internal/rosa: evaluate packages late

This also enables concurrent evaluation.

Signed-off-by: Ophestra <cat@gensokyo.uk>

3 files changed, 92 insertions, 67 deletions

diff --git a/cmd/mbf/main.go b/cmd/mbf/main.go
index 1910a100..86a3aa1e 100644
--- a/cmd/mbf/main.go
+++ b/cmd/mbf/main.go
@@ -84,15 +84,15 @@ func main() {
 		flagArch  string
 		flagCheck bool
 		flagLTO   bool
-		flagET    bool
+		flagPT    bool
 
 		flagCrossOverride int
 
 		addr net.UnixAddr
 	)
 	c := command.New(os.Stderr, log.Printf, "mbf", func([]string) error {
-		if flagET {
-			log.Println("evaluated in", rosa.EvalTime())
+		if flagPT {
+			log.Println("parsed in", rosa.ParseTime())
 		}
 
 		msg.SwapVerbose(!flagQuiet)
@@ -189,9 +189,9 @@ func main() {
 		"socket", command.StringFlag("$MBF_DAEMON_SOCKET"),
 		"Pathname of socket to bind to",
 	).Flag(
-		&flagET,
-		"eval-time", command.BoolFlag(false),
-		"Print duration of the initial azalea evaluation",
+		&flagPT,
+		"parse-time", command.BoolFlag(false),
+		"Print duration of the initial azalea parse",
 	)
 
 	c.NewCommand(
diff --git a/internal/rosa/rosa.go b/internal/rosa/rosa.go
index dde85e00..209b8942 100644
--- a/internal/rosa/rosa.go
+++ b/internal/rosa/rosa.go
@@ -614,11 +614,11 @@ var native S
 // Native returns the global [S].
 func Native() *S { return &native }
 
-// evalTime is the duration of the initial built-in evaluation.
-var evalTime time.Duration
+// parseTime is the duration of early parsing of built-in azalea expressions.
+var parseTime time.Duration
 
-// EvalTime returns the duration of the initial built-in evaluation.
-func EvalTime() time.Duration { return evalTime }
+// ParseTime returns the time taken by early parsing of built-in azalea expressions.
+func ParseTime() time.Duration { return parseTime }
 
 // nativeB is the backing directory of built-in azalea-based [Artifact]
 // implementations.
@@ -632,9 +632,9 @@ func init() {
 		panic(err)
 	}
 	t := time.Now()
-	if err = native.EvaluateFS(sub); err != nil {
+	if err = native.RegisterFS(sub); err != nil {
 		println(err.Error())
 		os.Exit(1)
 	}
-	evalTime = time.Since(t)
+	parseTime = time.Since(t)
 }
diff --git a/internal/rosa/state.go b/internal/rosa/state.go
index c2f0650b..7b858ed9 100644
--- a/internal/rosa/state.go
+++ b/internal/rosa/state.go
@@ -189,9 +189,11 @@ type S struct {
 	archOnce sync.Once
 
 	// Built-in functions.
-	s []azalea.Frame
-	// For initialising s.
-	sOnce sync.Once
+	frame azalea.Frame
+	// For initialising frame.
+	frameOnce sync.Once
+	// Must only be accessed after a call to getFrame.
+	spool sync.Pool
 
 	// Options for [pkg.Artifact] created against [S].
 	opts int
@@ -402,10 +404,15 @@ type deferredGit struct {
 	checksum string
 }
 
-// getS must be called before accessing s. This value is not currently safe for
-// concurrent use, but the underlying frame is immutable.
-func (s *S) getS() []azalea.Frame {
-	s.sOnce.Do(func() {
+// getFrame must be called before accessing s.
+func (s *S) getFrame() azalea.Frame {
+	s.frameOnce.Do(func() {
+		s.spool.New = func() any {
+			v := make([]azalea.Frame, 1, 1<<4)
+			v[0] = s.getFrame()
+			return v
+		}
+
 		s.wantsArch()
 		k := func(name string) unique.Handle[azalea.Ident] {
 			return unique.Make(azalea.Ident(name))
@@ -416,14 +423,13 @@ func (s *S) getS() []azalea.Frame {
 			identArch    = k(s.arch)
 		)
 
-		s.s = make([]azalea.Frame, 1, 1<<4)
-		s.s[0].Val = map[unique.Handle[azalea.Ident]]any{
+		s.frame.Val = map[unique.Handle[azalea.Ident]]any{
 			k("jobsE"):      jobsE,
 			k("jobsFlagE"):  jobsFlagE,
 			k("jobsLE"):     jobsLE,
 			k("jobsLFlagE"): jobsLFlagE,
 		}
-		s.s[0].Func = map[unique.Handle[azalea.Ident]]azalea.F{
+		s.frame.Func = map[unique.Handle[azalea.Ident]]azalea.F{
 
 			// intenral/pkg built-ins
 
@@ -551,9 +557,18 @@ func (s *S) getS() []azalea.Frame {
 			}},
 		}
 	})
-	return s.s
+	return s.frame
 }
 
+// getStack returns a new stack for azalea evaluation.
+func (s *S) getStack() []azalea.Frame {
+	s.getFrame()
+	return s.spool.Get().([]azalea.Frame)
+}
+
+// putStack returns a stack to spool.
+func (s *S) putStack(v []azalea.Frame) { s.spool.Put(v) }
+
 // toHandles makes handles out of an [azalea.Array] of identifiers.
 func toHandles(idents azalea.Array) (P, error) {
 	handles := make(P, len(idents))
@@ -576,11 +591,18 @@ func toHandles(idents azalea.Array) (P, error) {
 	return handles, nil
 }
 
-// evalContext holds per-reader context.
-type evalContext struct{ b fs.FS }
+// evalContext holds per-artifact context.
+type evalContext struct {
+	// Backing filesystem.
+	b fs.FS
+	// Pending azalea function.
+	expr *azalea.Func
+	// Current toolchain.
+	t Toolchain
+}
 
-// f implements [azalea.PF].
-func (ctx *evalContext) f(
+// pf implements [azalea.PF].
+func (ctx *evalContext) pf(
 	name azalea.Ident,
 	args azalea.FArgs,
 ) (v any, set bool, err error) {
@@ -649,31 +671,29 @@ func (ctx *evalContext) f(
 	}
 
 	meta.ID = int(anitya)
-	v = Artifact(func(t Toolchain) (*Metadata, pkg.Artifact) {
-		var source pkg.Artifact
-		switch p := sourceA.(type) {
-		case pkg.Artifact:
-			source = p
+	var source pkg.Artifact
+	switch p := sourceA.(type) {
+	case pkg.Artifact:
+		source = p
 
-		case deferredGit:
-			source = t.newTagRemote(p.url, p.tag, p.checksum)
+	case deferredGit:
+		source = ctx.t.newTagRemote(p.url, p.tag, p.checksum)
 
-		default:
-			panic(azalea.TypeError{
-				Concrete: reflect.TypeOf(sourceA),
-				Asserted: reflect.TypeFor[pkg.Artifact](),
-			})
-		}
+	default:
+		panic(azalea.TypeError{
+			Concrete: reflect.TypeOf(sourceA),
+			Asserted: reflect.TypeFor[pkg.Artifact](),
+		})
+	}
 
-		return &meta, t.NewPackage(
-			meta.Name,
-			meta.Version,
-			source,
-			&attr,
-			helper,
-			inputsH...,
-		)
-	})
+	v = cachedArtifact{&meta, ctx.t.NewPackage(
+		meta.Name,
+		meta.Version,
+		source,
+		&attr,
+		helper,
+		inputsH...,
+	)}
 	set = true
 	return
 }
@@ -684,9 +704,9 @@ var (
 	ErrToplevel = errors.New("top level must only contain package declarations")
 )
 
-// Evaluate defines all package declarations from r. The backing filesystem is
-// directly exposed to azalea pathnames.
-func (s *S) Evaluate(r io.Reader, b fs.FS) error {
+// RegisterAzalea registers all package declarations from r. The backing
+// filesystem is directly exposed to azalea pathnames.
+func (s *S) RegisterAzalea(r io.Reader, b fs.FS) error {
 	var pending []*azalea.Func
 	if expressions, err := azalea.Parse(r); err != nil {
 		return err
@@ -701,26 +721,31 @@ func (s *S) Evaluate(r io.Reader, b fs.FS) error {
 		}
 	}
 
-	ctx := evalContext{b}
 	for _, f := range pending {
-		lf, set, err := azalea.Evaluate[Artifact](ctx.f, s.getS(), *f)
-		if err != nil {
-			return err
-		} else if !set {
-			return errors.New("unexpected unset")
-		}
-		if !s.Register(string(f.Ident), lf) {
+		if !s.Register(string(f.Ident), func(t Toolchain) (*Metadata, pkg.Artifact) {
+			v, set, err := azalea.Evaluate[cachedArtifact](
+				(&evalContext{b, f, t}).pf,
+				s.getStack(),
+				*f,
+			)
+			if err != nil {
+				panic(err)
+			} else if !set {
+				panic(errors.New("unexpected unset"))
+			}
+			return v.meta, v.a
+		}) {
 			return RegisterError(H(string(f.Ident)))
 		}
 	}
 	return nil
 }
 
-// EvaluateFS evaluates azalea files discovered in fsys. A file is evaluated if
-// it is at the top level and its name has the suffix ".az", or it is in a
-// top-level directory with the exact file name "package.az". The backing
-// filesystem is directly exposed to azalea pathnames.
-func (s *S) EvaluateFS(fsys fs.FS) error {
+// RegisterFS registers from azalea files discovered in fsys. A file is
+// evaluated if it is at the top level and its name has the suffix ".az", or it
+// is in a top-level directory with the exact file name "package.az". The
+// backing filesystem is directly exposed to azalea pathnames.
+func (s *S) RegisterFS(fsys fs.FS) error {
 	dents, err := fs.ReadDir(fsys, ".")
 	if err != nil {
 		return err
@@ -743,7 +768,7 @@ func (s *S) EvaluateFS(fsys fs.FS) error {
 				return err
 			}
 
-			err = s.Evaluate(r, sub)
+			err = s.RegisterAzalea(r, sub)
 			if _err := r.Close(); err == nil {
 				err = _err
 			}
@@ -763,7 +788,7 @@ func (s *S) EvaluateFS(fsys fs.FS) error {
 			return err
 		}
 
-		err = s.Evaluate(r, fsys)
+		err = s.RegisterAzalea(r, fsys)
 		if _err := r.Close(); err == nil {
 			err = _err
 		}