# Copyright (c) 2008-2012 Zmanda, Inc.  All Rights Reserved.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License version 2 as published
# by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
#
# Contact information: Zmanda Inc., 465 S. Mathilda Ave., Suite 300
# Sunnyvale, CA 94085, USA, or: http://www.zmanda.com

package Amanda::Process;

use strict;
use warnings;
use Carp;
use POSIX ();
use Exporter;
use vars qw( @ISA @EXPORT_OK );
use File::Basename;
use Amanda::Constants;
@ISA = qw( Exporter );

=head1 NAME

Amanda::Process -- interface to process

=head1 SYNOPSIS

  use Amanda::Process;

  Amanda::Process::load_ps_table();

  Amanda::Process::scan_log($logfile);

  Amanda::Process::add_child();

  Amanda::Process::set_master_process(@pname);

  Amanda::Process::set_master($pname, $pid);

  Amanda::Process::kill_process($signal);

  my $count = Amanda::Process::process_running();

  my $count = Amanda::Process::count_process();

  my $alive = Amanda::Process::process_alive($pid, $pname);

=head1 INTERFACE

This module provides an object-oriented interface to track process used by
amanda.

my $Amanda_process = Amanda::Process->new($verbose);

=over

=item load_ps_table

  $Amanda_process->load_ps_table();

Load a table of all processes in the system.

=item scan_log

  $Amanda_process->scan_log($logfile);

Parse all 'pid' and 'pid-done' lines of the logfile.

=item add_child

  $Amanda_process->add_child();

Add all children of already known amanda processes.

=item set_master_process

  $Amanda_process->set_master_process($arg, @pname);

Search the process table to find a process in @pname and make it the master, $arg must be an argument of the process.

=item set_master

  $Amanda_process->set_master($pname, $pid);

Set $Amanda_process->{master_pname} and $Amanda_process->{master_pid}.

=item kill_process

  $Amanda_process->kill_process($signal);

Send the $signal to all amanda processes.

=item process_running

  my $count = $Amanda_process->process_running();

Return the number of amanda process alive.

=item count_process

  my $count = $Amanda_process->count_process();

Return the number of amanda process in the table.

=item process_alive

  my $alive = Amanda::Process::process_alive($pid, $pname);

Return 0 if the process is not alive.
Return 1 if the process is still alive.

=back

=cut

sub new {
    my $class = shift;
    my ($verbose) = shift;

    my $self = {
	verbose => $verbose,
	master_name => "",
	master_pid => "",
	pids => {},
	pstable => {},
	ppid => {},
    };
    bless ($self, $class);
    return $self;
}

# Get information about the current set of processes, using ps -e
# and ps -ef.
#
# Side effects:
# - sets %pstable to a map (pid => process name) of all running
#   processes
# - sets %ppid to a map (pid -> parent pid) of all running
#   processes' parent pids
#
sub load_ps_table() {
    my $self = shift;
    $self->{pstable} = {};
    $self->{ppid} = ();
    my $ps_argument = $Amanda::Constants::PS_ARGUMENT;
    if ($ps_argument eq "CYGWIN") {
	open(PSTABLE, "-|", "ps -f") || die("ps -f: $!");
	my $psline = <PSTABLE>; #header line
	while($psline = <PSTABLE>) {
	    chomp $psline;
	    my @psline = split " ", $psline;
	    my $pid = $psline[1];
	    my $ppid = $psline[2];
	    my $stime = $psline[4];
	    my $pname;
	    if ($stime =~ /:/) {  # 10:32:44
		$pname = basename($psline[5])
	    } else {              # May 22
		$pname = basename($psline[6])
	    }
	    $self->{pstable}->{$pid} = $pname;
	    $self->{ppid}->{$pid} = $ppid;
	}
	close(PSTABLE);
    } else {
	open(PSTABLE, "-|", "$Amanda::Constants::PS $ps_argument")
	    or die("$Amanda::Constants::PS $ps_argument: $!");
	my $psline = <PSTABLE>; #header line
	while($psline = <PSTABLE>) {
	    chomp $psline;
	    my ($pid, $ppid, $pname, $arg1, $arg2) = split " ", $psline;
	    $pname = basename($pname);
	    if ($pname =~ /^perl/ && defined $arg1) {
		if ($arg1 !~ /^\-/) {
		    $pname = $arg1;
		} elsif (defined $arg2) {
		    if ($arg2 !~ /^\-/) {
			$pname = $arg2;
		    }
		}
		$pname = basename($pname);
	    }
	    $self->{pstable}->{$pid} = $pname;
	    $self->{ppid}->{$pid} = $ppid;
	}
	close(PSTABLE);
    }
}

# Scan a logfile for processes that should still be running: processes
# having an "INFO foo bar pid 1234" line in the log, but no corresponding
# "INFO pid-done 1234", and only if pid 1234 has the correct process
# name.
#
# Prerequisites:
#  %pstable must be set up (use load_ps_table)
#
# Side effects:
# - sets %pids to a map (pid => process name) of all still-running
#   Amanda processes
# - sets $master_pname to the top-level process for this run (e.g.,
#   amdump, amflush)
# - sets $master_pid to the pid of $master_pname
#
# @param $logfile: the logfile to scan
#
sub scan_log($) {
    my $self = shift;
    my $logfile = shift;
    my $first = 1;
    my($line);

    open(LOGFILE, "<", $logfile) || die("$logfile: $!");
    while($line = <LOGFILE>) {
	if ($line =~ /^INFO .* (.*) pid (\d*)$/) {
	    my ($pname, $pid) = ($1, $2);
	    if ($first == 1) {
		$self->{master_pname} = $pname;
		$self->{master_pid} = $pid;
		$first = 0;
	    }
	    if (defined $self->{pstable}->{$pid} && $pname eq $self->{pstable}->{$pid}) {
		$self->{pids}->{$pid} = $pname;
	    } elsif (defined $self->{pstable}->{$pid} && $self->{pstable}->{$pid} =~ /^perl/) {
		# We can get 'perl' for a perl script.
		$self->{pids}->{$pid} = $pname;
	    } elsif (defined $self->{pstable}->{$pid}) {
		print "pid $pid doesn't match: ", $pname, " != ", $self->{pstable}->{$pid}, "\n" if $self->{verbose};
	    }
	} elsif ($line =~ /^INFO .* pid-done (\d*)$/) {
	    my $pid = $1;
	    print "pid $pid is done\n" if $self->{verbose};
	    delete $self->{pids}->{$pid};
	}
    }
    close(LOGFILE);

    # log unexpected dead process
    if ($self->{verbose}) {
	for my $pid (keys %{$self->{pids}}) {
	    if (!defined $self->{pstable}->{$pid}) {
		print "pid $pid is dead\n";
	    }
	}
    }
}

# Recursive function to add all child processes of $pid to %amprocess.
#
# Prerequisites:
# - %ppid must be set (load_ps_table)
#
# Side-effects:
# - adds all child processes of $pid to %amprocess
#
# @param $pid: the process to start at
#
sub add_child_pid($);
sub add_child_pid($) {
    my $self = shift;
    my $pid = shift;
    foreach my $cpid (keys %{$self->{ppid}}) {
	my $ppid = $self->{ppid}->{$cpid};
	if ($pid == $ppid) {
	    if (!defined $self->{amprocess}->{$cpid}) {
		$self->{amprocess}->{$cpid} = $cpid;
		$self->add_child_pid($cpid);
	    }
	}
    }
}

# Find all children of all amanda processes, as determined by traversing
# the process graph (via %ppid).
#
# Prerequisites:
# - %ppid must be set (load_ps_table)
# - %pids must be set (scan_log)
#
# Side-effects:
# - sets %amprocess to a map (pid => pid) of all amanda processes, including
#   children
#
sub add_child() {
    my $self = shift;
    foreach my $pid (keys %{$self->{pids}}) {
	if (defined $pid) {
	    $self->{amprocess}->{$pid} = $pid;
	}
    }

    foreach my $pid (keys %{$self->{pids}}) {
	$self->add_child_pid($pid);
    }
}

# Set master_pname and master_pid.
#
# Side-effects:
# - sets $self->{master_pname} and $self->{master_pid}.
#
sub set_master_process {
    my $self = shift;
    my $arg = shift;
    my @pname = @_;

    my $ps_argument_args = $Amanda::Constants::PS_ARGUMENT_ARGS;
    for my $pname (@pname) {
	my $pid;

	if ($ps_argument_args eq "CYGWIN") {
	    $pid = `ps -ef|grep -w ${pname}|grep -w ${arg}| grep -v grep | awk '{print \$2}'`;
	} else {
	    $pid = `$Amanda::Constants::PS $ps_argument_args|grep -w ${pname}|grep -w ${arg}| grep -v grep | awk '{print \$1}'`;
	}
	chomp $pid;
	if ($pid ne "") {
	    $self->set_master($pname, $pid);
	}
    }
}

# Set master_pname and master_pid.
#
# Side-effects:
# - sets $self->{master_pname} and $self->{master_pid}.
#
sub set_master($$) {
    my $self = shift;
    my $pname = shift;
    my $pid = shift;

    $self->{master_pname} = $pname;
    $self->{master_pid} = $pid;
    $self->{pids}->{$pid} = $pname;
}
# Send a signal to all amanda process
#
# Side-effects:
# - All amanda process receive the signal.
#
# Prerequisites:
# - %amprocess must be set (add_child)
#
# @param $signal: the signal to send
#
sub kill_process($) {
    my $self = shift;
    my $signal = shift;

    foreach my $pid (keys %{$self->{amprocess}}) {
	print "Sendding $signal signal to pid $pid\n" if $self->{verbose};
	kill $signal, $pid;
    }
}

# Count the number of processes in %amprocess that are still running.  This
# re-runs 'ps -e' every time, so calling it repeatedly may result in a
# decreasing count.
#
# Prerequisites:
# - %amprocess must be set (add_child)
#
# @returns: number of pids in %amprocess that are still alive
sub process_running() {
    my $self = shift;

    $self->load_ps_table();
    my $count = 0;
    foreach my $pid (keys %{$self->{amprocess}}) {
	if (defined $self->{pstable}->{$pid}) {
	    $count++;
	}
    }

    return $count;
}

# Count the number of processes in %amprocess.
#
# Prerequisites:
# - %amprocess must be set (add_child)
#
# @returns: number of pids in %amprocess.
sub count_process() {
    my $self = shift;

    return scalar keys( %{$self->{amprocess}} );
}

# return if a process is alive.  If $pname is provided,
# only returns 1 if the name matches.
#
# Prerequisites:
# - %pstable must be set (load_ps_table)
#
# @param $pid: the pid of the process
# @param $pname: the name of the process (optional)
#
# @returns: 1 if process is alive
#           '' if process is dead

sub process_alive() {
    my $self = shift;
    my $pid = shift;
    my $pname = shift;

    if (defined $pname && defined $self->{pstable}->{$pid}) {
	return $self->{pstable}->{$pid} eq $pname;
    } else {
	return defined $self->{pstable}->{$pid};
    }
}

1;
