P2p: implements peer swapping

scripts/launch-node.sh

@@ -27,7 +27,7 @@ node="$src_dir/tezos-node"
 cleanup () {
     set +e
     echo Cleaning up...
-#    rm -rf "$data_dir"
+    rm -rf "$data_dir"
 }
 trap cleanup EXIT INT
 

src/node/main/node_config_file.ml

@@ -72,6 +72,7 @@ let default_net_limits : P2p.limits = {
   known_peer_ids_history_size = 500 ;
   max_known_points = Some (400, 300) ;
   max_known_peer_ids = Some (400, 300) ;
+  swap_linger = 30. ;
 }
 
 let default_net = {
@@ -115,10 +116,11 @@ let limit : P2p.limits Data_encoding.t =
            incoming_message_queue_size ; outgoing_message_queue_size ;
            known_points_history_size ; known_peer_ids_history_size ;
            max_known_points ; max_known_peer_ids ;
+           swap_linger ;
          } ->
       ( ( authentification_timeout, min_connections, expected_connections,
           max_connections, backlog, max_incoming_connections,
-          max_download_speed, max_upload_speed) ,
+          max_download_speed, max_upload_speed, swap_linger) ,
         ( read_buffer_size, read_queue_size, write_queue_size,
           incoming_app_message_queue_size,
           incoming_message_queue_size, outgoing_message_queue_size,
@@ -127,7 +129,7 @@ let limit : P2p.limits Data_encoding.t =
         )))
     (fun ( ( authentification_timeout, min_connections, expected_connections,
              max_connections, backlog, max_incoming_connections,
-             max_download_speed, max_upload_speed) ,
+             max_download_speed, max_upload_speed, swap_linger) ,
            ( read_buffer_size, read_queue_size, write_queue_size,
              incoming_app_message_queue_size,
              incoming_message_queue_size, outgoing_message_queue_size,
@@ -141,10 +143,9 @@ let limit : P2p.limits Data_encoding.t =
         incoming_app_message_queue_size ;
         incoming_message_queue_size ; outgoing_message_queue_size ;
         known_points_history_size ; known_peer_ids_history_size ;
-        max_known_points ; max_known_peer_ids
+        max_known_points ; max_known_peer_ids ; swap_linger })
-      })
     (merge_objs
-       (obj8
+       (obj9
           (dft "authentification-timeout"
              float default_net_limits.authentification_timeout)
           (dft "min-connections" uint16
@@ -158,7 +159,8 @@ let limit : P2p.limits Data_encoding.t =
           (dft "max-incoming-connections" uint8
              default_net_limits.max_incoming_connections)
           (opt "max-download-speed" int31)
-          (opt "max-upload-speed" int31))
+          (opt "max-upload-speed" int31)
+          (dft "swap-linger" float default_net_limits.swap_linger))
        (obj10
           (dft "read-buffer-size" int31
              default_net_limits.read_buffer_size)

src/node/net/p2p.ml

@@ -66,6 +66,9 @@ type limits = {
   known_points_history_size : int ;
   max_known_peer_ids : (int * int) option ;
   max_known_points : (int * int) option ;
+
+  swap_linger : float ;
+
 }
 
 let create_scheduler limits =
@@ -100,6 +103,7 @@ let create_connection_pool config limits meta_cfg msg_cfg io_sched =
     known_points_history_size = limits.known_points_history_size ;
     max_known_points = limits.max_known_points ;
     max_known_peer_ids = limits.max_known_peer_ids ;
+    swap_linger = limits.swap_linger ;
   }
   in
   let pool =
@@ -130,7 +134,8 @@ let create_maintenance_worker limits pool disco =
       limits.max_connections
   in
   P2p_maintenance.run
-    ~connection_timeout:limits.authentification_timeout bounds pool disco
+    ~connection_timeout:limits.authentification_timeout
+    bounds pool disco
 
 let may_create_welcome_worker config limits pool =
   match config.listening_port with
@@ -190,14 +195,14 @@ module Real = struct
     P2p_io_scheduler.shutdown ~timeout:3.0 net.io_sched
 
   let connections { pool } () =
-    P2p_connection_pool.fold_connections pool
+    P2p_connection_pool.Connection.fold pool
       ~init:[] ~f:(fun _peer_id c acc -> c :: acc)
   let find_connection { pool } peer_id =
-    P2p_connection_pool.Peer_ids.find_connection pool peer_id
+    P2p_connection_pool.Connection.find_by_peer_id pool peer_id
   let connection_info _net conn =
-    P2p_connection_pool.connection_info conn
+    P2p_connection_pool.Connection.info conn
   let connection_stat _net conn =
-    P2p_connection_pool.connection_stat conn
+    P2p_connection_pool.Connection.stat conn
   let global_stat { pool } () =
     P2p_connection_pool.pool_stat pool
   let set_metadata { pool } conn meta =
@@ -209,12 +214,12 @@ module Real = struct
     P2p_connection_pool.read conn >>=? fun msg ->
     lwt_debug "message read from %a"
       Connection_info.pp
-      (P2p_connection_pool.connection_info conn) >>= fun () ->
+      (P2p_connection_pool.Connection.info conn) >>= fun () ->
     return msg
 
   let rec recv_any net () =
     let pipes =
-      P2p_connection_pool.fold_connections
+      P2p_connection_pool.Connection.fold
         net.pool ~init:[]
         ~f:begin fun _peer_id conn acc ->
         (P2p_connection_pool.is_readable conn >>= function
@@ -222,7 +227,7 @@ module Real = struct
           | Error _ -> Lwt_utils.never_ending) :: acc
       end in
     Lwt.pick (
-      ( P2p_connection_pool.PoolEvent.wait_new_connection net.pool >>= fun () ->
+      ( P2p_connection_pool.Pool_event.wait_new_connection net.pool >>= fun () ->
         Lwt.return_none )::
       pipes) >>= function
     | None -> recv_any net ()
@@ -231,12 +236,12 @@ module Real = struct
         | Ok msg ->
             lwt_debug "message read from %a"
               Connection_info.pp
-              (P2p_connection_pool.connection_info conn) >>= fun () ->
+              (P2p_connection_pool.Connection.info conn) >>= fun () ->
             Lwt.return (conn, msg)
         | Error _ ->
             lwt_debug "error reading message from %a"
               Connection_info.pp
-              (P2p_connection_pool.connection_info conn) >>= fun () ->
+              (P2p_connection_pool.Connection.info conn) >>= fun () ->
             Lwt_unix.yield () >>= fun () ->
             recv_any net ()
 
@@ -245,12 +250,12 @@ module Real = struct
     | Ok () ->
         lwt_debug "message sent to %a"
           Connection_info.pp
-          (P2p_connection_pool.connection_info conn) >>= fun () ->
+          (P2p_connection_pool.Connection.info conn) >>= fun () ->
         return ()
     | Error err ->
         lwt_debug "error sending message from %a: %a"
           Connection_info.pp
-          (P2p_connection_pool.connection_info conn)
+          (P2p_connection_pool.Connection.info conn)
           pp_print_error err >>= fun () ->
         Lwt.return (Error err)
 
@@ -259,12 +264,12 @@ module Real = struct
     | Ok v ->
         debug "message trysent to %a"
           Connection_info.pp
-          (P2p_connection_pool.connection_info conn) ;
+          (P2p_connection_pool.Connection.info conn) ;
         v
     | Error err ->
         debug "error trysending message to %a@ %a"
           Connection_info.pp
-          (P2p_connection_pool.connection_info conn)
+          (P2p_connection_pool.Connection.info conn)
           pp_print_error err ;
         false
 
@@ -273,10 +278,10 @@ module Real = struct
     debug "message broadcasted"
 
   let fold_connections { pool } ~init ~f =
-    P2p_connection_pool.fold_connections pool ~init ~f
+    P2p_connection_pool.Connection.fold pool ~init ~f
 
   let iter_connections { pool } f =
-    P2p_connection_pool.fold_connections pool
+    P2p_connection_pool.Connection.fold pool
       ~init:()
       ~f:(fun gid conn () -> f gid conn)
 
@@ -315,7 +320,7 @@ type ('msg, 'meta) t = {
   connection_info : ('msg, 'meta) connection -> Connection_info.t ;
   connection_stat : ('msg, 'meta) connection -> Stat.t ;
   global_stat : unit -> Stat.t ;
-  get_metadata : Peer_id.t -> 'meta option ;
+  get_metadata : Peer_id.t -> 'meta ;
   set_metadata : Peer_id.t -> 'meta -> unit ;
   recv : ('msg, 'meta) connection -> 'msg tzresult Lwt.t ;
   recv_any : unit -> (('msg, 'meta) connection * 'msg) Lwt.t ;
@@ -355,7 +360,7 @@ let create ~config ~limits meta_cfg msg_cfg =
     on_new_connection = Real.on_new_connection net ;
   }
 
-let faked_network = {
+let faked_network meta_config = {
   peer_id = Fake.id.peer_id ;
   maintain = Lwt.return ;
   roll = Lwt.return ;
@@ -365,7 +370,7 @@ let faked_network = {
   connection_info = (fun _ -> Fake.connection_info) ;
   connection_stat = (fun _ -> Fake.empty_stat) ;
   global_stat = (fun () -> Fake.empty_stat) ;
-  get_metadata = (fun _ -> None) ;
+  get_metadata = (fun _ -> meta_config.initial) ;
   set_metadata = (fun _ _ -> ()) ;
   recv = (fun _ -> Lwt_utils.never_ending) ;
   recv_any = (fun () -> Lwt_utils.never_ending) ;
@@ -402,6 +407,8 @@ module Raw = struct
   type 'a t = 'a P2p_connection_pool.Message.t =
     | Bootstrap
     | Advertise of P2p_types.Point.t list
+    | Swap_request of Point.t * Peer_id.t
+    | Swap_ack of Point.t * Peer_id.t
     | Message of 'a
     | Disconnect
   let encoding = P2p_connection_pool.Message.encoding
@@ -414,7 +421,7 @@ module RPC = struct
     | None -> Stat.empty
     | Some pool -> P2p_connection_pool.pool_stat pool
 
-  module Event = P2p_connection_pool.LogEvent
+  module Event = P2p_connection_pool.Log_event
 
   let watch net =
     match net.pool with
@@ -433,14 +440,14 @@ module RPC = struct
       | None -> None
       | Some pool ->
           map_option
-            (P2p_connection_pool.Peer_ids.find_connection pool peer_id)
+            (P2p_connection_pool.Connection.find_by_peer_id pool peer_id)
-            ~f:P2p_connection_pool.connection_info
+            ~f:P2p_connection_pool.Connection.info
 
     let kick net peer_id wait =
       match net.pool with
       | None -> Lwt.return_unit
       | Some pool ->
-          match P2p_connection_pool.Peer_ids.find_connection pool peer_id with
+          match P2p_connection_pool.Connection.find_by_peer_id pool peer_id with
           | None -> Lwt.return_unit
           | Some conn -> P2p_connection_pool.disconnect ~wait conn
 
@@ -448,10 +455,10 @@ module RPC = struct
       match net.pool with
       | None -> []
       | Some pool ->
-          P2p_connection_pool.fold_connections
+          P2p_connection_pool.Connection.fold
             pool ~init:[]
             ~f:begin fun _peer_id c acc ->
-              P2p_connection_pool.connection_info c :: acc
+              P2p_connection_pool.Connection.info c :: acc
             end
 
     let count net =
@@ -703,12 +710,11 @@ module RPC = struct
         | Disconnected -> Disconnected, None
       in
       let peer_id = Peer_info.peer_id i in
-      let meta = Peer_info.metadata i in
+      let score = Peer_ids.get_score pool peer_id in
-      let score = P2p_connection_pool.score pool meta in
       let stat =
-        match P2p_connection_pool.Peer_ids.find_connection pool peer_id with
+        match P2p_connection_pool.Connection.find_by_peer_id pool peer_id with
         | None -> Stat.empty
-        | Some conn -> P2p_connection_pool.connection_stat conn
+        | Some conn -> P2p_connection_pool.Connection.stat conn
       in Peer_info.{
           score ;
           trusted = trusted i ;

src/node/net/p2p.mli

@@ -122,6 +122,11 @@ type limits = {
   max_known_peer_ids : (int * int) option ;
   max_known_points : (int * int) option ;
   (** Optional limitation of internal hashtables (max, target) *)
+
+  swap_linger : float ;
+  (** Peer swapping does not occur more than once during a timespan of
+      [swap_linger] seconds. *)
+
 }
 
 type ('msg, 'meta) t
@@ -129,7 +134,7 @@ type ('msg, 'meta) net = ('msg, 'meta) t
 
 (** A faked p2p layer, which do not initiate any connection
     nor open any listening socket *)
-val faked_network : ('msg, 'meta) net
+val faked_network : 'meta meta_config -> ('msg, 'meta) net
 
 (** Main network initialisation function *)
 val create :
@@ -165,7 +170,7 @@ val connection_stat :
 val global_stat : ('msg, 'meta) net -> Stat.t
 
 (** Accessors for meta information about a global identifier *)
-val get_metadata : ('msg, 'meta) net -> Peer_id.t -> 'meta option
+val get_metadata : ('msg, 'meta) net -> Peer_id.t -> 'meta
 val set_metadata : ('msg, 'meta) net -> Peer_id.t -> 'meta -> unit
 
 (** Wait for a message from a given connection. *)
@@ -193,7 +198,7 @@ module RPC : sig
 
   val stat : ('msg, 'meta) net -> Stat.t
 
-  module Event = P2p_connection_pool.LogEvent
+  module Event = P2p_connection_pool.Log_event
 
   val watch : ('msg, 'meta) net -> Event.t Lwt_stream.t * Watcher.stopper
   val connect : ('msg, 'meta) net -> Point.t -> float -> unit tzresult Lwt.t
@@ -301,6 +306,8 @@ module Raw : sig
   type 'a t =
     | Bootstrap
     | Advertise of P2p_types.Point.t list
+    | Swap_request of Point.t * Peer_id.t
+    | Swap_ack of Point.t * Peer_id.t
     | Message of 'a
     | Disconnect
   val encoding: 'msg app_message_encoding list -> 'msg t Data_encoding.t

src/node/net/p2p_connection.ml

@@ -206,11 +206,16 @@ let authenticate
   return (info, (fd, info, cryptobox_data))
 
 type connection = {
+  id : int ;
   info : Connection_info.t ;
   fd : P2p_io_scheduler.connection ;
   cryptobox_data : Crypto.data ;
 }
 
+let next_conn_id =
+  let cpt = ref 0 in
+  fun () -> incr cpt ;!cpt
+
 module Reader = struct
 
   type 'msg t = {
@@ -349,6 +354,9 @@ type 'msg t = {
   writer : 'msg Writer.t ;
 }
 
+let equal { conn = { id = id1 } } { conn = { id = id2 } } = id1 = id2
+
+
 let pp ppf { conn } = Connection_info.pp ppf conn.info
 let info { conn } = conn.info
 
@@ -367,7 +375,7 @@ let accept
   end >>=? fun accepted ->
   fail_unless accepted Rejected >>=? fun () ->
   let canceler = Canceler.create () in
-  let conn = { fd ; info ; cryptobox_data } in
+  let conn = { id = next_conn_id (); fd ; info ; cryptobox_data } in
   let reader =
     Reader.run ?size:incoming_message_queue_size conn encoding canceler
   and writer =

src/node/net/p2p_connection.mli

@@ -36,6 +36,8 @@ type 'msg t
 (** Type of an accepted connection, parametrized by the type of
     messages exchanged between peers. *)
 
+val equal: 'mst t -> 'msg t -> bool
+
 val pp : Format.formatter -> 'msg t -> unit
 val info: 'msg t -> Connection_info.t
 

src/node/net/p2p_connection_pool.mli

@@ -108,6 +108,11 @@ type config = {
 
   max_known_peer_ids : (int * int) option ;
   (** Like [max_known_points], but for known peer_ids. *)
+
+  swap_linger : float ;
+  (** Peer swapping does not occur more than once during a timespan of
+      [spap_linger] seconds. *)
+
 }
 
 type 'meta meta_config = {
@@ -142,13 +147,12 @@ val pool_stat: ('msg, 'meta) pool -> Stat.t
 (** [pool_stat pool] is a snapshot of current bandwidth usage for the
     entire [pool]. *)
 
-val score: ('msg, 'meta) pool -> 'meta -> float
+val send_swap_request: ('msg, 'meta) pool -> unit
-(** [score pool meta] is the floating-point score of [meta] using
-    [pool]'s metrics. *)
 
 (** {2 Pool events} *)
 
-module PoolEvent : sig
+module Pool_event : sig
+
   val wait_too_few_connections: ('msg, 'meta) pool -> unit Lwt.t
   (** [wait_too_few_connections pool] is determined when the number of
       connections drops below the desired level. *)
@@ -164,54 +168,9 @@ module PoolEvent : sig
   val wait_new_connection: ('msg, 'meta) pool -> unit Lwt.t
   (** [wait_new_connection pool] is determined when a new connection is
       succesfully established in the pool. *)
+
 end
 
-module LogEvent : sig
-  type t =
-    (** Pool-level events *)
-
-    | Too_few_connections
-    | Too_many_connections
-
-    | New_point of Point.t
-    | New_peer of Peer_id.t
-
-    (** Connection-level events *)
-
-    | Incoming_connection of Point.t
-    (** We accept(2)-ed an incoming connection *)
-    | Outgoing_connection of Point.t
-    (** We connect(2)-ed to a remote endpoint *)
-    | Authentication_failed of Point.t
-    (** Remote point failed authentication *)
-
-    | Accepting_request of Point.t * Id_point.t * Peer_id.t
-    (** We accepted a connection after authentifying the remote peer. *)
-    | Rejecting_request of Point.t * Id_point.t * Peer_id.t
-    (** We rejected a connection after authentifying the remote peer. *)
-    | Request_rejected of Point.t * (Id_point.t * Peer_id.t) option
-    (** The remote peer rejected our connection. *)
-
-    | Connection_established of Id_point.t * Peer_id.t
-    (** We succesfully established a authentified connection. *)
-
-    | Disconnection of Peer_id.t
-    (** We decided to close the connection. *)
-    | External_disconnection of Peer_id.t
-    (** The connection was closed for external reason. *)
-
-    | Gc_points
-    (** Garbage collection of known point table has been triggered. *)
-    | Gc_peer_ids
-    (** Garbage collection of known peer_ids table has been triggered. *)
-
-  val encoding : t Data_encoding.t
-end
-
-val watch: ('msg, 'meta) pool -> LogEvent.t Lwt_stream.t * Watcher.stopper
-(** [watch pool] is a [stream, close] a [stream] of events and a
-    [close] function for this stream. *)
-
 (** {1 Connections management} *)
 
 type ('msg, 'meta) connection
@@ -245,18 +204,31 @@ val disconnect:
 (** [disconnect conn] cleanly closes [conn] and returns after [conn]'s
     internal worker has returned. *)
 
-val connection_info: ('msg, 'meta) connection -> Connection_info.t
+module Connection : sig
 
-val connection_stat:  ('msg, 'meta) connection -> Stat.t
+  val info: ('msg, 'meta) connection -> Connection_info.t
+
+  val stat:  ('msg, 'meta) connection -> Stat.t
   (** [stat conn] is a snapshot of current bandwidth usage for
       [conn]. *)
 
-val fold_connections:
+  val fold:
     ('msg, 'meta) pool ->
     init:'a ->
     f:(Peer_id.t ->  ('msg, 'meta) connection -> 'a -> 'a) ->
     'a
 
+  val list:
+    ('msg, 'meta) pool -> (Peer_id.t * ('msg, 'meta) connection) list
+
+  val find_by_point:
+    ('msg, 'meta) pool -> Point.t ->  ('msg, 'meta) connection option
+
+  val find_by_peer_id:
+    ('msg, 'meta) pool -> Peer_id.t ->  ('msg, 'meta) connection option
+
+end
+
 val on_new_connection:
   ('msg, 'meta) pool ->
   (Peer_id.t -> ('msg, 'meta) connection -> unit) -> unit
@@ -304,17 +276,14 @@ module Peer_ids : sig
   val info:
     ('msg, 'meta) pool -> Peer_id.t -> ('msg, 'meta) info option
 
-  val get_metadata: ('msg, 'meta) pool -> Peer_id.t -> 'meta option
+  val get_metadata: ('msg, 'meta) pool -> Peer_id.t -> 'meta
   val set_metadata: ('msg, 'meta) pool -> Peer_id.t -> 'meta -> unit
-  val get_score: ('msg, 'meta) pool -> Peer_id.t -> float option
+  val get_score: ('msg, 'meta) pool -> Peer_id.t -> float
 
   val get_trusted: ('msg, 'meta) pool -> Peer_id.t -> bool
   val set_trusted: ('msg, 'meta) pool -> Peer_id.t -> unit
   val unset_trusted: ('msg, 'meta) pool -> Peer_id.t -> unit
 
-  val find_connection:
-    ('msg, 'meta) pool -> Peer_id.t ->  ('msg, 'meta) connection option
-
   val fold_known:
     ('msg, 'meta) pool ->
     init:'a ->
@@ -342,9 +311,6 @@ module Points : sig
   val set_trusted: ('msg, 'meta) pool -> Point.t -> unit
   val unset_trusted: ('msg, 'meta) pool -> Point.t -> unit
 
-  val find_connection:
-    ('msg, 'meta) pool -> Point.t ->  ('msg, 'meta) connection option
-
   val fold_known:
     ('msg, 'meta) pool ->
     init:'a ->
@@ -359,6 +325,70 @@ module Points : sig
 
 end
 
+module Log_event : sig
+
+  type t =
+
+    (** Pool-level events *)
+
+    | Too_few_connections
+    | Too_many_connections
+
+    | New_point of Point.t
+    | New_peer of Peer_id.t
+
+    | Gc_points
+    (** Garbage collection of known point table has been triggered. *)
+    | Gc_peer_ids
+    (** Garbage collection of known peer_ids table has been triggered. *)
+
+    (** Connection-level events *)
+
+    | Incoming_connection of Point.t
+    (** We accept(2)-ed an incoming connection *)
+    | Outgoing_connection of Point.t
+    (** We connect(2)-ed to a remote endpoint *)
+    | Authentication_failed of Point.t
+    (** Remote point failed authentication *)
+
+    | Accepting_request of Point.t * Id_point.t * Peer_id.t
+    (** We accepted a connection after authentifying the remote peer. *)
+    | Rejecting_request of Point.t * Id_point.t * Peer_id.t
+    (** We rejected a connection after authentifying the remote peer. *)
+    | Request_rejected of Point.t * (Id_point.t * Peer_id.t) option
+    (** The remote peer rejected our connection. *)
+
+    | Connection_established of Id_point.t * Peer_id.t
+    (** We succesfully established a authentified connection. *)
+
+    | Swap_request_received of { source : Peer_id.t }
+    (** A swap request has been received. *)
+    | Swap_ack_received of { source : Peer_id.t }
+    (** A swap ack has been received *)
+    | Swap_request_sent of { source : Peer_id.t }
+    (** A swap request has been sent *)
+    | Swap_ack_sent of { source : Peer_id.t }
+    (** A swap ack has been sent *)
+    | Swap_request_ignored of { source : Peer_id.t }
+    (** A swap request has been ignored *)
+    | Swap_success of { source : Peer_id.t }
+    (** A swap operation has succeeded *)
+    | Swap_failure of { source : Peer_id.t }
+    (** A swap operation has failed *)
+
+    | Disconnection of Peer_id.t
+    (** We decided to close the connection. *)
+    | External_disconnection of Peer_id.t
+    (** The connection was closed for external reason. *)
+
+  val encoding : t Data_encoding.t
+
+end
+
+val watch: ('msg, 'meta) pool -> Log_event.t Lwt_stream.t * Watcher.stopper
+(** [watch pool] is a [stream, close] a [stream] of events and a
+    [close] function for this stream. *)
+
 (**/**)
 
 module Message : sig
@@ -366,6 +396,8 @@ module Message : sig
   type 'msg t =
     | Bootstrap
     | Advertise of Point.t list
+    | Swap_request of Point.t * Peer_id.t
+    | Swap_ack of Point.t * Peer_id.t
     | Message of 'msg
     | Disconnect
 

src/node/net/p2p_connection_pool_types.mli

@@ -133,6 +133,7 @@ module Point_info : sig
     }
 
     val encoding : t Data_encoding.t
+
   end
 
   val fold_events :

src/node/net/p2p_maintenance.ml

@@ -29,7 +29,7 @@ type 'meta t = {
   disco: P2p_discovery.t option ;
   just_maintained: unit Lwt_condition.t ;
   please_maintain: unit Lwt_condition.t ;
-  mutable worker : unit Lwt.t ;
+  mutable maintain_worker : unit Lwt.t ;
 }
 
 (** Select [expected] points amongst the disconnected known points.
@@ -37,6 +37,7 @@ type 'meta t = {
     failed after [start_time]. It first selects points with the oldest
     last tentative. *)
 let connectable st start_time expected =
+  let Pool pool = st.pool in
   let now = Time.now () in
   let module Bounded_point_info =
     Utils.Bounded(struct
@@ -49,9 +50,7 @@ let connectable st start_time expected =
         | Some t1, Some t2 -> Time.compare t2 t1
     end) in
   let acc = Bounded_point_info.create expected in
-  let Pool pool = st.pool in
+  P2p_connection_pool.Points.fold_known pool ~init:()
-  P2p_connection_pool.Points.fold_known
-    pool ~init:()
     ~f:begin fun point pi () ->
       match Point_info.State.get pi with
       | Disconnected -> begin
@@ -125,7 +124,7 @@ and too_few_connections st n_connected =
     P2p_connection_pool.broadcast_bootstrap_msg pool ;
     Lwt_utils.protect ~canceler:st.canceler begin fun () ->
       Lwt.pick [
-        P2p_connection_pool.PoolEvent.wait_new_peer pool ;
+        P2p_connection_pool.Pool_event.wait_new_peer pool ;
         Lwt_unix.sleep 5.0 (* TODO exponential back-off ??
                                    or wait for the existence of a
                                    non grey-listed peer ?? *)
@@ -139,7 +138,7 @@ and too_many_connections st n_connected =
   (* too many connections, start the russian roulette *)
   let to_kill = n_connected - st.bounds.max_target in
   lwt_debug "Too many connections, will kill %d" to_kill >>= fun () ->
-  snd @@ P2p_connection_pool.fold_connections pool
+  snd @@ P2p_connection_pool.Connection.fold pool
     ~init:(to_kill, Lwt.return_unit)
     ~f:(fun _ conn (i, t) ->
         if i = 0 then (0, t)
@@ -148,33 +147,43 @@ and too_many_connections st n_connected =
   maintain st
 
 let rec worker_loop st =
-  begin
   let Pool pool = st.pool in
+  begin
     Lwt_utils.protect ~canceler:st.canceler begin fun () ->
       Lwt.pick [
         Lwt_unix.sleep 120. ; (* every two minutes *)
         Lwt_condition.wait st.please_maintain ; (* when asked *)
-        P2p_connection_pool.PoolEvent.wait_too_few_connections pool ; (* limits *)
+        P2p_connection_pool.Pool_event.wait_too_few_connections pool ; (* limits *)
-        P2p_connection_pool.PoolEvent.wait_too_many_connections pool
+        P2p_connection_pool.Pool_event.wait_too_many_connections pool
       ] >>= fun () ->
       return ()
     end >>=? fun () ->
+    let n_connected = P2p_connection_pool.active_connections pool in
+    if n_connected < st.bounds.min_threshold
+       || st.bounds.max_threshold < n_connected then
       maintain st
+    else begin
+      P2p_connection_pool.send_swap_request pool ;
+      return ()
+    end
   end >>= function
   | Ok () -> worker_loop st
   | Error [Lwt_utils.Canceled] -> Lwt.return_unit
   | Error _ -> Lwt.return_unit
 
-let run ?(connection_timeout = 5.) bounds pool disco =
+let run ~connection_timeout bounds pool disco =
   let canceler = Canceler.create () in
   let st = {
-    canceler ; connection_timeout ;
+    canceler ;
-    bounds ; pool = Pool pool ; disco ;
+    connection_timeout ;
+    bounds ;
+    pool = Pool pool ;
+    disco ;
     just_maintained = Lwt_condition.create () ;
     please_maintain = Lwt_condition.create () ;
-    worker = Lwt.return_unit ;
+    maintain_worker = Lwt.return_unit ;
   } in
-  st.worker <-
+  st.maintain_worker <-
     Lwt_utils.worker "maintenance"
       (fun () -> worker_loop st)
       (fun () -> Canceler.cancel canceler) ;
@@ -185,8 +194,12 @@ let maintain { just_maintained ; please_maintain } =
   Lwt_condition.broadcast please_maintain () ;
   wait
 
-let shutdown { canceler ; worker ; just_maintained } =
+let shutdown {
+    canceler ;
+    maintain_worker ;
+    just_maintained } =
   Canceler.cancel canceler >>= fun () ->
-  worker >>= fun () ->
+  maintain_worker >>= fun () ->
   Lwt_condition.broadcast just_maintained () ;
   Lwt.return_unit
+

src/node/net/p2p_maintenance.mli

@@ -34,7 +34,7 @@ type 'meta t
 (** Type of a maintenance worker. *)
 
 val run:
-  ?connection_timeout:float ->
+  connection_timeout:float ->
   bounds ->
   ('msg, 'meta) P2p_connection_pool.t ->
   P2p_discovery.t option ->

src/node/shell/node.ml

@@ -70,7 +70,7 @@ let init_p2p net_params =
   match net_params with
   | None ->
       lwt_log_notice "P2P layer is disabled" >>= fun () ->
-      Lwt.return P2p.faked_network
+      Lwt.return (P2p.faked_network Distributed_db_metadata.cfg)
   | Some (config, limits) ->
       lwt_log_notice "bootstraping network..." >>= fun () ->
       P2p.create

test/test_p2p_connection_pool.ml

@@ -40,7 +40,7 @@ let rec connect ~timeout pool point =
   lwt_log_info "Connect to %a" Point.pp point >>= fun () ->
   P2p_connection_pool.connect pool point ~timeout >>= function
   | Error [P2p_connection_pool.Connected] -> begin
-      match P2p_connection_pool.Points.find_connection pool point with
+      match P2p_connection_pool.Connection.find_by_point pool point with
       | Some conn -> return conn
       | None -> failwith "Woops..."
     end
@@ -148,6 +148,7 @@ let make_net points repeat n =
     known_points_history_size = 100 ;
     max_known_points = None ;
     max_known_peer_ids = None ;
+    swap_linger = 0. ;
     } in
   Process.detach
     ~prefix:(Format.asprintf "%a " Peer_id.pp identity.peer_id)