package nanoev
Tiny event loop abstraction
Install
Dune Dependency
Authors
Maintainers
Sources
nanoev-0.1.tbz
sha256=2ec6b951b88383b3849240f7cd27e322797fc596dc0b3fc53e9c61b78bab6570
sha512=1e4fe800638102cc5bdcd404d2069f65bc34f429d0b9063c14b0ffebc20e9dad3beff49741304d4b57d98d1895f65ed903f4b11d224505d038fa2afb012d7d4f
doc/src/nanoev.unix/nanoev_unix.ml.html
Source file nanoev_unix.ml
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open struct module Trace_ = Nanoev.Trace_ let ( let@ ) = ( @@ ) let now_ : unit -> float = Unix.gettimeofday end (** Callback list *) type cbs = | Nil | Sub : 'a * 'b * (closed:bool -> 'a -> 'b -> unit) * cbs -> cbs let[@inline] cb_is_empty = function | Nil -> true | Sub _ -> false type timer_ev = | Timer : { deadline: float; x: 'a; y: 'b; f: 'a -> 'b -> unit; } -> timer_ev type per_fd = { fd: Unix.file_descr; mutable r: cbs; mutable w: cbs; } type st = { timer: timer_ev Heap.t; fds: (Unix.file_descr, per_fd) Hashtbl.t; mutable sub_r: Unix.file_descr list; mutable sub_w: Unix.file_descr list; mutable sub_up_to_date: bool; (** are [sub_r] and [sub_w] faithful reflections of [fds]? *) 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_select: bool Atomic.t; lock: Mutex.t; } let rec perform_cbs ~closed = function | Nil -> () | Sub (x, y, f, tail) -> f ~closed x y; perform_cbs ~closed tail let rec perform_cbs_closed ~closed = function | Nil -> () | Sub (x, y, f, tail) -> 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 = Hashtbl.create 16; sub_r = []; sub_w = []; sub_up_to_date = true; wakeup_rd; wakeup_wr; wakeup_triggered = Atomic.make false; in_select = Atomic.make false; lock = Mutex.create (); } let[@inline] with_lock_ (self : st) f = Mutex.lock self.lock; match f self with | exception e -> Mutex.unlock self.lock; raise e | res -> Mutex.unlock self.lock; res let clear (self : st) = let@ self = with_lock_ self in Heap.clear self.timer; Hashtbl.clear self.fds; self.sub_r <- []; self.sub_w <- []; self.sub_up_to_date <- true; () let wakeup_from_outside (self : st) : unit = if not (Atomic.exchange self.wakeup_triggered true) then let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.wakeup-from-outside" in let b = Bytes.make 1 '!' in ignore (Unix.write self.wakeup_wr b 0 1 : int) let get_fd_ (self : st) fd : per_fd = match Hashtbl.find self.fds fd with | per_fd -> per_fd | exception Not_found -> let per_fd = { fd; r = Nil; w = Nil } in Hashtbl.add self.fds fd per_fd; per_fd let close self fd : unit = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.close" in let r, w = let@ self = with_lock_ self in match Hashtbl.find self.fds fd with | per_fd -> Hashtbl.remove self.fds fd; self.sub_up_to_date <- false; if Atomic.get self.in_select then wakeup_from_outside self; 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 *) perform_cbs_closed ~closed:true r; perform_cbs_closed ~closed:true w; () let on_readable self fd x y f : unit = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.on-readable" in let@ self = with_lock_ self in let per_fd = get_fd_ self fd in per_fd.r <- Sub (x, y, f, per_fd.r); self.sub_up_to_date <- false; if Atomic.get self.in_select then wakeup_from_outside self let on_writable self fd x y f : unit = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.on-writable" in let@ self = with_lock_ self in let per_fd = get_fd_ self fd in per_fd.w <- Sub (x, y, f, per_fd.w); self.sub_up_to_date <- false; if Atomic.get self.in_select then wakeup_from_outside self let run_after_s self time x y f : unit = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.run-after-s" in let@ self = with_lock_ self in let deadline = now_ () +. time in Heap.insert self.timer (Timer { deadline; x; y; f }); if Atomic.get self.in_select then wakeup_from_outside self let recompute_if_needed (self : st) = if not self.sub_up_to_date then ( let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "recompute-if-needed" in self.sub_up_to_date <- true; self.sub_r <- []; self.sub_w <- []; Hashtbl.iter (fun fd per_fd -> if cb_is_empty per_fd.r && cb_is_empty per_fd.w then Hashtbl.remove self.fds fd; if not (cb_is_empty per_fd.r) then self.sub_r <- fd :: self.sub_r; if not (cb_is_empty per_fd.w) then self.sub_w <- fd :: self.sub_w) self.fds ) let next_deadline_ (self : st) : float option = match Heap.peek_min_exn self.timer with | exception Heap.Empty -> None | Timer t -> Some t.deadline let step (self : st) : unit = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.unix.step" in (* gather the subscriptions and timeout *) let now = now_ () in let timeout, sub_r, sub_w = let@ self = with_lock_ self in recompute_if_needed self; let timeout = match next_deadline_ self with | None -> 30. | Some d -> max 0. (d -. now) in timeout, self.sub_r, self.sub_w in (* run timers *) while if Heap.is_empty self.timer then false else ( let (Timer t) = Heap.peek_min_exn self.timer in if t.deadline <= now then ( ignore (Heap.pop_min_exn self.timer : timer_ev); t.f t.x t.y; true ) else false ) do () done; (* enter [select] *) Atomic.set self.in_select true; let r_reads, r_writes, _ = let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "select" ~data:(fun () -> [ "timeout", `Float timeout; "reads", `Int (List.length sub_r); "writes", `Int (List.length sub_w); ]) in Unix.select (self.wakeup_rd :: sub_r) sub_w [] timeout in Atomic.set self.in_select false; (* drain pipe *) if Atomic.exchange self.wakeup_triggered false then ( let b1 = Bytes.create 1 in while try Unix.read self.wakeup_rd b1 0 1 > 0 with _ -> false do () done ); (* gather the [per_fd] that are ready *) let ready_r = ref [] in let ready_w = ref [] in (* gather the [per_fd] that have updates *) (let@ self = with_lock_ self in if r_reads != [] || r_writes != [] then self.sub_up_to_date <- false; List.iter (fun fd -> if fd != self.wakeup_rd then ( let per_fd = Hashtbl.find self.fds fd in ready_r := per_fd :: !ready_r )) r_reads; List.iter (fun fd -> let per_fd = Hashtbl.find self.fds fd in ready_w := per_fd :: !ready_w) r_writes); (* call callbacks *) List.iter (fun fd -> perform_cbs ~closed:false fd.r; fd.r <- Nil) !ready_r; List.iter (fun fd -> perform_cbs ~closed:false fd.w; fd.w <- Nil) !ready_w; () (* limit for select is fixed and known *) let max_fds _ = 1024 let ops : st Nanoev.Impl.ops = { step; close; on_readable; on_writable; max_fds; run_after_s; wakeup_from_outside; clear; } include Nanoev let create () : t = Impl.build ops (create_st ())
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