wip: posix

nanoev-posix.opam

@@ -0,0 +1,32 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis: "Use mtime+iomux (posix compliant) as a backend for nanoev"
+maintainer: ["Simon Cruanes"]
+authors: ["Simon Cruanes"]
+license: "MIT"
+tags: ["unix" "select" "async" "iomux" "nanoev"]
+homepage: "https://github.com/c-cube/nanoev"
+bug-reports: "https://github.com/c-cube/nanoev/issues"
+depends: [
+  "ocaml"
+  "dune" {>= "2.7"}
+  "base-unix"
+  "iomux"
+  "mtime" {>= "2.0"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/c-cube/nanoev.git"

src/posix/dune

@@ -3,4 +3,4 @@
  (public_name nanoev-posix)
  (synopsis "posix backend (poll/ppoll+mtime)")
  (private_modules heap)
- (libraries nanoev unix iomux mtime mtime.clock.os))
+ (libraries threads nanoev unix iomux mtime mtime.clock.os))

src/posix/nanoev_posix.ml

@@ -18,11 +18,30 @@ module P = Iomux.Poll
 module Flags = P.Flags
 open Iomux.Util
 
+(* TODO: remove
+module Sync_queue = struct
+  type 'a t = {
+    q: 'a Queue.t;
+    mutex: Mutex.t;
+  }
+
+  let create () : _ t = { q = Queue.create (); mutex = Mutex.create () }
+
+  let push (self : _ t) x : unit =
+    Mutex.lock self.mutex;
+    Queue.push x self.q;
+    Mutex.unlock self.mutex
+end
+*)
+
 (** Callback list *)
 type cbs =
   | Nil
   | Sub : 'a * 'b * (closed:bool -> 'a -> 'b -> unit) * cbs -> cbs
 
+(** Single callback *)
+type cb = Cb : 'a * 'b * (closed:bool -> 'a -> 'b -> unit) -> cb
+
 let[@inline] cb_is_empty = function
   | Nil -> true
   | Sub _ -> false
@@ -38,25 +57,40 @@ type timer_ev =
 
 type per_fd = {
   fd: Unix.file_descr;
-  idx: int;  (** Index in the buffer *)
+  mutable idx: int;
+      (** Index in the buffer. Can change because we swap FDs sometimes to
+          remove items. *)
   mutable r: cbs;
   mutable w: cbs;
 }
 
+let[@inline] per_fd_flags (self : per_fd) : Flags.t =
+  let fl = ref Flags.empty in
+  (if self.r <> Nil then fl := Flags.(!fl + pollin));
+  (if self.w <> Nil then fl := Flags.(!fl + pollout));
+  !fl
+
+type queued_task =
+  | Q_timer of timer_ev
+  | Q_on_readable of Unix.file_descr * cb
+  | Q_on_writable of Unix.file_descr * cb
+  | Q_clear
+
 type st = {
   timer: timer_ev Heap.t;
   fds: per_fd Fd_tbl.t;
   poll: P.t;
-  mutable cur_idx: int;  (** index in the [poll] buffer *)
-  mutable idx_freelist: int list;
-      (** previously used indices that are recycled *)
+  mutable len: int;  (** length of the active prefix of the [poll] buffer *)
   wakeup_rd: Unix.file_descr;
   wakeup_wr: Unix.file_descr;
   wakeup_triggered: bool Atomic.t;
       (** Make [wakeup_from_outside] idempotent within an iteration of [step] *)
-  in_poll: bool Atomic.t;
-      (** Are we currently inside a call to [poll]? Useful for other threads to
-          know whether to wake us up via the pipe *)
+  in_poll: Thread.t option Atomic.t;
+      (** Are we currently inside a call to [poll], and in which thread? Useful
+          for other threads to know whether to wake us up via the pipe *)
+  queued_tasks: queued_task Queue.t;
+      (** While in [poll()], changes get queued, so we don't invalidate the poll
+          buffer before the syscall returns *)
   lock: Mutex.t;
 }
 
@@ -72,23 +106,7 @@ let rec perform_cbs_closed ~closed = function
     f ~closed x y;
     perform_cbs_closed ~closed tail
 
-let leq_timer (Timer a) (Timer b) = a.deadline <= b.deadline
-
-let create_st () : st =
-  let wakeup_rd, wakeup_wr = Unix.pipe () in
-  Unix.set_nonblock wakeup_rd;
-  {
-    timer = Heap.create ~leq:leq_timer ();
-    fds = Fd_tbl.create 16;
-    poll = P.create ();
-    cur_idx = 0;
-    idx_freelist = [];
-    wakeup_rd;
-    wakeup_wr;
-    wakeup_triggered = Atomic.make false;
-    in_poll = Atomic.make false;
-    lock = Mutex.create ();
-  }
+let[@inline] leq_timer (Timer a) (Timer b) = a.deadline <= b.deadline
 
 let[@inline] with_lock_ (self : st) f =
   Mutex.lock self.lock;
@@ -100,6 +118,24 @@ let[@inline] with_lock_ (self : st) f =
     Mutex.unlock self.lock;
     res
 
+let create_st () : st =
+  let wakeup_rd, wakeup_wr = Unix.pipe () in
+  Unix.set_nonblock wakeup_rd;
+  {
+    timer = Heap.create ~leq:leq_timer ();
+    fds = Fd_tbl.create 16;
+    poll = P.create ();
+    len = 0;
+    wakeup_rd;
+    wakeup_wr;
+    wakeup_triggered = Atomic.make false;
+    in_poll = Atomic.make None;
+    queued_tasks = Queue.create ();
+    lock = Mutex.create ();
+  }
+
+let max_fds (self : st) : int = P.maxfds self.poll
+
 let clear (self : st) =
   let@ self = with_lock_ self in
   Heap.clear self.timer;
@@ -107,8 +143,7 @@ let clear (self : st) =
   for i = 0 to P.maxfds self.poll - 1 do
     P.set_index self.poll i P.invalid_fd Flags.empty
   done;
-  self.cur_idx <- 0;
-  self.idx_freelist <- [];
+  self.len <- 0;
   ()
 
 let wakeup_from_outside (self : st) : unit =
@@ -124,36 +159,40 @@ let get_fd_ (self : st) fd : per_fd =
   | per_fd -> per_fd
   | exception Not_found ->
     let idx =
-      match self.idx_freelist with
-      | i :: tl ->
-        self.idx_freelist <- tl;
-        i
-      | [] ->
-        if self.cur_idx = P.maxfds self.poll then
-          invalid_arg "No available slot in poll";
-        let n = self.cur_idx in
-        self.cur_idx <- self.cur_idx + 1;
-        n
+      if self.len = P.maxfds self.poll then
+        invalid_arg "No available slot in poll";
+      let n = self.len in
+      self.len <- self.len + 1;
+      n
     in
     let per_fd = { idx; fd; r = Nil; w = Nil } in
     Fd_tbl.add self.fds fd per_fd;
     per_fd
 
-let close self fd : unit =
+let close_ (self : st) fd : unit =
   let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.close" in
   let r, w =
     let@ self = with_lock_ self in
     match Fd_tbl.find self.fds fd with
     | per_fd ->
       Fd_tbl.remove self.fds fd;
-      self.idx_freelist <- per_fd.idx :: self.idx_freelist;
-      if Atomic.get self.in_poll then wakeup_from_outside self;
+
+      (* not the last element, move the last element here *)
+      if per_fd.idx + 1 < self.len then (
+        let last_fd = P.get_fd self.poll (self.len - 1) in
+        match Fd_tbl.find_opt self.fds last_fd with
+        | None -> ()
+        | Some last_per_fd ->
+          last_per_fd.idx <- per_fd.idx;
+          P.set_index self.poll per_fd.idx last_fd (per_fd_flags last_per_fd)
+      );
+      self.len <- self.len - 1;
       per_fd.r, per_fd.w
     | exception Not_found ->
       invalid_arg "File descriptor is not known to Nanoev"
   in
 
-  (* call callbacks outside of the lock *)
+  (* call callbacks outside of the lock's critical section *)
   perform_cbs_closed ~closed:true r;
   perform_cbs_closed ~closed:true w;
   ()
@@ -282,6 +321,7 @@ let ops : st Nanoev.Impl.ops =
     on_readable;
     on_writable;
     run_after_s;
+    max_fds;
     wakeup_from_outside;
     clear;
   }