internal/core/adt: add Sharing option in CUE_DEBUG

This allows users to disable structure sharing.

Also:
- use cuedebug.Config in tests
- keep a copy of cuedebug.Config to runtime.Runtime

We modified existing methods for the runtime types,
rather than adding a new one, to enforce that we set
both values on all call sites: typically both should be
set.

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I7d2ea091cba0d79ba7ddbeedae67ee2487a7b95c
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1193637
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

cmd/cue/cmd/root.go

@@ -116,7 +116,7 @@ func mkRunE(c *Command, f runFunction) func(*cobra.Command, []string) error {
 		// in a non-tooling context.
 		if cueexperiment.Flags.EvalV3 {
 			const dev = internal.DevVersion
-			(*cueruntime.Runtime)(c.ctx).SetVersion(internal.EvaluatorVersion(dev))
+			(*cueruntime.Runtime)(c.ctx).SetSettings(internal.EvaluatorVersion(dev), cuedebug.Flags)
 		}
 
 		err := f(c, args)

internal/core/adt/context.go

@@ -167,7 +167,7 @@ type Runtime interface {
 	// type if available.
 	LoadType(t reflect.Type) (src ast.Expr, expr Expr, ok bool)
 
-	EvaluatorVersion() internal.EvaluatorVersion
+	Settings() (internal.EvaluatorVersion, cuedebug.Config)
 }
 
 type Config struct {
@@ -180,11 +180,13 @@ func New(v *Vertex, cfg *Config) *OpContext {
 	if cfg.Runtime == nil {
 		panic("nil Runtime")
 	}
+	version, flags := cfg.Runtime.Settings()
 	ctx := &OpContext{
 		Runtime:     cfg.Runtime,
 		Format:      cfg.Format,
 		vertex:      v,
-		Version:     cfg.Runtime.EvaluatorVersion(),
+		Version:     version,
+		Config:      flags,
 		taskContext: schedConfig,
 	}
 	if v != nil {

internal/core/adt/eval_test.go

@@ -36,6 +36,7 @@ import (
 	"cuelang.org/go/internal/core/eval"
 	"cuelang.org/go/internal/core/runtime"
 	"cuelang.org/go/internal/core/validate"
+	"cuelang.org/go/internal/cuedebug"
 	"cuelang.org/go/internal/cuetxtar"
 	_ "cuelang.org/go/pkg"
 )
@@ -58,7 +59,7 @@ func TestEval(t *testing.T) {
 	}
 
 	test.Run(t, func(tc *cuetxtar.Test) {
-		runEvalTest(tc, internal.DefaultVersion)
+		runEvalTest(tc, internal.DefaultVersion, cuedebug.Config{})
 	})
 }
 
@@ -79,6 +80,10 @@ func TestEvalAlpha(t *testing.T) {
 	//
 	// adt.DebugDeps = true // check unmatched dependencies.
 
+	flags := cuedebug.Config{
+		Sharing: true,
+	}
+
 	var todoAlpha = map[string]string{
 		// Crashes and hangs
 		"cycle/evaluate": "hang",
@@ -111,7 +116,7 @@ func TestEvalAlpha(t *testing.T) {
 		}
 		ran++
 
-		errorCount += runEvalTest(t, internal.DevVersion)
+		errorCount += runEvalTest(t, internal.DevVersion, flags)
 	})
 
 	t.Logf("todo: %d, ran: %d, skipped: %d, nodeErrors: %d",
@@ -140,9 +145,9 @@ func skipFiles(a ...*ast.File) (reason string) {
 	return reason
 }
 
-func runEvalTest(t *cuetxtar.Test, version internal.EvaluatorVersion) (errorCount int) {
+func runEvalTest(t *cuetxtar.Test, version internal.EvaluatorVersion, flags cuedebug.Config) (errorCount int) {
 	a := t.Instance()
-	r := runtime.NewVersioned(version)
+	r := runtime.NewWithSettings(version, flags)
 
 	v, err := r.Build(nil, a)
 	if err != nil {
@@ -153,6 +158,7 @@ func runEvalTest(t *cuetxtar.Test, version internal.EvaluatorVersion) (errorCoun
 	e := eval.New(r)
 	ctx := e.NewContext(v)
 	ctx.Version = version
+	ctx.Config = flags
 	v.Finalize(ctx)
 
 	// Print discrepancies in dependencies.
@@ -227,12 +233,14 @@ func runEvalTest(t *cuetxtar.Test, version internal.EvaluatorVersion) (errorCoun
 
 // TestX is for debugging. Do not delete.
 func TestX(t *testing.T) {
-	var verbosity int
-	verbosity = 1 // comment to turn logging off.
-
 	adt.DebugDeps = true
 	// adt.OpenGraphs = true
 
+	flags := cuedebug.Config{
+		Sharing: true, // Uncomment to turn sharing off.
+		LogEval: 1,    // Uncomment to turn logging off
+	}
+
 	var version internal.EvaluatorVersion
 	version = internal.DevVersion // comment to use default implementation.
 
@@ -253,7 +261,7 @@ module: "mod.test"
 		t.Fatal(instance.Err)
 	}
 
-	r := runtime.NewVersioned(version)
+	r := runtime.NewWithSettings(version, flags)
 
 	v, err := r.Build(nil, instance)
 	if err != nil {
@@ -262,7 +270,7 @@ module: "mod.test"
 
 	e := eval.New(r)
 	ctx := e.NewContext(v)
-	ctx.LogEval = verbosity
+	ctx.Config = flags
 	v.Finalize(ctx)
 
 	out := debug.NodeString(r, v, nil)

internal/core/adt/share.go

@@ -57,6 +57,9 @@ func (n *nodeContext) share(c Conjunct, arc *Vertex, id CloseInfo) {
 func (n *nodeContext) shareIfPossible(c Conjunct, arc *Vertex, id CloseInfo) bool {
 	// TODO: have an experiment here to enable or disable structure sharing.
 	// return false
+	if !n.ctx.Sharing {
+		return false
+	}
 
 	if n.noSharing || n.isShared || n.ctx.errs != nil {
 		return false

internal/core/eval/eval.go

@@ -32,7 +32,10 @@ func Evaluate(r adt.Runtime, v *adt.Vertex) {
 }
 
 func New(r adt.Runtime) *Unifier {
-	return &Unifier{r: r, e: NewContext(r, nil)}
+	ctx := NewContext(r, nil)
+	// TODO: we could access these directly if we can use runtime.Runtime directly.
+	ctx.Version, ctx.Config = r.Settings()
+	return &Unifier{r: r, e: ctx}
 }
 
 type Unifier struct {

internal/core/runtime/runtime.go

@@ -17,6 +17,7 @@ package runtime
 import (
 	"cuelang.org/go/cue/build"
 	"cuelang.org/go/internal"
+	"cuelang.org/go/internal/cuedebug"
 )
 
 // A Runtime maintains data structures for indexing and reuse for evaluation.
@@ -30,10 +31,12 @@ type Runtime struct {
 	interpreters map[string]Interpreter
 
 	version internal.EvaluatorVersion
+
+	flags cuedebug.Config
 }
 
-func (r *Runtime) EvaluatorVersion() internal.EvaluatorVersion {
-	return r.version
+func (r *Runtime) Settings() (internal.EvaluatorVersion, cuedebug.Config) {
+	return r.version, r.flags
 }
 
 func (r *Runtime) SetBuildData(b *build.Instance, x interface{}) {
@@ -52,18 +55,20 @@ func New() *Runtime {
 	return r
 }
 
-// NewVersioned creates a new Runtime using the given runtime version.
-// The builtins registered with RegisterBuiltin are available for evaluation.
-func NewVersioned(v internal.EvaluatorVersion) *Runtime {
-	r := &Runtime{version: v}
+// NewWithSettings creates a new Runtime using the given runtime version and
+// debug flags. The builtins registered with RegisterBuiltin are available for
+// evaluation.
+func NewWithSettings(v internal.EvaluatorVersion, flags cuedebug.Config) *Runtime {
+	r := &Runtime{version: v, flags: flags}
 	r.Init()
 	return r
 }
 
-// SetVersion sets the version to use for the Runtime. This should only be set
+// SetSettings sets the version to use for the Runtime. This should only be set
 // before first use.
-func (r *Runtime) SetVersion(v internal.EvaluatorVersion) {
+func (r *Runtime) SetSettings(v internal.EvaluatorVersion, flags cuedebug.Config) {
 	r.version = v
+	r.flags = flags
 }
 
 // IsInitialized reports whether the runtime has been initialized.

internal/cuedebug/debug.go

@@ -12,6 +12,11 @@ var Flags Config
 type Config struct {
 	HTTP bool
 
+	// TODO: consider moving these evaluator-related options into a separate
+	// struct, so that it can be used in an API. We should use embedding,
+	// or some other mechanism, in that case to allow for the full set of
+	// allowed environment variables to be known.
+
 	// Strict sets whether extra aggressive checking should be done.
 	// This should typically default to true for pre-releases and default to
 	// false otherwise.
@@ -23,6 +28,9 @@ type Config struct {
 	//	0: no logging
 	//	1: logging
 	LogEval int
+
+	// Sharing enables structure sharing.
+	Sharing bool `envflag:"default:true"`
 }
 
 // Init initializes Flags. Note: this isn't named "init" because we