libev/ev.c

/*
 * libev event processing core, watcher management
 *
 * Copyright (c) 2007,2008,2009,2010,2011,2012,2013 Marc Alexander Lehmann <libev@schmorp.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

/* this big block deduces configuration from config.h */
#ifndef EV_STANDALONE
# ifdef EV_CONFIG_H
#  include EV_CONFIG_H
# else
#  include "config.h"
# endif

# if HAVE_FLOOR
#  ifndef EV_USE_FLOOR
#   define EV_USE_FLOOR 1
#  endif
# endif

# if HAVE_CLOCK_SYSCALL
#  ifndef EV_USE_CLOCK_SYSCALL
#   define EV_USE_CLOCK_SYSCALL 1
#   ifndef EV_USE_REALTIME
#    define EV_USE_REALTIME  0
#   endif
#   ifndef EV_USE_MONOTONIC
#    define EV_USE_MONOTONIC 1
#   endif
#  endif
# elif !defined EV_USE_CLOCK_SYSCALL
#  define EV_USE_CLOCK_SYSCALL 0
# endif

# if HAVE_CLOCK_GETTIME
#  ifndef EV_USE_MONOTONIC
#   define EV_USE_MONOTONIC 1
#  endif
#  ifndef EV_USE_REALTIME
#   define EV_USE_REALTIME  0
#  endif
# else
#  ifndef EV_USE_MONOTONIC
#   define EV_USE_MONOTONIC 0
#  endif
#  ifndef EV_USE_REALTIME
#   define EV_USE_REALTIME  0
#  endif
# endif

# if HAVE_NANOSLEEP
#  ifndef EV_USE_NANOSLEEP
#    define EV_USE_NANOSLEEP EV_FEATURE_OS
#  endif
# else
#   undef EV_USE_NANOSLEEP
#   define EV_USE_NANOSLEEP 0
# endif

# if HAVE_SELECT && HAVE_SYS_SELECT_H
#  ifndef EV_USE_SELECT
#   define EV_USE_SELECT EV_FEATURE_BACKENDS
#  endif
# else
#  undef EV_USE_SELECT
#  define EV_USE_SELECT 0
# endif

# if HAVE_POLL && HAVE_POLL_H
#  ifndef EV_USE_POLL
#   define EV_USE_POLL EV_FEATURE_BACKENDS
#  endif
# else
#  undef EV_USE_POLL
#  define EV_USE_POLL 0
# endif
   
# if HAVE_EPOLL_CTL && HAVE_SYS_EPOLL_H
#  ifndef EV_USE_EPOLL
#   define EV_USE_EPOLL EV_FEATURE_BACKENDS
#  endif
# else
#  undef EV_USE_EPOLL
#  define EV_USE_EPOLL 0
# endif
   
# if HAVE_KQUEUE && HAVE_SYS_EVENT_H
#  ifndef EV_USE_KQUEUE
#   define EV_USE_KQUEUE EV_FEATURE_BACKENDS
#  endif
# else
#  undef EV_USE_KQUEUE
#  define EV_USE_KQUEUE 0
# endif
   
# if HAVE_PORT_H && HAVE_PORT_CREATE
#  ifndef EV_USE_PORT
#   define EV_USE_PORT EV_FEATURE_BACKENDS
#  endif
# else
#  undef EV_USE_PORT
#  define EV_USE_PORT 0
# endif

# if HAVE_INOTIFY_INIT && HAVE_SYS_INOTIFY_H
#  ifndef EV_USE_INOTIFY
#   define EV_USE_INOTIFY EV_FEATURE_OS
#  endif
# else
#  undef EV_USE_INOTIFY
#  define EV_USE_INOTIFY 0
# endif

# if HAVE_SIGNALFD && HAVE_SYS_SIGNALFD_H
#  ifndef EV_USE_SIGNALFD
#   define EV_USE_SIGNALFD EV_FEATURE_OS
#  endif
# else
#  undef EV_USE_SIGNALFD
#  define EV_USE_SIGNALFD 0
# endif

# if HAVE_EVENTFD
#  ifndef EV_USE_EVENTFD
#   define EV_USE_EVENTFD EV_FEATURE_OS
#  endif
# else
#  undef EV_USE_EVENTFD
#  define EV_USE_EVENTFD 0
# endif
 
#endif

#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <stddef.h>

#include <stdio.h>

#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <time.h>
#include <limits.h>

#include <signal.h>

#ifdef EV_H
# include EV_H
#else
# include "ev.h"
#endif

#if EV_NO_THREADS
# undef EV_NO_SMP
# define EV_NO_SMP 1
# undef ECB_NO_THREADS
# define ECB_NO_THREADS 1
#endif
#if EV_NO_SMP
# undef EV_NO_SMP
# define ECB_NO_SMP 1
#endif

#ifndef _WIN32
# include <sys/time.h>
# include <sys/wait.h>
# include <unistd.h>
#else
# include <io.h>
# define WIN32_LEAN_AND_MEAN
# include <winsock2.h>
# include <windows.h>
# ifndef EV_SELECT_IS_WINSOCKET
#  define EV_SELECT_IS_WINSOCKET 1
# endif
# undef EV_AVOID_STDIO
#endif

/* OS X, in its infinite idiocy, actually HARDCODES
 * a limit of 1024 into their select. Where people have brains,
 * OS X engineers apparently have a vacuum. Or maybe they were
 * ordered to have a vacuum, or they do anything for money.
 * This might help. Or not.
 */
#define _DARWIN_UNLIMITED_SELECT 1

/* this block tries to deduce configuration from header-defined symbols and defaults */

/* try to deduce the maximum number of signals on this platform */
#if defined EV_NSIG
/* use what's provided */
#elif defined NSIG
# define EV_NSIG (NSIG)
#elif defined _NSIG
# define EV_NSIG (_NSIG)
#elif defined SIGMAX
# define EV_NSIG (SIGMAX+1)
#elif defined SIG_MAX
# define EV_NSIG (SIG_MAX+1)
#elif defined _SIG_MAX
# define EV_NSIG (_SIG_MAX+1)
#elif defined MAXSIG
# define EV_NSIG (MAXSIG+1)
#elif defined MAX_SIG
# define EV_NSIG (MAX_SIG+1)
#elif defined SIGARRAYSIZE
# define EV_NSIG (SIGARRAYSIZE) /* Assume ary[SIGARRAYSIZE] */
#elif defined _sys_nsig
# define EV_NSIG (_sys_nsig) /* Solaris 2.5 */
#else
# define EV_NSIG (8 * sizeof (sigset_t) + 1)
#endif

#ifndef EV_USE_FLOOR
# define EV_USE_FLOOR 0
#endif

#ifndef EV_USE_CLOCK_SYSCALL
# if __linux && __GLIBC__ == 2 && __GLIBC_MINOR__ < 17
#  define EV_USE_CLOCK_SYSCALL EV_FEATURE_OS
# else
#  define EV_USE_CLOCK_SYSCALL 0
# endif
#endif

#if !(_POSIX_TIMERS > 0)
# ifndef EV_USE_MONOTONIC
#  define EV_USE_MONOTONIC 0
# endif
# ifndef EV_USE_REALTIME
#  define EV_USE_REALTIME 0
# endif
#endif

#ifndef EV_USE_MONOTONIC
# if defined _POSIX_MONOTONIC_CLOCK && _POSIX_MONOTONIC_CLOCK >= 0
#  define EV_USE_MONOTONIC EV_FEATURE_OS
# else
#  define EV_USE_MONOTONIC 0
# endif
#endif

#ifndef EV_USE_REALTIME
# define EV_USE_REALTIME !EV_USE_CLOCK_SYSCALL
#endif

#ifndef EV_USE_NANOSLEEP
# if _POSIX_C_SOURCE >= 199309L
#  define EV_USE_NANOSLEEP EV_FEATURE_OS
# else
#  define EV_USE_NANOSLEEP 0
# endif
#endif

#ifndef EV_USE_SELECT
# define EV_USE_SELECT EV_FEATURE_BACKENDS
#endif

#ifndef EV_USE_POLL
# ifdef _WIN32
#  define EV_USE_POLL 0
# else
#  define EV_USE_POLL EV_FEATURE_BACKENDS
# endif
#endif

#ifndef EV_USE_EPOLL
# if __linux && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 4))
#  define EV_USE_EPOLL EV_FEATURE_BACKENDS
# else
#  define EV_USE_EPOLL 0
# endif
#endif

#ifndef EV_USE_KQUEUE
# define EV_USE_KQUEUE 0
#endif

#ifndef EV_USE_PORT
# define EV_USE_PORT 0
#endif

#ifndef EV_USE_INOTIFY
# if __linux && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 4))
#  define EV_USE_INOTIFY EV_FEATURE_OS
# else
#  define EV_USE_INOTIFY 0
# endif
#endif

#ifndef EV_PID_HASHSIZE
# define EV_PID_HASHSIZE EV_FEATURE_DATA ? 16 : 1
#endif

#ifndef EV_INOTIFY_HASHSIZE
# define EV_INOTIFY_HASHSIZE EV_FEATURE_DATA ? 16 : 1
#endif

#ifndef EV_USE_EVENTFD
# if __linux && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7))
#  define EV_USE_EVENTFD EV_FEATURE_OS
# else
#  define EV_USE_EVENTFD 0
# endif
#endif

#ifndef EV_USE_SIGNALFD
# if __linux && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7))
#  define EV_USE_SIGNALFD EV_FEATURE_OS
# else
#  define EV_USE_SIGNALFD 0
# endif
#endif

#if 0 /* debugging */
# define EV_VERIFY 3
# define EV_USE_4HEAP 1
# define EV_HEAP_CACHE_AT 1
#endif

#ifndef EV_VERIFY
# define EV_VERIFY (EV_FEATURE_API ? 1 : 0)
#endif

#ifndef EV_USE_4HEAP
# define EV_USE_4HEAP EV_FEATURE_DATA
#endif

#ifndef EV_HEAP_CACHE_AT
# define EV_HEAP_CACHE_AT EV_FEATURE_DATA
#endif

#ifdef __ANDROID__
/* supposedly, android doesn't typedef fd_mask */
# undef EV_USE_SELECT
# define EV_USE_SELECT 0
/* supposedly, we need to include syscall.h, not sys/syscall.h, so just disable */
# undef EV_USE_CLOCK_SYSCALL
# define EV_USE_CLOCK_SYSCALL 0
#endif

/* aix's poll.h seems to cause lots of trouble */
#ifdef _AIX
/* AIX has a completely broken poll.h header */
# undef EV_USE_POLL
# define EV_USE_POLL 0
#endif

/* on linux, we can use a (slow) syscall to avoid a dependency on pthread, */
/* which makes programs even slower. might work on other unices, too. */
#if EV_USE_CLOCK_SYSCALL
# include <sys/syscall.h>
# ifdef SYS_clock_gettime
#  define clock_gettime(id, ts) syscall (SYS_clock_gettime, (id), (ts))
#  undef EV_USE_MONOTONIC
#  define EV_USE_MONOTONIC 1
# else
#  undef EV_USE_CLOCK_SYSCALL
#  define EV_USE_CLOCK_SYSCALL 0
# endif
#endif

/* this block fixes any misconfiguration where we know we run into trouble otherwise */

#ifndef CLOCK_MONOTONIC
# undef EV_USE_MONOTONIC
# define EV_USE_MONOTONIC 0
#endif

#ifndef CLOCK_REALTIME
# undef EV_USE_REALTIME
# define EV_USE_REALTIME 0
#endif

#if !EV_STAT_ENABLE
# undef EV_USE_INOTIFY
# define EV_USE_INOTIFY 0
#endif

#if !EV_USE_NANOSLEEP
/* hp-ux has it in sys/time.h, which we unconditionally include above */
# if !defined _WIN32 && !defined __hpux
#  include <sys/select.h>
# endif
#endif

#if EV_USE_INOTIFY
# include <sys/statfs.h>
# include <sys/inotify.h>
/* some very old inotify.h headers don't have IN_DONT_FOLLOW */
# ifndef IN_DONT_FOLLOW
#  undef EV_USE_INOTIFY
#  define EV_USE_INOTIFY 0
# endif
#endif

#if EV_USE_EVENTFD
/* our minimum requirement is glibc 2.7 which has the stub, but not the header */
# include <stdint.h>
# ifndef EFD_NONBLOCK
#  define EFD_NONBLOCK O_NONBLOCK
# endif
# ifndef EFD_CLOEXEC
#  ifdef O_CLOEXEC
#   define EFD_CLOEXEC O_CLOEXEC
#  else
#   define EFD_CLOEXEC 02000000
#  endif
# endif
EV_CPP(extern "C") int (eventfd) (unsigned int initval, int flags);
#endif

#if EV_USE_SIGNALFD
/* our minimum requirement is glibc 2.7 which has the stub, but not the header */
# include <stdint.h>
# ifndef SFD_NONBLOCK
#  define SFD_NONBLOCK O_NONBLOCK
# endif
# ifndef SFD_CLOEXEC
#  ifdef O_CLOEXEC
#   define SFD_CLOEXEC O_CLOEXEC
#  else
#   define SFD_CLOEXEC 02000000
#  endif
# endif
EV_CPP (extern "C") int signalfd (int fd, const sigset_t *mask, int flags);

struct signalfd_siginfo
{
  uint32_t ssi_signo;
  char pad[128 - sizeof (uint32_t)];
};
#endif

/**/

#if EV_VERIFY >= 3
# define EV_FREQUENT_CHECK ev_verify (EV_A)
#else
# define EV_FREQUENT_CHECK do { } while (0)
#endif

/*
 * This is used to work around floating point rounding problems.
 * This value is good at least till the year 4000.
 */
#define MIN_INTERVAL  0.0001220703125 /* 1/2**13, good till 4000 */
/*#define MIN_INTERVAL  0.00000095367431640625 /* 1/2**20, good till 2200 */

#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 EV_TV_SET(tv,t) do { tv.tv_sec = (long)t; tv.tv_usec = (long)((t - tv.tv_sec) * 1e6); } while (0)
#define EV_TS_SET(ts,t) do { ts.tv_sec = (long)t; ts.tv_nsec = (long)((t - ts.tv_sec) * 1e9); } while (0)

/* the following is ecb.h embedded into libev - use update_ev_c to update from an external copy */
/* ECB.H BEGIN */
/*
 * libecb - http://software.schmorp.de/pkg/libecb
 *
 * Copyright (©) 2009-2015 Marc Alexander Lehmann <libecb@schmorp.de>
 * Copyright (©) 2011 Emanuele Giaquinta
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#ifndef ECB_H
#define ECB_H

/* 16 bits major, 16 bits minor */
#define ECB_VERSION 0x00010005

#ifdef _WIN32
  typedef   signed char   int8_t;
  typedef unsigned char  uint8_t;
  typedef   signed short  int16_t;
  typedef unsigned short uint16_t;
  typedef   signed int    int32_t;
  typedef unsigned int   uint32_t;
  #if __GNUC__
    typedef   signed long long int64_t;
    typedef unsigned long long uint64_t;
  #else /* _MSC_VER || __BORLANDC__ */
    typedef   signed __int64   int64_t;
    typedef unsigned __int64   uint64_t;
  #endif
  #ifdef _WIN64
    #define ECB_PTRSIZE 8
    typedef uint64_t uintptr_t;
    typedef  int64_t  intptr_t;
  #else
    #define ECB_PTRSIZE 4
    typedef uint32_t uintptr_t;
    typedef  int32_t  intptr_t;
  #endif
#else
  #include <inttypes.h>
  #if (defined INTPTR_MAX ? INTPTR_MAX : ULONG_MAX) > 0xffffffffU
    #define ECB_PTRSIZE 8
  #else
    #define ECB_PTRSIZE 4
  #endif
#endif

#define ECB_GCC_AMD64 (__amd64 || __amd64__ || __x86_64 || __x86_64__)
#define ECB_MSVC_AMD64 (_M_AMD64 || _M_X64)

/* work around x32 idiocy by defining proper macros */
#if ECB_GCC_AMD64 || ECB_MSVC_AMD64
  #if _ILP32
    #define ECB_AMD64_X32 1
  #else
    #define ECB_AMD64 1
  #endif
#endif

/* many compilers define _GNUC_ to some versions but then only implement
 * what their idiot authors think are the "more important" extensions,
 * causing enormous grief in return for some better fake benchmark numbers.
 * or so.
 * we try to detect these and simply assume they are not gcc - if they have
 * an issue with that they should have done it right in the first place.
 */
#if !defined __GNUC_MINOR__ || defined __INTEL_COMPILER || defined __SUNPRO_C || defined __SUNPRO_CC || defined __llvm__ || defined __clang__
  #define ECB_GCC_VERSION(major,minor) 0
#else
  #define ECB_GCC_VERSION(major,minor) (__GNUC__ > (major) || (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))
#endif

#define ECB_CLANG_VERSION(major,minor) (__clang_major__ > (major) || (__clang_major__ == (major) && __clang_minor__ >= (minor)))

#if __clang__ && defined __has_builtin
  #define ECB_CLANG_BUILTIN(x) __has_builtin (x)
#else
  #define ECB_CLANG_BUILTIN(x) 0
#endif

#if __clang__ && defined __has_extension
  #define ECB_CLANG_EXTENSION(x) __has_extension (x)
#else
  #define ECB_CLANG_EXTENSION(x) 0
#endif

#define ECB_CPP   (__cplusplus+0)
#define ECB_CPP11 (__cplusplus >= 201103L)

#if ECB_CPP
  #define ECB_C            0
  #define ECB_STDC_VERSION 0
#else
  #define ECB_C            1
  #define ECB_STDC_VERSION __STDC_VERSION__
#endif

#define ECB_C99   (ECB_STDC_VERSION >= 199901L)
#define ECB_C11   (ECB_STDC_VERSION >= 201112L)

#if ECB_CPP
  #define ECB_EXTERN_C extern "C"
  #define ECB_EXTERN_C_BEG ECB_EXTERN_C {
  #define ECB_EXTERN_C_END }
#else
  #define ECB_EXTERN_C extern
  #define ECB_EXTERN_C_BEG
  #define ECB_EXTERN_C_END
#endif

/*****************************************************************************/

/* ECB_NO_THREADS - ecb is not used by multiple threads, ever */
/* ECB_NO_SMP     - ecb might be used in multiple threads, but only on a single cpu */

#if ECB_NO_THREADS
  #define ECB_NO_SMP 1
#endif

#if ECB_NO_SMP
  #define ECB_MEMORY_FENCE do { } while (0)
#endif

/* http://www-01.ibm.com/support/knowledgecenter/SSGH3R_13.1.0/com.ibm.xlcpp131.aix.doc/compiler_ref/compiler_builtins.html */
#if __xlC__ && ECB_CPP
  #include <builtins.h>
#endif

#if 1400 <= _MSC_VER
  #include <intrin.h> /* fence functions _ReadBarrier, also bit search functions _BitScanReverse */
#endif

#ifndef ECB_MEMORY_FENCE
  #if ECB_GCC_VERSION(2,5) || defined __INTEL_COMPILER || (__llvm__ && __GNUC__) || __SUNPRO_C >= 0x5110 || __SUNPRO_CC >= 0x5110
    #if __i386 || __i386__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("lock; orb $0, -1(%%esp)" : : : "memory")
      #define ECB_MEMORY_FENCE_ACQUIRE __asm__ __volatile__ (""                        : : : "memory")
      #define ECB_MEMORY_FENCE_RELEASE __asm__ __volatile__ ("")
    #elif ECB_GCC_AMD64
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("mfence"   : : : "memory")
      #define ECB_MEMORY_FENCE_ACQUIRE __asm__ __volatile__ (""         : : : "memory")
      #define ECB_MEMORY_FENCE_RELEASE __asm__ __volatile__ ("")
    #elif __powerpc__ || __ppc__ || __powerpc64__ || __ppc64__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("sync"     : : : "memory")
    #elif defined __ARM_ARCH_2__ \
      || defined __ARM_ARCH_3__  || defined __ARM_ARCH_3M__  \
      || defined __ARM_ARCH_4__  || defined __ARM_ARCH_4T__  \
      || defined __ARM_ARCH_5__  || defined __ARM_ARCH_5E__  \
      || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__ \
      || defined __ARM_ARCH_5TEJ__
      /* should not need any, unless running old code on newer cpu - arm doesn't support that */
    #elif defined __ARM_ARCH_6__  || defined __ARM_ARCH_6J__  \
       || defined __ARM_ARCH_6K__ || defined __ARM_ARCH_6ZK__ \
       || defined __ARM_ARCH_6T2__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("mcr p15,0,%0,c7,c10,5" : : "r" (0) : "memory")
    #elif defined __ARM_ARCH_7__  || defined __ARM_ARCH_7A__  \
       || defined __ARM_ARCH_7R__ || defined __ARM_ARCH_7M__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("dmb"      : : : "memory")
    #elif __aarch64__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("dmb ish"  : : : "memory")
    #elif (__sparc || __sparc__) && !(__sparc_v8__ || defined __sparcv8)
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("membar #LoadStore | #LoadLoad | #StoreStore | #StoreLoad" : : : "memory")
      #define ECB_MEMORY_FENCE_ACQUIRE __asm__ __volatile__ ("membar #LoadStore | #LoadLoad"                            : : : "memory")
      #define ECB_MEMORY_FENCE_RELEASE __asm__ __volatile__ ("membar #LoadStore             | #StoreStore")
    #elif defined __s390__ || defined __s390x__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("bcr 15,0" : : : "memory")
    #elif defined __mips__
      /* GNU/Linux emulates sync on mips1 architectures, so we force its use */
      /* anybody else who still uses mips1 is supposed to send in their version, with detection code. */
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ (".set mips2; sync; .set mips0" : : : "memory")
    #elif defined __alpha__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("mb"       : : : "memory")
    #elif defined __hppa__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ (""         : : : "memory")
      #define ECB_MEMORY_FENCE_RELEASE __asm__ __volatile__ ("")
    #elif defined __ia64__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("mf"       : : : "memory")
    #elif defined __m68k__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ (""         : : : "memory")
    #elif defined __m88k__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("tb1 0,%%r0,128" : : : "memory")
    #elif defined __sh__
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ (""         : : : "memory")
    #endif
  #endif
#endif

#ifndef ECB_MEMORY_FENCE
  #if ECB_GCC_VERSION(4,7)
    /* see comment below (stdatomic.h) about the C11 memory model. */
    #define ECB_MEMORY_FENCE         __atomic_thread_fence (__ATOMIC_SEQ_CST)
    #define ECB_MEMORY_FENCE_ACQUIRE __atomic_thread_fence (__ATOMIC_ACQUIRE)
    #define ECB_MEMORY_FENCE_RELEASE __atomic_thread_fence (__ATOMIC_RELEASE)

  #elif ECB_CLANG_EXTENSION(c_atomic)
    /* see comment below (stdatomic.h) about the C11 memory model. */
    #define ECB_MEMORY_FENCE         __c11_atomic_thread_fence (__ATOMIC_SEQ_CST)
    #define ECB_MEMORY_FENCE_ACQUIRE __c11_atomic_thread_fence (__ATOMIC_ACQUIRE)
    #define ECB_MEMORY_FENCE_RELEASE __c11_atomic_thread_fence (__ATOMIC_RELEASE)

  #elif ECB_GCC_VERSION(4,4) || defined __INTEL_COMPILER || defined __clang__