Adds new constructor NewFromEndOfFile

Ignores OOMs that occurred before the parser was created.

Author: jesseward

utils/oomparser/oomexample/main.go

@@ -25,11 +25,19 @@ import (
 // demonstrates how to run oomparser.OomParser to get OomInstance information
 func main() {
 	klog.InitFlags(nil)
+	ignoreOldOOMs := flag.Bool("ignore_old", false, "Read only new OOM events, ignoring old. ")
 	flag.Parse()
 	// out is a user-provided channel from which the user can read incoming
 	// OomInstance objects
 	outStream := make(chan *oomparser.OomInstance)
-	oomLog, err := oomparser.New()
+
+	var oomLog *oomparser.OomParser
+	var err error
+	if *ignoreOldOOMs {
+		oomLog, err = oomparser.NewFromEndOfFile()
+	} else {
+		oomLog, err = oomparser.New()
+	}
 	if err != nil {
 		klog.Infof("Couldn't make a new oomparser. %v", err)
 	} else {

utils/oomparser/oomparser.go

@@ -149,6 +149,21 @@ func (p *OomParser) StreamOoms(outStream chan<- *OomInstance) {
 	klog.Errorf("exiting analyzeLines. OOM events will not be reported.")
 }
 
+// NewFromEndOfFile initializes an OomParser object that starts reading from the end of the kernel log.
+// This will ignore any OOM events that occurred before the parser was created.
+func NewFromEndOfFile() (*OomParser, error) {
+	parser, err := New()
+	if err != nil {
+		return nil, err
+	}
+
+	// seek to and set the offset at the end of /dev/kmsg to avoid reporting old OOM events
+	if err := parser.parser.SeekEnd(); err != nil {
+		return nil, err
+	}
+	return parser, nil
+}
+
 // initializes an OomParser object. Returns an OomParser object and an error.
 func New() (*OomParser, error) {
 	parser, err := kmsgparser.NewParser()