跨平台中对于 信号量(semaphore) 的包装

信号量，常用于线程间同步。

说明：

跨平台宏(platform.hpp)的定义参见另一篇博文，当然截取代码实现时可以换成自己习惯的定义。跨平台中条件编译的使用使得代码不是那么容易看，但是还好每个函数只有几句话

/** * @file - * @author jingqi * @date 2012-07-10 * @last-edit 2012-07-10 21:23:00 jingqi */#ifndef ___HEADFILE_49083D01_04DA_4385_A1BD_6D1F2902FA7A_#define ___HEADFILE_49083D01_04DA_4385_A1BD_6D1F2902FA7A_#include <assert.h>#include <nut/platform/platform.hpp>#if defined(NUT_PLATFORM_OS_WINDOWS)#   include <windows.h>#else#   include <semaphore.h>#endifnamespace nut{class Semaphore{#if defined(NUT_PLATFORM_OS_WINDOWS)    HANDLE m_sema;#else    sem_t m_sem;#endifpublic:    Semaphore(int initValue)    {#if defined(NUT_PLATFORM_OS_WINDOWS)        m_sema = ::CreateSemaphoreA(            NULL, // security attributes            initValue, // initial count            0x7fffffff, // maximum value            NULL); // name        assert(NULL != m_sema);#else        int rs = ::sem_init(&m_sem, 0, initValue);        assert(0 == rs);#endif    }    ~Semaphore()    {#if defined(NUT_PLATFORM_OS_WINDOWS)        BOOL rs = ::CloseHandle(m_sema);        assert(rs);#else        int rs = ::sem_destroy(&m_sem);        assert(0 == rs);#endif    }    void wait()    {#if defined(NUT_PLATFORM_OS_WINDOWS)        DWORD rs = ::WaitForSingleObject(m_sema, INFINITE);        assert(WAIT_OBJECT_0 == rs);#else        int rs = ::sem_wait(&m_sem);        assert(0 == rs);#endif    }    void post()    {#if defined(NUT_PLATFORM_OS_WINDOWS)        BOOL rs = ::ReleaseSemaphore(m_sema, 1, NULL);        assert(rs);#else        int rs = ::sem_post(&m_sem);        assert(0 == rs);#endif    }    bool trywait()    {#if defined(NUT_PLATFORM_OS_WINDOWS)        return WAIT_OBJECT_0 == ::WaitForSingleObject(m_sema, 0);#else        return 0 == ::sem_trywait(&m_sem);#endif    }    bool timedwait(unsigned s, unsigned ms)    {#if defined(NUT_PLATFORM_OS_WINDOWS)        DWORD dwMilliseconds = s * 1000 + ms;        return WAIT_OBJECT_0 == ::WaitForSingleObject(m_sema, dwMilliseconds);#else        struct timespec abstime;        clock_gettime(CLOCK_REALTIME, &abstime);        abstime.tv_sec += s;        abstime.tv_nsec += ((long)ms) * 1000 * 1000;        return 0 == ::sem_timedwait(&m_sem, &abstime);#endif    }};}#endif