Merge pull request #1756 from gevent/libev-4.33

Update to libev 4.33. Fixes #1754.

_setuplibev.py

@@ -75,8 +75,13 @@ def build_extension():
                                        'src/gevent/libev/stathelper.c',
                                        'src/gevent/libev/libev*.h',
                                        'deps/libev/*.[ch]'))
+    # While we don't actually use periodic watchers,
+    # on Windows we need to enable them to work around an issue
+    # in libev 4.33 where ``have_monotonic`` is not defined.
+    EV_PERIODIC_ENABLE = "0"
     if WIN:
         CORE.define_macros.append(('EV_STANDALONE', '1'))
+        EV_PERIODIC_ENABLE = "1"
     # QQQ libev can also use -lm, however it seems to be added implicitly
 
     if LIBEV_EMBED:
@@ -88,7 +93,7 @@ def build_extension():
             # libev watchers that we don't use currently:
             ('EV_CLEANUP_ENABLE', '0'),
             ('EV_EMBED_ENABLE', '0'),
-            ("EV_PERIODIC_ENABLE", '0'),
+            ("EV_PERIODIC_ENABLE", EV_PERIODIC_ENABLE),
             # Time keeping. If possible, use the realtime and/or monotonic
             # clocks. On Linux, this can reduce the number of observable syscalls.
             # On older linux, such as the version in manylinux2010, this requires

deps/libev/Changes

 Revision history for libev, a high-performance and full-featured event loop.
 
-TODO: revisit 59.x timer in the light of modern powersaving
+TODO: for next ABI/API change, consider moving EV__IOFDSSET into io->fd instead and provide a getter.
 TODO: document EV_TSTAMP_T
 
+4.33 Wed Mar 18 13:22:29 CET 2020
+	- no changes w.r.t. 4.32.
+
+4.32 (EV only)
+	- the 4.31 timerfd code wrongly changed the priority of the signal
+          fd watcher, which is usually harmless unless signal fds are
+          also used (found via cpan tester service).
+        - the documentation wrongly claimed that user may modify fd and events
+          members in io watchers when the watcher was stopped
+          (found by b_jonas).
+        - new ev_io_modify mutator which changes only the events member,
+          which can be faster. also added ev::io::set (int events) method
+          to ev++.h.
+        - officially allow a zero events mask for io watchers. this should
+          work with older libev versions as well but was not officially
+          allowed before.
+        - do not wake up every minute when timerfd is used to detect timejumps.
+        - do not wake up every minute when periodics are disabled and we have
+          a monotonic clock.
+        - support a lot more "uncommon" compile time configurations,
+          such as ev_embed enabled but ev_timer disabled.
+        - use a start/stop wrapper class to reduce code duplication in
+          ev++.h and make it needlessly more c++-y.
+        - the linux aio backend is no longer compiled in by default.
+        - update to libecb version 0x00010008.
+
 4.31 Fri Dec 20 21:58:29 CET 2019
 	- handle backends with minimum wait time a bit better by not
           waiting in the presence of already-expired timers

deps/libev/configure

 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for libev 4.31.
+# Generated by GNU Autoconf 2.69 for libev 4.33.
 #
 #
 # Copyright (C) 1992-1996, 1998-2012 Free Software Foundation, Inc.
@@ -587,8 +587,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='libev'
 PACKAGE_TARNAME='libev'
-PACKAGE_VERSION='4.31'
-PACKAGE_STRING='libev 4.31'
+PACKAGE_VERSION='4.33'
+PACKAGE_STRING='libev 4.33'
 PACKAGE_BUGREPORT=''
 PACKAGE_URL=''
 
@@ -1325,7 +1325,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures libev 4.31 to adapt to many kinds of systems.
+\`configure' configures libev 4.33 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1396,7 +1396,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of libev 4.31:";;
+     short | recursive ) echo "Configuration of libev 4.33:";;
    esac
   cat <<\_ACEOF
 
@@ -1509,7 +1509,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-libev configure 4.31
+libev configure 4.33
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -1928,7 +1928,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by libev $as_me 4.31, which was
+It was created by libev $as_me 4.33, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -2795,7 +2795,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='libev'
- VERSION='4.31'
+ VERSION='4.33'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -12871,7 +12871,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by libev $as_me 4.31, which was
+This file was extended by libev $as_me 4.33, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -12937,7 +12937,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-libev config.status 4.31
+libev config.status 4.33
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 

deps/libev/ev++.h

 /*
  * libev simple C++ wrapper classes
  *
- * Copyright (c) 2007,2008,2010,2018 Marc Alexander Lehmann <libev@schmorp.de>
+ * Copyright (c) 2007,2008,2010,2018,2020 Marc Alexander Lehmann <libev@schmorp.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modifica-
@@ -421,6 +421,24 @@ namespace ev {
   template<class ev_watcher, class watcher>
   struct base : ev_watcher
   {
+    // scoped pause/unpause of a watcher
+    struct freeze_guard
+    {
+      watcher &w;
+      bool active;
+
+      freeze_guard (watcher *self) EV_NOEXCEPT
+      : w (*self), active (w.is_active ())
+      {
+        if (active) w.stop ();
+      }
+
+      ~freeze_guard ()
+      {
+        if (active) w.start ();
+      }
+    };
+
     #if EV_MULTIPLICITY
       EV_PX;
 
@@ -614,18 +632,14 @@ namespace ev {
   EV_BEGIN_WATCHER (io, io)
     void set (int fd, int events) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_io_set (static_cast<ev_io *>(this), fd, events);
-      if (active) start ();
     }
 
     void set (int events) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
-      ev_io_set (static_cast<ev_io *>(this), fd, events);
-      if (active) start ();
+      freeze_guard freeze (this);
+      ev_io_modify (static_cast<ev_io *>(this), events);
     }
 
     void start (int fd, int events) EV_NOEXCEPT
@@ -638,10 +652,8 @@ namespace ev {
   EV_BEGIN_WATCHER (timer, timer)
     void set (ev_tstamp after, ev_tstamp repeat = 0.) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_timer_set (static_cast<ev_timer *>(this), after, repeat);
-      if (active) start ();
     }
 
     void start (ev_tstamp after, ev_tstamp repeat = 0.) EV_NOEXCEPT
@@ -665,10 +677,8 @@ namespace ev {
   EV_BEGIN_WATCHER (periodic, periodic)
     void set (ev_tstamp at, ev_tstamp interval = 0.) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_periodic_set (static_cast<ev_periodic *>(this), at, interval, 0);
-      if (active) start ();
     }
 
     void start (ev_tstamp at, ev_tstamp interval = 0.) EV_NOEXCEPT
@@ -688,10 +698,8 @@ namespace ev {
   EV_BEGIN_WATCHER (sig, signal)
     void set (int signum) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_signal_set (static_cast<ev_signal *>(this), signum);
-      if (active) start ();
     }
 
     void start (int signum) EV_NOEXCEPT
@@ -706,10 +714,8 @@ namespace ev {
   EV_BEGIN_WATCHER (child, child)
     void set (int pid, int trace = 0) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_child_set (static_cast<ev_child *>(this), pid, trace);
-      if (active) start ();
     }
 
     void start (int pid, int trace = 0) EV_NOEXCEPT
@@ -724,10 +730,8 @@ namespace ev {
   EV_BEGIN_WATCHER (stat, stat)
     void set (const char *path, ev_tstamp interval = 0.) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_stat_set (static_cast<ev_stat *>(this), path, interval);
-      if (active) start ();
     }
 
     void start (const char *path, ev_tstamp interval = 0.) EV_NOEXCEPT
@@ -766,10 +770,8 @@ namespace ev {
   EV_BEGIN_WATCHER (embed, embed)
     void set_embed (struct ev_loop *embedded_loop) EV_NOEXCEPT
     {
-      int active = is_active ();
-      if (active) stop ();
+      freeze_guard freeze (this);
       ev_embed_set (static_cast<ev_embed *>(this), embedded_loop);
-      if (active) start ();
     }
 
     void start (struct ev_loop *embedded_loop) EV_NOEXCEPT

deps/libev/ev.3

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "LIBEV 3"
-.TH LIBEV 3 "2019-12-21" "libev-4.31" "libev - high performance full featured event loop"
+.TH LIBEV 3 "2020-03-12" "libev-4.31" "libev - high performance full featured event loop"
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -1351,8 +1351,9 @@ with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher
 corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR.
 .PP
 As long as your watcher is active (has been started but not stopped) you
-must not touch the values stored in it. Most specifically you must never
-reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro.
+must not touch the values stored in it except when explicitly documented
+otherwise. Most specifically you must never reinitialise it or call its
+\&\f(CW\*(C`ev_TYPE_set\*(C'\fR macro.
 .PP
 Each and every callback receives the event loop pointer as first, the
 registered watcher structure as second, and a bitset of received events as
@@ -1769,14 +1770,18 @@ This section describes each watcher in detail, but will not repeat
 information given in the last section. Any initialisation/set macros,
 functions and members specific to the watcher type are explained.
 .PP
-Members are additionally marked with either \fI[read\-only]\fR, meaning that,
-while the watcher is active, you can look at the member and expect some
-sensible content, but you must not modify it (you can modify it while the
-watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
-means you can expect it to have some sensible content while the watcher
-is active, but you can also modify it. Modifying it may not do something
+Most members are additionally marked with either \fI[read\-only]\fR, meaning
+that, while the watcher is active, you can look at the member and expect
+some sensible content, but you must not modify it (you can modify it while
+the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
+means you can expect it to have some sensible content while the watcher is
+active, but you can also modify it (within the same thread as the event
+loop, i.e. without creating data races). Modifying it may not do something
 sensible or take immediate effect (or do anything at all), but libev will
 not crash or malfunction in any way.
+.PP
+In any case, the documentation for each member will explain what the
+effects are, and if there are any additional access restrictions.
 .ie n .SS """ev_io"" \- is this file descriptor readable or writable?"
 .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?"
 .IX Subsection "ev_io - is this file descriptor readable or writable?"
@@ -1952,14 +1957,33 @@ opportunity for a DoS attack.
 .IX Item "ev_io_set (ev_io *, int fd, int events)"
 .PD
 Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
-receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
-\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events.
-.IP "int fd [read\-only]" 4
-.IX Item "int fd [read-only]"
-The file descriptor being watched.
-.IP "int events [read\-only]" 4
-.IX Item "int events [read-only]"
-The events being watched.
+receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR, both
+\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR or \f(CW0\fR, to express the desire to receive the given
+events.
+.Sp
+Note that setting the \f(CW\*(C`events\*(C'\fR to \f(CW0\fR and starting the watcher is
+supported, but not specially optimized \- if your program sometimes happens
+to generate this combination this is fine, but if it is easy to avoid
+starting an io watcher watching for no events you should do so.
+.IP "ev_io_modify (ev_io *, int events)" 4
+.IX Item "ev_io_modify (ev_io *, int events)"
+Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the requested events. Using this
+might be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR
+still refers to the same underlying file description, something it cannot
+do when using \f(CW\*(C`ev_io_set\*(C'\fR.
+.IP "int fd [no\-modify]" 4
+.IX Item "int fd [no-modify]"
+The file descriptor being watched. While it can be read at any time, you
+must not modify this member even when the watcher is stopped \- always use
+\&\f(CW\*(C`ev_io_set\*(C'\fR for that.
+.IP "int events [no\-modify]" 4
+.IX Item "int events [no-modify]"
+The set of events the fd is being watched for, among other flags. Remember
+that this is a bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events &
+EV_READ\*(C'\fR, and similarly for \f(CW\*(C`EV_WRITE\*(C'\fR.
+.Sp
+As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is
+stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that.
 .PP
 \fIExamples\fR
 .IX Subsection "Examples"
@@ -4397,6 +4421,9 @@ method.
 .Sp
 For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid
 clashing with the \f(CW\*(C`set (loop)\*(C'\fR method.
+.Sp
+For \f(CW\*(C`ev::io\*(C'\fR watchers there is an additional \f(CW\*(C`set\*(C'\fR method that acepts a
+new event mask only, and internally calls \f(CW\*(C`ev_io_modfify\*(C'\fR.
 .IP "w\->start ()" 4
 .IX Item "w->start ()"
 Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the

deps/libev/ev.h

 /*
  * libev native API header
  *
- * Copyright (c) 2007-2019 Marc Alexander Lehmann <libev@schmorp.de>
+ * Copyright (c) 2007-2020 Marc Alexander Lehmann <libev@schmorp.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modifica-
@@ -215,7 +215,7 @@ struct ev_loop;
 /*****************************************************************************/
 
 #define EV_VERSION_MAJOR 4
-#define EV_VERSION_MINOR 31
+#define EV_VERSION_MINOR 33
 
 /* eventmask, revents, events... */
 enum {
@@ -392,14 +392,12 @@ typedef struct ev_stat
 } ev_stat;
 #endif
 
-#if EV_IDLE_ENABLE
 /* invoked when the nothing else needs to be done, keeps the process from blocking */
 /* revent EV_IDLE */
 typedef struct ev_idle
 {
   EV_WATCHER (ev_idle)
 } ev_idle;
-#endif
 
 /* invoked for each run of the mainloop, just before the blocking call */
 /* you can still change events in any way you like */
@@ -416,23 +414,19 @@ typedef struct ev_check
   EV_WATCHER (ev_check)
 } ev_check;
 
-#if EV_FORK_ENABLE
 /* the callback gets invoked before check in the child process when a fork was detected */
 /* revent EV_FORK */
 typedef struct ev_fork
 {
   EV_WATCHER (ev_fork)
 } ev_fork;
-#endif
 
-#if EV_CLEANUP_ENABLE
 /* is invoked just before the loop gets destroyed */
 /* revent EV_CLEANUP */
 typedef struct ev_cleanup
 {
   EV_WATCHER (ev_cleanup)
 } ev_cleanup;
-#endif
 
 #if EV_EMBED_ENABLE
 /* used to embed an event loop inside another */
@@ -442,16 +436,18 @@ typedef struct ev_embed
   EV_WATCHER (ev_embed)
 
   struct ev_loop *other; /* ro */
+#undef EV_IO_ENABLE
+#define EV_IO_ENABLE 1
   ev_io io;              /* private */
+#undef EV_PREPARE_ENABLE
+#define EV_PREPARE_ENABLE 1
   ev_prepare prepare;    /* private */
   ev_check check;        /* unused */
   ev_timer timer;        /* unused */
   ev_periodic periodic;  /* unused */
   ev_idle idle;          /* unused */
   ev_fork fork;          /* private */
-#if EV_CLEANUP_ENABLE
   ev_cleanup cleanup;    /* unused */
-#endif
 } ev_embed;
 #endif
 
@@ -526,7 +522,7 @@ enum {
   EVBACKEND_KQUEUE   = 0x00000008U, /* bsd, broken on osx */
   EVBACKEND_DEVPOLL  = 0x00000010U, /* solaris 8 */ /* NYI */
   EVBACKEND_PORT     = 0x00000020U, /* solaris 10 */
-  EVBACKEND_LINUXAIO = 0x00000040U, /* linuix AIO, 4.19+ */
+  EVBACKEND_LINUXAIO = 0x00000040U, /* linux AIO, 4.19+ */
   EVBACKEND_IOURING  = 0x00000080U, /* linux io_uring, 5.1+ */
   EVBACKEND_ALL      = 0x000000FFU, /* all known backends */
   EVBACKEND_MASK     = 0x0000FFFFU  /* all future backends */
@@ -660,6 +656,8 @@ EV_API_DECL void ev_unref (EV_P) EV_NOEXCEPT;
  */
 EV_API_DECL void ev_once (EV_P_ int fd, int events, ev_tstamp timeout, void (*cb)(int revents, void *arg), void *arg) EV_NOEXCEPT;
 
+EV_API_DECL void ev_invoke_pending (EV_P); /* invoke all pending watchers */
+
 # if EV_FEATURE_API
 EV_API_DECL unsigned int ev_iteration (EV_P) EV_NOEXCEPT; /* number of loop iterations */
 EV_API_DECL unsigned int ev_depth     (EV_P) EV_NOEXCEPT; /* #ev_loop enters - #ev_loop leaves */
@@ -677,7 +675,6 @@ EV_API_DECL void ev_set_invoke_pending_cb (EV_P_ ev_loop_callback invoke_pending
 EV_API_DECL void ev_set_loop_release_cb (EV_P_ void (*release)(EV_P) EV_NOEXCEPT, void (*acquire)(EV_P) EV_NOEXCEPT) EV_NOEXCEPT;
 
 EV_API_DECL unsigned int ev_pending_count (EV_P) EV_NOEXCEPT; /* number of pending events, if any */
-EV_API_DECL void ev_invoke_pending (EV_P); /* invoke all pending watchers */
 
 /*
  * stop/start the timer handling.
@@ -697,6 +694,7 @@ EV_API_DECL void ev_resume  (EV_P) EV_NOEXCEPT;
   ev_set_cb ((ev), cb_);			\
 } while (0)
 
+#define ev_io_modify(ev,events_)             do { (ev)->events = (ev)->events & EV__IOFDSET | (events_); } while (0)
 #define ev_io_set(ev,fd_,events_)            do { (ev)->fd = (fd_); (ev)->events = (events_) | EV__IOFDSET; } while (0)
 #define ev_timer_set(ev,after_,repeat_)      do { ((ev_watcher_time *)(ev))->at = (after_); (ev)->repeat = (repeat_); } while (0)
 #define ev_periodic_set(ev,ofs_,ival_,rcb_)  do { (ev)->offset = (ofs_); (ev)->interval = (ival_); (ev)->reschedule_cb = (rcb_); } while (0)
@@ -742,6 +740,7 @@ EV_API_DECL void ev_resume  (EV_P) EV_NOEXCEPT;
 #define ev_periodic_at(ev)                   (+((ev_watcher_time *)(ev))->at)
 
 #ifndef ev_set_cb
+/* memmove is used here to avoid strict aliasing violations, and hopefully is optimized out by any reasonable compiler */
 # define ev_set_cb(ev,cb_)                   (ev_cb_ (ev) = (cb_), memmove (&((ev_watcher *)(ev))->cb, &ev_cb_ (ev), sizeof (ev_cb_ (ev))))
 #endif
 

deps/libev/ev.pod

@@ -1220,8 +1220,9 @@ with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher
 corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>.
 
 As long as your watcher is active (has been started but not stopped) you
-must not touch the values stored in it. Most specifically you must never
-reinitialise it or call its C<ev_TYPE_set> macro.
+must not touch the values stored in it except when explicitly documented
+otherwise. Most specifically you must never reinitialise it or call its
+C<ev_TYPE_set> macro.
 
 Each and every callback receives the event loop pointer as first, the
 registered watcher structure as second, and a bitset of received events as
@@ -1650,15 +1651,18 @@ This section describes each watcher in detail, but will not repeat
 information given in the last section. Any initialisation/set macros,
 functions and members specific to the watcher type are explained.
 
-Members are additionally marked with either I<[read-only]>, meaning that,
-while the watcher is active, you can look at the member and expect some
-sensible content, but you must not modify it (you can modify it while the
-watcher is stopped to your hearts content), or I<[read-write]>, which
-means you can expect it to have some sensible content while the watcher
-is active, but you can also modify it. Modifying it may not do something
+Most members are additionally marked with either I<[read-only]>, meaning
+that, while the watcher is active, you can look at the member and expect
+some sensible content, but you must not modify it (you can modify it while
+the watcher is stopped to your hearts content), or I<[read-write]>, which
+means you can expect it to have some sensible content while the watcher is
+active, but you can also modify it (within the same thread as the event
+loop, i.e. without creating data races). Modifying it may not do something
 sensible or take immediate effect (or do anything at all), but libev will
 not crash or malfunction in any way.
 
+In any case, the documentation for each member will explain what the
+effects are, and if there are any additional access restrictions.
 
 =head2 C<ev_io> - is this file descriptor readable or writable?
 
@@ -1828,16 +1832,36 @@ opportunity for a DoS attack.
 =item ev_io_set (ev_io *, int fd, int events)
 
 Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
-receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or
-C<EV_READ | EV_WRITE>, to express the desire to receive the given events.
+receive events for and C<events> is either C<EV_READ>, C<EV_WRITE>, both
+C<EV_READ | EV_WRITE> or C<0>, to express the desire to receive the given
+events.
 
-=item int fd [read-only]
+Note that setting the C<events> to C<0> and starting the watcher is
+supported, but not specially optimized - if your program sometimes happens
+to generate this combination this is fine, but if it is easy to avoid
+starting an io watcher watching for no events you should do so.
 
-The file descriptor being watched.
+=item ev_io_modify (ev_io *, int events)
 
-=item int events [read-only]
+Similar to C<ev_io_set>, but only changes the requested events. Using this
+might be faster with some backends, as libev can assume that the C<fd>
+still refers to the same underlying file description, something it cannot
+do when using C<ev_io_set>.
 
-The events being watched.
+=item int fd [no-modify]
+
+The file descriptor being watched. While it can be read at any time, you
+must not modify this member even when the watcher is stopped - always use
+C<ev_io_set> for that.
+
+=item int events [no-modify]
+
+The set of events the fd is being watched for, among other flags. Remember
+that this is a bit set - to test for C<EV_READ>, use C<< w->events &
+EV_READ >>, and similarly for C<EV_WRITE>.
+
+As with C<fd>, you must not modify this member even when the watcher is
+stopped, always use C<ev_io_set> or C<ev_io_modify> for that.
 
 =back
 
@@ -4245,6 +4269,9 @@ method.
 For C<ev::embed> watchers this method is called C<set_embed>, to avoid
 clashing with the C<set (loop)> method.
 
+For C<ev::io> watchers there is an additional C<set> method that acepts a
+new event mask only, and internally calls C<ev_io_modfify>.
+
 =item w->start ()
 
 Starts the watcher. Note that there is no C<loop> argument, as the

deps/libev/ev_linuxaio.c

@@ -270,8 +270,7 @@ linuxaio_modify (EV_P_ int fd, int oev, int nev)
       ++anfd->egen;
     }
 
-  iocb->io.aio_buf =
-      (nev & EV_READ ? POLLIN : 0)
+  iocb->io.aio_buf = (nev & EV_READ  ? POLLIN  : 0)
                    | (nev & EV_WRITE ? POLLOUT : 0);
 
   if (nev)

deps/libev/ev_vars.h

@@ -145,7 +145,6 @@ VARx(uint32_t, iouring_cq_cqes)
 VARx(ev_tstamp, iouring_tfd_to)
 VARx(int, iouring_tfd)
 VARx(ev_io, iouring_tfd_w)
-VARx(ev_io, iouring_epoll_w)
 #endif
 
 #if EV_USE_KQUEUE || EV_GENWRAP

deps/libev/ev_wrap.h

@@ -53,7 +53,6 @@
 #define iouring_cq_ring_size ((loop)->iouring_cq_ring_size)
 #define iouring_cq_tail ((loop)->iouring_cq_tail)
 #define iouring_entries ((loop)->iouring_entries)
-#define iouring_epoll_w ((loop)->iouring_epoll_w)
 #define iouring_fd ((loop)->iouring_fd)
 #define iouring_max_entries ((loop)->iouring_max_entries)
 #define iouring_sq_array ((loop)->iouring_sq_array)
@@ -189,7 +188,6 @@
 #undef iouring_cq_ring_size
 #undef iouring_cq_tail
 #undef iouring_entries
-#undef iouring_epoll_w
 #undef iouring_fd
 #undef iouring_max_entries
 #undef iouring_sq_array

docs/changes/1754.feature

+Update the embedded libev from 4.31 to 4.33.