1 package RRDp;
3 =head1 NAME
5 RRDp - Attach RRDtool from within a perl script via a set of pipes;
7 =head1 SYNOPSIS
9 use B<RRDp>
11 B<RRDp::start> I<path to RRDtool executable>
13 B<RRDp::cmd> I<rrdtool commandline>
15 $answer = B<RRD::read>
17 $status = B<RRD::end>
19 B<$RRDp::user>, B<$RRDp::sys>, B<$RRDp::real>, B<$RRDp::error_mode>, B<$RRDp::error>
21 =head1 DESCRIPTION
23 With this module you can safely communicate with the RRDtool.
25 After every B<RRDp::cmd> you have to issue an B<RRDp::read> command to get
26 B<RRDtool>s answer to your command. The answer is returned as a pointer,
27 in order to speed things up. If the last command did not return any
28 data, B<RRDp::read> will return an undefined variable.
30 If you import the PERFORMANCE variables into your namespace,
31 you can access RRDtool's internal performance measurements.
33 =over 8
35 =item use B<RRDp>
37 Load the RRDp::pipe module.
39 =item B<RRDp::start> I<path to RRDtool executable>
41 start RRDtool. The argument must be the path to the RRDtool executable
43 =item B<RRDp::cmd> I<rrdtool commandline>
45 pass commands on to RRDtool. check the RRDtool documentation for
46 more info on the RRDtool commands.
48 =item $answer = B<RRDp::read>
50 read RRDtool's response to your command. Note that the $answer variable will
51 only contain a pointer to the returned data. The reason for this is, that
52 RRDtool can potentially return quite excessive amounts of data
53 and we don't want to copy this around in memory. So when you want to
54 access the contents of $answer you have to use $$answer which dereferences
55 the variable.
57 =item $status = B<RRDp::end>
59 terminates RRDtool and returns RRDtool's status ...
61 =item B<$RRDp::user>, B<$RRDp::sys>, B<$RRDp::real>
63 these variables will contain totals of the user time, system time and
64 real time as seen by RRDtool. User time is the time RRDtool is
65 running, System time is the time spend in system calls and real time
66 is the total time RRDtool has been running.
68 The difference between user + system and real is the time spent
69 waiting for things like the hard disk and new input from the perl
70 script.
72 =item B<$RRDp::error_mode> and B<$RRDp::error>
74 If you set the variable $RRDp::error_mode to the value 'catch' before you run RRDp::read a potential
75 ERROR message will not cause the program to abort but will be returned in this variable. If no error
76 occurs the variable will be empty.
78 $RRDp::error_mode = 'catch';
79 RRDp::cmd qw(info file.rrd);
80 print $RRDp::error if $RRDp::error;
82 =back
85 =head1 EXAMPLE
87 use RRDp;
88 RRDp::start "/usr/local/bin/rrdtool";
89 RRDp::cmd qw(create demo.rrd --step 100
90 DS:in:GAUGE:100:U:U
91 RRA:AVERAGE:0.5:1:10);
92 $answer = RRDp::read;
93 print $$answer;
94 ($usertime,$systemtime,$realtime) = ($RRDp::user,$RRDp::sys,$RRDp::real);
96 =head1 SEE ALSO
98 For more information on how to use RRDtool, check the manpages.
100 =head1 AUTHOR
102 Tobias Oetiker <tobi@oetiker.ch>
104 =cut
105 #' this is to make cperl.el happy
107 use strict;
108 use Fcntl;
109 use Carp;
110 use IO::Handle;
111 use IPC::Open2;
112 use vars qw($Sequence $RRDpid $VERSION);
113 my $Sequence;
114 my $RRDpid;
116 # Prototypes
118 sub start ($);
119 sub cmd (@);
120 sub end ();
121 sub read ();
123 $VERSION=1.2025;
125 sub start ($){
126 croak "rrdtool is already running"
127 if defined $Sequence;
128 $Sequence = 'S';
129 my $rrdtool = shift @_;
130 $RRDpid = open2 \*RRDreadHand,\*RRDwriteHand, $rrdtool,"-"
131 or croak "Can't Start rrdtool: $!";
132 RRDwriteHand->autoflush(); #flush after every write
133 fcntl RRDreadHand, F_SETFL,O_NONBLOCK|O_NDELAY; #make readhandle NON BLOCKING
134 return $RRDpid;
135 }
138 sub read () {
139 croak "RRDp::read can only be called after RRDp::cmd"
140 unless $Sequence eq 'C';
141 $RRDp::error = undef;
142 $Sequence = 'R';
143 my $inmask = 0;
144 my $srbuf;
145 my $minibuf;
146 my $buffer;
147 my $nfound;
148 my $timeleft;
149 my $ERR = 0;
150 vec($inmask,fileno(RRDreadHand),1) = 1; # setup select mask for Reader
151 while (1) {
152 my $rout;
153 $nfound = select($rout=$inmask,undef,undef,2);
154 if ($nfound == 0 ) {
155 # here, we could do something sensible ...
156 next;
157 }
158 sysread(RRDreadHand,$srbuf,4096);
159 $minibuf .= $srbuf;
160 while ($minibuf =~ s|^(.+?)\n||s) {
161 my $line = $1;
162 # print $line,"\n";
163 $RRDp::error = undef;
164 if ($line =~ m|^ERROR|) {
165 $RRDp::error_mode eq 'catch' ? $RRDp::error = $line : croak $line;
166 $ERR = 1;
167 }
168 elsif ($line =~ m|^OK u:([\d\.]+) s:([\d\.]+) r:([\d\.]+)|){
169 ($RRDp::sys,$RRDp::user,$RRDp::real)=($1,$2,$3);
170 return $ERR == 1 ? undef : \$buffer;
171 } else {
172 $buffer .= $line. "\n";
173 }
174 }
175 }
176 }
178 sub cmd (@){
179 croak "RRDp::cmd can only be called after RRDp::read or RRDp::start"
180 unless $Sequence eq 'R' or $Sequence eq 'S';
181 $Sequence = 'C';
182 my $cmd = join " ", @_;
183 if ($Sequence ne 'S') {
184 }
185 $cmd =~ s/\n/ /gs;
186 $cmd =~ s/\s/ /gs;
187 print RRDwriteHand "$cmd\n";
188 }
190 sub end (){
191 croak "RRDp::end can only be called after RRDp::start"
192 unless $Sequence;
193 close RRDwriteHand;
194 close RRDreadHand;
195 $Sequence = undef;
196 waitpid $RRDpid,0;
197 return $?
198 }
200 1;