Merge pull request #10 from ishank011/ctx

Use reflection to manipulate valueCtx objects
cs3org · Aug 3, 2021 · 07dde32 · 07dde32
2 parents eaa3683 + dff1379
commit 07dde32
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Showing 2 changed files with 55 additions and 37 deletions.
diff --git a/pkg/appctx/ctxmap.go b/pkg/appctx/ctxmap.go
@@ -20,44 +20,50 @@ package appctx
 
 import (
 	"context"
+	"reflect"
 	"unsafe"
 )
 
-type emptyCtx int
-
-type valueCtx struct {
-	context.Context
-	key, val interface{}
-}
-
-type iface struct {
-	itab, data uintptr //nolint
+// PutKeyValuesToCtx puts all the key-value pairs from the provided map to a background context.
+func PutKeyValuesToCtx(m map[interface{}]interface{}) context.Context {
+	ctx := context.Background()
+	for key, value := range m {
+		ctx = context.WithValue(ctx, key, value)
+	}
+	return ctx
 }
 
-// GetKeyValues retrieves all the key-value pairs from the provided context.
-func GetKeyValues(ctx context.Context) map[interface{}]interface{} {
+// GetKeyValuesFromCtx retrieves all the key-value pairs from the provided context.
+func GetKeyValuesFromCtx(ctx context.Context) map[interface{}]interface{} {
 	m := make(map[interface{}]interface{})
 	getKeyValue(ctx, m)
 	return m
 }
 
-// PutKeyValues puts
-func PutKeyValues(m map[interface{}]interface{}) context.Context {
-	ctx := context.Background()
-	for key, value := range m {
-		ctx = context.WithValue(ctx, key, value)
+func getKeyValue(ctx context.Context, m map[interface{}]interface{}) {
+	ctxVals := reflect.ValueOf(ctx).Elem()
+	ctxType := reflect.TypeOf(ctx).Elem()
+
+	if ctxType.Kind() == reflect.Struct {
+		for i := 0; i < ctxVals.NumField(); i++ {
+			currField, currIf := extractField(ctxVals, ctxType, i)
+			switch currField {
+			case "Context":
+				getKeyValue(currIf.(context.Context), m)
+			case "key":
+				nextField, nextIf := extractField(ctxVals, ctxType, i+1)
+				if nextField == "val" {
+					m[currIf] = nextIf
+					i++
+				}
+			}
+		}
 	}
-	return ctx
 }
 
-func getKeyValue(ctx context.Context, m map[interface{}]interface{}) {
-	ictx := *(*iface)(unsafe.Pointer(&ctx))
-	if ictx.data == 0 || int(*(*emptyCtx)(unsafe.Pointer(ictx.data))) == 0 {
-		return
-	}
-	valCtx := (*valueCtx)(unsafe.Pointer(ictx.data))
-	if valCtx != nil && valCtx.key != nil {
-		m[valCtx.key] = valCtx.val
-	}
-	getKeyValue(valCtx.Context, m)
+func extractField(vals reflect.Value, fieldType reflect.Type, pos int) (string, interface{}) {
+	currVal := vals.Field(pos)
+	currVal = reflect.NewAt(currVal.Type(), unsafe.Pointer(currVal.UnsafeAddr())).Elem()
+	currField := fieldType.Field(pos)
+	return currField.Name, currVal.Interface()
 }
diff --git a/pkg/appctx/ctxmap_test.go b/pkg/appctx/ctxmap_test.go
@@ -22,9 +22,13 @@ import (
 	"context"
 	"testing"
 
+	userpb "github.com/cs3org/go-cs3apis/cs3/identity/user/v1beta1"
 	"github.com/stretchr/testify/assert"
 )
 
+type ctxStringKey string
+type ctxIntKey int
+
 func TestGetKeyValues(t *testing.T) {
 	tests := []struct {
 		name string
@@ -38,24 +42,32 @@ func TestGetKeyValues(t *testing.T) {
 		},
 		{
 			"Context with Values",
-			context.WithValue(context.Background(), "key", "value"), //nolint
+			context.WithValue(context.Background(), ctxStringKey("key"), "value"),
+			map[interface{}]interface{}{
+				ctxStringKey("key"): "value",
+			},
+		},
+		{
+			"Context with user object",
+			context.WithValue(context.WithValue(context.Background(), ctxStringKey("key"), "value"), ctxStringKey("user"), &userpb.User{Username: "einstein"}),
 			map[interface{}]interface{}{
-				"key": "value",
+				ctxStringKey("key"):  "value",
+				ctxStringKey("user"): &userpb.User{Username: "einstein"},
 			},
 		},
 		{
-			"Nested Context with Values",
-			context.WithValue(context.WithValue(context.Background(), "key", "value"), "key2", "value2"), //nolint
+			"Nested Context with Values of different types",
+			context.WithValue(context.WithValue(context.Background(), ctxStringKey("key"), "value"), ctxIntKey(123), "value2"),
 			map[interface{}]interface{}{
-				"key":  "value",
-				"key2": "value2",
+				ctxStringKey("key"): "value",
+				ctxIntKey(123):      "value2",
 			},
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			kvMap := GetKeyValues(tt.ctx)
+			kvMap := GetKeyValuesFromCtx(tt.ctx)
 			assert.Equal(t, tt.m, kvMap)
 		})
 	}
@@ -75,15 +87,15 @@ func TestPutKeyValues(t *testing.T) {
 		{
 			"single kv pair",
 			map[interface{}]interface{}{
-				"key": "value",
+				ctxStringKey("key"): "value",
 			},
-			context.WithValue(context.Background(), "key", "value"), //nolint
+			context.WithValue(context.Background(), ctxStringKey("key"), "value"),
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			ctx := PutKeyValues(tt.m)
+			ctx := PutKeyValuesToCtx(tt.m)
 			assert.Equal(t, tt.ctx, ctx)
 		})
 	}