Atomic swap (and monadic swap)

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/Utilities.ml b/lib/Utilities.ml
index 9ae0119..0a5bd9d 100644
--- a/lib/Utilities.ml
+++ b/lib/Utilities.ml
@@ -10,3 +10,20 @@ module Result = struct
                       ms
                       (Ok [])
 end
+
+module Atomic = struct
+  let rec swap atom f =
+    let v = Atomic.get atom in
+    let v' = f v in
+    if Atomic.compare_and_set atom v v'
+    then atom
+    else swap atom f
+
+  let rec mswap atom f =
+    let open Result in
+    let v = Atomic.get atom in
+    let* v' = f v in
+    if Atomic.compare_and_set atom v v'
+    then Ok atom
+    else mswap atom f
+end