| // 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 android | 
 |  | 
 | // This file contains all the foundation components for override modules and their base module | 
 | // types. Override modules are a kind of opposite of default modules in that they override certain | 
 | // properties of an existing base module whereas default modules provide base module data to be | 
 | // overridden. However, unlike default and defaultable module pairs, both override and overridable | 
 | // modules generate and output build actions, and it is up to product make vars to decide which one | 
 | // to actually build and install in the end. In other words, default modules and defaultable modules | 
 | // can be compared to abstract classes and concrete classes in C++ and Java. By the same analogy, | 
 | // both override and overridable modules act like concrete classes. | 
 | // | 
 | // There is one more crucial difference from the logic perspective. Unlike default pairs, most Soong | 
 | // actions happen in the base (overridable) module by creating a local variant for each override | 
 | // module based on it. | 
 |  | 
 | import ( | 
 | 	"sort" | 
 | 	"sync" | 
 |  | 
 | 	"github.com/google/blueprint" | 
 | 	"github.com/google/blueprint/proptools" | 
 | ) | 
 |  | 
 | // Interface for override module types, e.g. override_android_app, override_apex | 
 | type OverrideModule interface { | 
 | 	Module | 
 |  | 
 | 	getOverridingProperties() []interface{} | 
 | 	setOverridingProperties(properties []interface{}) | 
 |  | 
 | 	getOverrideModuleProperties() *OverrideModuleProperties | 
 |  | 
 | 	// Internal funcs to handle interoperability between override modules and prebuilts. | 
 | 	// i.e. cases where an overriding module, too, is overridden by a prebuilt module. | 
 | 	setOverriddenByPrebuilt(overridden bool) | 
 | 	getOverriddenByPrebuilt() bool | 
 | } | 
 |  | 
 | // Base module struct for override module types | 
 | type OverrideModuleBase struct { | 
 | 	moduleProperties OverrideModuleProperties | 
 |  | 
 | 	overridingProperties []interface{} | 
 |  | 
 | 	overriddenByPrebuilt bool | 
 | } | 
 |  | 
 | type OverrideModuleProperties struct { | 
 | 	// Name of the base module to be overridden | 
 | 	Base *string | 
 |  | 
 | 	// TODO(jungjw): Add an optional override_name bool flag. | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) getOverridingProperties() []interface{} { | 
 | 	return o.overridingProperties | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) setOverridingProperties(properties []interface{}) { | 
 | 	o.overridingProperties = properties | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) getOverrideModuleProperties() *OverrideModuleProperties { | 
 | 	return &o.moduleProperties | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) GetOverriddenModuleName() string { | 
 | 	return proptools.String(o.moduleProperties.Base) | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) setOverriddenByPrebuilt(overridden bool) { | 
 | 	o.overriddenByPrebuilt = overridden | 
 | } | 
 |  | 
 | func (o *OverrideModuleBase) getOverriddenByPrebuilt() bool { | 
 | 	return o.overriddenByPrebuilt | 
 | } | 
 |  | 
 | func InitOverrideModule(m OverrideModule) { | 
 | 	m.setOverridingProperties(m.GetProperties()) | 
 |  | 
 | 	m.AddProperties(m.getOverrideModuleProperties()) | 
 | } | 
 |  | 
 | // Interface for overridable module types, e.g. android_app, apex | 
 | type OverridableModule interface { | 
 | 	Module | 
 | 	moduleBase() *OverridableModuleBase | 
 |  | 
 | 	setOverridableProperties(prop []interface{}) | 
 |  | 
 | 	addOverride(o OverrideModule) | 
 | 	getOverrides() []OverrideModule | 
 |  | 
 | 	override(ctx BaseModuleContext, o OverrideModule) | 
 | 	GetOverriddenBy() string | 
 |  | 
 | 	setOverridesProperty(overridesProperties *[]string) | 
 |  | 
 | 	// Due to complications with incoming dependencies, overrides are processed after DepsMutator. | 
 | 	// So, overridable properties need to be handled in a separate, dedicated deps mutator. | 
 | 	OverridablePropertiesDepsMutator(ctx BottomUpMutatorContext) | 
 | } | 
 |  | 
 | type overridableModuleProperties struct { | 
 | 	OverriddenBy string `blueprint:"mutated"` | 
 | } | 
 |  | 
 | // Base module struct for overridable module types | 
 | type OverridableModuleBase struct { | 
 | 	// List of OverrideModules that override this base module | 
 | 	overrides []OverrideModule | 
 | 	// Used to parallelize registerOverrideMutator executions. Note that only addOverride locks this | 
 | 	// mutex. It is because addOverride and getOverride are used in different mutators, and so are | 
 | 	// guaranteed to be not mixed. (And, getOverride only reads from overrides, and so don't require | 
 | 	// mutex locking.) | 
 | 	overridesLock sync.Mutex | 
 |  | 
 | 	overridableProperties []interface{} | 
 |  | 
 | 	// If an overridable module has a property to list other modules that itself overrides, it should | 
 | 	// set this to a pointer to the property through the InitOverridableModule function, so that | 
 | 	// override information is propagated and aggregated correctly. | 
 | 	overridesProperty *[]string | 
 |  | 
 | 	overridableModuleProperties overridableModuleProperties | 
 | } | 
 |  | 
 | func InitOverridableModule(m OverridableModule, overridesProperty *[]string) { | 
 | 	m.setOverridableProperties(m.(Module).GetProperties()) | 
 | 	m.setOverridesProperty(overridesProperty) | 
 | 	m.AddProperties(&m.moduleBase().overridableModuleProperties) | 
 | } | 
 |  | 
 | func (o *OverridableModuleBase) moduleBase() *OverridableModuleBase { | 
 | 	return o | 
 | } | 
 |  | 
 | func (b *OverridableModuleBase) setOverridableProperties(prop []interface{}) { | 
 | 	b.overridableProperties = prop | 
 | } | 
 |  | 
 | func (b *OverridableModuleBase) addOverride(o OverrideModule) { | 
 | 	b.overridesLock.Lock() | 
 | 	b.overrides = append(b.overrides, o) | 
 | 	b.overridesLock.Unlock() | 
 | } | 
 |  | 
 | // Should NOT be used in the same mutator as addOverride. | 
 | func (b *OverridableModuleBase) getOverrides() []OverrideModule { | 
 | 	b.overridesLock.Lock() | 
 | 	sort.Slice(b.overrides, func(i, j int) bool { | 
 | 		return b.overrides[i].Name() < b.overrides[j].Name() | 
 | 	}) | 
 | 	b.overridesLock.Unlock() | 
 | 	return b.overrides | 
 | } | 
 |  | 
 | func (b *OverridableModuleBase) setOverridesProperty(overridesProperty *[]string) { | 
 | 	b.overridesProperty = overridesProperty | 
 | } | 
 |  | 
 | // Overrides a base module with the given OverrideModule. | 
 | func (b *OverridableModuleBase) override(ctx BaseModuleContext, o OverrideModule) { | 
 | 	for _, p := range b.overridableProperties { | 
 | 		for _, op := range o.getOverridingProperties() { | 
 | 			if proptools.TypeEqual(p, op) { | 
 | 				err := proptools.ExtendProperties(p, op, nil, proptools.OrderReplace) | 
 | 				if err != nil { | 
 | 					if propertyErr, ok := err.(*proptools.ExtendPropertyError); ok { | 
 | 						ctx.PropertyErrorf(propertyErr.Property, "%s", propertyErr.Err.Error()) | 
 | 					} else { | 
 | 						panic(err) | 
 | 					} | 
 | 				} | 
 | 			} | 
 | 		} | 
 | 	} | 
 | 	// Adds the base module to the overrides property, if exists, of the overriding module. See the | 
 | 	// comment on OverridableModuleBase.overridesProperty for details. | 
 | 	if b.overridesProperty != nil { | 
 | 		*b.overridesProperty = append(*b.overridesProperty, ctx.ModuleName()) | 
 | 	} | 
 | 	b.overridableModuleProperties.OverriddenBy = o.Name() | 
 | } | 
 |  | 
 | // GetOverriddenBy returns the name of the override module that has overridden this module. | 
 | // For example, if an override module foo has its 'base' property set to bar, then another local variant | 
 | // of bar is created and its properties are overriden by foo. This method returns bar when called from | 
 | // the new local variant. It returns "" when called from the original variant of bar. | 
 | func (b *OverridableModuleBase) GetOverriddenBy() string { | 
 | 	return b.overridableModuleProperties.OverriddenBy | 
 | } | 
 |  | 
 | func (b *OverridableModuleBase) OverridablePropertiesDepsMutator(ctx BottomUpMutatorContext) { | 
 | } | 
 |  | 
 | // Mutators for override/overridable modules. All the fun happens in these functions. It is critical | 
 | // to keep them in this order and not put any order mutators between them. | 
 | func RegisterOverridePostDepsMutators(ctx RegisterMutatorsContext) { | 
 | 	ctx.BottomUp("override_deps", overrideModuleDepsMutator).Parallel() | 
 | 	ctx.TopDown("register_override", registerOverrideMutator).Parallel() | 
 | 	ctx.BottomUp("perform_override", performOverrideMutator).Parallel() | 
 | 	// overridableModuleDepsMutator calls OverridablePropertiesDepsMutator so that overridable modules can | 
 | 	// add deps from overridable properties. | 
 | 	ctx.BottomUp("overridable_deps", overridableModuleDepsMutator).Parallel() | 
 | 	// Because overridableModuleDepsMutator is run after PrebuiltPostDepsMutator, | 
 | 	// prebuilt's ReplaceDependencies doesn't affect to those deps added by overridable properties. | 
 | 	// By running PrebuiltPostDepsMutator again after overridableModuleDepsMutator, deps via overridable properties | 
 | 	// can be replaced with prebuilts. | 
 | 	ctx.BottomUp("replace_deps_on_prebuilts_for_overridable_deps_again", PrebuiltPostDepsMutator).Parallel() | 
 | 	ctx.BottomUp("replace_deps_on_override", replaceDepsOnOverridingModuleMutator).Parallel() | 
 | } | 
 |  | 
 | type overrideBaseDependencyTag struct { | 
 | 	blueprint.BaseDependencyTag | 
 | } | 
 |  | 
 | var overrideBaseDepTag overrideBaseDependencyTag | 
 |  | 
 | // Adds dependency on the base module to the overriding module so that they can be visited in the | 
 | // next phase. | 
 | func overrideModuleDepsMutator(ctx BottomUpMutatorContext) { | 
 | 	if module, ok := ctx.Module().(OverrideModule); ok { | 
 | 		base := String(module.getOverrideModuleProperties().Base) | 
 | 		if !ctx.OtherModuleExists(base) { | 
 | 			ctx.PropertyErrorf("base", "%q is not a valid module name", base) | 
 | 			return | 
 | 		} | 
 | 		// See if there's a prebuilt module that overrides this override module with prefer flag, | 
 | 		// in which case we call HideFromMake on the corresponding variant later. | 
 | 		ctx.VisitDirectDepsWithTag(PrebuiltDepTag, func(dep Module) { | 
 | 			prebuilt, ok := dep.(PrebuiltInterface) | 
 | 			if !ok { | 
 | 				panic("PrebuiltDepTag leads to a non-prebuilt module " + dep.Name()) | 
 | 			} | 
 | 			if prebuilt.Prebuilt().UsePrebuilt() { | 
 | 				module.setOverriddenByPrebuilt(true) | 
 | 				return | 
 | 			} | 
 | 		}) | 
 | 		ctx.AddDependency(ctx.Module(), overrideBaseDepTag, *module.getOverrideModuleProperties().Base) | 
 | 	} | 
 | } | 
 |  | 
 | // Visits the base module added as a dependency above, checks the module type, and registers the | 
 | // overriding module. | 
 | func registerOverrideMutator(ctx TopDownMutatorContext) { | 
 | 	ctx.VisitDirectDepsWithTag(overrideBaseDepTag, func(base Module) { | 
 | 		if o, ok := base.(OverridableModule); ok { | 
 | 			o.addOverride(ctx.Module().(OverrideModule)) | 
 | 		} else { | 
 | 			ctx.PropertyErrorf("base", "unsupported base module type") | 
 | 		} | 
 | 	}) | 
 | } | 
 |  | 
 | // Now, goes through all overridable modules, finds all modules overriding them, creates a local | 
 | // variant for each of them, and performs the actual overriding operation by calling override(). | 
 | func performOverrideMutator(ctx BottomUpMutatorContext) { | 
 | 	if b, ok := ctx.Module().(OverridableModule); ok { | 
 | 		overrides := b.getOverrides() | 
 | 		if len(overrides) == 0 { | 
 | 			return | 
 | 		} | 
 | 		variants := make([]string, len(overrides)+1) | 
 | 		// The first variant is for the original, non-overridden, base module. | 
 | 		variants[0] = "" | 
 | 		for i, o := range overrides { | 
 | 			variants[i+1] = o.(Module).Name() | 
 | 		} | 
 | 		mods := ctx.CreateLocalVariations(variants...) | 
 | 		// Make the original variation the default one to depend on if no other override module variant | 
 | 		// is specified. | 
 | 		ctx.AliasVariation(variants[0]) | 
 | 		for i, o := range overrides { | 
 | 			mods[i+1].(OverridableModule).override(ctx, o) | 
 | 			if o.getOverriddenByPrebuilt() { | 
 | 				// The overriding module itself, too, is overridden by a prebuilt. Skip its installation. | 
 | 				mods[i+1].HideFromMake() | 
 | 			} | 
 | 		} | 
 | 	} else if o, ok := ctx.Module().(OverrideModule); ok { | 
 | 		// Create a variant of the overriding module with its own name. This matches the above local | 
 | 		// variant name rule for overridden modules, and thus allows ReplaceDependencies to match the | 
 | 		// two. | 
 | 		ctx.CreateLocalVariations(o.Name()) | 
 | 		// To allow dependencies to be added without having to know the above variation. | 
 | 		ctx.AliasVariation(o.Name()) | 
 | 	} | 
 | } | 
 |  | 
 | func overridableModuleDepsMutator(ctx BottomUpMutatorContext) { | 
 | 	if b, ok := ctx.Module().(OverridableModule); ok { | 
 | 		b.OverridablePropertiesDepsMutator(ctx) | 
 | 	} | 
 | } | 
 |  | 
 | func replaceDepsOnOverridingModuleMutator(ctx BottomUpMutatorContext) { | 
 | 	if b, ok := ctx.Module().(OverridableModule); ok { | 
 | 		if o := b.GetOverriddenBy(); o != "" { | 
 | 			// Redirect dependencies on the overriding module to this overridden module. Overriding | 
 | 			// modules are basically pseudo modules, and all build actions are associated to overridden | 
 | 			// modules. Therefore, dependencies on overriding modules need to be forwarded there as well. | 
 | 			ctx.ReplaceDependencies(o) | 
 | 		} | 
 | 	} | 
 | } | 
 |  | 
 | // ModuleNameWithPossibleOverride returns the name of the OverrideModule that overrides the current | 
 | // variant of this OverridableModule, or ctx.ModuleName() if this module is not an OverridableModule | 
 | // or if this variant is not overridden. | 
 | func ModuleNameWithPossibleOverride(ctx ModuleContext) string { | 
 | 	if overridable, ok := ctx.Module().(OverridableModule); ok { | 
 | 		if o := overridable.GetOverriddenBy(); o != "" { | 
 | 			return o | 
 | 		} | 
 | 	} | 
 | 	return ctx.ModuleName() | 
 | } |