internal/legacy: guarantee one-to-one generation of wrapper types
When concurrent requests to wrap a type occurs, it is possible that
two different descriptors are created for the same Go type.
Add sufficient synchronization to ensure that one descriptor is ever
returned for one Go type.
Change-Id: Idbbca4c1877a70317b39900ae83bfc3085d4a9c5
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/168398
Reviewed-by: Herbie Ong <herbie@google.com>
diff --git a/internal/legacy/enum.go b/internal/legacy/enum.go
index 98fd0fa..23eebd8 100644
--- a/internal/legacy/enum.go
+++ b/internal/legacy/enum.go
@@ -45,8 +45,10 @@
m.Store(n, e)
return e
})
- enumTypeCache.Store(t, et)
- return et.(pref.EnumType)
+ if et, ok := enumTypeCache.LoadOrStore(t, et); ok {
+ return et.(pref.EnumType)
+ }
+ return et
}
type enumWrapper struct {
@@ -83,8 +85,8 @@
// which must be an int32 kind and not implement the v2 API already.
func loadEnumDesc(t reflect.Type) pref.EnumDescriptor {
// Fast-path: check if an EnumDescriptor is cached for this concrete type.
- if v, ok := enumDescCache.Load(t); ok {
- return v.(pref.EnumDescriptor)
+ if ed, ok := enumDescCache.Load(t); ok {
+ return ed.(pref.EnumDescriptor)
}
// Slow-path: initialize EnumDescriptor from the proto descriptor.
@@ -157,6 +159,8 @@
if err != nil {
panic(err)
}
- enumDescCache.Store(t, ed)
+ if ed, ok := enumDescCache.LoadOrStore(t, ed); ok {
+ return ed.(pref.EnumDescriptor)
+ }
return ed
}