common/alsem.cpp

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 1999-2007 by authors.
   4  * This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  *  License along with this library; if not, write to the
  16  *  Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  * Or go to http://www.gnu.org/copyleft/lgpl.html
  19  */
  20
  21 #include "config.h"
  22
  23 #include "alsem.h"
  24
  25 #include <system_error>
  26
  27 #include "opthelpers.h"
  28
  29
  30 #ifdef _WIN32
  31 #define WIN32_LEAN_AND_MEAN
  32 #include <windows.h>
  33
  34 #include <limits>
  35
  36 namespace al {
  37
  38 semaphore::semaphore(unsigned int initial)
  39 {
  40     if(initial > static_cast<unsigned int>(std::numeric_limits<int>::max()))
  41         throw std::system_error(std::make_error_code(std::errc::value_too_large));
  42     mSem = CreateSemaphore(nullptr, initial, std::numeric_limits<int>::max(), nullptr);
  43     if(mSem == nullptr)
  44         throw std::system_error(std::make_error_code(std::errc::resource_unavailable_try_again));
  45 }
  46
  47 semaphore::~semaphore()
  48 { CloseHandle(mSem); }
  49
  50 void semaphore::post()
  51 {
  52     if(!ReleaseSemaphore(static_cast<HANDLE>(mSem), 1, nullptr))
  53         throw std::system_error(std::make_error_code(std::errc::value_too_large));
  54 }
  55
  56 void semaphore::wait() noexcept
  57 { WaitForSingleObject(static_cast<HANDLE>(mSem), INFINITE); }
  58
  59 bool semaphore::try_wait() noexcept
  60 { return WaitForSingleObject(static_cast<HANDLE>(mSem), 0) == WAIT_OBJECT_0; }
  61
  62 } // namespace al
  63
  64 #else
  65
  66 /* Do not try using libdispatch on systems where it is absent. */
  67 #if defined(AL_APPLE_HAVE_DISPATCH)
  68
  69 namespace al {
  70
  71 semaphore::semaphore(unsigned int initial)
  72 {
  73     mSem = dispatch_semaphore_create(initial);
  74     if(!mSem)
  75         throw std::system_error(std::make_error_code(std::errc::resource_unavailable_try_again));
  76 }
  77
  78 semaphore::~semaphore()
  79 { dispatch_release(mSem); }
  80
  81 void semaphore::post()
  82 { dispatch_semaphore_signal(mSem); }
  83
  84 void semaphore::wait() noexcept
  85 { dispatch_semaphore_wait(mSem, DISPATCH_TIME_FOREVER); }
  86
  87 bool semaphore::try_wait() noexcept
  88 { return dispatch_semaphore_wait(mSem, DISPATCH_TIME_NOW) == 0; }
  89
  90 } // namespace al
  91
  92 #else /* !__APPLE__ */
  93
  94 #include <cerrno>
  95
  96 namespace al {
  97
  98 semaphore::semaphore(unsigned int initial)
  99 {
 100     if(sem_init(&mSem, 0, initial) != 0)
 101         throw std::system_error(std::make_error_code(std::errc::resource_unavailable_try_again));
 102 }
 103
 104 semaphore::~semaphore()
 105 { sem_destroy(&mSem); }
 106
 107 void semaphore::post()
 108 {
 109     if(sem_post(&mSem) != 0)
 110         throw std::system_error(std::make_error_code(std::errc::value_too_large));
 111 }
 112
 113 void semaphore::wait() noexcept
 114 {
 115     while(sem_wait(&mSem) == -1 && errno == EINTR) {
 116     }
 117 }
 118
 119 bool semaphore::try_wait() noexcept
 120 { return sem_trywait(&mSem) == 0; }
 121
 122 } // namespace al
 123
 124 #endif /* __APPLE__ */
 125
 126 #endif /* _WIN32 */