Use select() instead of epoll()/poll()

OMakefile

@@ -1,13 +1,10 @@
 OCAMLPACKS[] = 
     unix
     str
-OCAML_CLIBS = ocamlepoll
 OCAMLCFLAGS += -g
 
 .DEFAULT: bot
 
-StaticCLibrary(ocamlepoll, epoll_wrapper)
-
 OCamlProgram(bot, bot irc command iobuf dispatch)
 
 section

dispatch.ml

@@ -1,6 +1,6 @@
-type event = Input | Priority | Output | Error | Hangup
+type event = Input | Output | Exception
 type timer_handler = float -> unit
-type fd_handler = Unix.file_descr -> event list -> unit
+type fd_handler = Unix.file_descr -> event -> unit
 
 module Timer =
   Set.Make (struct
@@ -15,9 +15,10 @@ module Fd_map =
             end)
 
 type t = {
-  e : Epoll.t;
+  read_fds : Unix.file_descr list ref;
-  fds : (fd_handler * event list) Fd_map.t ref;
+  write_fds : Unix.file_descr list ref;
-  numfds : int ref;
+  except_fds : Unix.file_descr list ref;
+  handlers : fd_handler Fd_map.t ref;
   timers : Timer.t ref;
 }
 
@@ -29,53 +30,52 @@ type t = {
 
 let timeout_fudge = 0.001
 
-let to_epoll = function
-  | Input -> Epoll.In
-  | Priority -> Epoll.Priority
-  | Output -> Epoll.Out
-  | Error -> Epoll.Error
-  | Hangup -> Epoll.Hangup
-
-let from_epoll = function
-  | Epoll.In -> Input
-  | Epoll.Priority -> Priority
-  | Epoll.Out -> Output
-  | Epoll.Error -> Error
-  | Epoll.Hangup -> Hangup
-
-let rec epoll_events_of_events = List.map to_epoll
-  
-let rec events_of_epoll_events = List.map from_epoll
-
 let create size =
-  {e = Epoll.create size;
+  {read_fds = ref [];
-   fds = ref Fd_map.empty;
+   write_fds = ref [];
-   numfds = ref 0;
+   except_fds = ref [];
+   handlers = ref Fd_map.empty;
    timers = ref Timer.empty}
 
 let destroy d =
-  Epoll.destroy d.e;
   (* Explicitly unreference fds and timers, in case d sticks around *)
-  d.fds := Fd_map.empty;
+  d.handlers := Fd_map.empty;
-  d.numfds := 0;
   d.timers := Timer.empty
 
-let add d fd handler events =
+let get_fds d event =
-  Epoll.ctl d.e Epoll.Add (fd, (epoll_events_of_events events));
+  match event with
-  d.fds := Fd_map.add fd (handler, events) !(d.fds);
+    | Input -> d.read_fds
-  d.numfds := !(d.numfds) + 1
+    | Output -> d.write_fds
+    | Exception -> d.except_fds
 
 let modify d fd events =
-  Epoll.ctl d.e Epoll.Modify (fd, (epoll_events_of_events events))
+  let add_event event =
+    let l = get_fds d event in
+    let nl = (List.filter ((<>) fd) !l) in
+      if List.mem event events then
+        l := fd :: nl
+      else
+        l := nl
+  in
+    if Fd_map.mem fd !(d.handlers) then
+      List.iter add_event [Input; Output; Exception]
+    else
+      raise Not_found
 
 let set_handler d fd handler =
-  let (_, events) = Fd_map.find fd !(d.fds) in
+  d.handlers := Fd_map.add fd handler !(d.handlers)
-    d.fds := Fd_map.add fd (handler, events) !(d.fds)
+
+let add d fd handler events =
+  set_handler d fd handler;
+  modify d fd events
 
 let delete d fd =
-  Epoll.ctl d.e Epoll.Delete (fd, []);
+  let del_event event =
-  d.fds := Fd_map.remove fd !(d.fds);
+    let l = get_fds d event in
-  d.numfds := !(d.numfds) - 1
+      l := (List.filter ((<>) fd) !l)
+  in
+    d.handlers := Fd_map.remove fd !(d.handlers);
+    List.iter del_event [Input; Output; Exception]
 
 let add_timer d handler time =
   d.timers := Timer.add (time, handler) !(d.timers)
@@ -98,15 +98,19 @@ let rec dispatch_timers d now =
         dispatch_timers d now
       end
 
-let rec dispatch_results d events_list =
+let rec dispatch_results d (read_ready, write_ready, except_ready) =
-  match events_list with
+  let rec dispatch event fd_list =
+    match fd_list with
       | [] ->
           ()
-    | (fd, epoll_events) :: tl ->
+      | fd :: tl ->
-        let handler, _ = Fd_map.find fd !(d.fds) in
+          let handler = Fd_map.find fd !(d.handlers) in
-        let events = events_of_epoll_events epoll_events in
+            handler fd event;
-          handler fd events;
+            dispatch event tl
-          dispatch_results d tl
+  in
+    dispatch Input read_ready;
+    dispatch Output write_ready;
+    dispatch Exception except_ready
 
 let once d =
   let now = Unix.gettimeofday () in
@@ -118,19 +122,16 @@ let once d =
     with Not_found ->
       (-1.0)
   in
-    (if !(d.numfds) = 0 then
+    (* select () waits *at most* timeout ms.  If you have fds but they're
-       (* epoll()--and probably poll()--barfs if it has no file descriptors *)
+not
-       ignore (Unix.select [] [] [] timeout)
+       doing anything, multiple calls to once may be required.  This is
-     else
+       lame. *)
-       (* poll() and epoll() wait *at most* timeout ms.  If you have fds but they're not
+  let result = Unix.select !(d.read_fds) !(d.write_fds) !(d.except_fds) timeout in
-	  doing anything, multiple calls to once may be required.  This is lame. *)
+    dispatch_results d result;
-       let timeout_ms = int_of_float (timeout *. 1000.0) in
-       let result = Epoll.wait d.e !(d.numfds) timeout_ms in
-	 dispatch_results d result);
     dispatch_timers d (Unix.gettimeofday ())
 
 let rec run d =    
-  if ((!(d.fds) == Fd_map.empty) &&
+  if ((!(d.handlers) == Fd_map.empty) &&
         (!(d.timers) == Timer.empty)) then
     ()
   else begin

dispatch.mli

@@ -1,18 +1,18 @@
 type t
 (** The type of event dispatchers *)
 
-type event = Input | Priority | Output | Error | Hangup
+type event = Input | Output | Exception
 (** An event associated with a file descriptor *)
 
-type fd_handler = Unix.file_descr -> event list -> unit
+type fd_handler = Unix.file_descr -> event -> unit
-(** [fd_handler d fd evt] handles an [event] generated by dispatcher [d] *)
+(** [fd_handler fd evt] handles event [evt] from file descriptor [fd] *)
 
 type timer_handler = float -> unit
-(** [timer_handler d when] is called at or after [when] by dispatcher [d] *)
+(** [timer_handler d when] is called at or after [when] *)
 
 val create : int -> t
-(** Create a new event dispatcher, preallocating [size] fd events.  [size]
+(** Create a new event dispatcher, preallocating [size] fd events.
-    is just a hint, the fd list will grow on demand. *)
+    [size] is just a hint, the fd list will grow on demand. *)
 
 val destroy : t -> unit
 (** Destroy an event dispatcher *)

epoll.mli

@@ -1,33 +0,0 @@
-(*
- * OCaml epoll() interface
- * Author: Neale Pickett <neale@woozle.org>
- * Time-stamp: <2008-03-14 11:49:20 neale>
- *)
-
-(**
- * This module provides an interface to epoll() on Linux, or poll() on
- * everything else.
- *)
-
-type t
-
-type event = In | Priority | Out | Error | Hangup
-  (** Event types, mirroring poll() and epoll() event constants. *)
-
-type op = Add | Modify | Delete
-  (** Operations for ctl *)
-
-external create : int -> t = "ocaml_epoll_create"
-  (** Create a new poll structure *)
-
-external destroy : t -> unit = "ocaml_epoll_destroy"
-  (** Destroy a poll structure *)
-
-external ctl : t -> op -> (Unix.file_descr * event list) -> unit = "ocaml_epoll_ctl"
-  (** Add, Modify, or Delete an event list *)
-
-external wait : t -> int -> int -> (Unix.file_descr * event list) list = "ocaml_epoll_wait"
-(** [wait e maxevents timeout] returns a list of at most [maxevents]
-    (file descriptor * event list)s that occurred before at least
-    [timeout] milliseconds elapsed.
- *)

epoll_wrapper.c

@@ -1,415 +0,0 @@
-/** OCaml poll() interface
- *
- * Time-stamp: <2008-03-12 23:20:54 neale>
- *
- * Copyright (C) 2008 Neale Pickett
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-
-#include <caml/mlvalues.h>
-#include <caml/fail.h>
-#include <caml/custom.h>
-#include <caml/memory.h>
-#include <caml/alloc.h>
-
-#ifdef __linux
-#  include <sys/epoll.h>
-#  define EPOLL
-#else
-#  include <poll.h>
-#  undef EPOLL
-#  define EPOLLIN POLLIN
-#  define EPOLLPRI POLLPRI
-#  define EPOLLOUT POLLOUT
-#  define EPOLLERR POLLERR
-#  define EPOLLHUP POLLHUP
-#endif
-
-#include <stdio.h>
-#include <errno.h>
-#include <stdlib.h>
-
-#define puke()                                                          \
-  {                                                                     \
-    char errstr[512];                                                   \
-    snprintf(errstr, sizeof(errstr), "%s: %s", __FUNCTION__, strerror(errno)); \
-    caml_failwith(errstr);                                              \
-  }
-
-enum {
-  caml_POLLIN,
-  caml_POLLPRI,
-  caml_POLLOUT,
-  caml_POLLERR,
-  caml_POLLHUP
-};
-
-enum {
-  caml_POLL_ADD,
-  caml_POLL_MOD,
-  caml_POLL_DEL
-};
-
-
-static int
-list_length(value list)
-{
-  CAMLparam1(list);
-  CAMLlocal1(l);
-
-  int   len = 0;
-
-  for (l = list; l != Val_int(0); l = Field(l, 1)) {
-    len += 1;
-  }
-  CAMLreturn(len);
-}
-
-static int
-int_of_event_list(value list)
-{
-  CAMLparam1(list);
-  CAMLlocal1(l);
-
-  int acc = 0;
-
-  for (l = list; l != Val_int(0); l = Field(l, 1)) {
-    switch (Int_val(Field(l, 0))) {
-      case caml_POLLIN:
-        acc |= EPOLLIN;
-        break;
-      case caml_POLLPRI:
-        acc |= EPOLLPRI;
-        break;
-      case caml_POLLOUT:
-        acc |= EPOLLOUT;
-        break;
-      case caml_POLLERR:
-        acc |= EPOLLERR;
-        break;
-      case caml_POLLHUP:
-        acc |= EPOLLHUP;
-        break;
-    }
-  }
-  CAMLreturn(acc);
-}
-
-static value
-cons(value item, value list)
-{
-  CAMLparam2(item, list);
-  CAMLlocal1(new);
-
-  new = alloc_small(2, 0);
-
-  Field(new, 0) = item;
-  Field(new, 1) = list;
-  CAMLreturn(new);
-}
-
-static value
-event_list_of_int(int events)
-{
-  CAMLparam0();
-  CAMLlocal1(result);
-
-  result = Val_int(0);
-
-  /* Do these in reverse order since we're prepending to the list */
-  if (events & EPOLLHUP) {
-    result = cons(Val_int(caml_POLLHUP), result);
-  }
-  if (events & EPOLLERR) {
-    result = cons(Val_int(caml_POLLERR), result);
-  }
-  if (events & EPOLLOUT) {
-    result = cons(Val_int(caml_POLLOUT), result);
-  }
-  if (events & EPOLLPRI) {
-    result = cons(Val_int(caml_POLLPRI), result);
-  }
-  if (events & EPOLLIN) {
-    result = cons(Val_int(caml_POLLIN), result);
-  }
-  CAMLreturn(result);
-}
-
-#ifdef EPOLL
-/********************************************************************************
- *
- * epoll()
- *
- ********************************************************************************/
-
-CAMLprim value
-ocaml_epoll_create(value size)
-{
-  CAMLparam1(size);
-  CAMLlocal1(result);
-
-  int            ret;
-
-  ret = epoll_create(Int_val(size));
-  if (-1 == ret) {
-    puke();
-  }
-
-  result = Val_int(ret);
-  CAMLreturn(result);
-}
-
-CAMLprim value
-ocaml_epoll_destroy(value t)
-{
-  CAMLparam1(t);
-
-  int            ret;
-
-  ret = close(Int_val(t));
-  if (-1 == ret) {
-    puke();
-  }
-  CAMLreturn(Val_unit);
-}
-
-/* There are three reasons why I can't store a continuation or any other
- * complex type in evt.data:
- *
- * 1. GC might blow them away
- * 2. Heap compaction might move them
- * 3. The kernel can remove events from its internal table without
- *    telling us (this is why there's no EPOLLNVAL)
- *
- * 1 and 2 can be solved by calling caml_register_global_root for each
- * continuation, but this does not solve 3.  So you get file
- * descriptors.  You can make a nice record type and wrap a Set around
- * it. */
-CAMLprim value
-ocaml_epoll_ctl(value t, value op, value what)
-{
-  CAMLparam3(t, op, what);
-
-  int                 op_;
-  int                 fd;
-  struct epoll_event  evt;
-  int                 ret;
-
-  switch (Int_val(op)) {
-    case caml_POLL_ADD:
-      op_ = EPOLL_CTL_ADD;
-      break;
-    case caml_POLL_MOD:
-      op_ = EPOLL_CTL_MOD;
-      break;
-    case caml_POLL_DEL:
-      op_ = EPOLL_CTL_DEL;
-      break;
-  }
-  fd = Int_val(Field(what, 0));
-  evt.events = int_of_event_list(Field(what, 1));
-  evt.data.fd = fd;
-
-  ret = epoll_ctl(Int_val(t), op_, fd, &evt);
-  if (-1 == ret) {
-    puke();
-  }
-
-  CAMLreturn(Val_unit);
-}
-
-CAMLprim value
-ocaml_epoll_wait(value t, value maxevents, value timeout)
-{
-  CAMLparam2(t, timeout);
-  CAMLlocal2(result, item);
-
-  int                maxevents_ = Int_val(maxevents);
-  struct epoll_event events[maxevents_];
-  int                i;
-  int                ret;
-
-  caml_enter_blocking_section();
-  ret = epoll_wait(Int_val(t), events, maxevents_, Int_val(timeout));
-  caml_leave_blocking_section();
-  if (-1 == ret) {
-    puke();
-  }
-
-  result = Val_int(0);
-  for (i = 0; i < ret; i += 1) {
-    item = alloc_small(2,0);
-    Field(item, 0) = Val_int(events[i].data.fd);
-    Field(item, 1) = event_list_of_int(events[i].events);
-    result = cons(item, result);
-  }
-
-  CAMLreturn(result);
-}
-
-#else
-/********************************************************************************
- *
- * poll() compatibility
- *
- ********************************************************************************/
-
-struct t {
-  int            nfds;
-  int            size;
-  struct pollfd *fds;
-};
-
-CAMLprim value
-ocaml_epoll_create(value size)
-{
-  CAMLparam1(size);
-  CAMLlocal1(result);
-
-  struct t *t_;
-
-  t_ = (struct t *)malloc(sizeof(struct t));
-  t_->nfds = 0;
-  t_->size = size;
-  t_->fds = (struct pollfd *)calloc(size, sizeof(struct pollfd));
-
-  result = caml_alloc(1, Abstract_tag);
-  Field(result, 0) = (value)t_;
-
-  CAMLreturn(result);
-}
-
-CAMLprim value
-ocaml_epoll_destroy(value t)
-{
-  CAMLparam1(t);
-
-  struct t *t_ = (struct t *)Field(t, 0);
-
-  free(t_->fds);
-  free(t_);
-  CAMLreturn(Val_unit);
-}
-
-
-CAMLprim value
-ocaml_epoll_ctl(value t, value op, value what)
-{
-  CAMLparam3(t, op, what);
-
-  struct t *t_ = (struct t *)Field(t, 0);
-  int            op_ = Int_val(op);
-  struct pollfd  pfd;
-  int            i;
-
-  pfd.fd = Int_val(Field(what, 0));
-  pfd.events = int_of_event_list(Field(what, 1));
-
-  /* Find this fd in our list */
-  for (i == 0; i < t_->nfds; i += 1) {
-    struct pollfd *p = &(t_->fds[i]);
-
-    if (p->fd == pfd.fd) {
-      break;
-    }
-  }
-
-  switch (op_) {
-    case caml_POLL_ADD:
-      if (i < t_->nfds) {
-        caml_failwith("file descriptor already present");
-      }
-      if (i >= t_->size) {
-        struct pollfd *newfds;
-        int            newsize;
-
-        newsize = t_->size + 20;
-        newfds = (struct pollfd *)realloc(t_, (sizeof(struct pollfd)) * newsize);
-        if (! newfds) {
-          caml_failwith("out of memory");
-        }
-        t_->size = newsize;
-        t_->fds = newfds;
-      }
-      t_->nfds += 1;
-      t_->fds[i] = pfd;
-      break;
-
-    case caml_POLL_MOD:
-      t_->fds[i] = pfd;
-      break;
-
-    case caml_POLL_DEL:
-      if (i == t_->nfds) {
-        caml_failwith("file descriptor not present");
-      }
-      t_->nfds -= 1;
-      for(; i < t_->nfds; i += 1) {
-        t_->fds[i] = t_->fds[i+1];
-      }
-      break;
-  }
-}
-
-#include "obj.h"
-
-CAMLprim value
-ocaml_epoll_wait(value t, value maxevents, value timeout)
-{
-  CAMLparam3(t, maxevents, timeout);
-  CAMLlocal2(result, v);
-
-  struct t *t_         = (struct t *)Field(t, 0);
-  int       maxevents_ = Int_val(maxevents);
-  int       i;
-  int       j;
-  int       ret;
-
-  /* Call poll */
-  caml_enter_blocking_section();
-  ret = poll(t_->fds, t_->nfds, Int_val(timeout));
-  caml_leave_blocking_section();
-  if (-1 == ret) {
-    puke();
-  }
-
-  result = Val_int(0);
-  if (0 < ret) {
-    j = 0;
-    for (i = 0; ((i < t_->nfds) && (i < maxevents_)); i += 1) {
-      struct pollfd *p = &(t_->fds[i]);
-
-      if (p->revents & POLLNVAL) {
-        /* Don't let j increment: remove this item */
-        continue;
-      } else if (p->revents) {
-        v = alloc_small(2, 0);
-        Field(v, 0) = Val_int(p->fd);
-        Field(v, 1) = event_list_of_int(p->revents);
-        result = cons(v, result);
-      }
-      if (i != j) {
-        t_->fds[i] = t_->fds[j];
-      }
-      j += 1;
-    }
-    t_->nfds = j;
-  }
-  CAMLreturn(result);
-#error "I haven't yet figured out why this causes a segfault."
-}
-
-#endif

iobuf.ml

@@ -54,21 +54,20 @@ let write iobuf cmd =
       if ((len = 0) && (!(iobuf.unsent) = ""))  then
         Dispatch.modify iobuf.d iobuf.fd [Dispatch.Input; Dispatch.Output]
 
-let rec handle_events iobuf fd events =
+let handle_event iobuf fd event =
-  match events with
+  match event with
-    | [] ->
+    | Dispatch.Input ->
-	()
-    | Dispatch.Input :: tl ->
         let size = ibuf_max - !(iobuf.ibuf_len) in
-        let len = Unix.read fd iobuf.ibuf !(iobuf.ibuf_len) size in
+          (match Unix.read fd iobuf.ibuf !(iobuf.ibuf_len) size with
+             | 0 ->
+                 close iobuf "Hangup"
+             | len ->
                  iobuf.ibuf_len := !(iobuf.ibuf_len) + len;
                  handle_input iobuf;
                  if (!(iobuf.ibuf_len) = ibuf_max) then
                    (* No newline found, and the buffer is full *)
-	    close iobuf "Input buffer overrun"
+	           close iobuf "Input buffer overrun")
-	  else
+    | Dispatch.Output ->
-	    handle_events iobuf fd tl
-    | Dispatch.Output :: tl ->
         let buf = Buffer.create obuf_max in
           Buffer.add_string buf !(iobuf.unsent);
           while (((Buffer.length buf) < obuf_max) &&
@@ -82,25 +81,18 @@ let rec handle_events iobuf fd events =
           let n = Unix.single_write fd bufstr 0 buflen in
 	    if n < buflen then begin
               iobuf.unsent := Str.string_after bufstr n;
-	      handle_events iobuf fd tl
             end else if Queue.is_empty iobuf.outq then
               if !(iobuf.alive) then begin
                 (* We're out of data to send *)
 	        Dispatch.modify iobuf.d fd [Dispatch.Input];
-	        handle_events iobuf fd tl
               end else begin
                 (* Close dead connection after all output has despooled *)
                 Dispatch.delete iobuf.d iobuf.fd;
                 Unix.close iobuf.fd
               end
-    | Dispatch.Priority :: tl ->
+    | Dispatch.Exception ->
 	let s = String.create 4096 in
-	  ignore (Unix.recv fd s 0 4096 [Unix.MSG_OOB]);
+	  ignore (Unix.recv fd s 0 4096 [Unix.MSG_OOB])
-	  handle_events iobuf fd tl
-    | Dispatch.Error :: tl ->
-	close iobuf "Error"
-    | Dispatch.Hangup :: tl ->
-	close iobuf "Hangup"
 
 let bind iobuf handle_command handle_error =
   iobuf.handle_command := handle_command;
@@ -117,5 +109,5 @@ let create d fd name handle_command handle_error =
                handle_command = ref handle_command;
                handle_error = ref handle_error;
                alive = ref true} in
-    Dispatch.add d fd (handle_events iobuf) [Dispatch.Input];
+    Dispatch.add d fd (handle_event iobuf) [Dispatch.Input];
     iobuf