Added some comments

client/driver/syslog/parser.go

@@ -11,6 +11,7 @@ import (
 	"github.com/jeromer/syslogparser"
 )
 
+// Errors related to parsing priority
 var (
 	ErrPriorityNoStart  = fmt.Errorf("No start char found for priority")
 	ErrPriorityEmpty    = fmt.Errorf("Priority field empty")
@@ -20,40 +21,52 @@ var (
 	ErrPriorityNonDigit = fmt.Errorf("Non digit found in priority")
 )
 
+// Priority header and ending characters
 const (
 	PRI_PART_START = '<'
 	PRI_PART_END   = '>'
 )
 
+// Priority holds all the priority bits in a syslog log line
 type Priority struct {
 	P syslog.Priority
 	F syslog.Priority
 	S syslog.Priority
 }
 
+// DockerLogParser parses a line of log message that the docker daemon ships
 type DockerLogParser struct {
-	line []byte
+	line     []byte
+	content  []byte
+	severity Priority
 
 	log *log.Logger
 }
 
+// NewDockerLogParser creates a new DockerLogParser
 func NewDockerLogParser(line []byte) *DockerLogParser {
 	return &DockerLogParser{line: line}
 }
 
+// Parse parses a syslog log line
 func (d *DockerLogParser) Parse() error {
+	severity, _, _ := d.parsePriority(d.line)
+	msgIdx := d.logContentIndex(d.line)
+	d.severity = severity
+	d.content = d.line[msgIdx:]
 	return nil
 }
 
+// Dump creates a map of the parsed log line and severity
 func (d *DockerLogParser) Dump() syslogparser.LogParts {
-	severity, _, _ := d.parsePriority(d.line)
-	msgIdx := d.logContentIndex(d.line)
 	return map[string]interface{}{
-		"content":  d.line[msgIdx:],
-		"severity": severity.S,
+		"content":  d.content,
+		"severity": d.severity,
 	}
 }
 
+// logContentIndex finds out the index of the start index of the content in a
+// syslog line
 func (d *DockerLogParser) logContentIndex(line []byte) int {
 	cursor := 0
 	numSpace := 0
@@ -75,6 +88,7 @@ func (d *DockerLogParser) logContentIndex(line []byte) int {
 	return cursor + 1
 }
 
+// parsePriority parses the priority in a syslog message
 func (d *DockerLogParser) parsePriority(line []byte) (Priority, int, error) {
 	cursor := 0
 	pri := d.newPriority(0)
@@ -112,10 +126,12 @@ func (d *DockerLogParser) parsePriority(line []byte) (Priority, int, error) {
 	return pri, cursor, ErrPriorityNoEnd
 }
 
+// isDigit checks if a byte is a numeric char
 func (d *DockerLogParser) isDigit(c byte) bool {
 	return c >= '0' && c <= '9'
 }
 
+// newPriority creates a new default priority
 func (d *DockerLogParser) newPriority(p int) Priority {
 	// The Priority value is calculated by first multiplying the Facility
 	// number by 8 and then adding the numerical value of the Severity.
@@ -129,6 +145,7 @@ func (d *DockerLogParser) newPriority(p int) Priority {
 func (d *DockerLogParser) Location(location *time.Location) {
 }
 
+// CustomParser is a parser to parse docker syslog lines
 type CustomParser struct {
 	logger *log.Logger
 }