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Commit 571cccfc authored by Colin Cross's avatar Colin Cross
Browse files

Prepare for a type-safe OnceKey 

Add an opaque OnceKey type and use it for all calls to Once in
build/soong.  A future patch will convert the arguments to
Once* to OnceKey once users outside build/soong have been updated.

Test: onceper_test.go
Change-Id: Ifcb338e6e603e804e507203c9508d30ffb2df966
parent 5cb5b093

Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -78,6 +78,7 @@ bootstrap_go_package { 
        "android/expand_test.go",

        "android/namespace_test.go",

        "android/neverallow_test.go",

        "android/onceper_test.go",

        "android/paths_test.go",

        "android/prebuilt_test.go",

        "android/prebuilt_etc_test.go",

android/apex.go

+2 −1
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ func (m *ApexModuleBase) CreateApexVariations(mctx BottomUpMutatorContext) []blu 


var apexData OncePer

var apexNamesMapMutex sync.Mutex

var apexNamesKey = NewOnceKey("apexNames")



// This structure maintains the global mapping in between modules and APEXes.

// Examples:
@@ -147,7 +148,7 @@ var apexNamesMapMutex sync.Mutex 
// apexNamesMap()["foo"]["bar"] == false: module foo is indirectly depended on by APEX bar

// apexNamesMap()["foo"]["bar"] doesn't exist: foo is not built for APEX bar

func apexNamesMap() map[string]map[string]bool {

	return apexData.Once("apexNames", func() interface{} {

	return apexData.Once(apexNamesKey, func() interface{} {

		return make(map[string]map[string]bool)

	}).(map[string]map[string]bool)

}

android/api_levels.go

+3 −1
Original line number Diff line number Diff line
@@ -51,8 +51,10 @@ func GetApiLevelsJson(ctx PathContext) WritablePath { 
	return PathForOutput(ctx, "api_levels.json")

}



var apiLevelsMapKey = NewOnceKey("ApiLevelsMap")



func getApiLevelsMap(config Config) map[string]int {

	return config.Once("ApiLevelsMap", func() interface{} {

	return config.Once(apiLevelsMapKey, func() interface{} {

		baseApiLevel := 9000

		apiLevelsMap := map[string]int{

			"G":     9,

android/arch.go

+1 −1
Original line number Diff line number Diff line
@@ -879,7 +879,7 @@ func InitArchModule(m Module) { 
				propertiesValue.Interface()))

		}



		archPropTypes := archPropTypeMap.Once(t, func() interface{} {

		archPropTypes := archPropTypeMap.Once(NewCustomOnceKey(t), func() interface{} {

			return createArchType(t)

		}).([]reflect.Type)

android/onceper.go

+22 −2
Original line number Diff line number Diff line
@@ -24,8 +24,6 @@ type OncePer struct { 
	valuesLock sync.Mutex

}



type valueMap map[interface{}]interface{}



// Once computes a value the first time it is called with a given key per OncePer, and returns the

// value without recomputing when called with the same key.  key must be hashable.

func (once *OncePer) Once(key interface{}, value func() interface{}) interface{} {
@@ -50,6 +48,8 @@ func (once *OncePer) Once(key interface{}, value func() interface{}) interface{} 
	return v

}



// Get returns the value previously computed with Once for a given key.  If Once has not been called for the given

// key Get will panic.

func (once *OncePer) Get(key interface{}) interface{} {

	v, ok := once.values.Load(key)

	if !ok {
@@ -59,10 +59,12 @@ func (once *OncePer) Get(key interface{}) interface{} { 
	return v

}



// OnceStringSlice is the same as Once, but returns the value cast to a []string

func (once *OncePer) OnceStringSlice(key interface{}, value func() []string) []string {

	return once.Once(key, func() interface{} { return value() }).([]string)

}



// OnceStringSlice is the same as Once, but returns two values cast to []string

func (once *OncePer) Once2StringSlice(key interface{}, value func() ([]string, []string)) ([]string, []string) {

	type twoStringSlice [2][]string

	s := once.Once(key, func() interface{} {
@@ -72,3 +74,21 @@ func (once *OncePer) Once2StringSlice(key interface{}, value func() ([]string, [ 
	}).(twoStringSlice)

	return s[0], s[1]

}



// OnceKey is an opaque type to be used as the key in calls to Once.

type OnceKey struct {

	key interface{}

}



// NewOnceKey returns an opaque OnceKey object for the provided key.  Two calls to NewOnceKey with the same key string

// DO NOT produce the same OnceKey object.

func NewOnceKey(key string) OnceKey {

	return OnceKey{&key}

}



// NewCustomOnceKey returns an opaque OnceKey object for the provided key.  The key can be any type that is valid as the

// key in a map, i.e. comparable.  Two calls to NewCustomOnceKey with key values that compare equal will return OnceKey

// objects that access the same value stored with Once.

func NewCustomOnceKey(key interface{}) OnceKey {

	return OnceKey{key}

}