/* * *  C++ Portable Types Library (PTypes) *  Version 1.7.5   Released 9-Mar-2003 * *  Copyright (c) 2001, 2002, 2003 Hovik Melikyan * *  http://www.melikyan.com/ptypes/ *  http://ptypes.sourceforge.net/ * */#ifdef WIN32#  include <windows.h>#else#  include <pthread.h>#endif#include "pasync.h"PTYPES_BEGINstatic void rwlock_fail(){    fatal(CRIT_FIRST + 41, "rwlock failed");}inline void syscheck(int r){    if (r != 0)        rwlock_fail();}#ifdef __PTYPES_RWLOCK__#  ifdef WIN32//// this implementation of the read/write lock is derived// from Apache Portable Runtime (APR) source, which // in turn was originally based on an erroneous (or just// incomplete?) example in one of the MSDN technical articles.// rwlock::rwlock()    : mutex(), readcnt(-1), writecnt(0){    reading = CreateEvent(0, true, false, 0);    finished = CreateEvent(0, false, true, 0);    if (reading == 0 || finished == 0)        rwlock_fail();}rwlock::~rwlock(){    CloseHandle(reading);    CloseHandle(finished);}void rwlock::rdlock(){    if (pincrement(&readcnt) == 0)     {        WaitForSingleObject(finished, INFINITE);        SetEvent(reading);    }    WaitForSingleObject(reading, INFINITE);}void rwlock::wrlock(){    mutex::enter();    WaitForSingleObject(finished, INFINITE);    writecnt++;}void rwlock::unlock(){    if (writecnt != 0)     {        writecnt--;        SetEvent(finished);        mutex::leave();    }     else if (pdecrement(&readcnt) < 0)     {        ResetEvent(reading);        SetEvent(finished);    } }#  else	  // !defined(WIN32)//// for other platforms that lack POSIX rwlock we implement// the rwlock object using POSIX condvar. the code below// is based on Sean Burke's algorithm posted in // comp.programming.threads.//rwlock::rwlock()    : locks(0), writers(0), readers(0){    syscheck(pthread_mutex_init(&mtx, 0));    syscheck(pthread_cond_init(&readcond, 0));    syscheck(pthread_cond_init(&writecond, 0));}rwlock::~rwlock(){    pthread_cond_destroy(&writecond);    pthread_cond_destroy(&readcond);    pthread_mutex_destroy(&mtx);}void rwlock::rdlock(){    pthread_mutex_lock(&mtx);    readers++;    while (locks < 0)	pthread_cond_wait(&readcond, &mtx);    readers--;    locks++;    pthread_mutex_unlock(&mtx);}void rwlock::wrlock(){    pthread_mutex_lock(&mtx);    writers++;    while (locks != 0)	pthread_cond_wait(&writecond, &mtx);    locks = -1;    writers--;    pthread_mutex_unlock(&mtx);}void rwlock::unlock(){    pthread_mutex_lock(&mtx);    if (locks > 0)    {	locks--;	if (locks == 0)	    pthread_cond_signal(&writecond);    }    else    {	locks = 0;        if (readers != 0)	    pthread_cond_broadcast(&readcond);        else	    pthread_cond_signal(&writecond);    }    pthread_mutex_unlock(&mtx);}#  endif#else	// !defined(__PTYPES_RWLOCK__)//// for other systems we declare a fully-inlined rwlock// object in pasync.h//rwlock::rwlock(){    syscheck(pthread_rwlock_init(&rw, 0));}#endifPTYPES_END