ceph/src/boost/boost/fiber/detail/futex.hpp

   1
   2 //          Copyright Oliver Kowalke 2016.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_FIBERS_DETAIL_FUTEX_H
   8 #define BOOST_FIBERS_DETAIL_FUTEX_H
   9
  10 #include <boost/config.hpp>
  11 #include <boost/predef.h>
  12
  13 #include <boost/fiber/detail/config.hpp>
  14
  15 #if BOOST_OS_LINUX
  16 extern "C" {
  17 #include <linux/futex.h>
  18 #include <sys/syscall.h>
  19 }
  20 #elif BOOST_OS_WINDOWS
  21 #include <windows.h>
  22 #endif
  23
  24 namespace boost {
  25 namespace fibers {
  26 namespace detail {
  27
  28 #if BOOST_OS_LINUX
  29 BOOST_FORCEINLINE
  30 int sys_futex( void * addr, std::int32_t op, std::int32_t x) {
  31     return ::syscall( SYS_futex, addr, op, x, nullptr, nullptr, 0);
  32 }
  33
  34 BOOST_FORCEINLINE
  35 int futex_wake( std::atomic< std::int32_t > * addr) {
  36     return 0 <= sys_futex( static_cast< void * >( addr), FUTEX_WAKE_PRIVATE, 1) ? 0 : -1;
  37 }
  38
  39 BOOST_FORCEINLINE
  40 int futex_wait( std::atomic< std::int32_t > * addr, std::int32_t x) {
  41     return 0 <= sys_futex( static_cast< void * >( addr), FUTEX_WAIT_PRIVATE, x) ? 0 : -1;
  42 }
  43 #elif BOOST_OS_WINDOWS
  44 BOOST_FORCEINLINE
  45 int futex_wake( std::atomic< std::int32_t > * addr) {
  46     ::WakeByAddressSingle( static_cast< void * >( addr) );
  47     return 0;
  48 }
  49
  50 BOOST_FORCEINLINE
  51 int futex_wait( std::atomic< std::int32_t > * addr, std::int32_t x) {
  52     ::WaitOnAddress( static_cast< volatile void * >( addr), & x, sizeof( x), INFINITE);
  53     return 0;
  54 }
  55 #else
  56 # warn "no futex support on this platform"
  57 #endif
  58
  59 }}}
  60
  61 #endif // BOOST_FIBERS_DETAIL_FUTEX_H