fix golint issues in core/fx (#486)

core/fx/timeout.go

@@ -3,21 +3,27 @@ package fx
 import (
 	"context"
 	"time"
+
+	"github.com/tal-tech/go-zero/core/contextx"
 )
 
 var (
+	// ErrCanceled is the error returned when the context is canceled.
 	ErrCanceled = context.Canceled
-	ErrTimeout  = context.DeadlineExceeded
+	// ErrTimeout is the error returned when the context's deadline passes.
+	ErrTimeout = context.DeadlineExceeded
 )
 
-type FxOption func() context.Context
+// DoOption defines the method to customize a DoWithTimeout call.
+type DoOption func() context.Context
 
-func DoWithTimeout(fn func() error, timeout time.Duration, opts ...FxOption) error {
+// DoWithTimeout runs fn with timeout control.
+func DoWithTimeout(fn func() error, timeout time.Duration, opts ...DoOption) error {
 	parentCtx := context.Background()
 	for _, opt := range opts {
 		parentCtx = opt()
 	}
-	ctx, cancel := context.WithTimeout(parentCtx, timeout)
+	ctx, cancel := contextx.ShrinkDeadline(parentCtx, timeout)
 	defer cancel()
 
 	done := make(chan error)
@@ -42,7 +48,8 @@ func DoWithTimeout(fn func() error, timeout time.Duration, opts ...FxOption) err
 	}
 }
 
-func WithContext(ctx context.Context) FxOption {
+// WithContext customizes a DoWithTimeout call with given ctx.
+func WithContext(ctx context.Context) DoOption {
 	return func() context.Context {
 		return ctx
 	}