Use backoff library

Author: polytypic

CHANGES.md

@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file.
 
 Next version:
 
+- Move `Backoff` module to its own `backoff` package (@lyrm, @polytypic)
 - Support padding to avoid false sharing (@polytypic)
 - Pass through `?timeoutf` to blocking operations on data structures
   (@polytypic)

dune-project

@@ -11,6 +11,7 @@
  (description "A software transactional memory (STM) implementation based on an atomic lock-free multi-word compare-and-set (MCAS) algorithm enhanced with read-only compare operations and ability to block awaiting for changes.")
  (depends 
   (ocaml (>= 4.13.0))
+  (backoff (>= 0.1.0))
   (domain-local-await (>= 0.2.0))
   (domain-local-timeout (>= 0.1.0))
   (multicore-magic (>= 1.0.0))

kcas.opam

@@ -15,6 +15,7 @@ bug-reports: "https://github.com/ocaml-multicore/kcas/issues"
 depends: [
   "dune" {>= "3.3"}
   "ocaml" {>= "4.13.0"}
+  "backoff" {>= "0.1.0"}
   "domain-local-await" {>= "0.2.0"}
   "domain-local-timeout" {>= "0.1.0"}
   "multicore-magic" {>= "1.0.0"}

src/kcas/backoff.ml

@@ -1,21 +1,12 @@
 (library
  (name kcas)
  (public_name kcas)
- (libraries domain-local-await domain-local-timeout multicore-magic))
-
-(rule
- (targets domain.ml)
- (deps domain.ocaml4.ml)
- (enabled_if
-  (< %{ocaml_version} 5.0.0))
- (action
-  (progn
-   (copy domain.ocaml4.ml domain.ml))))
+ (libraries domain-local-await domain-local-timeout backoff multicore-magic))
 
 (mdx
  (package kcas)
  (deps
   (package kcas))
  (preludes kcas.prelude.ml)
- (libraries kcas domain_shims)
+ (libraries kcas backoff domain_shims)
  (files kcas.mli))

src/kcas/backoff.mli

@@ -17,8 +17,6 @@ let fenceless_get = Atomic.get
 let fenceless_set = Atomic.set
 *)
 
-module Backoff = Backoff
-
 module Timeout = struct
   exception Timeout
 

src/kcas/domain.ocaml4.ml

@@ -101,8 +101,6 @@
     can skip over these.  The documentation links back to these modules where
     appropriate. *)
 
-module Backoff : module type of Backoff
-
 (** Timeout support. *)
 module Timeout : sig
   exception Timeout

src/kcas/dune

@@ -348,18 +348,6 @@ let test_post_commit () =
 
 (* *)
 
-let test_backoff () =
-  let b = Backoff.create ~lower_wait_log:5 ~upper_wait_log:6 () in
-  assert (Backoff.get_wait_log b = 5);
-  let b = Backoff.once b in
-  assert (Backoff.get_wait_log b = 6);
-  let b = Backoff.once b in
-  assert (Backoff.get_wait_log b = 6);
-  let b = Backoff.reset b in
-  assert (Backoff.get_wait_log b = 5)
-
-(* *)
-
 let test_blocking () =
   let state = Loc.make `Spawned in
   let await state' =
@@ -674,7 +662,6 @@ let () =
         [ Alcotest.test_case "" `Quick test_presort_and_is_in_log_xt ] );
       ("updates", [ Alcotest.test_case "" `Quick test_updates ]);
       ("post commit", [ Alcotest.test_case "" `Quick test_post_commit ]);
-      ("backoff", [ Alcotest.test_case "" `Quick test_backoff ]);
       ("blocking", [ Alcotest.test_case "" `Quick test_blocking ]);
       ( "no unnecessary wakeups",
         [ Alcotest.test_case "" `Quick test_no_unnecessary_wakeups ] );