Add sortableComponent abstraction

In preparation for following changes that will ensure the order of
registration (and so execution) for mutators, singletons and
pre-singletons in tests match the order in runtime this change creates
the sortableComponent interface to allow those to be sorted in the same
way without having to resort to reflection.

By moving the registration code into each component type this change
also eliminates some unnecessary duplication of that code.

Bug: 181953909
Test: m nothing
Change-Id: I597b461b966c84faaeb13e7dff765f1fadd99981

android/mutator.go

@@ -33,22 +33,8 @@ import (
 //   run FinalDeps mutators (CreateVariations disallowed in this phase)
 //   continue on to GenerateAndroidBuildActions
 
-func registerMutatorsToContext(ctx *blueprint.Context, mutators []*mutator) {
-	for _, t := range mutators {
-		var handle blueprint.MutatorHandle
-		if t.bottomUpMutator != nil {
-			handle = ctx.RegisterBottomUpMutator(t.name, t.bottomUpMutator)
-		} else if t.topDownMutator != nil {
-			handle = ctx.RegisterTopDownMutator(t.name, t.topDownMutator)
-		}
-		if t.parallel {
-			handle.Parallel()
-		}
-	}
-}
-
 // RegisterMutatorsForBazelConversion is a alternate registration pipeline for bp2build. Exported for testing.
-func RegisterMutatorsForBazelConversion(ctx *blueprint.Context, preArchMutators, depsMutators, bp2buildMutators []RegisterMutatorFunc) {
+func RegisterMutatorsForBazelConversion(ctx *Context, preArchMutators, depsMutators, bp2buildMutators []RegisterMutatorFunc) {
 	mctx := &registerMutatorsContext{
 		bazelConversionMode: true,
 	}
@@ -80,10 +66,10 @@ func RegisterMutatorsForBazelConversion(ctx *blueprint.Context, preArchMutators,
 		f(mctx)
 	}
 
-	registerMutatorsToContext(ctx, mctx.mutators)
+	mctx.mutators.registerAll(ctx)
 }
 
-func registerMutators(ctx *blueprint.Context, preArch, preDeps, postDeps, finalDeps []RegisterMutatorFunc) {
+func registerMutators(ctx *Context, preArch, preDeps, postDeps, finalDeps []RegisterMutatorFunc) {
 	mctx := &registerMutatorsContext{}
 
 	register := func(funcs []RegisterMutatorFunc) {
@@ -103,11 +89,11 @@ func registerMutators(ctx *blueprint.Context, preArch, preDeps, postDeps, finalD
 	mctx.finalPhase = true
 	register(finalDeps)
 
-	registerMutatorsToContext(ctx, mctx.mutators)
+	mctx.mutators.registerAll(ctx)
 }
 
 type registerMutatorsContext struct {
-	mutators            []*mutator
+	mutators            sortableComponents
 	finalPhase          bool
 	bazelConversionMode bool
 }
@@ -473,6 +459,23 @@ func (x *registerMutatorsContext) TopDown(name string, m TopDownMutator) Mutator
 	return mutator
 }
 
+func (mutator *mutator) componentName() string {
+	return mutator.name
+}
+
+func (mutator *mutator) register(ctx *Context) {
+	blueprintCtx := ctx.Context
+	var handle blueprint.MutatorHandle
+	if mutator.bottomUpMutator != nil {
+		handle = blueprintCtx.RegisterBottomUpMutator(mutator.name, mutator.bottomUpMutator)
+	} else if mutator.topDownMutator != nil {
+		handle = blueprintCtx.RegisterTopDownMutator(mutator.name, mutator.topDownMutator)
+	}
+	if mutator.parallel {
+		handle.Parallel()
+	}
+}
+
 type MutatorHandle interface {
 	Parallel() MutatorHandle
 }

android/register.go

@@ -21,21 +21,78 @@ import (
 	"github.com/google/blueprint"
 )
 
+// A sortable component is one whose registration order affects the order in which it is executed
+// and so affects the behavior of the build system. As a result it is important for the order in
+// which they are registered during tests to match the order used at runtime and so the test
+// infrastructure will sort them to match.
+//
+// The sortable components are mutators, singletons and pre-singletons. Module types are not
+// sortable because their order of registration does not affect the runtime behavior.
+type sortableComponent interface {
+	// componentName returns the name of the component.
+	//
+	// Uniquely identifies the components within the set of components used at runtimr and during
+	// tests.
+	componentName() string
+
+	// register registers this component in the supplied context.
+	register(ctx *Context)
+}
+
+type sortableComponents []sortableComponent
+
+// registerAll registers all components in this slice with the supplied context.
+func (r sortableComponents) registerAll(ctx *Context) {
+	for _, c := range r {
+		c.register(ctx)
+	}
+}
+
 type moduleType struct {
 	name    string
 	factory ModuleFactory
 }
 
+func (t moduleType) register(ctx *Context) {
+	ctx.RegisterModuleType(t.name, ModuleFactoryAdaptor(t.factory))
+}
+
 var moduleTypes []moduleType
 var moduleTypesForDocs = map[string]reflect.Value{}
 
 type singleton struct {
+	// True if this should be registered as a pre-singleton, false otherwise.
+	pre bool
+
 	name    string
 	factory SingletonFactory
 }
 
-var singletons []singleton
-var preSingletons []singleton
+func newSingleton(name string, factory SingletonFactory) singleton {
+	return singleton{false, name, factory}
+}
+
+func newPreSingleton(name string, factory SingletonFactory) singleton {
+	return singleton{true, name, factory}
+}
+
+func (s singleton) componentName() string {
+	return s.name
+}
+
+func (s singleton) register(ctx *Context) {
+	adaptor := SingletonFactoryAdaptor(ctx, s.factory)
+	if s.pre {
+		ctx.RegisterPreSingletonType(s.name, adaptor)
+	} else {
+		ctx.RegisterSingletonType(s.name, adaptor)
+	}
+}
+
+var _ sortableComponent = singleton{}
+
+var singletons sortableComponents
+var preSingletons sortableComponents
 
 type mutator struct {
 	name            string
@@ -44,6 +101,8 @@ type mutator struct {
 	parallel        bool
 }
 
+var _ sortableComponent = &mutator{}
+
 type ModuleFactory func() Module
 
 // ModuleFactoryAdaptor wraps a ModuleFactory into a blueprint.ModuleFactory by converting a Module
@@ -84,11 +143,11 @@ func RegisterModuleTypeForDocs(name string, factory reflect.Value) {
 }
 
 func RegisterSingletonType(name string, factory SingletonFactory) {
-	singletons = append(singletons, singleton{name, factory})
+	singletons = append(singletons, newSingleton(name, factory))
 }
 
 func RegisterPreSingletonType(name string, factory SingletonFactory) {
-	preSingletons = append(preSingletons, singleton{name, factory})
+	preSingletons = append(preSingletons, newPreSingleton(name, factory))
 }
 
 type Context struct {
@@ -107,33 +166,29 @@ func NewContext(config Config) *Context {
 // files to semantically equivalent BUILD files.
 func (ctx *Context) RegisterForBazelConversion() {
 	for _, t := range moduleTypes {
-		ctx.RegisterModuleType(t.name, ModuleFactoryAdaptor(t.factory))
+		t.register(ctx)
 	}
 
 	// Required for SingletonModule types, even though we are not using them.
 	for _, t := range singletons {
-		ctx.RegisterSingletonType(t.name, SingletonFactoryAdaptor(ctx, t.factory))
+		t.register(ctx)
 	}
 
-	RegisterMutatorsForBazelConversion(ctx.Context, bp2buildPreArchMutators, bp2buildDepsMutators, bp2buildMutators)
+	RegisterMutatorsForBazelConversion(ctx, bp2buildPreArchMutators, bp2buildDepsMutators, bp2buildMutators)
 }
 
 // Register the pipeline of singletons, module types, and mutators for
 // generating build.ninja and other files for Kati, from Android.bp files.
 func (ctx *Context) Register() {
-	for _, t := range preSingletons {
-		ctx.RegisterPreSingletonType(t.name, SingletonFactoryAdaptor(ctx, t.factory))
-	}
+	preSingletons.registerAll(ctx)
 
 	for _, t := range moduleTypes {
-		ctx.RegisterModuleType(t.name, ModuleFactoryAdaptor(t.factory))
+		t.register(ctx)
 	}
 
-	for _, t := range singletons {
-		ctx.RegisterSingletonType(t.name, SingletonFactoryAdaptor(ctx, t.factory))
-	}
+	singletons.registerAll(ctx)
 
-	registerMutators(ctx.Context, preArch, preDeps, postDeps, finalDeps)
+	registerMutators(ctx, preArch, preDeps, postDeps, finalDeps)
 
 	ctx.RegisterSingletonType("bazeldeps", SingletonFactoryAdaptor(ctx, BazelSingleton))
 

android/testing.go

@@ -141,14 +141,14 @@ func (ctx *TestContext) DepsBp2BuildMutators(f RegisterMutatorFunc) {
 }
 
 func (ctx *TestContext) Register() {
-	registerMutators(ctx.Context.Context, ctx.preArch, ctx.preDeps, ctx.postDeps, ctx.finalDeps)
+	registerMutators(ctx.Context, ctx.preArch, ctx.preDeps, ctx.postDeps, ctx.finalDeps)
 
 	ctx.RegisterSingletonType("env", EnvSingleton)
 }
 
 // RegisterForBazelConversion prepares a test context for bp2build conversion.
 func (ctx *TestContext) RegisterForBazelConversion() {
-	RegisterMutatorsForBazelConversion(ctx.Context.Context, ctx.bp2buildPreArch, ctx.bp2buildDeps, ctx.bp2buildMutators)
+	RegisterMutatorsForBazelConversion(ctx.Context, ctx.bp2buildPreArch, ctx.bp2buildDeps, ctx.bp2buildMutators)
 }
 
 func (ctx *TestContext) ParseFileList(rootDir string, filePaths []string) (deps []string, errs []error) {