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
diff --git a/android/apex.go b/android/apex.go
index a93baf6..bf11ba2 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -139,6 +139,7 @@
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 @@
// 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)
}
diff --git a/android/api_levels.go b/android/api_levels.go
index 1b56625..51d4703 100644
--- a/android/api_levels.go
+++ b/android/api_levels.go
@@ -51,8 +51,10 @@
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,
diff --git a/android/arch.go b/android/arch.go
index 953e6cf..ad812a4 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -879,7 +879,7 @@
propertiesValue.Interface()))
}
- archPropTypes := archPropTypeMap.Once(t, func() interface{} {
+ archPropTypes := archPropTypeMap.Once(NewCustomOnceKey(t), func() interface{} {
return createArchType(t)
}).([]reflect.Type)
diff --git a/android/onceper.go b/android/onceper.go
index f19f75c..6160506 100644
--- a/android/onceper.go
+++ b/android/onceper.go
@@ -24,8 +24,6 @@
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 @@
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 @@
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 @@
}).(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}
+}
diff --git a/android/onceper_test.go b/android/onceper_test.go
new file mode 100644
index 0000000..d2ca9ad
--- /dev/null
+++ b/android/onceper_test.go
@@ -0,0 +1,135 @@
+// Copyright 2019 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 (
+ "testing"
+)
+
+func TestOncePer_Once(t *testing.T) {
+ once := OncePer{}
+ key := NewOnceKey("key")
+
+ a := once.Once(key, func() interface{} { return "a" }).(string)
+ b := once.Once(key, func() interface{} { return "b" }).(string)
+
+ if a != "a" {
+ t.Errorf(`first call to Once should return "a": %q`, a)
+ }
+
+ if b != "a" {
+ t.Errorf(`second call to Once with the same key should return "a": %q`, b)
+ }
+}
+
+func TestOncePer_Get(t *testing.T) {
+ once := OncePer{}
+ key := NewOnceKey("key")
+
+ a := once.Once(key, func() interface{} { return "a" }).(string)
+ b := once.Get(key).(string)
+
+ if a != "a" {
+ t.Errorf(`first call to Once should return "a": %q`, a)
+ }
+
+ if b != "a" {
+ t.Errorf(`Get with the same key should return "a": %q`, b)
+ }
+}
+
+func TestOncePer_Get_panic(t *testing.T) {
+ once := OncePer{}
+ key := NewOnceKey("key")
+
+ defer func() {
+ p := recover()
+
+ if p == nil {
+ t.Error("call to Get for unused key should panic")
+ }
+ }()
+
+ once.Get(key)
+}
+
+func TestOncePer_OnceStringSlice(t *testing.T) {
+ once := OncePer{}
+ key := NewOnceKey("key")
+
+ a := once.OnceStringSlice(key, func() []string { return []string{"a"} })
+ b := once.OnceStringSlice(key, func() []string { return []string{"a"} })
+
+ if a[0] != "a" {
+ t.Errorf(`first call to OnceStringSlice should return ["a"]: %q`, a)
+ }
+
+ if b[0] != "a" {
+ t.Errorf(`second call to OnceStringSlice with the same key should return ["a"]: %q`, b)
+ }
+}
+
+func TestOncePer_Once2StringSlice(t *testing.T) {
+ once := OncePer{}
+ key := NewOnceKey("key")
+
+ a, b := once.Once2StringSlice(key, func() ([]string, []string) { return []string{"a"}, []string{"b"} })
+ c, d := once.Once2StringSlice(key, func() ([]string, []string) { return []string{"c"}, []string{"d"} })
+
+ if a[0] != "a" || b[0] != "b" {
+ t.Errorf(`first call to Once2StringSlice should return ["a"], ["b"]: %q, %q`, a, b)
+ }
+
+ if c[0] != "a" || d[0] != "b" {
+ t.Errorf(`second call to Once2StringSlice with the same key should return ["a"], ["b"]: %q, %q`, c, d)
+ }
+}
+
+func TestNewOnceKey(t *testing.T) {
+ once := OncePer{}
+ key1 := NewOnceKey("key")
+ key2 := NewOnceKey("key")
+
+ a := once.Once(key1, func() interface{} { return "a" }).(string)
+ b := once.Once(key2, func() interface{} { return "b" }).(string)
+
+ if a != "a" {
+ t.Errorf(`first call to Once should return "a": %q`, a)
+ }
+
+ if b != "b" {
+ t.Errorf(`second call to Once with the NewOnceKey from same string should return "b": %q`, b)
+ }
+}
+
+func TestNewCustomOnceKey(t *testing.T) {
+ type key struct {
+ key string
+ }
+ once := OncePer{}
+ key1 := NewCustomOnceKey(key{"key"})
+ key2 := NewCustomOnceKey(key{"key"})
+
+ a := once.Once(key1, func() interface{} { return "a" }).(string)
+ b := once.Once(key2, func() interface{} { return "b" }).(string)
+
+ if a != "a" {
+ t.Errorf(`first call to Once should return "a": %q`, a)
+ }
+
+ if b != "a" {
+ t.Errorf(`second call to Once with the NewCustomOnceKey from equal key should return "a": %q`, b)
+ }
+}