From f40c418d0fa10a4fe854dfad2f29bd251eed8948 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gr=C3=A9goire=20Henry?= <gregoire.henry@ocamlpro.com>
Date: Wed, 8 Nov 2017 12:06:20 +0100
Subject: [PATCH] Distributed_db: remove the last "lol-object".

---
 src/node/shell/distributed_db_functors.ml | 75 ++++++++++++-----------
 1 file changed, 39 insertions(+), 36 deletions(-)

diff --git a/src/node/shell/distributed_db_functors.ml b/src/node/shell/distributed_db_functors.ml
index 984c613f5..60cda7335 100644
--- a/src/node/shell/distributed_db_functors.ml
+++ b/src/node/shell/distributed_db_functors.ml
@@ -7,6 +7,8 @@
 (*                                                                        *)
 (**************************************************************************)
 
+module Canceler = Lwt_utils.Canceler
+
 module type DISTRIBUTED_DB = sig
 
   type t
@@ -284,9 +286,20 @@ end = struct
   type param = Request.param
 
   type t = {
-    push_to_worker: event -> unit ;
-    cancel_worker: unit -> unit Lwt.t ;
-    worker: unit Lwt.t ;
+    param: Request.param ;
+    pending: status Table.t ;
+
+    queue: event Lwt_pipe.t ;
+    mutable events: event list Lwt.t ;
+
+    canceler: Canceler.t ;
+    mutable worker: unit Lwt.t ;
+  }
+
+  and status = {
+    peers: P2p.Peer_id.Set.t ;
+    next_request: float ;
+    delay: float ;
   }
 
   and event =
@@ -298,41 +311,27 @@ end = struct
     | Notify_unrequested of P2p.Peer_id.t * key
 
   let request t p k =
-    t.push_to_worker (Request (p, k))
+    assert (Lwt_pipe.push_now t.queue (Request (p, k)))
   let notify t p k =
     debug "push received %a from %a"
       Hash.pp k P2p.Peer_id.pp_short p ;
-    t.push_to_worker (Notify (p, k))
+    assert (Lwt_pipe.push_now t.queue (Notify (p, k)))
   let notify_cancelation t k =
     debug "push cancelation %a"
       Hash.pp k ;
-    t.push_to_worker (Notify_cancelation k)
+    assert (Lwt_pipe.push_now t.queue (Notify_cancelation k))
   let notify_invalid t p k =
     debug "push received invalid %a from %a"
       Hash.pp k P2p.Peer_id.pp_short p ;
-    t.push_to_worker (Notify_invalid (p, k))
+    assert (Lwt_pipe.push_now t.queue (Notify_invalid (p, k)))
   let notify_duplicate t p k =
     debug "push received duplicate %a from %a"
       Hash.pp k P2p.Peer_id.pp_short p ;
-    t.push_to_worker (Notify_duplicate (p, k))
+    assert (Lwt_pipe.push_now t.queue (Notify_duplicate (p, k)))
   let notify_unrequested t p k =
     debug "push received unrequested %a from %a"
       Hash.pp k P2p.Peer_id.pp_short p ;
-    t.push_to_worker (Notify_unrequested (p, k))
-
-  type worker_state = {
-    param: Request.param ;
-    pending: status Table.t ;
-    cancelation: unit -> unit Lwt.t ;
-    wait_events: unit -> event list Lwt.t ;
-    mutable events: event list Lwt.t ;
-  }
-
-  and status = {
-    peers: P2p.Peer_id.Set.t ;
-    next_request: float ;
-    delay: float ;
-  }
+    assert (Lwt_pipe.push_now t.queue (Notify_unrequested (p, k)))
 
   let compute_timeout state =
     let next =
@@ -412,16 +411,17 @@ end = struct
         Lwt.return_unit
 
   let rec worker_loop state =
-    let shutdown = state.cancelation ()
+    let shutdown = Canceler.cancelation state.canceler
     and timeout = compute_timeout state in
-    Lwt.choose [ (state.events >|= fun _ -> ()) ; timeout ; shutdown ] >>= fun () ->
+    Lwt.choose
+      [ (state.events >|= fun _ -> ()) ; timeout ; shutdown ] >>= fun () ->
     if Lwt.state shutdown <> Lwt.Sleep then
       lwt_debug "terminating" >>= fun () ->
       Lwt.return_unit
     else if Lwt.state state.events <> Lwt.Sleep then
       let now = Unix.gettimeofday () in
       state.events >>= fun events ->
-      state.events <- state.wait_events () ;
+      state.events <- Lwt_pipe.pop_all state.queue ;
       Lwt_list.iter_s (process_event state now) events >>= fun () ->
       worker_loop state
     else
@@ -465,19 +465,22 @@ end = struct
       worker_loop state
 
   let create param =
-    let cancelation, cancel_worker, _ = Lwt_utils.canceler () in
-    let push_to_worker, wait_events = Lwt_utils.queue () in
-    let pending = Table.create 17 in
-    let worker_state =
-      { cancelation ; wait_events ; pending ; param ; events = wait_events () } in
-    let worker =
+    let state = {
+      param ;
+      queue = Lwt_pipe.create () ;
+      pending = Table.create 17 ;
+      events = Lwt.return [] ;
+      canceler = Canceler.create () ;
+      worker = Lwt.return_unit ;
+    } in
+    state.worker <-
       Lwt_utils.worker "db_request_scheduler"
-        ~run:(fun () -> worker_loop worker_state)
-        ~cancel:cancel_worker in
-    { cancel_worker ; push_to_worker ; worker }
+        ~run:(fun () -> worker_loop state)
+        ~cancel:(fun () -> Canceler.cancel state.canceler) ;
+    state
 
   let shutdown s =
-    s.cancel_worker () >>= fun () ->
+    Canceler.cancel s.canceler >>= fun () ->
     s.worker
 
 end