refactor: populate segments in parallel

engine.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"sync"
 )
 
 type engine struct {
@@ -83,20 +84,16 @@ func (e *engine) renderSegmentText(text string) {
 func (e *engine) renderBlockSegments(block *Block) string {
 	defer e.reset()
 	e.activeBlock = block
-	cwd := e.env.getcwd()
+	e.setStringValues(block.Segments)
 	for _, segment := range block.Segments {
-		if segment.hasValue(IgnoreFolders, cwd) {
-			continue
-		}
-		props, err := segment.mapSegmentWithWriter(e.env)
-		if err != nil || !segment.enabled() {
+		if !segment.active {
 			continue
 		}
 		e.activeSegment = segment
 		e.endPowerline()
 		text := segment.string()
-		e.activeSegment.Background = props.background
-		e.activeSegment.Foreground = props.foreground
+		e.activeSegment.Background = segment.props.background
+		e.activeSegment.Foreground = segment.props.foreground
 		e.renderSegmentText(text)
 	}
 	if e.previousActiveSegment != nil && e.previousActiveSegment.Style == Powerline {
@@ -105,6 +102,22 @@ func (e *engine) renderBlockSegments(block *Block) string {
 	return e.renderer.string()
 }
 
+func (e *engine) setStringValues(segments []*Segment) {
+	wg := sync.WaitGroup{}
+	wg.Add(len(segments))
+	defer wg.Wait()
+	cwd := e.env.getcwd()
+	for _, segment := range segments {
+		go func(s *Segment) {
+			defer wg.Done()
+			err := s.mapSegmentWithWriter(e.env)
+			if err == nil && !s.hasValue(IgnoreFolders, cwd) && s.enabled() {
+				s.stringValue = s.string()
+			}
+		}(segment)
+	}
+}
+
 func (e *engine) render() {
 	for _, block := range e.settings.Blocks {
 		// if line break, append a line break

segment.go

@@ -13,7 +13,10 @@ type Segment struct {
 	LeadingDiamond  string                   `json:"leading_diamond"`
 	TrailingDiamond string                   `json:"trailing_diamond"`
 	Properties      map[Property]interface{} `json:"properties"`
+	props           *properties
 	writer          SegmentWriter
+	stringValue     string
+	active          bool
 }
 
 //SegmentWriter is the interface used to define what and if to write to the prompt
@@ -73,7 +76,8 @@ func (segment *Segment) string() string {
 }
 
 func (segment *Segment) enabled() bool {
-	return segment.writer.enabled()
+	segment.active = segment.writer.enabled()
+	return segment.active
 }
 
 func (segment *Segment) getValue(property Property, defaultValue string) string {
@@ -96,7 +100,7 @@ func (segment *Segment) hasValue(property Property, match string) bool {
 	return false
 }
 
-func (segment *Segment) mapSegmentWithWriter(env environmentInfo) (*properties, error) {
+func (segment *Segment) mapSegmentWithWriter(env environmentInfo) error {
 	functions := map[SegmentType]SegmentWriter{
 		Session:   &session{},
 		Path:      &path{},
@@ -122,7 +126,8 @@ func (segment *Segment) mapSegmentWithWriter(env environmentInfo) (*properties,
 		}
 		writer.init(props, env)
 		segment.writer = writer
-		return props, nil
+		segment.props = props
+		return nil
 	}
-	return nil, errors.New("Unable to map writer")
+	return errors.New("Unable to map writer")
 }

segment_test.go

@@ -12,8 +12,8 @@ func TestMapSegmentWriterCanMap(t *testing.T) {
 		Type: Session,
 	}
 	env := new(MockedEnvironment)
-	props, err := sc.mapSegmentWithWriter(env)
-	assert.NotNil(t, props)
+	err := sc.mapSegmentWithWriter(env)
+	assert.NotNil(t, sc.props)
 	assert.NoError(t, err)
 	assert.NotNil(t, sc.writer)
 }
@@ -23,8 +23,8 @@ func TestMapSegmentWriterCannotMap(t *testing.T) {
 		Type: "nilwriter",
 	}
 	env := new(MockedEnvironment)
-	props, err := sc.mapSegmentWithWriter(env)
-	assert.Nil(t, props)
+	err := sc.mapSegmentWithWriter(env)
+	assert.Nil(t, sc.props)
 	assert.Error(t, err)
 }