AnyEvent::Watchdog::Util::restart; |
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|
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Use AnyEvent::Watchdog to kill the program and exit when the event loop |
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fails to run for more than two minutes: |
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|
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use AnyEvent::Watchdog autorestart => 1, heartbeat => 120; |
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|
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Use AnyEvent::Watchdog to automatically kill (but not restart) the program when it fails |
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to handle events for longer than 5 minutes: |
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|
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use AnyEvent::Watchdog heartbeat => 300; |
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|
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=head1 VARIABLES/FUNCTIONS |
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This module is controlled via the L<AnyEvent::Watchdog::Util> module: |
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use AnyEvent::Watchdog::Util; |
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|
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# attempt restart |
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AnyEvent::Watchdog::Util::restart; |
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|
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# check if it is running |
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AnyEvent::Watchdog::Util::enabled |
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or croak "not running under watchdog!"; |
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|
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=cut |
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|
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package AnyEvent::Watchdog; |
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|
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# load modules we will use later anyways |
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use common::sense; |
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|
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use Carp (); |
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|
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our $VERSION = '1.02'; |
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|
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our $PID; # child pid |
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our $ENABLED = 0; # also version |
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our $AUTORESTART; # actually exit |
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our ($P, $C); |
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|
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sub poll($) { |
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(vec my $v, fileno $P, 1) = 1; |
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CORE::select $v, undef, undef, $_[0] |
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} |
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|
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sub server { |
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my $expected;# do we expect a program exit? |
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my $heartbeat; |
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|
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$AUTORESTART = 0; |
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|
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local $SIG{HUP} = 'IGNORE'; |
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local $SIG{INT} = 'IGNORE'; |
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local $SIG{TERM} = 'IGNORE'; |
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|
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while () { |
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if ($heartbeat) { |
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unless (poll $heartbeat) { |
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$expected = 1; |
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warn "AnyEvent::Watchdog: heartbeat failed. killing.\n"; |
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kill 9, $PID; |
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last; |
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} |
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} |
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|
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sysread $P, my $cmd, 1 |
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or last; |
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|
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if ($cmd eq chr 0) { |
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$AUTORESTART = 0; |
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|
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} elsif ($cmd eq chr 1) { |
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$AUTORESTART = 1; |
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|
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} elsif ($cmd eq chr 2) { |
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sysread $P, my $timeout, 1 |
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or last; |
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$timeout = ord $timeout; |
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|
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unless (poll $timeout) { |
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warn "AnyEvent::Watchdog: program attempted restart, but failed to do so within $timeout seconds. killing.\n"; |
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kill 9, $PID; |
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} |
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|
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if (sysread $P, my $dummy, 1) { |
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warn "AnyEvent::Watchdog: unexpected program output. killing.\n"; |
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kill 9, $PID; |
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} |
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$expected = 1; |
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last; |
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|
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} elsif ($cmd eq chr 3) { |
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sysread $P, my $interval, 1 |
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or last; |
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$heartbeat = ord $interval; |
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|
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} elsif ($cmd eq chr 4) { |
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# heartbeat |
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# TODO: should only reset heartbeat timeout with \005 |
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|
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} else { |
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warn "AnyEvent::Watchdog: unexpected program output. killing.\n"; |
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kill 9, $PID; |
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last; |
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} |
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} |
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waitpid $PID, 0; |
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require POSIX; |
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|
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my $termsig = POSIX::WIFSIGNALED ($?) && POSIX::WTERMSIG ($?); |
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|
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if ($termsig == POSIX::SIGINT () || $termsig == POSIX::SIGTERM ()) { |
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$AUTORESTART = 0; |
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$expected = 1; |
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} |
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unless ($expected) { |
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warn "AnyEvent::Watchdog: program exited unexpectedly with status $?.\n" |
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if $? >> 8; |
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} |
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if ($AUTORESTART) { |
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warn "AnyEvent::Watchdog: attempting automatic restart.\n"; |
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} else { |
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if ($termsig) { |
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$SIG{$_} = 'DEFAULT' for keys %SIG; |
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kill $termsig, $$; |
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POSIX::_exit (127); |
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} else { |
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POSIX::_exit ($? >> 8); |
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} |
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} |
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} |
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|
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our %SEEKPOS; |
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# due to bugs in perl, try to remember file offsets for all fds, and restore them later |
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# (the parser otherwise exhausts the input files) |
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|
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# this causes perlio to flush its handles internally, so |
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# seek offsets become correct. |
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exec "."; # toi toi toi |
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#{ |
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# local $SIG{CHLD} = 'DEFAULT'; |
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# my $pid = fork; |
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# |
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# if ($pid) { |
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# waitpid $pid, 0; |
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# } else { |
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# kill 9, $$; |
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# } |
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#} |
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|
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# now record "all" fd positions, assuming 1023 is more than enough. |
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for (0 .. 1023) { |
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open my $fh, "<&$_" or next; |
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$SEEKPOS{$_} = (sysseek $fh, 0, 1 or next); |
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} |
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|
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while () { |
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if ($^O =~ /mswin32/i) { |
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require AnyEvent::Util; |
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($P, $C) = AnyEvent::Util::portable_socketpair () |
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or Carp::croak "AnyEvent::Watchdog: unable to create restarter pipe: $!\n"; |
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} else { |
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require Socket; |
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socketpair $P, $C, Socket::AF_UNIX (), Socket::SOCK_STREAM (), 0 |
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or Carp::croak "AnyEvent::Watchdog: unable to create restarter pipe: $!\n"; |
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} |
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local $SIG{CHLD} = 'DEFAULT'; |
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$PID = fork; |
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unless (defined $PID) { |
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warn "AnyEvent::Watchdog: '$!', retrying in one second...\n"; |
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sleep 1; |
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} elsif ($PID) { |
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# parent code |
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close $C; |
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server; |
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} else { |
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# child code |
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$ENABLED = 1; # also version |
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|
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# restore seek offsets |
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while (my ($k, $v) = each %SEEKPOS) { |
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open my $fh, "<&$k" or next; |
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sysseek $fh, $v, 0; |
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} |
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# continue the program normally |
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close $P; |
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last; |
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} |
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} |
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|
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sub import { |
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shift; |
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|
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while (@_) { |
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my $k = shift; |
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require AnyEvent::Watchdog::Util; |
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|
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if ($k eq "autorestart") { |
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AnyEvent::Watchdog::Util::autorestart (! ! shift); |
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} elsif ($k eq "heartbeat") { |
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AnyEvent::Watchdog::Util::heartbeat (shift || 60); |
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} else { |
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Carp::croak "AnyEvent::Watchdog: '$_' is not a valid import argument"; |
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} |
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} |
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} |
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# used by AnyEvent::Watchdog::Util. |
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our $end; |
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END { $end && &$end } |
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=head1 SEE ALSO |
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|
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L<AnyEvent::Watchdog::Util>, L<AnyEvent>. |
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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=cut |
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1 |
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