Fix thread safety of debug raw value accumulator (#1337)

HISTORY.md

@@ -1,3 +1,8 @@
+# 0.40.16
+
+Fixed `Base.copy` for `VNTAccumulator` and `TSVNTAccumulator` to also copy the `acc.f` field, not just `acc.values`.
+This makes sure that the accumulator is thread-safe if `acc.f` contains some mutable state.
+
 # 0.40.15
 
 DynamicPPL now allows you to set the type that log-probabilities are initialised with, using the `DynamicPPL.set_logprob_type!` function.

Project.toml

@@ -1,6 +1,6 @@
 name = "DynamicPPL"
 uuid = "366bfd00-2699-11ea-058f-f148b4cae6d8"
-version = "0.40.15"
+version = "0.40.16"
 
 [deps]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"

src/accumulators/vnt.jl

@@ -59,7 +59,7 @@ end
 for acc_type in (:VNTAccumulator, :TSVNTAccumulator)
     @eval begin
         function Base.copy(acc::$acc_type{AccName}) where {AccName}
-            return $acc_type{AccName}(acc.f, copy(acc.values))
+            return $acc_type{AccName}(copy(acc.f), copy(acc.values))
         end
         accumulator_name(::$acc_type{AccName}) where {AccName} = AccName