Update to libev 4.33. Fixes #1754.

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.c

@@ -119,7 +119,7 @@
    
 # if HAVE_LINUX_AIO_ABI_H
 #  ifndef EV_USE_LINUXAIO
-#   define EV_USE_LINUXAIO EV_FEATURE_BACKENDS
+#   define EV_USE_LINUXAIO 0 /* was: EV_FEATURE_BACKENDS, always off by default */
 #  endif
 # else
 #  undef EV_USE_LINUXAIO
@@ -346,7 +346,7 @@
 
 #ifndef EV_USE_LINUXAIO
 # if __linux /* libev currently assumes linux/aio_abi.h is always available on linux */
-#  define EV_USE_LINUXAIO 1
+#  define EV_USE_LINUXAIO 0 /* was: 1, always off by default */
 # else
 #  define EV_USE_LINUXAIO 0
 # endif
@@ -581,6 +581,7 @@ struct signalfd_siginfo
 
 #define MIN_TIMEJUMP   1. /* minimum timejump that gets detected (if monotonic clock available) */
 #define MAX_BLOCKTIME  59.743 /* never wait longer than this time (to detect time jumps) */
+#define MAX_BLOCKTIME2 1500001.07 /* same, but when timerfd is used to detect jumps, also safe delay to not overflow */
 
 /* find a portable timestamp that is "always" in the future but fits into time_t.
  * this is quite hard, and we are mostly guessing - we handle 32 bit signed/unsigned time_t,
@@ -605,7 +606,7 @@ struct signalfd_siginfo
 /*
  * libecb - http://software.schmorp.de/pkg/libecb
  *
- * Copyright (©) 2009-2015 Marc Alexander Lehmann <libecb@schmorp.de>
+ * Copyright (©) 2009-2015,2018-2020 Marc Alexander Lehmann <libecb@schmorp.de>
  * Copyright (©) 2011 Emanuele Giaquinta
  * All rights reserved.
  *
@@ -646,15 +647,23 @@ struct signalfd_siginfo
 #define ECB_H
 
 /* 16 bits major, 16 bits minor */
-#define ECB_VERSION 0x00010006
+#define ECB_VERSION 0x00010008
 
-#ifdef _WIN32
+#include <string.h> /* for memcpy */
+
+#if defined (_WIN32) && !defined (__MINGW32__)
   typedef   signed char   int8_t;
   typedef unsigned char  uint8_t;
+  typedef   signed char   int_fast8_t;
+  typedef unsigned char  uint_fast8_t;
   typedef   signed short  int16_t;
   typedef unsigned short uint16_t;
+  typedef   signed int    int_fast16_t;
+  typedef unsigned int   uint_fast16_t;
   typedef   signed int    int32_t;
   typedef unsigned int   uint32_t;
+  typedef   signed int    int_fast32_t;
+  typedef unsigned int   uint_fast32_t;
   #if __GNUC__
     typedef   signed long long int64_t;
     typedef unsigned long long uint64_t;
@@ -662,6 +671,8 @@ struct signalfd_siginfo
     typedef   signed __int64   int64_t;
     typedef unsigned __int64   uint64_t;
   #endif
+  typedef  int64_t  int_fast64_t;
+  typedef uint64_t uint_fast64_t;
   #ifdef _WIN64
     #define ECB_PTRSIZE 8
     typedef uint64_t uintptr_t;
@@ -683,6 +694,14 @@ struct signalfd_siginfo
 #define ECB_GCC_AMD64 (__amd64 || __amd64__ || __x86_64 || __x86_64__)
 #define ECB_MSVC_AMD64 (_M_AMD64 || _M_X64)
 
+#ifndef ECB_OPTIMIZE_SIZE
+  #if __OPTIMIZE_SIZE__
+    #define ECB_OPTIMIZE_SIZE 1
+  #else
+    #define ECB_OPTIMIZE_SIZE 0
+  #endif
+#endif
+
 /* work around x32 idiocy by defining proper macros */
 #if ECB_GCC_AMD64 || ECB_MSVC_AMD64
   #if _ILP32
@@ -1198,6 +1217,44 @@ ecb_inline ecb_const uint32_t ecb_rotr32 (uint32_t x, unsigned int count) { retu
 ecb_inline ecb_const uint64_t ecb_rotl64 (uint64_t x, unsigned int count) { return (x >> (64 - count)) | (x << count); }
 ecb_inline ecb_const uint64_t ecb_rotr64 (uint64_t x, unsigned int count) { return (x << (64 - count)) | (x >> count); }
 
+#if ECB_CPP
+
+inline uint8_t  ecb_ctz (uint8_t  v) { return ecb_ctz32 (v); }
+inline uint16_t ecb_ctz (uint16_t v) { return ecb_ctz32 (v); }
+inline uint32_t ecb_ctz (uint32_t v) { return ecb_ctz32 (v); }
+inline uint64_t ecb_ctz (uint64_t v) { return ecb_ctz64 (v); }
+
+inline bool ecb_is_pot (uint8_t  v) { return ecb_is_pot32 (v); }
+inline bool ecb_is_pot (uint16_t v) { return ecb_is_pot32 (v); }
+inline bool ecb_is_pot (uint32_t v) { return ecb_is_pot32 (v); }
+inline bool ecb_is_pot (uint64_t v) { return ecb_is_pot64 (v); }
+
+inline int ecb_ld (uint8_t  v) { return ecb_ld32 (v); }
+inline int ecb_ld (uint16_t v) { return ecb_ld32 (v); }
+inline int ecb_ld (uint32_t v) { return ecb_ld32 (v); }
+inline int ecb_ld (uint64_t v) { return ecb_ld64 (v); }
+
+inline int ecb_popcount (uint8_t  v) { return ecb_popcount32 (v); }
+inline int ecb_popcount (uint16_t v) { return ecb_popcount32 (v); }
+inline int ecb_popcount (uint32_t v) { return ecb_popcount32 (v); }
+inline int ecb_popcount (uint64_t v) { return ecb_popcount64 (v); }
+
+inline uint8_t  ecb_bitrev (uint8_t  v) { return ecb_bitrev8  (v); }
+inline uint16_t ecb_bitrev (uint16_t v) { return ecb_bitrev16 (v); }
+inline uint32_t ecb_bitrev (uint32_t v) { return ecb_bitrev32 (v); }
+
+inline uint8_t  ecb_rotl (uint8_t  v, unsigned int count) { return ecb_rotl8  (v, count); }
+inline uint16_t ecb_rotl (uint16_t v, unsigned int count) { return ecb_rotl16 (v, count); }
+inline uint32_t ecb_rotl (uint32_t v, unsigned int count) { return ecb_rotl32 (v, count); }
+inline uint64_t ecb_rotl (uint64_t v, unsigned int count) { return ecb_rotl64 (v, count); }
+
+inline uint8_t  ecb_rotr (uint8_t  v, unsigned int count) { return ecb_rotr8  (v, count); }
+inline uint16_t ecb_rotr (uint16_t v, unsigned int count) { return ecb_rotr16 (v, count); }
+inline uint32_t ecb_rotr (uint32_t v, unsigned int count) { return ecb_rotr32 (v, count); }
+inline uint64_t ecb_rotr (uint64_t v, unsigned int count) { return ecb_rotr64 (v, count); }
+
+#endif
+
 #if ECB_GCC_VERSION(4,3) || (ECB_CLANG_BUILTIN(__builtin_bswap32) && ECB_CLANG_BUILTIN(__builtin_bswap64))
   #if ECB_GCC_VERSION(4,8) || ECB_CLANG_BUILTIN(__builtin_bswap16)
   #define ecb_bswap16(x)  __builtin_bswap16 (x)
@@ -1278,6 +1335,78 @@ ecb_inline ecb_const ecb_bool ecb_big_endian    (void) { return ecb_byteorder_he
 ecb_inline ecb_const ecb_bool ecb_little_endian (void);
 ecb_inline ecb_const ecb_bool ecb_little_endian (void) { return ecb_byteorder_helper () == 0x44332211; }
 
+/*****************************************************************************/
+/* unaligned load/store */
+
+ecb_inline uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v) { return ecb_little_endian () ? ecb_bswap16 (v) : v; }
+ecb_inline uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v) { return ecb_little_endian () ? ecb_bswap32 (v) : v; }
+ecb_inline uint_fast64_t ecb_be_u64_to_host (uint_fast64_t v) { return ecb_little_endian () ? ecb_bswap64 (v) : v; }
+
+ecb_inline uint_fast16_t ecb_le_u16_to_host (uint_fast16_t v) { return ecb_big_endian    () ? ecb_bswap16 (v) : v; }
+ecb_inline uint_fast32_t ecb_le_u32_to_host (uint_fast32_t v) { return ecb_big_endian    () ? ecb_bswap32 (v) : v; }
+ecb_inline uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v) { return ecb_big_endian    () ? ecb_bswap64 (v) : v; }
+
+ecb_inline uint_fast16_t ecb_peek_u16_u (const void *ptr) { uint16_t v; memcpy (&v, ptr, sizeof (v)); return v; }
+ecb_inline uint_fast32_t ecb_peek_u32_u (const void *ptr) { uint32_t v; memcpy (&v, ptr, sizeof (v)); return v; }
+ecb_inline uint_fast64_t ecb_peek_u64_u (const void *ptr) { uint64_t v; memcpy (&v, ptr, sizeof (v)); return v; }
+
+ecb_inline uint_fast16_t ecb_peek_be_u16_u (const void *ptr) { return ecb_be_u16_to_host (ecb_peek_u16_u (ptr)); }
+ecb_inline uint_fast32_t ecb_peek_be_u32_u (const void *ptr) { return ecb_be_u32_to_host (ecb_peek_u32_u (ptr)); }
+ecb_inline uint_fast64_t ecb_peek_be_u64_u (const void *ptr) { return ecb_be_u64_to_host (ecb_peek_u64_u (ptr)); }
+
+ecb_inline uint_fast16_t ecb_peek_le_u16_u (const void *ptr) { return ecb_le_u16_to_host (ecb_peek_u16_u (ptr)); }
+ecb_inline uint_fast32_t ecb_peek_le_u32_u (const void *ptr) { return ecb_le_u32_to_host (ecb_peek_u32_u (ptr)); }
+ecb_inline uint_fast64_t ecb_peek_le_u64_u (const void *ptr) { return ecb_le_u64_to_host (ecb_peek_u64_u (ptr)); }
+
+ecb_inline uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v) { return ecb_little_endian () ? ecb_bswap16 (v) : v; }
+ecb_inline uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v) { return ecb_little_endian () ? ecb_bswap32 (v) : v; }
+ecb_inline uint_fast64_t ecb_host_to_be_u64 (uint_fast64_t v) { return ecb_little_endian () ? ecb_bswap64 (v) : v; }
+
+ecb_inline uint_fast16_t ecb_host_to_le_u16 (uint_fast16_t v) { return ecb_big_endian    () ? ecb_bswap16 (v) : v; }
+ecb_inline uint_fast32_t ecb_host_to_le_u32 (uint_fast32_t v) { return ecb_big_endian    () ? ecb_bswap32 (v) : v; }
+ecb_inline uint_fast64_t ecb_host_to_le_u64 (uint_fast64_t v) { return ecb_big_endian    () ? ecb_bswap64 (v) : v; }
+
+ecb_inline void ecb_poke_u16_u (void *ptr, uint16_t v) { memcpy (ptr, &v, sizeof (v)); }
+ecb_inline void ecb_poke_u32_u (void *ptr, uint32_t v) { memcpy (ptr, &v, sizeof (v)); }
+ecb_inline void ecb_poke_u64_u (void *ptr, uint64_t v) { memcpy (ptr, &v, sizeof (v)); }
+
+ecb_inline void ecb_poke_be_u16_u (void *ptr, uint_fast16_t v) { ecb_poke_u16_u (ptr, ecb_host_to_be_u16 (v)); }
+ecb_inline void ecb_poke_be_u32_u (void *ptr, uint_fast32_t v) { ecb_poke_u32_u (ptr, ecb_host_to_be_u32 (v)); }
+ecb_inline void ecb_poke_be_u64_u (void *ptr, uint_fast64_t v) { ecb_poke_u64_u (ptr, ecb_host_to_be_u64 (v)); }
+                                                                                                
+ecb_inline void ecb_poke_le_u16_u (void *ptr, uint_fast16_t v) { ecb_poke_u16_u (ptr, ecb_host_to_le_u16 (v)); }
+ecb_inline void ecb_poke_le_u32_u (void *ptr, uint_fast32_t v) { ecb_poke_u32_u (ptr, ecb_host_to_le_u32 (v)); }
+ecb_inline void ecb_poke_le_u64_u (void *ptr, uint_fast64_t v) { ecb_poke_u64_u (ptr, ecb_host_to_le_u64 (v)); }
+
+#if ECB_CPP
+
+inline uint8_t  ecb_bswap (uint8_t  v) { return v; }
+inline uint16_t ecb_bswap (uint16_t v) { return ecb_bswap16 (v); }
+inline uint32_t ecb_bswap (uint32_t v) { return ecb_bswap32 (v); }
+inline uint64_t ecb_bswap (uint64_t v) { return ecb_bswap64 (v); }
+
+template<typename T> inline T ecb_be_to_host (T v) { return ecb_little_endian () ? ecb_bswap (v) : v; }
+template<typename T> inline T ecb_le_to_host (T v) { return ecb_big_endian    () ? ecb_bswap (v) : v; }
+template<typename T> inline T ecb_peek       (const void *ptr) { return *(const T *)ptr; }
+template<typename T> inline T ecb_peek_be    (const void *ptr) { return ecb_be_to_host (ecb_peek  <T> (ptr)); }
+template<typename T> inline T ecb_peek_le    (const void *ptr) { return ecb_le_to_host (ecb_peek  <T> (ptr)); }
+template<typename T> inline T ecb_peek_u     (const void *ptr) { T v; memcpy (&v, ptr, sizeof (v)); return v; }
+template<typename T> inline T ecb_peek_be_u  (const void *ptr) { return ecb_be_to_host (ecb_peek_u<T> (ptr)); }
+template<typename T> inline T ecb_peek_le_u  (const void *ptr) { return ecb_le_to_host (ecb_peek_u<T> (ptr)); }
+
+template<typename T> inline T ecb_host_to_be (T v) { return ecb_little_endian () ? ecb_bswap (v) : v; }
+template<typename T> inline T ecb_host_to_le (T v) { return ecb_big_endian    () ? ecb_bswap (v) : v; }
+template<typename T> inline void ecb_poke      (void *ptr, T v) { *(T *)ptr = v; }
+template<typename T> inline void ecb_poke_be   (void *ptr, T v) { return ecb_poke  <T> (ptr, ecb_host_to_be (v)); }
+template<typename T> inline void ecb_poke_le   (void *ptr, T v) { return ecb_poke  <T> (ptr, ecb_host_to_le (v)); }
+template<typename T> inline void ecb_poke_u    (void *ptr, T v) { memcpy (ptr, &v, sizeof (v)); }
+template<typename T> inline void ecb_poke_be_u (void *ptr, T v) { return ecb_poke_u<T> (ptr, ecb_host_to_be (v)); }
+template<typename T> inline void ecb_poke_le_u (void *ptr, T v) { return ecb_poke_u<T> (ptr, ecb_host_to_le (v)); }
+
+#endif
+
+/*****************************************************************************/
+
 #if ECB_GCC_VERSION(3,0) || ECB_C99
   #define ecb_mod(m,n) ((m) % (n) + ((m) % (n) < 0 ? (n) : 0))
 #else
@@ -1311,6 +1440,8 @@ ecb_inline ecb_const ecb_bool ecb_little_endian (void) { return ecb_byteorder_he
   #define ecb_array_length(name) (sizeof (name) / sizeof (name [0]))
 #endif
 
+/*****************************************************************************/
+
 ecb_function_ ecb_const uint32_t ecb_binary16_to_binary32 (uint32_t x);
 ecb_function_ ecb_const uint32_t
 ecb_binary16_to_binary32 (uint32_t x)
@@ -1428,7 +1559,6 @@ ecb_binary32_to_binary16 (uint32_t x)
     || (defined __arm__ && (defined __ARM_EABI__ || defined __EABI__ || defined __VFP_FP__ || defined _WIN32_WCE || defined __ANDROID__)) \
     || defined __aarch64__
   #define ECB_STDFP 1
-  #include <string.h> /* for memcpy */
 #else
   #define ECB_STDFP 0
 #endif
@@ -1660,7 +1790,7 @@ ecb_binary32_to_binary16 (uint32_t x)
  * TODO: arm is also common nowadays, maybe even mips and x86
  * TODO: after implementing this, it suddenly looks like overkill, but its hard to remove...
  */
-#if __GNUC__ && __linux && ECB_AMD64 && !defined __OPTIMIZE_SIZE__
+#if __GNUC__ && __linux && ECB_AMD64 && !EV_FEATURE_CODE
   /* the costly errno access probably kills this for size optimisation */
 
   #define ev_syscall(nr,narg,arg1,arg2,arg3,arg4,arg5,arg6)            \
@@ -2264,8 +2394,20 @@ fd_reify (EV_P)
 {
   int i;
 
+  /* most backends do not modify the fdchanges list in backend_modfiy.
+   * except io_uring, which has fixed-size buffers which might force us
+   * to handle events in backend_modify, causing fdchanges to be amended,
+   * which could result in an endless loop.
+   * to avoid this, we do not dynamically handle fds that were added
+   * during fd_reify. that means that for those backends, fdchangecnt
+   * might be non-zero during poll, which must cause them to not block.
+   * to not put too much of a burden on other backends, this detail
+   * needs to be handled in the backend.
+   */
+  int changecnt = fdchangecnt;
+
 #if EV_SELECT_IS_WINSOCKET || EV_USE_IOCP
-  for (i = 0; i < fdchangecnt; ++i)
+  for (i = 0; i < changecnt; ++i)
     {
       int fd = fdchanges [i];
       ANFD *anfd = anfds + fd;
@@ -2289,7 +2431,7 @@ fd_reify (EV_P)
     }
 #endif
 
-  for (i = 0; i < fdchangecnt; ++i)
+  for (i = 0; i < changecnt; ++i)
     {
       int fd = fdchanges [i];
       ANFD *anfd = anfds + fd;
@@ -2315,7 +2457,14 @@ fd_reify (EV_P)
         backend_modify (EV_A_ fd, o_events, anfd->events);
     }
 
-  fdchangecnt = 0;
+  /* normally, fdchangecnt hasn't changed. if it has, then new fds have been added.
+   * this is a rare case (see beginning comment in this function), so we copy them to the
+   * front and hope the backend handles this case.
+   */
+  if (ecb_expect_false (fdchangecnt != changecnt))
+    memmove (fdchanges, fdchanges + changecnt, (fdchangecnt - changecnt) * sizeof (*fdchanges));
+
+  fdchangecnt -= changecnt;
 }
 
 /* something about the given fd changed */
@@ -2324,7 +2473,7 @@ void
 fd_change (EV_P_ int fd, int flags)
 {
   unsigned char reify = anfds [fd].reify;
-  anfds [fd].reify |= flags;
+  anfds [fd].reify = reify | flags;
 
   if (ecb_expect_true (!reify))
     {
@@ -2563,7 +2712,7 @@ reheap (ANHE *heap, int N)
 
 /*****************************************************************************/
 
-/* associate signal watchers to a signal signal */
+/* associate signal watchers to a signal */
 typedef struct
 {
   EV_ATOMIC_T pending;
@@ -2886,10 +3035,7 @@ timerfdcb (EV_P_ ev_io *iow, int revents)
 {
   struct itimerspec its = { 0 };
 
-  /* since we can't easily come zup with a (portable) maximum value of time_t,
-   * we wake up once per month, which hopefully is rare enough to not
-   * be a problem. */
-  its.it_value.tv_sec = ev_rt_now + 86400 * 30;
+  its.it_value.tv_sec = ev_rt_now + (int)MAX_BLOCKTIME2;
   timerfd_settime (timerfd, TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET, &its, 0);
 
   ev_rt_now = ev_time ();
@@ -2899,7 +3045,9 @@ timerfdcb (EV_P_ ev_io *iow, int revents)
   now_floor = EV_TS_CONST (0.);
   time_update (EV_A_ EV_TSTAMP_HUGE);
   */
+#if EV_PERIODIC_ENABLE
   periodics_reschedule (EV_A);
+#endif
 }
 
 ecb_noinline ecb_cold
@@ -2915,7 +3063,7 @@ evtimerfd_init (EV_P)
           fd_intern (timerfd); /* just to be sure */
 
           ev_io_init (&timerfd_w, timerfdcb, timerfd, EV_READ);
-          ev_set_priority (&sigfd_w, EV_MINPRI);
+          ev_set_priority (&timerfd_w, EV_MINPRI);
           ev_io_start (EV_A_ &timerfd_w);
           ev_unref (EV_A); /* watcher should not keep loop alive */
 
@@ -2987,8 +3135,8 @@ ev_supported_backends (void) EV_NOEXCEPT
   if (EV_USE_PORT                                      ) flags |= EVBACKEND_PORT;
   if (EV_USE_KQUEUE                                    ) flags |= EVBACKEND_KQUEUE;
   if (EV_USE_EPOLL                                     ) flags |= EVBACKEND_EPOLL;
-  if (EV_USE_LINUXAIO) flags |= EVBACKEND_LINUXAIO;
-  if (EV_USE_IOURING ) flags |= EVBACKEND_IOURING;
+  if (EV_USE_LINUXAIO                                  ) flags |= EVBACKEND_LINUXAIO;
+  if (EV_USE_IOURING && ev_linux_version () >= 0x050601) flags |= EVBACKEND_IOURING; /* 5.6.1+ */
   if (EV_USE_POLL                                      ) flags |= EVBACKEND_POLL;
   if (EV_USE_SELECT                                    ) flags |= EVBACKEND_SELECT;
 
@@ -3031,7 +3179,7 @@ ecb_cold
 unsigned int
 ev_embeddable_backends (void) EV_NOEXCEPT
 {
-  int flags = EVBACKEND_EPOLL | EVBACKEND_KQUEUE | EVBACKEND_PORT;
+  int flags = EVBACKEND_EPOLL | EVBACKEND_KQUEUE | EVBACKEND_PORT | EVBACKEND_IOURING;
 
   /* epoll embeddability broken on all linux versions up to at least 2.6.23 */
   if (ev_linux_version () < 0x020620) /* disable it on linux < 2.6.32 */
@@ -3039,11 +3187,6 @@ ev_embeddable_backends (void) EV_NOEXCEPT
 
   /* EVBACKEND_LINUXAIO is theoretically embeddable, but suffers from a performance overhead */
 
-  /* EVBACKEND_IOURING is practically embeddable, but the current implementation is not
-   * because our backend_fd is the epoll fd we need as fallback.
-   * if the kernel ever is fixed, this might change...
-   */
-
   return flags;
 }
 
@@ -3951,6 +4094,18 @@ ev_run (EV_P_ int flags)
           {
             waittime = EV_TS_CONST (MAX_BLOCKTIME);
 
+#if EV_USE_TIMERFD
+            /* sleep a lot longer when we can reliably detect timejumps */
+            if (ecb_expect_true (timerfd >= 0))
+              waittime = EV_TS_CONST (MAX_BLOCKTIME2);
+#endif
+#if !EV_PERIODIC_ENABLE
+            /* without periodics but with monotonic clock there is no need */
+            /* for any time jump detection, so sleep longer */
+            if (ecb_expect_true (have_monotonic))
+              waittime = EV_TS_CONST (MAX_BLOCKTIME2);
+#endif
+
             if (timercnt)
               {
                 ev_tstamp to = ANHE_at (timers [HEAP0]) - mn_now;
@@ -5078,6 +5233,7 @@ embed_prepare_cb (EV_P_ ev_prepare *prepare, int revents)
   }
 }
 
+#if EV_FORK_ENABLE
 static void
 embed_fork_cb (EV_P_ ev_fork *fork_w, int revents)
 {
@@ -5094,6 +5250,7 @@ embed_fork_cb (EV_P_ ev_fork *fork_w, int revents)
 
   ev_embed_start (EV_A_ w);
 }
+#endif
 
 #if 0
 static void
@@ -5124,8 +5281,10 @@ ev_embed_start (EV_P_ ev_embed *w) EV_NOEXCEPT
   ev_set_priority (&w->prepare, EV_MINPRI);
   ev_prepare_start (EV_A_ &w->prepare);
 
+#if EV_FORK_ENABLE
   ev_fork_init (&w->fork, embed_fork_cb);
   ev_fork_start (EV_A_ &w->fork);
+#endif
 
   /*ev_idle_init (&w->idle, e,bed_idle_cb);*/
 
@@ -5145,7 +5304,9 @@ ev_embed_stop (EV_P_ ev_embed *w) EV_NOEXCEPT
 
   ev_io_stop      (EV_A_ &w->io);
   ev_prepare_stop (EV_A_ &w->prepare);
+#if EV_FORK_ENABLE
   ev_fork_stop    (EV_A_ &w->fork);
+#endif
 
   ev_stop (EV_A_ (W)w);
 

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_iouring.c

 /*
  * libev linux io_uring fd activity backend
  *
- * Copyright (c) 2019 Marc Alexander Lehmann <libev@schmorp.de>
+ * Copyright (c) 2019-2020 Marc Alexander Lehmann <libev@schmorp.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modifica-
@@ -46,11 +46,11 @@
  *    of linux aio or epoll and so on and so on. and you could do event stuff
  *    without any syscalls. what's not to like?
  * d) ok, it's vastly more complex, but that's ok, really.
- * e) why 3 mmaps instead of one? one would be more space-efficient,
- *    and I can't see what benefit three would have (other than being
+ * e) why two mmaps instead of one? one would be more space-efficient,
+ *    and I can't see what benefit two would have (other than being
  *    somehow resizable/relocatable, but that's apparently not possible).
- * f) hmm, it's practiclaly undebuggable (gdb can't access the memory, and
-      the bizarre way structure offsets are commuinicated makes it hard to
+ * f) hmm, it's practically undebuggable (gdb can't access the memory, and
+ *    the bizarre way structure offsets are communicated makes it hard to
  *    just print the ring buffer heads, even *iff* the memory were visible
  *    in gdb. but then, that's also ok, really.
  * g) well, you cannot specify a timeout when waiting for events. no,
@@ -60,27 +60,32 @@
  *    like a µ-optimisation by the io_uring author for his personal
  *    applications, to the detriment of everybody else who just wants
  *    an event loop. but, umm, ok, if that's all, it could be worse.
- * h) there is a hardcoded limit of 4096 outstanding events. okay,
- *    at least there is no arbitrary low system-wide limit...
+ *    (from what I gather from the author Jens Axboe, it simply didn't
+ *    occur to him, and he made good on it by adding an unlimited nuber
+ *    of timeouts later :).
+ * h) initially there was a hardcoded limit of 4096 outstanding events.
+ *    later versions not only bump this to 32k, but also can handle
+ *    an unlimited amount of events, so this only affects the batch size.
  * i) unlike linux aio, you *can* register more then the limit
- *    of fd events, and the kernel will "gracefully" signal an
- *    overflow, after which you could destroy and recreate the kernel
- *    state, a bit bigger, or fall back to e.g. poll. thats not
- *    totally insane, but kind of questions the point a high
- *    performance I/O framework when it doesn't really work
- *    under stress.
- * j) but, oh my! is has exactly the same bugs as the linux aio backend,
- *    where some undocumented poll combinations just fail.
- *    so we need epoll AGAIN as a fallback. AGAIN! epoll!! and of course,
- *    this is completely undocumented, have I mantioned this already?
+ *    of fd events. while early verisons of io_uring signalled an overflow
+ *    and you ended up getting wet. 5.5+ does not do this anymore.
+ * j) but, oh my! it had exactly the same bugs as the linux aio backend,
+ *    where some undocumented poll combinations just fail. fortunately,
+ *    after finally reaching the author, he was more than willing to fix
+ *    this probably in 5.6+.
  * k) overall, the *API* itself is, I dare to say, not a total trainwreck.
- *    the big isuess with it are the bugs requiring epoll, which might
- *    or might not get fixed (do I hold my breath?).
+ *    once the bugs ae fixed (probably in 5.6+), it will be without
+ *    competition.
  */
 
+/* TODO: use internal TIMEOUT */
+/* TODO: take advantage of single mmap, NODROP etc. */
+/* TODO: resize cq/sq size independently */
+
 #include <sys/timerfd.h>
 #include <sys/mman.h>
 #include <poll.h>
+#include <stdint.h>
 
 #define IOURING_INIT_ENTRIES 32
 
@@ -98,7 +103,10 @@ struct io_uring_sqe
   __u8 flags;
   __u16 ioprio;
   __s32 fd;
+  union {
     __u64 off;
+    __u64 addr2;
+  };
   __u64 addr;
   __u32 len;
   union {
@@ -107,6 +115,11 @@ struct io_uring_sqe
     __u16 poll_events;
     __u32 sync_range_flags;
     __u32 msg_flags;
+    __u32 timeout_flags;
+    __u32 accept_flags;
+    __u32 cancel_flags;
+    __u32 open_flags;
+    __u32 statx_flags;
   };
   __u64 user_data;
   union {
@@ -153,13 +166,27 @@ struct io_uring_params
   __u32 flags;
   __u32 sq_thread_cpu;
   __u32 sq_thread_idle;
-  __u32 resv[5];
+  __u32 features;
+  __u32 resv[4];
   struct io_sqring_offsets sq_off;
   struct io_cqring_offsets cq_off;
 };
 
+#define IORING_SETUP_CQSIZE 0x00000008
+
 #define IORING_OP_POLL_ADD        6
 #define IORING_OP_POLL_REMOVE     7
+#define IORING_OP_TIMEOUT        11
+#define IORING_OP_TIMEOUT_REMOVE 12
+
+/* relative or absolute, reference clock is CLOCK_MONOTONIC */
+struct iouring_kernel_timespec
+{
+  int64_t tv_sec;
+  long long tv_nsec;
+};
+
+#define IORING_TIMEOUT_ABS 0x00000001
 
 #define IORING_ENTER_GETEVENTS 0x01
 
@@ -167,6 +194,10 @@ struct io_uring_params
 #define IORING_OFF_CQ_RING 0x08000000ULL
 #define IORING_OFF_SQES	   0x10000000ULL
 
+#define IORING_FEAT_SINGLE_MMAP   0x00000001
+#define IORING_FEAT_NODROP        0x00000002
+#define IORING_FEAT_SUBMIT_STABLE 0x00000004
+
 inline_size
 int
 evsys_io_uring_setup (unsigned entries, struct io_uring_params *params)
@@ -195,20 +226,62 @@ evsys_io_uring_enter (int fd, unsigned to_submit, unsigned min_complete, unsigne
 #define EV_SQES         ((struct io_uring_sqe *)         iouring_sqes)
 #define EV_CQES         ((struct io_uring_cqe *)((char *)iouring_cq_ring + iouring_cq_cqes))
 
+inline_speed
+int
+iouring_enter (EV_P_ ev_tstamp timeout)
+{
+  int res;
+
+  EV_RELEASE_CB;
+
+  res = evsys_io_uring_enter (iouring_fd, iouring_to_submit, 1,
+                              timeout > EV_TS_CONST (0.) ? IORING_ENTER_GETEVENTS : 0, 0, 0);
+
+  assert (("libev: io_uring_enter did not consume all sqes", (res < 0 || res == iouring_to_submit)));
+
+  iouring_to_submit = 0;
+
+  EV_ACQUIRE_CB;
+
+  return res;
+}
+
+/* TODO: can we move things around so we don't need this forward-reference? */
+static void
+iouring_poll (EV_P_ ev_tstamp timeout);
+
 static
 struct io_uring_sqe *
 iouring_sqe_get (EV_P)
 {
-  unsigned tail = EV_SQ_VAR (tail);
+  unsigned tail;
   
-  if (tail + 1 - EV_SQ_VAR (head) > EV_SQ_VAR (ring_entries))
+  for (;;)
     {
-      /* queue full, flush */
-      evsys_io_uring_enter (iouring_fd, iouring_to_submit, 0, 0, 0, 0);
-      iouring_to_submit = 0;
+      tail = EV_SQ_VAR (tail);
+
+      if (ecb_expect_true (tail + 1 - EV_SQ_VAR (head) <= EV_SQ_VAR (ring_entries)))
+        break; /* whats the problem, we have free sqes */
+
+      /* queue full, need to flush and possibly handle some events */
+
+#if EV_FEATURE_CODE
+      /* first we ask the kernel nicely, most often this frees up some sqes */
+      int res = iouring_enter (EV_A_ EV_TS_CONST (0.));
+
+      ECB_MEMORY_FENCE_ACQUIRE; /* better safe than sorry */
+
+      if (res >= 0)
+        continue; /* yes, it worked, try again */
+#endif
+
+      /* some problem, possibly EBUSY - do the full poll and let it handle any issues */
+
+      iouring_poll (EV_A_ EV_TS_CONST (0.));
+      /* iouring_poll should have done ECB_MEMORY_FENCE_ACQUIRE for us */
     }
 
-  assert (("libev: io_uring queue full after flush", tail + 1 - EV_SQ_VAR (head) <= EV_SQ_VAR (ring_entries)));
+  /*assert (("libev: io_uring queue full after flush", tail + 1 - EV_SQ_VAR (head) <= EV_SQ_VAR (ring_entries)));*/
 
   return EV_SQES + (tail & EV_SQ_VAR (ring_mask));
 }
@@ -238,12 +311,6 @@ iouring_tfd_cb (EV_P_ struct ev_io *w, int revents)
   iouring_tfd_to = EV_TSTAMP_HUGE;
 }
 
-static void
-iouring_epoll_cb (EV_P_ struct ev_io *w, int revents)
-{
-  epoll_poll (EV_A_ 0);
-}
-
 /* called for full and partial cleanup */
 ecb_cold
 static int
@@ -256,8 +323,11 @@ iouring_internal_destroy (EV_P)
   if (iouring_cq_ring != MAP_FAILED) munmap (iouring_cq_ring, iouring_cq_ring_size);
   if (iouring_sqes    != MAP_FAILED) munmap (iouring_sqes   , iouring_sqes_size   );
 
-  if (ev_is_active (&iouring_epoll_w)) ev_ref (EV_A); ev_io_stop (EV_A_ &iouring_epoll_w);
-  if (ev_is_active (&iouring_tfd_w  )) ev_ref (EV_A); ev_io_stop (EV_A_ &iouring_tfd_w  );
+  if (ev_is_active (&iouring_tfd_w))
+    {
+      ev_ref (EV_A);
+      ev_io_stop (EV_A_ &iouring_tfd_w);
+    }
 }
 
 ecb_cold
@@ -273,6 +343,9 @@ iouring_internal_init (EV_P)
   iouring_cq_ring = MAP_FAILED;
   iouring_sqes    = MAP_FAILED;
 
+  if (!have_monotonic) /* cannot really happen, but what if11 */
+    return -1;
+
   for (;;)
     {
       iouring_fd = evsys_io_uring_setup (iouring_entries, &params);
@@ -283,6 +356,11 @@ iouring_internal_init (EV_P)
       if (errno != EINVAL)
         return -1; /* we failed */
 
+#if TODO
+      if ((~params.features) & (IORING_FEAT_NODROP | IORING_FEATURE_SINGLE_MMAP | IORING_FEAT_SUBMIT_STABLE))
+        return -1; /* we require the above features */
+#endif
+
       /* EINVAL: lots of possible reasons, but maybe
        * it is because we hit the unqueryable hardcoded size limit
        */
@@ -344,14 +422,7 @@ iouring_fork (EV_P)
   while (iouring_internal_init (EV_A) < 0)
     ev_syserr ("(libev) io_uring_setup");
 
-  /* forking epoll should also effectively unregister all fds from the backend */
-  epoll_fork (EV_A);
-  /* epoll_fork already did this. hopefully */
-  /*fd_rearm_all (EV_A);*/
-
-  ev_io_stop  (EV_A_ &iouring_epoll_w);
-  ev_io_set   (EV_A_ &iouring_epoll_w, backend_fd, EV_READ);
-  ev_io_start (EV_A_ &iouring_epoll_w);
+  fd_rearm_all (EV_A);
 
   ev_io_stop  (EV_A_ &iouring_tfd_w);
   ev_io_set   (EV_A_ &iouring_tfd_w, iouring_tfd, EV_READ);
@@ -363,22 +434,19 @@ iouring_fork (EV_P)
 static void
 iouring_modify (EV_P_ int fd, int oev, int nev)
 {
-  if (ecb_expect_false (anfds [fd].eflags))
-    {
-      /* we handed this fd over to epoll, so undo this first */
-      /* we do it manually because the optimisations on epoll_modify won't do us any good */
-      epoll_ctl (iouring_fd, EPOLL_CTL_DEL, fd, 0);
-      anfds [fd].eflags = 0;
-      oev = 0;
-    }
-
   if (oev)
     {
       /* we assume the sqe's are all "properly" initialised */
       struct io_uring_sqe *sqe = iouring_sqe_get (EV_A);
       sqe->opcode    = IORING_OP_POLL_REMOVE;
       sqe->fd        = fd;
-      sqe->user_data = -1;
+      /* Jens Axboe notified me that user_data is not what is documented, but is
+       * some kind of unique ID that has to match, otherwise the request cannot
+       * be removed. Since we don't *really* have that, we pass in the old
+       * generation counter - if that fails, too bad, it will hopefully be removed
+       * at close time and then be ignored. */
+      sqe->addr      = (uint32_t)fd | ((__u64)(uint32_t)anfds [fd].egen << 32);
+      sqe->user_data = (uint64_t)-1;
       iouring_sqe_submit (EV_A_ sqe);
 
       /* increment generation counter to avoid handling old events */
@@ -390,6 +458,7 @@ iouring_modify (EV_P_ int fd, int oev, int nev)
       struct io_uring_sqe *sqe = iouring_sqe_get (EV_A);
       sqe->opcode      = IORING_OP_POLL_ADD;
       sqe->fd          = fd;
+      sqe->addr        = 0;
       sqe->user_data   = (uint32_t)fd | ((__u64)(uint32_t)anfds [fd].egen << 32);
       sqe->poll_events =
         (nev & EV_READ ? POLLIN : 0)
@@ -429,9 +498,9 @@ iouring_process_cqe (EV_P_ struct io_uring_cqe *cqe)
   uint32_t gen = cqe->user_data >> 32;
   int      res = cqe->res;
 
-  /* ignore fd removal events, if there are any. TODO: verify */
-  if (cqe->user_data == (__u64)-1)
-    abort ();//D
+  /* user_data -1 is a remove that we are not atm. interested in */
+  if (cqe->user_data == (uint64_t)-1)
+    return;
 
   assert (("libev: io_uring fd must be in-bounds", fd >= 0 && fd < anfdmax));
 
@@ -442,23 +511,16 @@ iouring_process_cqe (EV_P_ struct io_uring_cqe *cqe)
    */
 
   /* ignore event if generation doesn't match */
+  /* other than skipping removal events, */
   /* this should actually be very rare */
   if (ecb_expect_false (gen != (uint32_t)anfds [fd].egen))
     return;
 
   if (ecb_expect_false (res < 0))
     {
-      if (res == -EINVAL)
-        {
-          /* we assume this error code means the fd/poll combination is buggy
-           * and fall back to epoll.
-           * this error code might also indicate a bug, but the kernel doesn't
-           * distinguish between those two conditions, so... sigh...
-           */
+      /*TODO: EINVAL handling (was something failed with this fd)*/
 
-          epoll_modify (EV_A_ fd, 0, anfds [fd].events);
-        }
-      else if (res == -EBADF)
+      if (res == -EBADF)
         {
           assert (("libev: event loop rejected bad fd", res != -EBADF));
           fd_kill (EV_A_ fd);
@@ -494,7 +556,7 @@ iouring_overflow (EV_P)
   /* we have two options, resize the queue (by tearing down
    * everything and recreating it, or living with it
    * and polling.
-   * we implement this by resizing tghe queue, and, if that fails,
+   * we implement this by resizing the queue, and, if that fails,
    * we just recreate the state on every failure, which
    * kind of is a very inefficient poll.
    * one danger is, due to the bios toward lower fds,
@@ -516,12 +578,12 @@ iouring_overflow (EV_P)
       /* we hit the kernel limit, we should fall back to something else.
        * we can either poll() a few times and hope for the best,
        * poll always, or switch to epoll.
-       * since we use epoll anyways, go epoll.
+       * TODO: is this necessary with newer kernels?
        */
 
       iouring_internal_destroy (EV_A);
 
-      /* this should make it so that on return, we don'T call any uring functions */
+      /* this should make it so that on return, we don't call any uring functions */
       iouring_to_submit = 0;
 
       for (;;)
@@ -572,7 +634,11 @@ static void
 iouring_poll (EV_P_ ev_tstamp timeout)
 {
   /* if we have events, no need for extra syscalls, but we might have to queue events */
-  if (iouring_handle_cq (EV_A))
+  /* we also clar the timeout if there are outstanding fdchanges */
+  /* the latter should only happen if both the sq and cq are full, most likely */
+  /* because we have a lot of event sources that immediately complete */
+  /* TODO: fdchacngecnt is always 0 because fd_reify does not have two buffers yet */
+  if (iouring_handle_cq (EV_A) || fdchangecnt)
     timeout = EV_TS_CONST (0.);
   else
     /* no events, so maybe wait for some */
@@ -581,19 +647,13 @@ iouring_poll (EV_P_ ev_tstamp timeout)
   /* only enter the kernel if we have something to submit, or we need to wait */
   if (timeout || iouring_to_submit)
     {
-      int res;
-
-      EV_RELEASE_CB;
-
-      res = evsys_io_uring_enter (iouring_fd, iouring_to_submit, 1,
-                                  timeout > EV_TS_CONST (0.) ? IORING_ENTER_GETEVENTS : 0, 0, 0);
-      iouring_to_submit = 0;
-
-      EV_ACQUIRE_CB;
+      int res = iouring_enter (EV_A_ timeout);
 
       if (ecb_expect_false (res < 0))
         if (errno == EINTR)
           /* ignore */;
+        else if (errno == EBUSY)
+          /* cq full, cannot submit - should be rare because we flush the cq first, so simply ignore */;
         else
           ev_syserr ("(libev) iouring setup");
       else
@@ -605,9 +665,6 @@ inline_size
 int
 iouring_init (EV_P_ int flags)
 {
-  if (!epoll_init (EV_A_ 0))
-    return 0;
-
   iouring_entries     = IOURING_INIT_ENTRIES;
   iouring_max_entries = 0;
 
@@ -617,15 +674,8 @@ iouring_init (EV_P_ int flags)
       return 0;
     }
 
-  ev_io_init  (&iouring_epoll_w, iouring_epoll_cb, backend_fd, EV_READ);
-  ev_set_priority (&iouring_epoll_w, EV_MAXPRI);
-
   ev_io_init  (&iouring_tfd_w, iouring_tfd_cb, iouring_tfd, EV_READ);
-  ev_set_priority (&iouring_tfd_w, EV_MAXPRI);
-
-  ev_io_start (EV_A_ &iouring_epoll_w);
-  ev_unref (EV_A); /* watcher should not keep loop alive */
-
+  ev_set_priority (&iouring_tfd_w, EV_MINPRI);
   ev_io_start (EV_A_ &iouring_tfd_w);
   ev_unref (EV_A); /* watcher should not keep loop alive */
 
@@ -640,6 +690,5 @@ void
 iouring_destroy (EV_P)
 {
   iouring_internal_destroy (EV_A);
-  epoll_destroy (EV_A);
 }
 

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.