RRDs - Access rrdtool as a shared module
use RRDs; RRDs::error RRDs::last ... RRDs::info ... RRDs::create ... RRDs::update ... RRDs::graph ... RRDs::fetch ... RRDs::tune ... RRDs::times(start, end)
This module accesses rrdtool functionality directly from within perl. The arguments to the functions listed in the SYNOPSIS are explained in the regular rrdtool documentation. The commandline call
rrdtool update mydemo.rrd --template in:out N:12:13
gets turned into
RRDs::update ("mydemo.rrd", "--template", "in:out", "N:12:13");
Note that
--template=in:out
is also valid.
The RRDs::times function takes two parameters: a ``start'' and ``end'' time. These should be specified in the AT-STYLE TIME SPECIFICATION format used by rrdtool. See the rrdfetch documentation for a detailed explanation on how to specify time.
The RRD functions will not abort your program even when they can not make sense out of the arguments you fed them.
The function RRDs::error should be called to get the error status after each function call. If RRDs::error does not return anything then the previous function has completed its task successfully.
use RRDs;
RRDs::update ("mydemo.rrd","N:12:13");
my $ERR=RRDs::error;
die "ERROR while updating mydemo.rrd: $ERR\n" if $ERR;
The functions RRDs::last, RRDs::graph, RRDs::info, RRDs::fetch and RRDs::times return their findings.
RRDs::last returns a single INTEGER representing the last update time.
$lastupdate = RRDs::last ...
RRDs::graph returns an pointer to an ARRAY containing the x-size and y-size of the created gif and results of the PRINT arguments.
($averages,$xsize,$ysize) = RRDs::graph ...
print "Gifsize: ${xsize}x${ysize}\n";
print "Averages: ", (join ", ", @$averages);
RRDs::info returns a pointer to a hash. The keys of the hash represent the property names of the rrd and the values of the hash are the values of the properties.
$hash = RRDs::info "example.rrd";
foreach my $key (keys %$hash){
print "$key = $$hash{$key}\n";
}
RRDs::fetch is the most complex of the pack regarding return values. There are 4 values. Two normal integers, a pointer to an array and a pointer to a array of pointers.
my ($start,$step,$names,$data) = RRDs::fetch ... print "Start: ", scalar localtime($start01-01-1970). While updating the database, update time is also specified. This update time MUST occur after start time and MUST be in seconds since epoch.The step of 300 seconds indicates that database expects new values every 300 seconds. The wrapper script should be scheduled to run every step seconds so that it updates the database every step seconds.
DS (Data Source) is the actual variable which relates to the parameter on the device that has to be monitored. Its syntax is
DS:variable_name:DST:heartbeat:min:maxDS is a key word.
variable_nameis a name under which the parameter is saved in database. There can be as many DSs in a database as needed. After every step interval, a new value of DS is supplied to update the database. This value is also called as Primary Data Point (PDP). In our example mentioned above, a new PDP is generated every 300 seconds.Note, that if you do NOT supply new datapoints exactly every 300 seconds, this is not problem, RRDTool will interpolate the data accordingly.
DST (Data Source Type) defines type of DS. It can be COUNTE