#!/usr/bin/perl
# -*- perl -*-
#
# proc_ - Munin plugin to for Process information
# Copyright (C) 2009  Redpill Linpro AS
# Copyright (C) 2010  Trygve Vea
#
# Author: Kristian Lyngstøl <kristian@redpill-linpro.com>
# Author: Trygve Vea <tv@redpill-linpro.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

=head1 NAME

proc_ - Munin plugin to monitor various aspects of named processes

=head1 APPLICABLE SYSTEMS

Processes running under Linux

=head1 CONFIGURATION

The plugin needs to be able to parse the /proc-filesystem.

The configuration section shows the defaults
  [proc_*]
     env.procname init
     env.category Process Info

env.procname defines the processname as seen inside the parenthesis of the
second column in /proc/pid/stat. If you don't get the data you expect, you
can check if the value is what you expect here.

env.category is used to override the default category the plugin will show
up in.

=head1 INTERPRETATION

Each graph uses data from the proc filesystem.

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf suggest

=head1 VERSION

 $Id$

=head1 BUGS

The CPU usage graph will be misleading in an event where you have multiple
processes monitored, but less then all of them is restarted (or exits). This
is due to the nature of counters, and I need to track state of individual
processes to do this in a reliable way. It's on my TODO.

=head1 PATCHES-TO

Dunno.

=head1 AUTHOR

Kristian Lyngstøl <kristian@redpill-linpro.com>
Trygve Vea <tv@redpill-linpro.com>

=head1 THANKS

Thanks to Kristian Lyngstøl, I stole most of the code in this plugin from his
varnish_-plugin, which is a really nice outline of how a wildcardplugin should
look like.

=head1 LICENSE

GPLv2

=cut

use strict;

# Set to 1 to enable output when a variable is defined in a graph but
# omitted because it doesn't exist in varnishstat.
my $DEBUG = 0;

# Set to 1 to ignore 'DEBUG' and suggest all available aspects.
my $FULL_SUGGEST = 0;

# You should set the env-var "procname" to filter processes of their name.
# This will default to "init" unless you specify anything else.
my $procname = exists $ENV{'procname'} ? $ENV{'procname'} : "init";

# You can set the env-var "procargs" to filter processes of their running
# arguments.
my $args = exists $ENV{'procargs'} ? $ENV{'procargs'} : undef;

# You can set the env-var "category" to override the default category.
my $category = exists $ENV{'category'} ? $ENV{'category'} : "Process info";

my %procstats = ();
my $self;


# Parameters that can be defined on top level of a graph. Config will print
# them as "graph_$foo $value\n"
my @graph_parameters = ('title','total','order','scale','vlabel','args');

# Parameters that can be defined on a value-to-value basis and will be
# blindly passed to config. Printed as "$fieldname.$param $value\n".
my @field_parameters = ('graph', 'min', 'max', 'draw', 'cdef', 'warning',
                        'colour', 'info', 'type');
# Data structure that defines all possible graphs (aspects) and how they
# are to be plotted. Every top-level entry is a graph/aspect. Each top-level graph
# MUST have title set and 'values'.
#
# Graphs with 'DEBUG' set to anything is omitted from 'suggest'.
#
# 'rpn' on values allows easy access to graphs consisting of multiple
# values from procstats. (Reverse polish notation). The RPN
# implementation only accepts +-*/ and procstats-values.
#
# Any value left undefined will be left up to Munin to define/ignore/yell
# about.
#
# See munin documentation or rrdgraph/rrdtool for more information.
my %ASPECTS = (
    'cpu' => {
        'title' => "CPU Usage: $procname",
        'order' => 'stime utime',
        'args' => '-l 0',
        'values' => {
            'utime' => {
                'type' => 'COUNTER',
                'label' => 'User time',
                'draw' => 'STACK'
            },
            'stime' => {
                'type' => 'COUNTER',
                'label' => 'System time',
                'draw' => 'AREA'
            }
        }
    },
    'ctxt_switches' => {
        'title' => "Context switches: $procname",
        'values' => {
            'voluntary_ctxt_switches' => {
                'type' => 'COUNTER',
                'label' => 'Voluntary Context Switches'
            },
            'nonvoluntary_ctxt_switches' => {
                'type' => 'COUNTER',
                'label' => 'Nonvoluntary Context Switches'
            }
        }
    },
    'threads' => {
        'title' => "Thread count: $procname",
        'values' => {
            'threads' => {
                'type' => 'GAUGE',
                'label' => 'Number of threads'
            }
        }
    },
    'processes' => {
        'title' => "Process count: $procname",
        'values' => {
            'processes' => {
                'type' => 'GAUGE',
                'label' => 'Number of processes'
            }
        }
    },
    'memory' => {
        'title' => "Memory usage: $procname",
        'vlabel' => 'bytes',
        'order' => 'VmStk VmExe VmLib VmData VmRSS VmSize',
        'args' => '-l 0',
        'values' => {
            'VmSize' => {
                'type' => 'GAUGE',
                'label' => 'Virtual Memory Size'
            },
            'VmRSS' => {
                'type' => 'GAUGE',
                'label' => 'Resident set size',
            },
            'VmData' => {
                'type' => 'GAUGE',
                'label' => 'Data size',
            },
            'VmStk' => {
                'type' => 'GAUGE',
                'label' => 'Stack size',
            },
            'VmExe' => {
                'type' => 'GAUGE',
                'label' => 'Segments size',
            },
            'VmLib' => {
                'type' => 'GAUGE',
                'label' => 'Shared library size',
            }
        }
    }
);

# Populate %procstats with values.
sub populate_stats
{
    foreach my $line(`grep -h \\\($procname\\\) /proc/*/stat`) {
        if ($line =~ /^(\d+) \((.*)\) (.) \-?\d+ \-?\d+ \-?\d+ \-?\d+ \-?\d+ \d+ \d+ \d+ \d+ \d+ (\d+) (\d+) \d+ \d+ \d+ \d+ (\d+) \-?\d+ \d+ (\d+) (\d+)/) {
            $procstats{"utime"} += $4;
            $procstats{"stime"} += $5;
            $procstats{"threads"} += $6;
            $procstats{"vsize"} += $7;
            $procstats{"rss"} += $8;
            $procstats{"processes"} += 1;
            foreach my $line(`cat /proc/$1/status`){
                if ($line =~ /^Vm(.*):\s+(\d+) kB$/){
                    $procstats{"Vm$1"} += ($2*1024);
                }
                if ($line =~ /^(.*)_ctxt_switches:\s+(\d+)$/){
                    $procstats{"$1_ctxt_switches"} += $2;
                }
            }
        }
    }
}

# Bail-function.
sub usage
{
    if (@_ && "@_" ne "") {
        print STDERR "@_" . "\n\n";
    }
    print STDERR "Known arguments: suggest, config, autoconf.\n";
    print STDERR "Run with suggest to get a list of known aspects.\n";
    exit 1;
}

# Print 'yes' and exit true if it's reasonable to use this plugin.
# Otherwise exit with false and a human-readable reason.
sub autoconf
{
    print "no (Probably a yes, read about the plugin!)\n";
    exit 0;
}

# Suggest relevant aspects/values of $self.
# 'DEBUG'-graphs are excluded.
sub suggest
{
    foreach my $key (keys %ASPECTS) {
        if (defined($ASPECTS{$key}{'DEBUG'}) && $FULL_SUGGEST != 1) {
            next;
        }
        print "$key\n";
    }
}

# Print the value of a two-dimensional hash if it exist.
# Returns false if non-existent.
#
# Output is formatted for plugins if arg4 is blank, otherwise arg4 is used
# as the title/name of the field (ie: arg4=graph_title).
sub print_if_exist
{
    my %values = %{$_[0]};
    my $value = $_[1];
    my $field = $_[2];
    my $title = "$value.$field";
    if (defined($_[3])) {
        $title = $_[3];
    }
    if (defined($values{$value}{$field})) {
        print "$title $values{$value}{$field}\n";
    } else {
        return 0;
    }
}

# Walk through the relevant aspect and print all top-level configuration
# values and value-definitions.
sub get_config
{
    my $graph = $_[0];

    # Need to double-check since set_aspect only checks this if there
    # is no argument (suggest/autoconf doesn't require a valid aspect)
    if (!defined($ASPECTS{$graph})) {
        usage "No such aspect";
    }
    my %values = %{$ASPECTS{$graph}{'values'}};

    print "graph_category $category\n";
    foreach my $field (@graph_parameters) {
        print_if_exist(\%ASPECTS,$graph,$field,"graph_$field");
    }

    foreach my $value (keys %values) {
        # Need either RPN definition or a procstats value.
        if (!defined($procstats{$value}) &&
            !defined($values{$value}{'rpn'})) {
                if ($DEBUG) {
                    print "ERROR: $value not part of procstats.\n"
                }
                next;
        }

        if (!print_if_exist(\%values,$value,'label')) {
            print "$value.label ".$ASPECTS{$self}{'values'}{$value}{'label'}."\n";
        }
        foreach my $field (@field_parameters) {
            print_if_exist(\%values,$value,$field);
        }
    }
}

# Read and verify the aspect ($self).
sub set_aspect
{
    $self = $0;
    $self =~ s/^.*proc_//;
    if (!defined($ASPECTS{$self}) && @ARGV == 0) {
        usage "No such aspect";
    }
}

# Handle arguments (config, autoconf, suggest)
# Populate stats for config is necessary, but we want to avoid it for
# autoconf as it would generate a nasty error.
sub check_args
{
    if (@ARGV && $ARGV[0] eq '') {
        shift @ARGV;
    }
    if (@ARGV == 1) {
        if ($ARGV[0] eq "config") {
            populate_stats;
            get_config($self);
            exit 0;
        } elsif ($ARGV[0] eq "autoconf") {
            autoconf($self);
            exit 0;
        } elsif ($ARGV[0] eq "suggest") {
#            suggest;
            exit 0;
        }
        usage "Unknown argument";
    }
}

# Braindead RPN: +,-,/,* will pop two items from @stack, and perform
# the relevant operation on the items. If the item in the array isn't one
# of the 4 basic math operations, a value from procstats is pushed on to
# the stack. IE: 'client_req','client_conn','/' will leave the value of
# "client_req/client_conn" on the stack.
#
# If only one item is left on the stack, it is printed. Otherwise, an error
# message is printed.
sub rpn
{
    my @stack;
    my $left;
    my $right;
    foreach my $item (@{$_[0]}) {
        if ($item eq "+") {
            $right = pop(@stack);
            $left = pop(@stack);
            push(@stack,$left+$right);
        } elsif ($item eq "-") {
            $right = pop(@stack);
            $left = pop(@stack);
            push(@stack,$left-$right);
        } elsif ($item eq "/") {
            $right = pop(@stack);
            $left = pop(@stack);
            push(@stack,$left/$right);
        } elsif ($item eq "*") {
            $right = pop(@stack);
            $left = pop(@stack);
            push(@stack,$left*$right);
        } else {
            push(@stack,int($procstats{$item}));
        }
    }
    if (@stack > 1)
    {
        print STDERR "RPN error: Stack has more than one item left.\n";
        print STDERR "@stack\n";
        exit 255;
    }
    print "@stack";
    print "\n";
}

################################
# Execution starts here        #
################################

set_aspect;
check_args;
populate_stats;

# We only get here if we're supposed to.

# Walks through the relevant values and either prints the procstat, or
# if the 'rpn' variable is set, calls rpn() to execute ... the rpn.
foreach my $value (keys %{$ASPECTS{$self}{'values'}}) {
    if (defined($ASPECTS{$self}{'values'}{$value}{'rpn'})) {
        print "$value.value ";
        rpn($ASPECTS{$self}{'values'}{$value}{'rpn'});
    } else {
        print "$value.value ";
        if (!defined($procstats{$value})) {
            print "0\n";
            next;
        }
        print "$procstats{$value}\n";
    }
}