1 files changed, 172 insertions, 0 deletions
diff --git a/sdk/sdk.go b/sdk/sdk.go
new file mode 100644
index 000000000..fcb3fb7fe
--- /dev/null
+++ b/sdk/sdk.go
@@ -0,0 +1,172 @@
+// 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 (
+	"github.com/google/blueprint"
+
+	"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() {
+	android.RegisterModuleType("sdk", ModuleFactory)
+	android.PreDepsMutators(RegisterPreDepsMutators)
+	android.PostDepsMutators(RegisterPostDepsMutators)
+}
+
+type sdk struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	properties sdkProperties
+}
+
+type sdkProperties struct {
+	// The list of java_import modules that provide Java stubs for this SDK
+	Java_libs          []string
+	Native_shared_libs []string
+}
+
+// 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 ModuleFactory() android.Module {
+	s := &sdk{}
+	s.AddProperties(&s.properties)
+	android.InitAndroidMultiTargetsArchModule(s, android.HostAndDeviceSupported, android.MultilibCommon)
+	android.InitDefaultableModule(s)
+	return s
+}
+
+func (s *sdk) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// TODO(jiyong): add build rules for creating stubs from members of this SDK
+}
+
+// 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()
+}
+
+// RegisterPostDepshMutators 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()
+}
+
+type dependencyTag struct {
+	blueprint.BaseDependencyTag
+}
+
+// For dependencies from an SDK module to its members
+// e.g. mysdk -> libfoo and libbar
+var sdkMemberDepTag 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 sdkMemberVesionedDepTag struct {
+	dependencyTag
+	member  string
+	version string
+}
+
+// Step 1: create dependencies from an SDK module to its members.
+func memberMutator(mctx android.BottomUpMutatorContext) {
+	if m, ok := mctx.Module().(*sdk); ok {
+		mctx.AddVariationDependencies(nil, sdkMemberDepTag, m.properties.Java_libs...)
+
+		targets := mctx.MultiTargets()
+		for _, target := range targets {
+			mctx.AddFarVariationDependencies([]blueprint.Variation{
+				{Mutator: "arch", Variation: target.String()},
+				{Mutator: "image", Variation: "core"},
+				{Mutator: "link", Variation: "shared"},
+			}, sdkMemberDepTag, m.properties.Native_shared_libs...)
+		}
+	}
+}
+
+// Step 2: record that dependencies of SDK modules are members of the SDK modules
+func memberDepsMutator(mctx android.TopDownMutatorContext) {
+	if _, ok := mctx.Module().(*sdk); ok {
+		mySdkRef := android.ParseSdkRef(mctx, mctx.ModuleName(), "name")
+		mctx.VisitDirectDeps(func(child android.Module) {
+			if member, ok := child.(android.SdkAware); ok {
+				member.MakeMemberOf(mySdkRef)
+			}
+		})
+	}
+}
+
+// Step 3: create dependencies from the in-development version of an SDK member to frozen 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().IsCurrentVersion() {
+			memberName := m.MemberName()
+			tag := sdkMemberVesionedDepTag{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 m, ok := mctx.Module().(android.SdkAware); ok {
+		// Module types for Mainline modules (e.g. APEX) are expected to implement RequiredSdks()
+		// by reading its own properties like `uses_sdks`.
+		requiredSdks := m.RequiredSdks()
+		if len(requiredSdks) > 0 {
+			mctx.VisitDirectDeps(func(m android.Module) {
+				if dep, ok := m.(android.SdkAware); ok {
+					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 m, ok := mctx.Module().(android.SdkAware); ok && m.IsInAnySdk() {
+		if sdk := m.ContainingSdk(); !sdk.IsCurrentVersion() {
+			if m.RequiredSdks().Contains(sdk) {
+				// Note that this replacement is done only for the modules that have the same
+				// variations as the current module. Since current module is already mutated for
+				// apex references in other APEXes are not affected by this replacement.
+				memberName := m.MemberName()
+				mctx.ReplaceDependencies(memberName)
+			}
+		}
+	}
+}