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- // Copyright 2020 Google Inc. All rights reserved.
- //
- // 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
- import (
- "fmt"
- "sync"
- "github.com/google/blueprint"
- )
- // A SingletonModule is halfway between a Singleton and a Module. It has access to visiting
- // other modules via its GenerateSingletonBuildActions method, but must be defined in an Android.bp
- // file and can also be depended on like a module. It must be used zero or one times in an
- // Android.bp file, and it can only have a single variant.
- //
- // The SingletonModule's GenerateAndroidBuildActions method will be called before any normal or
- // singleton module that depends on it, but its GenerateSingletonBuildActions method will be called
- // after all modules, in registration order with other singletons and singleton modules.
- // GenerateAndroidBuildActions and GenerateSingletonBuildActions will not be called if the
- // SingletonModule was not instantiated in an Android.bp file.
- //
- // Since the SingletonModule rules likely depend on the modules visited during
- // GenerateSingletonBuildActions, the GenerateAndroidBuildActions is unlikely to produce any
- // rules directly. Instead, it will probably set some providers to paths that will later have rules
- // generated to produce them in GenerateSingletonBuildActions.
- //
- // The expected use case for a SingletonModule is a module that produces files that depend on all
- // modules in the tree and will be used by other modules. For example it could produce a text
- // file that lists all modules that meet a certain criteria, and that text file could be an input
- // to another module. Care must be taken that the ninja rules produced by the SingletonModule
- // don't produce a cycle by referencing output files of rules of modules that depend on the
- // SingletonModule.
- //
- // A SingletonModule must embed a SingletonModuleBase struct, and its factory method must be
- // registered with RegisterSingletonModuleType from an init() function.
- //
- // A SingletonModule can also implement SingletonMakeVarsProvider to export values to Make.
- type SingletonModule interface {
- Module
- GenerateSingletonBuildActions(SingletonContext)
- singletonModuleBase() *SingletonModuleBase
- }
- // SingletonModuleBase must be embedded into implementers of the SingletonModule interface.
- type SingletonModuleBase struct {
- ModuleBase
- lock sync.Mutex
- bp string
- variant string
- }
- // GenerateBuildActions wraps the ModuleBase GenerateBuildActions method, verifying it was only
- // called once to prevent multiple variants of a SingletonModule.
- func (smb *SingletonModuleBase) GenerateBuildActions(ctx blueprint.ModuleContext) {
- smb.lock.Lock()
- if smb.variant != "" {
- ctx.ModuleErrorf("GenerateAndroidBuildActions already called for variant %q, SingletonModules can only have one variant", smb.variant)
- }
- smb.variant = ctx.ModuleSubDir()
- smb.lock.Unlock()
- smb.ModuleBase.GenerateBuildActions(ctx)
- }
- // InitAndroidSingletonModule must be called from the SingletonModule's factory function to
- // initialize SingletonModuleBase.
- func InitAndroidSingletonModule(sm SingletonModule) {
- InitAndroidModule(sm)
- }
- // singletonModuleBase retrieves the embedded SingletonModuleBase from a SingletonModule.
- func (smb *SingletonModuleBase) singletonModuleBase() *SingletonModuleBase { return smb }
- // SingletonModuleFactory is a factory method that returns a SingletonModule.
- type SingletonModuleFactory func() SingletonModule
- // SingletonModuleFactoryAdaptor converts a SingletonModuleFactory into a SingletonFactory and a
- // ModuleFactory.
- func SingletonModuleFactoryAdaptor(name string, factory SingletonModuleFactory) (SingletonFactory, ModuleFactory) {
- // The sm variable acts as a static holder of the only SingletonModule instance. Calls to the
- // returned SingletonFactory and ModuleFactory lambdas will always return the same sm value.
- // The SingletonFactory is only expected to be called once, but the ModuleFactory may be
- // called multiple times if the module is replaced with a clone of itself at the end of
- // blueprint.ResolveDependencies.
- var sm SingletonModule
- s := func() Singleton {
- sm = factory()
- return &singletonModuleSingletonAdaptor{sm}
- }
- m := func() Module {
- if sm == nil {
- panic(fmt.Errorf("Singleton %q for SingletonModule was not instantiated", name))
- }
- // Check for multiple uses of a SingletonModule in a LoadHook. Checking directly in the
- // factory would incorrectly flag when the factory was called again when the module is
- // replaced with a clone of itself at the end of blueprint.ResolveDependencies.
- AddLoadHook(sm, func(ctx LoadHookContext) {
- smb := sm.singletonModuleBase()
- smb.lock.Lock()
- defer smb.lock.Unlock()
- if smb.bp != "" {
- ctx.ModuleErrorf("Duplicate SingletonModule %q, previously used in %s", name, smb.bp)
- }
- smb.bp = ctx.BlueprintsFile()
- })
- return sm
- }
- return s, m
- }
- // singletonModuleSingletonAdaptor makes a SingletonModule into a Singleton by translating the
- // GenerateSingletonBuildActions method to Singleton.GenerateBuildActions.
- type singletonModuleSingletonAdaptor struct {
- sm SingletonModule
- }
- // GenerateBuildActions calls the SingletonModule's GenerateSingletonBuildActions method, but only
- // if the module was defined in an Android.bp file.
- func (smsa *singletonModuleSingletonAdaptor) GenerateBuildActions(ctx SingletonContext) {
- if smsa.sm.singletonModuleBase().bp != "" {
- smsa.sm.GenerateSingletonBuildActions(ctx)
- }
- }
- func (smsa *singletonModuleSingletonAdaptor) MakeVars(ctx MakeVarsContext) {
- if smsa.sm.singletonModuleBase().bp != "" {
- if makeVars, ok := smsa.sm.(SingletonMakeVarsProvider); ok {
- makeVars.MakeVars(ctx)
- }
- }
- }
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