Refactor logformats so that they don't use reflection anymore.

5 files changed, 57 insertions, 55 deletions

diff --git a/internal/mapr/logformat/default.go b/internal/mapr/logformat/default.go
index a44b49a..a499bc5 100644
--- a/internal/mapr/logformat/default.go
+++ b/internal/mapr/logformat/default.go
@@ -7,8 +7,21 @@ import (
 	"github.com/mimecast/dtail/internal/protocol"
 )
 
-// MakeFieldsDEFAULT is the default DTail log file key-value parser.
-func (p *Parser) MakeFieldsDEFAULT(maprLine string) (map[string]string, error) {
+type defaultParser struct {
+	hostname       string
+	timeZoneName   string
+	timeZoneOffset string
+}
+
+func newDefaultParser(hostname, timeZoneName string, timeZoneOffset int) (*defaultParser, error) {
+	return &defaultParser{
+		hostname:       hostname,
+		timeZoneName:   timeZoneName,
+		timeZoneOffset: fmt.Sprintf("%d", timeZoneOffset),
+	}, nil
+}
+
+func (p *defaultParser) MakeFields(maprLine string) (map[string]string, error) {
 	splitted := strings.Split(maprLine, protocol.FieldDelimiter)
 
 	if len(splitted) < 11 || !strings.HasPrefix(splitted[9], "MAPREDUCE:") ||
diff --git a/internal/mapr/logformat/default_test.go b/internal/mapr/logformat/default_test.go
index 28e1acc..4eae81b 100644
--- a/internal/mapr/logformat/default_test.go
+++ b/internal/mapr/logformat/default_test.go
@@ -87,6 +87,10 @@ func TestDefaultLogFormat(t *testing.T) {
 	}
 
 	fields, err := parser.MakeFields("foozoo=bar|bazbay")
+	if err != nil && err != ErrIgnoreFields {
+		t.Errorf(err.Error())
+	}
+
 	if _, ok := fields["foo"]; ok {
 		t.Errorf("Expected fiending field 'foo', but found it\n")
 	}
diff --git a/internal/mapr/logformat/generic.go b/internal/mapr/logformat/generic.go
index 14ac2a9..32d9b4a 100644
--- a/internal/mapr/logformat/generic.go
+++ b/internal/mapr/logformat/generic.go
@@ -1,7 +1,18 @@
 package logformat
 
-// MakeFieldsGENERIC is the generic log line parser.
-func (p *Parser) MakeFieldsGENERIC(maprLine string) (map[string]string, error) {
+type genericParser struct {
+	defaultParser
+}
+
+func newGenericParser(hostname, timeZoneName string, timeZoneOffset int) (*genericParser, error) {
+	defaultParser, err := newDefaultParser(hostname, timeZoneName, timeZoneOffset)
+	if err != nil {
+		return &genericParser{}, err
+	}
+	return &genericParser{defaultParser: *defaultParser}, nil
+}
+
+func (p *genericParser) MakeFields(maprLine string) (map[string]string, error) {
 	fields := make(map[string]string, 3)
 
 	fields["*"] = "*"
diff --git a/internal/mapr/logformat/generickv.go b/internal/mapr/logformat/generickv.go
index 3452e97..9c3de92 100644
--- a/internal/mapr/logformat/generickv.go
+++ b/internal/mapr/logformat/generickv.go
@@ -6,8 +6,19 @@ import (
 	"github.com/mimecast/dtail/internal/protocol"
 )
 
-// MakeFieldsGENERIGKV is the generic key-value logfile parser.
-func (p *Parser) MakeFieldsGENERIGKV(maprLine string) (map[string]string, error) {
+type genericKVParser struct {
+	defaultParser
+}
+
+func newGenericKVParser(hostname, timeZoneName string, timeZoneOffset int) (*genericKVParser, error) {
+	defaultParser, err := newDefaultParser(hostname, timeZoneName, timeZoneOffset)
+	if err != nil {
+		return &genericKVParser{}, err
+	}
+	return &genericKVParser{defaultParser: *defaultParser}, nil
+}
+
+func (p *genericKVParser) MakeFields(maprLine string) (map[string]string, error) {
 	splitted := strings.Split(maprLine, protocol.FieldDelimiter)
 	fields := make(map[string]string, len(splitted))
 
diff --git a/internal/mapr/logformat/parser.go b/internal/mapr/logformat/parser.go
index b980e3d..2d9634d 100644
--- a/internal/mapr/logformat/parser.go
+++ b/internal/mapr/logformat/parser.go
@@ -2,9 +2,6 @@ package logformat
 
 import (
 	"errors"
-	"fmt"
-	"reflect"
-	"strings"
 	"time"
 
 	"github.com/mimecast/dtail/internal/config"
@@ -15,61 +12,27 @@ import (
 var ErrIgnoreFields error = errors.New("Ignore this field set")
 
 // Parser is used to parse the mapreduce information from the server log files.
-type Parser struct {
-	hostname           string
-	makeFieldsFunc     reflect.Value
-	makeFieldsReceiver reflect.Value
-	timeZoneName       string
-	timeZoneOffset     string
+type Parser interface {
+	// MakeFields creates a field map from an input log line.
+	MakeFields(string) (map[string]string, error)
 }
 
 // NewParser returns a new log parser.
-func NewParser(logFormatName string, query *mapr.Query) (*Parser, error) {
+func NewParser(logFormatName string, query *mapr.Query) (Parser, error) {
 	hostname, err := config.Hostname()
 	if err != nil {
 		return nil, err
 	}
 	now := time.Now()
-	zone, offset := now.Zone()
+	timeZoneName, timeZoneOffset := now.Zone()
 
-	p := Parser{
-		hostname:       hostname,
-		timeZoneName:   zone,
-		timeZoneOffset: fmt.Sprintf("%d", offset),
-	}
-
-	err = p.reflectLogFormat(logFormatName)
-	if err != nil {
-		return nil, err
-	}
-	return &p, nil
-}
-
-// The aim of this is that everyone can plug in their own mapr log format
-// parsing method to DTail. Just add a method MakeFieldsMODULENAME to type
-// Parser. Whereas MODULENAME must be a upeprcase string.
-func (p *Parser) reflectLogFormat(logFormatName string) error {
-	methodName := fmt.Sprintf("MakeFields%s", strings.ToUpper(logFormatName))
-	rt := reflect.TypeOf(p)
-	method, ok := rt.MethodByName(methodName)
-	if !ok {
-		return errors.New("No such mapr log format module: " + methodName)
-	}
-
-	p.makeFieldsFunc = method.Func
-	p.makeFieldsReceiver = reflect.ValueOf(p)
-	return nil
-}
+	switch logFormatName {
+	case "generic":
+		return newGenericParser(hostname, timeZoneName, timeZoneOffset)
+	case "generickv":
+		return newGenericKVParser(hostname, timeZoneName, timeZoneOffset)
+	default:
+		return newDefaultParser(hostname, timeZoneName, timeZoneOffset)
 
-// MakeFields is for returning the fields from a given log line.
-func (p *Parser) MakeFields(maprLine string) (fields map[string]string, err error) {
-	inputValues := []reflect.Value{p.makeFieldsReceiver, reflect.ValueOf(maprLine)}
-	returnValues := p.makeFieldsFunc.Call(inputValues)
-	errInterface := returnValues[1].Interface()
-	if errInterface == nil {
-		fields, err = returnValues[0].Interface().(map[string]string), nil
-		return
 	}
-	fields, err = returnValues[0].Interface().(map[string]string), errInterface.(error)
-	return
 }