sync: add new Map method LoadAndDelete #33762
Description
Problem
It is not currently possible to determine if a value was deleted from a sync.Map. For example:
actual, ok := m.Load("key")
if ok {
m.Delete("key")
doSomething(actual)
}
This is not atomic in that another goroutine could Delete the value between Load and Delete and doSomething() would be called twice.
Previous issues #25396 and #23547 suggested modifying Delete signature which would break backwards compatibility.
Solution
Create a new function:
func DeleteWithLoad(key interface{}) (actual interface{}, deleted bool)
If the key is found in the map, this function would return the deleted value and true. If the value is not found, this would return nil, false. The above code would then become:
actual, deleted := m.DeleteWithLoad("key")
if deleted {
doSomething(actual)
}