sdk/sdk.go - SHIFTPHONES/android_build_soong - Gitiles

 // Copyright (C) 2019 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package sdk

 import (
 	"fmt"
 	"io"
 	"reflect"
 	"strconv"

 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"

 	"android/soong/android"
 	// This package doesn't depend on the apex package, but import it to make its mutators to be
 	// registered before mutators in this package. See RegisterPostDepsMutators for more details.
 	_ "android/soong/apex"
 )

 func init() {
 	pctx.Import("android/soong/android")
 	pctx.Import("android/soong/java/config")

 	android.RegisterModuleType("sdk", SdkModuleFactory)
 	android.RegisterModuleType("sdk_snapshot", SnapshotModuleFactory)
 	android.PreDepsMutators(RegisterPreDepsMutators)
 	android.PostDepsMutators(RegisterPostDepsMutators)
 }

 type sdk struct {
 	android.ModuleBase
 	android.DefaultableModuleBase

 	// The dynamically generated information about the registered SdkMemberType
 	dynamicSdkMemberTypes *dynamicSdkMemberTypes

 	// The dynamically created instance of the properties struct containing the sdk member
 	// list properties, e.g. java_libs.
 	dynamicMemberTypeListProperties interface{}

 	// Information about the OsType specific member variants associated with this variant.
 	//
 	// Set by OsType specific variants in the collectMembers() method and used by the
 	// CommonOS variant when building the snapshot. That work is all done on separate
 	// calls to the sdk.GenerateAndroidBuildActions method which is guaranteed to be
 	// called for the OsType specific variants before the CommonOS variant (because
 	// the latter depends on the former).
 	memberRefs []sdkMemberRef

 	// The multilib variants that are used by this sdk variant.
 	multilibUsages multilibUsage

 	properties sdkProperties

 	snapshotFile android.OptionalPath

 	// The builder, preserved for testing.
 	builderForTests *snapshotBuilder
 }

 type sdkProperties struct {
 	Snapshot bool `blueprint:"mutated"`

 	// True if this is a module_exports (or module_exports_snapshot) module type.
 	Module_exports bool `blueprint:"mutated"`

 	// The additional visibility to add to the prebuilt modules to allow them to
 	// reference each other.
 	//
 	// This can only be used to widen the visibility of the members:
 	//
 	// * Specifying //visibility:public here will make all members visible and
 	//   essentially ignore their own visibility.
 	// * Specifying //visibility:private here is an error.
 	// * Specifying any other rule here will add it to the members visibility and
 	//   be output to the member prebuilt in the snapshot. Duplicates will be
 	//   dropped. Adding a rule to members that have //visibility:private will
 	//   cause the //visibility:private to be discarded.
 	Prebuilt_visibility []string
 }

 // Contains information about the sdk properties that list sdk members, e.g.
 // Java_header_libs.
 type sdkMemberListProperty struct {
 	// getter for the list of member names
 	getter func(properties interface{}) []string

 	// the type of member referenced in the list
 	memberType android.SdkMemberType

 	// the dependency tag used for items in this list that can be used to determine the memberType
 	// for a resolved dependency.
 	dependencyTag android.SdkMemberTypeDependencyTag
 }

 func (p *sdkMemberListProperty) propertyName() string {
 	return p.memberType.SdkPropertyName()
 }

 // Cache of dynamically generated dynamicSdkMemberTypes objects. The key is the pointer
 // to a slice of SdkMemberType instances held in android.SdkMemberTypes.
 var dynamicSdkMemberTypesMap android.OncePer

 // A dynamically generated set of member list properties and associated structure type.
 type dynamicSdkMemberTypes struct {
 	// The dynamically generated structure type.
 	//
 	// Contains one []string exported field for each android.SdkMemberTypes. The name of the field
 	// is the exported form of the value returned by SdkMemberType.SdkPropertyName().
 	propertiesStructType reflect.Type

 	// Information about each of the member type specific list properties.
 	memberListProperties []*sdkMemberListProperty
 }

 func (d *dynamicSdkMemberTypes) createMemberListProperties() interface{} {
 	return reflect.New(d.propertiesStructType).Interface()
 }

 func getDynamicSdkMemberTypes(registry *android.SdkMemberTypesRegistry) *dynamicSdkMemberTypes {

 	// Get a key that uniquely identifies the registry contents.
 	key := registry.UniqueOnceKey()

 	// Get the registered types.
 	registeredTypes := registry.RegisteredTypes()

 	// Get the cached value, creating new instance if necessary.
 	return dynamicSdkMemberTypesMap.Once(key, func() interface{} {
 		return createDynamicSdkMemberTypes(registeredTypes)
 	}).(*dynamicSdkMemberTypes)
 }

 // Create the dynamicSdkMemberTypes from the list of registered member types.
 //
 // A struct is created which contains one exported field per member type corresponding to
 // the SdkMemberType.SdkPropertyName() value.
 //
 // A list of sdkMemberListProperty instances is created, one per member type that provides:
 // * a reference to the member type.
 // * a getter for the corresponding field in the properties struct.
 // * a dependency tag that identifies the member type of a resolved dependency.
 //
 func createDynamicSdkMemberTypes(sdkMemberTypes []android.SdkMemberType) *dynamicSdkMemberTypes {

 	var listProperties []*sdkMemberListProperty
 	var fields []reflect.StructField

 	// Iterate over the member types creating StructField and sdkMemberListProperty objects.
 	for f, memberType := range sdkMemberTypes {
 		p := memberType.SdkPropertyName()

 		// Create a dynamic exported field for the member type's property.
 		fields = append(fields, reflect.StructField{
 			Name: proptools.FieldNameForProperty(p),
 			Type: reflect.TypeOf([]string{}),
 			Tag:  `android:"arch_variant"`,
 		})

 		// Copy the field index for use in the getter func as using the loop variable directly will
 		// cause all funcs to use the last value.
 		fieldIndex := f

 		// Create an sdkMemberListProperty for the member type.
 		memberListProperty := &sdkMemberListProperty{
 			getter: func(properties interface{}) []string {
 				// The properties is expected to be of the following form (where
 				// <Module_types> is the name of an SdkMemberType.SdkPropertyName().
 				//     properties *struct {<Module_types> []string, ....}
 				//
 				// Although it accesses the field by index the following reflection code is equivalent to:
 				//    *properties.<Module_types>
 				//
 				list := reflect.ValueOf(properties).Elem().Field(fieldIndex).Interface().([]string)
 				return list
 			},

 			memberType: memberType,

 			dependencyTag: android.DependencyTagForSdkMemberType(memberType),
 		}

 		listProperties = append(listProperties, memberListProperty)
 	}

 	// Create a dynamic struct from the collated fields.
 	propertiesStructType := reflect.StructOf(fields)

 	return &dynamicSdkMemberTypes{
 		memberListProperties: listProperties,
 		propertiesStructType: propertiesStructType,
 	}
 }

 // sdk defines an SDK which is a logical group of modules (e.g. native libs, headers, java libs, etc.)
 // which Mainline modules like APEX can choose to build with.
 func SdkModuleFactory() android.Module {
 	return newSdkModule(false)
 }

 func newSdkModule(moduleExports bool) *sdk {
 	s := &sdk{}
 	s.properties.Module_exports = moduleExports
 	// Get the dynamic sdk member type data for the currently registered sdk member types.
 	var registry *android.SdkMemberTypesRegistry
 	if moduleExports {
 		registry = android.ModuleExportsMemberTypes
 	} else {
 		registry = android.SdkMemberTypes
 	}
 	s.dynamicSdkMemberTypes = getDynamicSdkMemberTypes(registry)
 	// Create an instance of the dynamically created struct that contains all the
 	// properties for the member type specific list properties.
 	s.dynamicMemberTypeListProperties = s.dynamicSdkMemberTypes.createMemberListProperties()
 	s.AddProperties(&s.properties, s.dynamicMemberTypeListProperties)

 	// Make sure that the prebuilt visibility property is verified for errors.
 	android.AddVisibilityProperty(s, "prebuilt_visibility", &s.properties.Prebuilt_visibility)
 	android.InitCommonOSAndroidMultiTargetsArchModule(s, android.HostAndDeviceSupported, android.MultilibCommon)
 	android.InitDefaultableModule(s)
 	android.AddLoadHook(s, func(ctx android.LoadHookContext) {
 		type props struct {
 			Compile_multilib *string
 		}
 		p := &props{Compile_multilib: proptools.StringPtr("both")}
 		ctx.PrependProperties(p)
 	})
 	return s
 }

 // sdk_snapshot is a versioned snapshot of an SDK. This is an auto-generated module.
 func SnapshotModuleFactory() android.Module {
 	s := newSdkModule(false)
 	s.properties.Snapshot = true
 	return s
 }

 func (s *sdk) memberListProperties() []*sdkMemberListProperty {
 	return s.dynamicSdkMemberTypes.memberListProperties
 }

 func (s *sdk) getExportedMembers() map[string]struct{} {
 	// Collect all the exported members.
 	exportedMembers := make(map[string]struct{})

 	for _, memberListProperty := range s.memberListProperties() {
 		names := memberListProperty.getter(s.dynamicMemberTypeListProperties)

 		// Every member specified explicitly in the properties is exported by the sdk.
 		for _, name := range names {
 			exportedMembers[name] = struct{}{}
 		}
 	}

 	return exportedMembers
 }

 func (s *sdk) snapshot() bool {
 	return s.properties.Snapshot
 }

 func (s *sdk) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	if s.snapshot() {
 		// We don't need to create a snapshot out of sdk_snapshot.
 		// That doesn't make sense. We need a snapshot to create sdk_snapshot.
 		return
 	}

 	// This method is guaranteed to be called on OsType specific variants before it is called
 	// on their corresponding CommonOS variant.
 	if !s.IsCommonOSVariant() {
 		// Update the OsType specific sdk variant with information about its members.
 		s.collectMembers(ctx)
 	} else {
 		// Get the OsType specific variants on which the CommonOS depends.
 		osSpecificVariants := android.GetOsSpecificVariantsOfCommonOSVariant(ctx)
 		var sdkVariants []*sdk
 		for _, m := range osSpecificVariants {
 			if sdkVariant, ok := m.(*sdk); ok {
 				sdkVariants = append(sdkVariants, sdkVariant)
 			}
 		}

 		// Generate the snapshot from the member info.
 		p := s.buildSnapshot(ctx, sdkVariants)
 		s.snapshotFile = android.OptionalPathForPath(p)
 		ctx.InstallFile(android.PathForMainlineSdksInstall(ctx), s.Name()+"-current.zip", p)
 	}
 }

 func (s *sdk) AndroidMkEntries() []android.AndroidMkEntries {
 	if !s.snapshotFile.Valid() {
 		return []android.AndroidMkEntries{}
 	}

 	return []android.AndroidMkEntries{android.AndroidMkEntries{
 		Class:      "FAKE",
 		OutputFile: s.snapshotFile,
 		DistFiles:  android.MakeDefaultDistFiles(s.snapshotFile.Path()),
 		Include:    "$(BUILD_PHONY_PACKAGE)",
 		ExtraFooters: []android.AndroidMkExtraFootersFunc{
 			func(w io.Writer, name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
 				// Allow the sdk to be built by simply passing its name on the command line.
 				fmt.Fprintln(w, ".PHONY:", s.Name())
 				fmt.Fprintln(w, s.Name()+":", s.snapshotFile.String())
 			},
 		},
 	}}
 }

 // RegisterPreDepsMutators registers pre-deps mutators to support modules implementing SdkAware
 // interface and the sdk module type. This function has been made public to be called by tests
 // outside of the sdk package
 func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
 	ctx.BottomUp("SdkMember", memberMutator).Parallel()
 	ctx.TopDown("SdkMember_deps", memberDepsMutator).Parallel()
 	ctx.BottomUp("SdkMemberInterVersion", memberInterVersionMutator).Parallel()
 }

 // RegisterPostDepsMutators registers post-deps mutators to support modules implementing SdkAware
 // interface and the sdk module type. This function has been made public to be called by tests
 // outside of the sdk package
 func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
 	// These must run AFTER apexMutator. Note that the apex package is imported even though there is
 	// no direct dependency to the package here. sdkDepsMutator sets the SDK requirements from an
 	// APEX to its dependents. Since different versions of the same SDK can be used by different
 	// APEXes, the apex and its dependents (which includes the dependencies to the sdk members)
 	// should have been mutated for the apex before the SDK requirements are set.
 	ctx.TopDown("SdkDepsMutator", sdkDepsMutator).Parallel()
 	ctx.BottomUp("SdkDepsReplaceMutator", sdkDepsReplaceMutator).Parallel()
 	ctx.TopDown("SdkRequirementCheck", sdkRequirementsMutator).Parallel()
 }

 type dependencyTag struct {
 	blueprint.BaseDependencyTag
 }

 // Mark this tag so dependencies that use it are excluded from APEX contents.
 func (t dependencyTag) ExcludeFromApexContents() {}

 var _ android.ExcludeFromApexContentsTag = dependencyTag{}

 // For dependencies from an in-development version of an SDK member to frozen versions of the same member
 // e.g. libfoo -> libfoo.mysdk.11 and libfoo.mysdk.12
 type sdkMemberVersionedDepTag struct {
 	dependencyTag
 	member  string
 	version string
 }

 // Mark this tag so dependencies that use it are excluded from visibility enforcement.
 func (t sdkMemberVersionedDepTag) ExcludeFromVisibilityEnforcement() {}

 // Step 1: create dependencies from an SDK module to its members.
 func memberMutator(mctx android.BottomUpMutatorContext) {
 	if s, ok := mctx.Module().(*sdk); ok {
 		// Add dependencies from enabled and non CommonOS variants to the sdk member variants.
 		if s.Enabled() && !s.IsCommonOSVariant() {
 			for _, memberListProperty := range s.memberListProperties() {
 				names := memberListProperty.getter(s.dynamicMemberTypeListProperties)
 				if len(names) > 0 {
 					tag := memberListProperty.dependencyTag
 					memberListProperty.memberType.AddDependencies(mctx, tag, names)
 				}
 			}
 		}
 	}
 }

 // Step 2: record that dependencies of SDK modules are members of the SDK modules
 func memberDepsMutator(mctx android.TopDownMutatorContext) {
 	if s, ok := mctx.Module().(*sdk); ok {
 		mySdkRef := android.ParseSdkRef(mctx, mctx.ModuleName(), "name")
 		if s.snapshot() && mySdkRef.Unversioned() {
 			mctx.PropertyErrorf("name", "sdk_snapshot should be named as <name>@<version>. "+
 				"Did you manually modify Android.bp?")
 		}
 		if !s.snapshot() && !mySdkRef.Unversioned() {
 			mctx.PropertyErrorf("name", "sdk shouldn't be named as <name>@<version>.")
 		}
 		if mySdkRef.Version != "" && mySdkRef.Version != "current" {
 			if _, err := strconv.Atoi(mySdkRef.Version); err != nil {
 				mctx.PropertyErrorf("name", "version %q is neither a number nor \"current\"", mySdkRef.Version)
 			}
 		}

 		mctx.VisitDirectDeps(func(child android.Module) {
 			if member, ok := child.(android.SdkAware); ok {
 				member.MakeMemberOf(mySdkRef)
 			}
 		})
 	}
 }

 // Step 3: create dependencies from the unversioned SDK member to snapshot versions
 // of the same member. By having these dependencies, they are mutated for multiple Mainline modules
 // (apex and apk), each of which might want different sdks to be built with. For example, if both
 // apex A and B are referencing libfoo which is a member of sdk 'mysdk', the two APEXes can be
 // built with libfoo.mysdk.11 and libfoo.mysdk.12, respectively depending on which sdk they are
 // using.
 func memberInterVersionMutator(mctx android.BottomUpMutatorContext) {
 	if m, ok := mctx.Module().(android.SdkAware); ok && m.IsInAnySdk() {
 		if !m.ContainingSdk().Unversioned() {
 			memberName := m.MemberName()
 			tag := sdkMemberVersionedDepTag{member: memberName, version: m.ContainingSdk().Version}
 			mctx.AddReverseDependency(mctx.Module(), tag, memberName)
 		}
 	}
 }

 // Step 4: transitively ripple down the SDK requirements from the root modules like APEX to its
 // descendants
 func sdkDepsMutator(mctx android.TopDownMutatorContext) {
 	if parent, ok := mctx.Module().(interface {
 		android.DepIsInSameApex
 		android.RequiredSdks
 	}); ok {
 		// Module types for Mainline modules (e.g. APEX) are expected to implement RequiredSdks()
 		// by reading its own properties like `uses_sdks`.
 		requiredSdks := parent.RequiredSdks()
 		if len(requiredSdks) > 0 {
 			mctx.VisitDirectDeps(func(m android.Module) {
 				// Only propagate required sdks from the apex onto its contents.
 				if dep, ok := m.(android.SdkAware); ok && parent.DepIsInSameApex(mctx, dep) {
 					dep.BuildWithSdks(requiredSdks)
 				}
 			})
 		}
 	}
 }

 // Step 5: if libfoo.mysdk.11 is in the context where version 11 of mysdk is requested, the
 // versioned module is used instead of the un-versioned (in-development) module libfoo
 func sdkDepsReplaceMutator(mctx android.BottomUpMutatorContext) {
 	if versionedSdkMember, ok := mctx.Module().(android.SdkAware); ok && versionedSdkMember.IsInAnySdk() {
 		if sdk := versionedSdkMember.ContainingSdk(); !sdk.Unversioned() {
 			// Only replace dependencies to <sdkmember> with <sdkmember@required-version>
 			// if the depending module requires it. e.g.
 			//      foo -> sdkmember
 			// will be transformed to:
 			//      foo -> sdkmember@1
 			// if and only if foo is a member of an APEX that requires version 1 of the
 			// sdk containing sdkmember.
 			memberName := versionedSdkMember.MemberName()

 			// Replace dependencies on sdkmember with a dependency on the current module which
 			// is a versioned prebuilt of the sdkmember if required.
 			mctx.ReplaceDependenciesIf(memberName, func(from blueprint.Module, tag blueprint.DependencyTag, to blueprint.Module) bool {
 				// from - foo
 				// to - sdkmember
 				replace := false
 				if parent, ok := from.(android.RequiredSdks); ok {
 					replace = parent.RequiredSdks().Contains(sdk)
 				}
 				return replace
 			})
 		}
 	}
 }

 // Step 6: ensure that the dependencies outside of the APEX are all from the required SDKs
 func sdkRequirementsMutator(mctx android.TopDownMutatorContext) {
 	if m, ok := mctx.Module().(interface {
 		android.DepIsInSameApex
 		android.RequiredSdks
 	}); ok {
 		requiredSdks := m.RequiredSdks()
 		if len(requiredSdks) == 0 {
 			return
 		}
 		mctx.VisitDirectDeps(func(dep android.Module) {
 			tag := mctx.OtherModuleDependencyTag(dep)
 			if tag == android.DefaultsDepTag {
 				// dependency to defaults is always okay
 				return
 			}

 			// Ignore the dependency from the unversioned member to any versioned members as an
 			// apex that depends on the unversioned member will not also be depending on a versioned
 			// member.
 			if _, ok := tag.(sdkMemberVersionedDepTag); ok {
 				return
 			}

 			// If the dep is outside of the APEX, but is not in any of the
 			// required SDKs, we know that the dep is a violation.
 			if sa, ok := dep.(android.SdkAware); ok {
 				if !m.DepIsInSameApex(mctx, dep) && !requiredSdks.Contains(sa.ContainingSdk()) {
 					mctx.ModuleErrorf("depends on %q (in SDK %q) that isn't part of the required SDKs: %v",
 						sa.Name(), sa.ContainingSdk(), requiredSdks)
 				}
 			}
 		})
 	}
 }
	// Copyright (C) 2019 The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package sdk

	import (
	"fmt"
	"io"
	"reflect"
	"strconv"

	"github.com/google/blueprint"
	"github.com/google/blueprint/proptools"

	"android/soong/android"
	// This package doesn't depend on the apex package, but import it to make its mutators to be
	// registered before mutators in this package. See RegisterPostDepsMutators for more details.
	_ "android/soong/apex"
	)

	func init() {
	pctx.Import("android/soong/android")
	pctx.Import("android/soong/java/config")

	android.RegisterModuleType("sdk", SdkModuleFactory)
	android.RegisterModuleType("sdk_snapshot", SnapshotModuleFactory)
	android.PreDepsMutators(RegisterPreDepsMutators)
	android.PostDepsMutators(RegisterPostDepsMutators)
	}

	type sdk struct {
	android.ModuleBase
	android.DefaultableModuleBase

	// The dynamically generated information about the registered SdkMemberType
	dynamicSdkMemberTypes *dynamicSdkMemberTypes

	// The dynamically created instance of the properties struct containing the sdk member
	// list properties, e.g. java_libs.
	dynamicMemberTypeListProperties interface{}

	// Information about the OsType specific member variants associated with this variant.
	//
	// Set by OsType specific variants in the collectMembers() method and used by the
	// CommonOS variant when building the snapshot. That work is all done on separate
	// calls to the sdk.GenerateAndroidBuildActions method which is guaranteed to be
	// called for the OsType specific variants before the CommonOS variant (because
	// the latter depends on the former).
	memberRefs []sdkMemberRef

	// The multilib variants that are used by this sdk variant.
	multilibUsages multilibUsage

	properties sdkProperties

	snapshotFile android.OptionalPath

	// The builder, preserved for testing.
	builderForTests *snapshotBuilder
	}

	type sdkProperties struct {
	Snapshot bool `blueprint:"mutated"`

	// True if this is a module_exports (or module_exports_snapshot) module type.
	Module_exports bool `blueprint:"mutated"`

	// The additional visibility to add to the prebuilt modules to allow them to
	// reference each other.
	//
	// This can only be used to widen the visibility of the members:
	//
	// * Specifying //visibility:public here will make all members visible and
	// essentially ignore their own visibility.
	// * Specifying //visibility:private here is an error.
	// * Specifying any other rule here will add it to the members visibility and
	// be output to the member prebuilt in the snapshot. Duplicates will be
	// dropped. Adding a rule to members that have //visibility:private will
	// cause the //visibility:private to be discarded.
	Prebuilt_visibility []string
	}

	// Contains information about the sdk properties that list sdk members, e.g.
	// Java_header_libs.
	type sdkMemberListProperty struct {
	// getter for the list of member names
	getter func(properties interface{}) []string

	// the type of member referenced in the list
	memberType android.SdkMemberType

	// the dependency tag used for items in this list that can be used to determine the memberType
	// for a resolved dependency.
	dependencyTag android.SdkMemberTypeDependencyTag
	}

	func (p *sdkMemberListProperty) propertyName() string {
	return p.memberType.SdkPropertyName()
	}

	// Cache of dynamically generated dynamicSdkMemberTypes objects. The key is the pointer
	// to a slice of SdkMemberType instances held in android.SdkMemberTypes.
	var dynamicSdkMemberTypesMap android.OncePer

	// A dynamically generated set of member list properties and associated structure type.
	type dynamicSdkMemberTypes struct {
	// The dynamically generated structure type.
	//
	// Contains one []string exported field for each android.SdkMemberTypes. The name of the field
	// is the exported form of the value returned by SdkMemberType.SdkPropertyName().
	propertiesStructType reflect.Type

	// Information about each of the member type specific list properties.
	memberListProperties []*sdkMemberListProperty
	}

	func (d *dynamicSdkMemberTypes) createMemberListProperties() interface{} {
	return reflect.New(d.propertiesStructType).Interface()
	}

	func getDynamicSdkMemberTypes(registry android.SdkMemberTypesRegistry) dynamicSdkMemberTypes {

	// Get a key that uniquely identifies the registry contents.
	key := registry.UniqueOnceKey()

	// Get the registered types.
	registeredTypes := registry.RegisteredTypes()

	// Get the cached value, creating new instance if necessary.
	return dynamicSdkMemberTypesMap.Once(key, func() interface{} {
	return createDynamicSdkMemberTypes(registeredTypes)
	}).(*dynamicSdkMemberTypes)
	}

	// Create the dynamicSdkMemberTypes from the list of registered member types.
	//
	// A struct is created which contains one exported field per member type corresponding to
	// the SdkMemberType.SdkPropertyName() value.
	//
	// A list of sdkMemberListProperty instances is created, one per member type that provides:
	// * a reference to the member type.
	// * a getter for the corresponding field in the properties struct.
	// * a dependency tag that identifies the member type of a resolved dependency.
	//
	func createDynamicSdkMemberTypes(sdkMemberTypes []android.SdkMemberType) *dynamicSdkMemberTypes {

	var listProperties []*sdkMemberListProperty
	var fields []reflect.StructField

	// Iterate over the member types creating StructField and sdkMemberListProperty objects.
	for f, memberType := range sdkMemberTypes {
	p := memberType.SdkPropertyName()

	// Create a dynamic exported field for the member type's property.
	fields = append(fields, reflect.StructField{
	Name: proptools.FieldNameForProperty(p),
	Type: reflect.TypeOf([]string{}),
	Tag: `android:"arch_variant"`,
	})

	// Copy the field index for use in the getter func as using the loop variable directly will
	// cause all funcs to use the last value.
	fieldIndex := f

	// Create an sdkMemberListProperty for the member type.
	memberListProperty := &sdkMemberListProperty{
	getter: func(properties interface{}) []string {
	// The properties is expected to be of the following form (where
	// <Module_types> is the name of an SdkMemberType.SdkPropertyName().
	// properties *struct {<Module_types> []string, ....}
	//
	// Although it accesses the field by index the following reflection code is equivalent to:
	// *properties.<Module_types>
	//
	list := reflect.ValueOf(properties).Elem().Field(fieldIndex).Interface().([]string)
	return list
	},

	memberType: memberType,

	dependencyTag: android.DependencyTagForSdkMemberType(memberType),
	}

	listProperties = append(listProperties, memberListProperty)
	}

	// Create a dynamic struct from the collated fields.
	propertiesStructType := reflect.StructOf(fields)

	return &dynamicSdkMemberTypes{
	memberListProperties: listProperties,
	propertiesStructType: propertiesStructType,
	}
	}

	// sdk defines an SDK which is a logical group of modules (e.g. native libs, headers, java libs, etc.)
	// which Mainline modules like APEX can choose to build with.
	func SdkModuleFactory() android.Module {
	return newSdkModule(false)
	}

	func newSdkModule(moduleExports bool) *sdk {
	s := &sdk{}
	s.properties.Module_exports = moduleExports
	// Get the dynamic sdk member type data for the currently registered sdk member types.
	var registry *android.SdkMemberTypesRegistry
	if moduleExports {
	registry = android.ModuleExportsMemberTypes
	} else {
	registry = android.SdkMemberTypes
	}
	s.dynamicSdkMemberTypes = getDynamicSdkMemberTypes(registry)
	// Create an instance of the dynamically created struct that contains all the
	// properties for the member type specific list properties.
	s.dynamicMemberTypeListProperties = s.dynamicSdkMemberTypes.createMemberListProperties()
	s.AddProperties(&s.properties, s.dynamicMemberTypeListProperties)

	// Make sure that the prebuilt visibility property is verified for errors.
	android.AddVisibilityProperty(s, "prebuilt_visibility", &s.properties.Prebuilt_visibility)
	android.InitCommonOSAndroidMultiTargetsArchModule(s, android.HostAndDeviceSupported, android.MultilibCommon)
	android.InitDefaultableModule(s)
	android.AddLoadHook(s, func(ctx android.LoadHookContext) {
	type props struct {
	Compile_multilib *string
	}
	p := &props{Compile_multilib: proptools.StringPtr("both")}
	ctx.PrependProperties(p)
	})
	return s
	}

	// sdk_snapshot is a versioned snapshot of an SDK. This is an auto-generated module.
	func SnapshotModuleFactory() android.Module {
	s := newSdkModule(false)
	s.properties.Snapshot = true
	return s
	}

	func (s sdk) memberListProperties() []sdkMemberListProperty {
	return s.dynamicSdkMemberTypes.memberListProperties
	}

	func (s *sdk) getExportedMembers() map[string]struct{} {
	// Collect all the exported members.
	exportedMembers := make(map[string]struct{})

	for _, memberListProperty := range s.memberListProperties() {
	names := memberListProperty.getter(s.dynamicMemberTypeListProperties)

	// Every member specified explicitly in the properties is exported by the sdk.
	for _, name := range names {
	exportedMembers[name] = struct{}{}
	}
	}

	return exportedMembers
	}

	func (s *sdk) snapshot() bool {
	return s.properties.Snapshot
	}

	func (s *sdk) GenerateAndroidBuildActions(ctx android.ModuleContext) {
	if s.snapshot() {
	// We don't need to create a snapshot out of sdk_snapshot.
	// That doesn't make sense. We need a snapshot to create sdk_snapshot.
	return
	}

	// This method is guaranteed to be called on OsType specific variants before it is called
	// on their corresponding CommonOS variant.
	if !s.IsCommonOSVariant() {
	// Update the OsType specific sdk variant with information about its members.
	s.collectMembers(ctx)
	} else {
	// Get the OsType specific variants on which the CommonOS depends.
	osSpecificVariants := android.GetOsSpecificVariantsOfCommonOSVariant(ctx)
	var sdkVariants []*sdk
	for _, m := range osSpecificVariants {
	if sdkVariant, ok := m.(*sdk); ok {
	sdkVariants = append(sdkVariants, sdkVariant)
	}
	}

	// Generate the snapshot from the member info.
	p := s.buildSnapshot(ctx, sdkVariants)
	s.snapshotFile = android.OptionalPathForPath(p)
	ctx.InstallFile(android.PathForMainlineSdksInstall(ctx), s.Name()+"-current.zip", p)
	}
	}

	func (s *sdk) AndroidMkEntries() []android.AndroidMkEntries {
	if !s.snapshotFile.Valid() {
	return []android.AndroidMkEntries{}
	}

	return []android.AndroidMkEntries{android.AndroidMkEntries{
	Class: "FAKE",
	OutputFile: s.snapshotFile,
	DistFiles: android.MakeDefaultDistFiles(s.snapshotFile.Path()),
	Include: "$(BUILD_PHONY_PACKAGE)",
	ExtraFooters: []android.AndroidMkExtraFootersFunc{
	func(w io.Writer, name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
	// Allow the sdk to be built by simply passing its name on the command line.
	fmt.Fprintln(w, ".PHONY:", s.Name())
	fmt.Fprintln(w, s.Name()+":", s.snapshotFile.String())
	},
	},
	}}
	}

	// RegisterPreDepsMutators registers pre-deps mutators to support modules implementing SdkAware
	// interface and the sdk module type. This function has been made public to be called by tests
	// outside of the sdk package
	func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
	ctx.BottomUp("SdkMember", memberMutator).Parallel()
	ctx.TopDown("SdkMember_deps", memberDepsMutator).Parallel()
	ctx.BottomUp("SdkMemberInterVersion", memberInterVersionMutator).Parallel()
	}

	// RegisterPostDepsMutators registers post-deps mutators to support modules implementing SdkAware
	// interface and the sdk module type. This function has been made public to be called by tests
	// outside of the sdk package
	func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
	// These must run AFTER apexMutator. Note that the apex package is imported even though there is
	// no direct dependency to the package here. sdkDepsMutator sets the SDK requirements from an
	// APEX to its dependents. Since different versions of the same SDK can be used by different
	// APEXes, the apex and its dependents (which includes the dependencies to the sdk members)
	// should have been mutated for the apex before the SDK requirements are set.
	ctx.TopDown("SdkDepsMutator", sdkDepsMutator).Parallel()
	ctx.BottomUp("SdkDepsReplaceMutator", sdkDepsReplaceMutator).Parallel()
	ctx.TopDown("SdkRequirementCheck", sdkRequirementsMutator).Parallel()
	}

	type dependencyTag struct {
	blueprint.BaseDependencyTag
	}

	// Mark this tag so dependencies that use it are excluded from APEX contents.
	func (t dependencyTag) ExcludeFromApexContents() {}

	var _ android.ExcludeFromApexContentsTag = dependencyTag{}

	// For dependencies from an in-development version of an SDK member to frozen versions of the same member
	// e.g. libfoo -> libfoo.mysdk.11 and libfoo.mysdk.12
	type sdkMemberVersionedDepTag struct {
	dependencyTag
	member string
	version string
	}

	// Mark this tag so dependencies that use it are excluded from visibility enforcement.
	func (t sdkMemberVersionedDepTag) ExcludeFromVisibilityEnforcement() {}

	// Step 1: create dependencies from an SDK module to its members.
	func memberMutator(mctx android.BottomUpMutatorContext) {
	if s, ok := mctx.Module().(*sdk); ok {
	// Add dependencies from enabled and non CommonOS variants to the sdk member variants.
	if s.Enabled() && !s.IsCommonOSVariant() {
	for _, memberListProperty := range s.memberListProperties() {
	names := memberListProperty.getter(s.dynamicMemberTypeListProperties)
	if len(names) > 0 {
	tag := memberListProperty.dependencyTag
	memberListProperty.memberType.AddDependencies(mctx, tag, names)
	}
	}
	}
	}
	}

	// Step 2: record that dependencies of SDK modules are members of the SDK modules
	func memberDepsMutator(mctx android.TopDownMutatorContext) {
	if s, ok := mctx.Module().(*sdk); ok {
	mySdkRef := android.ParseSdkRef(mctx, mctx.ModuleName(), "name")
	if s.snapshot() && mySdkRef.Unversioned() {
	mctx.PropertyErrorf("name", "sdk_snapshot should be named as <name>@<version>. "+
	"Did you manually modify Android.bp?")
	}
	if !s.snapshot() && !mySdkRef.Unversioned() {
	mctx.PropertyErrorf("name", "sdk shouldn't be named as <name>@<version>.")
	}
	if mySdkRef.Version != "" && mySdkRef.Version != "current" {
	if _, err := strconv.Atoi(mySdkRef.Version); err != nil {
	mctx.PropertyErrorf("name", "version %q is neither a number nor \"current\"", mySdkRef.Version)
	}
	}

	mctx.VisitDirectDeps(func(child android.Module) {
	if member, ok := child.(android.SdkAware); ok {
	member.MakeMemberOf(mySdkRef)
	}
	})
	}
	}

	// Step 3: create dependencies from the unversioned SDK member to snapshot versions
	// of the same member. By having these dependencies, they are mutated for multiple Mainline modules
	// (apex and apk), each of which might want different sdks to be built with. For example, if both
	// apex A and B are referencing libfoo which is a member of sdk 'mysdk', the two APEXes can be
	// built with libfoo.mysdk.11 and libfoo.mysdk.12, respectively depending on which sdk they are
	// using.
	func memberInterVersionMutator(mctx android.BottomUpMutatorContext) {
	if m, ok := mctx.Module().(android.SdkAware); ok && m.IsInAnySdk() {
	if !m.ContainingSdk().Unversioned() {
	memberName := m.MemberName()
	tag := sdkMemberVersionedDepTag{member: memberName, version: m.ContainingSdk().Version}
	mctx.AddReverseDependency(mctx.Module(), tag, memberName)
	}
	}
	}

	// Step 4: transitively ripple down the SDK requirements from the root modules like APEX to its
	// descendants
	func sdkDepsMutator(mctx android.TopDownMutatorContext) {
	if parent, ok := mctx.Module().(interface {
	android.DepIsInSameApex
	android.RequiredSdks
	}); ok {
	// Module types for Mainline modules (e.g. APEX) are expected to implement RequiredSdks()
	// by reading its own properties like `uses_sdks`.
	requiredSdks := parent.RequiredSdks()
	if len(requiredSdks) > 0 {
	mctx.VisitDirectDeps(func(m android.Module) {
	// Only propagate required sdks from the apex onto its contents.
	if dep, ok := m.(android.SdkAware); ok && parent.DepIsInSameApex(mctx, dep) {
	dep.BuildWithSdks(requiredSdks)
	}
	})
	}
	}
	}

	// Step 5: if libfoo.mysdk.11 is in the context where version 11 of mysdk is requested, the
	// versioned module is used instead of the un-versioned (in-development) module libfoo
	func sdkDepsReplaceMutator(mctx android.BottomUpMutatorContext) {
	if versionedSdkMember, ok := mctx.Module().(android.SdkAware); ok && versionedSdkMember.IsInAnySdk() {
	if sdk := versionedSdkMember.ContainingSdk(); !sdk.Unversioned() {
	// Only replace dependencies to <sdkmember> with <sdkmember@required-version>
	// if the depending module requires it. e.g.
	// foo -> sdkmember
	// will be transformed to:
	// foo -> sdkmember@1
	// if and only if foo is a member of an APEX that requires version 1 of the
	// sdk containing sdkmember.
	memberName := versionedSdkMember.MemberName()

	// Replace dependencies on sdkmember with a dependency on the current module which
	// is a versioned prebuilt of the sdkmember if required.
	mctx.ReplaceDependenciesIf(memberName, func(from blueprint.Module, tag blueprint.DependencyTag, to blueprint.Module) bool {
	// from - foo
	// to - sdkmember
	replace := false
	if parent, ok := from.(android.RequiredSdks); ok {
	replace = parent.RequiredSdks().Contains(sdk)
	}
	return replace
	})
	}
	}
	}

	// Step 6: ensure that the dependencies outside of the APEX are all from the required SDKs
	func sdkRequirementsMutator(mctx android.TopDownMutatorContext) {
	if m, ok := mctx.Module().(interface {
	android.DepIsInSameApex
	android.RequiredSdks
	}); ok {
	requiredSdks := m.RequiredSdks()
	if len(requiredSdks) == 0 {
	return
	}
	mctx.VisitDirectDeps(func(dep android.Module) {
	tag := mctx.OtherModuleDependencyTag(dep)
	if tag == android.DefaultsDepTag {
	// dependency to defaults is always okay
	return
	}

	// Ignore the dependency from the unversioned member to any versioned members as an
	// apex that depends on the unversioned member will not also be depending on a versioned
	// member.
	if _, ok := tag.(sdkMemberVersionedDepTag); ok {
	return
	}

	// If the dep is outside of the APEX, but is not in any of the
	// required SDKs, we know that the dep is a violation.
	if sa, ok := dep.(android.SdkAware); ok {
	if !m.DepIsInSameApex(mctx, dep) && !requiredSdks.Contains(sa.ContainingSdk()) {
	mctx.ModuleErrorf("depends on %q (in SDK %q) that isn't part of the required SDKs: %v",
	sa.Name(), sa.ContainingSdk(), requiredSdks)
	}
	}
	})
	}
	}