Revert "Use backoff to be sure to be in sync when we update sources (@…

…reynir)"

This reverts commit 37267b3.

mirage-crypto-rng.opam

@@ -18,7 +18,6 @@ depends: [
   "dune-configurator" {>= "2.0.0"}
   "duration"
   "logs"
-  "backoff"
   "mirage-crypto" {=version}
   "digestif" {>= "1.1.4"}
   "ounit2" {with-test}

rng/dune

@@ -1,5 +1,5 @@
 (library
  (name mirage_crypto_rng)
  (public_name mirage-crypto-rng)
- (libraries mirage-crypto backoff digestif)
+ (libraries mirage-crypto digestif)
  (private_modules entropy fortuna hmac_drbg rng))

rng/entropy.ml

@@ -55,15 +55,10 @@ let _sources = Atomic.make S.empty
 type source = Rng.source
 
 let register_source name =
-  let rec go backoff =
-    let seen = Atomic.get _sources in
-    let n = S.cardinal seen in
-    let source = (n, name) in
-    let after = S.add source (Atomic.get _sources) in
-    if Atomic.compare_and_set _sources seen after = false
-    then go (Backoff.once backoff)
-    else source in
-  go Backoff.default
+  let n = S.cardinal (Atomic.get _sources) in
+  let source = (n, name) in
+  Atomic.set _sources (S.add source (Atomic.get _sources));
+  source
 
 let id (idx, _) = idx