add percentile support to network traffic graphs

Set $CONFIG['percentile'] to a number and a XXth percentile line + legend
will be added to all network traffic (if_octets) graphs.

Closes #81

conf/config.php

@@ -55,6 +55,10 @@
 # use the negative X-axis in I/O graphs
 $CONFIG['negative_io'] = false;
 
+# add XXth percentile line + legend to network graphs
+# false = disabled; 95 = 95th percentile
+$CONFIG['percentile'] = false;
+
 # create smooth graphs (rrdtool -E)
 $CONFIG['graph_smooth'] = false;
 

graph.php

@@ -92,6 +92,9 @@
 if (isset($plugin_json[$type]['datasize']) and $plugin_json[$type]['datasize'])
 	$obj->scale = $CONFIG['network_datasize'] == 'bits' ? 8 : 1;
 
+if ($type == 'if_octets')
+	$obj->percentile = $CONFIG['percentile'];
+
 if (isset($plugin_json[$type]['scale']))
 	$obj->scale = $plugin_json[$type]['scale'];
 

type/Base.class.php

@@ -22,6 +22,7 @@ class Type_Base {
 	var $height;
 	var $graph_type;
 	var $negative_io;
+	var $percentile = false;
 	var $graph_smooth;
 
 	var $files;

type/GenericIO.class.php

@@ -33,6 +33,8 @@ function rrd_gen_graph() {
 					if ($i == 1)
 						$rrdgraph[] = sprintf('CDEF:avg_%s_neg=avg_%1$s_raw,%s%s,*', crc32hex($sources[$i]), $this->negative_io ? '-' : '', $this->scale);
 					$rrdgraph[] = sprintf('VDEF:tot_%1$s=avg_%1$s,TOTAL', crc32hex($sources[$i]));
+					if ($this->percentile)
+						$rrdgraph[] = sprintf('VDEF:pct_%1$s=avg_%1$s_raw,%2$s,PERCENT', crc32hex($sources[$i]), $this->percentile);
 					$i++;
 				}
 			}
@@ -66,6 +68,15 @@ function rrd_gen_graph() {
 			$i++;
 		}
 
+		if ($this->percentile) {
+			$rrdgraph[] = sprintf('"COMMENT: \l"');
+			foreach($sources as $source) {
+				$legend = empty($this->legend[$source]) ? $source : $this->legend[$source];
+				$rrdgraph[] = sprintf('"HRULE:pct_%s#%s:%sth Percentile %s"', crc32hex($source), $this->get_faded_color($this->colors[$source], '000000', 0.6), $this->percentile, $this->rrd_escape($legend));
+				$rrdgraph[] = sprintf('"GPRINT:pct_%s:%s\l"', crc32hex($source), $this->rrd_format);
+			}
+		}
+
 		return $rrdgraph;
 	}
 }