feat(brake): implement brake feature

pkg/brake/config.go

@@ -0,0 +1,54 @@
+package brake
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/cyrilix/robocar-throttle/pkg/types"
+	"os"
+)
+
+var (
+	defaultBrakeConfig = Config{
+		DeltaSteps: []float32{0.05, 0.3, 0.5},
+		Data:       []types.Throttle{-0.1, -0.5, -1.},
+	}
+)
+
+func NewConfig() *Config {
+	return &defaultBrakeConfig
+}
+
+func NewConfigFromJson(fileName string) (*Config, error) {
+	content, err := os.ReadFile(fileName)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read content from %s file: %w", fileName, err)
+	}
+	var ft Config
+	err = json.Unmarshal(content, &ft)
+	if err != nil {
+		return nil, fmt.Errorf("unable to unmarshal json content from %s file: %w", fileName, err)
+	}
+	return &ft, nil
+}
+
+type Config struct {
+	DeltaSteps []float32        `json:"delta_steps"`
+	Data       []types.Throttle `json:"data"`
+}
+
+func (tc *Config) ValueOf(currentThrottle, targetThrottle types.Throttle) types.Throttle {
+	delta := float32(currentThrottle - targetThrottle)
+
+	if delta < tc.DeltaSteps[0] {
+		return targetThrottle
+	}
+	if delta >= tc.DeltaSteps[len(tc.DeltaSteps)-1] {
+		return tc.Data[len(tc.Data)-1]
+	}
+	for idx, step := range tc.DeltaSteps {
+		if delta < step {
+			return tc.Data[idx-1]
+		}
+	}
+	return tc.Data[len(tc.Data)-1]
+}

pkg/brake/config_test.go

@@ -0,0 +1,132 @@
+package brake
+
+import (
+	"github.com/cyrilix/robocar-throttle/pkg/types"
+	"reflect"
+	"testing"
+)
+
+func TestNewConfigFromJson(t *testing.T) {
+	type args struct {
+		fileName string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *Config
+		wantErr bool
+	}{
+		{
+			name: "default config",
+			args: args{
+				fileName: "test_data/config.json",
+			},
+			want: &defaultBrakeConfig,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := NewConfigFromJson(tt.args.fileName)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("NewConfigFromJson() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(*got, *tt.want) {
+				t.Errorf("NewConfigFromJson() got = %v, want %v", got, tt.want)
+			}
+			if !reflect.DeepEqual(got.DeltaSteps, tt.want.DeltaSteps) {
+				t.Errorf("NewConfigFromJson(), bad DeltaSteps: got = %v, want %v", got.DeltaSteps, tt.want.DeltaSteps)
+			}
+		})
+	}
+}
+
+func TestConfig_ValueOf(t *testing.T) {
+	type fields struct {
+		DeltaSteps []float32
+		MinValue   int
+		Data       []types.Throttle
+	}
+	type args struct {
+		currentThrottle, targetThrottle types.Throttle
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   types.Throttle
+	}{
+		{
+			name: "delta > 0",
+			fields: fields{
+				DeltaSteps: defaultBrakeConfig.DeltaSteps,
+				Data:       defaultBrakeConfig.Data,
+			},
+			args: args{
+				currentThrottle: 0.5,
+				targetThrottle:  0.8,
+			},
+			want: 0.8,
+		},
+		{
+			name: "no delta",
+			fields: fields{
+				DeltaSteps: defaultBrakeConfig.DeltaSteps,
+				Data:       defaultBrakeConfig.Data,
+			},
+			args: args{
+				currentThrottle: 0.5,
+				targetThrottle:  0.5,
+			},
+			want: 0.5,
+		},
+		{
+			name: "delta very low (< 1st step)",
+			fields: fields{
+				DeltaSteps: defaultBrakeConfig.DeltaSteps,
+				Data:       defaultBrakeConfig.Data,
+			},
+			args: args{
+				currentThrottle: 0.5,
+				targetThrottle:  0.495,
+			},
+			want: 0.495,
+		},
+		{
+			name: "low delta ( 1st step < delta < 2nd step )",
+			fields: fields{
+				DeltaSteps: defaultBrakeConfig.DeltaSteps,
+				Data:       defaultBrakeConfig.Data,
+			},
+			args: args{
+				currentThrottle: 0.5,
+				targetThrottle:  0.38,
+			},
+			want: -0.1,
+		},
+		{
+			name: "high delta",
+			fields: fields{
+				DeltaSteps: defaultBrakeConfig.DeltaSteps,
+				Data:       defaultBrakeConfig.Data,
+			},
+			args: args{
+				currentThrottle: 0.8,
+				targetThrottle:  0.3,
+			},
+			want: -1.,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f := &Config{
+				DeltaSteps: tt.fields.DeltaSteps,
+				Data:       tt.fields.Data,
+			}
+			got := f.ValueOf(tt.args.currentThrottle, tt.args.targetThrottle)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("ValueOf() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

pkg/brake/controller.go

@@ -0,0 +1,55 @@
+package brake
+
+import (
+	"github.com/cyrilix/robocar-throttle/pkg/types"
+	"go.uber.org/zap"
+	"sync"
+)
+
+type Controller interface {
+	SetRealThrottle(t types.Throttle)
+	AdjustThrottle(targetThrottle types.Throttle) types.Throttle
+}
+
+func NewCustomController() *CustomController {
+	return &CustomController{cfg: NewConfig()}
+}
+
+func NewCustomControllerWithJsonConfig(filename string) *CustomController {
+	config, err := NewConfigFromJson(filename)
+	if err != nil {
+		zap.S().Panicf("unable to init brake controller with json config '%s': %v", filename, err)
+	}
+	return &CustomController{cfg: config}
+}
+
+type CustomController struct {
+	muRealThrottle sync.RWMutex
+	realThrottle   types.Throttle
+	cfg            *Config
+}
+
+func (b *CustomController) SetRealThrottle(t types.Throttle) {
+	b.muRealThrottle.Lock()
+	defer b.muRealThrottle.Unlock()
+	b.realThrottle = t
+}
+
+func (b *CustomController) GetRealThrottle() types.Throttle {
+	b.muRealThrottle.RLock()
+	defer b.muRealThrottle.RUnlock()
+	res := b.realThrottle
+	return res
+}
+
+func (b *CustomController) AdjustThrottle(targetThrottle types.Throttle) types.Throttle {
+	return b.cfg.ValueOf(b.GetRealThrottle(), targetThrottle)
+}
+
+type DisabledController struct{}
+
+func (d *DisabledController) SetRealThrottle(_ types.Throttle) {}
+
+func (d *DisabledController) AdjustThrottle(targetThrottle types.Throttle) types.Throttle {
+	return targetThrottle
+}

pkg/brake/controller_test.go

@@ -0,0 +1,92 @@
+package brake
+
+import (
+	"github.com/cyrilix/robocar-throttle/pkg/types"
+	"testing"
+)
+
+func TestController_AdjustThrottle(t *testing.T) {
+	type fields struct {
+		realThrottle types.Throttle
+	}
+	type args struct {
+		targetThrottle types.Throttle
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   types.Throttle
+	}{
+		{
+			name:   "target same as current throttle",
+			fields: fields{realThrottle: 0.2},
+			args:   args{targetThrottle: 0.2},
+			want:   0.2,
+		},
+		{
+			name:   "target > as current throttle",
+			fields: fields{realThrottle: 0.2},
+			args:   args{targetThrottle: 0.3},
+			want:   0.3,
+		},
+		{
+			name:   "target >> as current throttle",
+			fields: fields{realThrottle: 0.2},
+			args:   args{targetThrottle: 0.5},
+			want:   0.5,
+		},
+		{
+			name:   "target < as current throttle",
+			fields: fields{realThrottle: 0.8},
+			args:   args{targetThrottle: 0.7},
+			want:   -0.1,
+		},
+		{
+			name:   "target << as current throttle",
+			fields: fields{realThrottle: 0.8},
+			args:   args{targetThrottle: 0.5},
+			want:   -0.5,
+		},
+		{
+			name:   "target <<< as current throttle",
+			fields: fields{realThrottle: 0.8},
+			args:   args{targetThrottle: 0.2},
+			want:   -1.,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := &CustomController{cfg: NewConfig()}
+			b.SetRealThrottle(tt.fields.realThrottle)
+			if got := b.AdjustThrottle(tt.args.targetThrottle); got != tt.want {
+				t.Errorf("AdjustThrottle() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestDisabledController_AdjustThrottle(t *testing.T) {
+	type args struct {
+		targetThrottle types.Throttle
+	}
+	tests := []struct {
+		name string
+		args args
+		want types.Throttle
+	}{
+		{
+			name: "doesn't modify value",
+			args: args{targetThrottle: 0.5},
+			want: 0.5,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			d := &DisabledController{}
+			if got := d.AdjustThrottle(tt.args.targetThrottle); got != tt.want {
+				t.Errorf("AdjustThrottle() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

pkg/brake/test_data/config.json

@@ -0,0 +1,4 @@
+{
+  "delta_steps": [ 0.05, 0.3, 0.5 ],
+  "data": [ -0.1, -0.5, -1.0 ]
+}