critsec.cpp

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/*
**  Command & Conquer Generals Zero Hour(tm)
**  Copyright 2025 Electronic Arts Inc.
**
**  This program is free software: you can redistribute it and/or modify
**  it under the terms of the GNU General Public License as published by
**  the Free Software Foundation, either version 3 of the License, or
**  (at your option) any later version.
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**  GNU General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "critsec.h"
#include <assert.h>
#include "wlib/wdebug.h"
 
 
 
CritSec::CritSec()
{
#ifdef _UNIX
  pthread_mutex_init(&Mutex_, NULL);
  RefCount_ = 0;
#elif defined(_WIN32)
  InitializeCriticalSection(&CritSec_);
#endif
}
 
CritSec::~CritSec()
{
 #ifdef _UNIX
   pthread_mutex_destroy(&Mutex_);
 #elif defined(_WIN32)
   DeleteCriticalSection(&CritSec_);
 #endif
}
 
// The "lock" function blocks until the mutex is available.
// Returns 0 on success, error code on error.
//
// A thread that already has a lock will increment a reference count if it calls
//  lock again.  It must then call unlock() enough times to get the reference to 0.
//
// If refcount is not null you can get the current ref counter after the lock.
//
sint32 CritSec::lock(int *refcount) RO 
{
 #ifdef _UNIX
    sint32    status;
 
    // I TRY to get the lock. IF I succeed, OR if I fail because
    // I already have the lock, I  just increment the reference
    // count and return.
    if (((status = pthread_mutex_trylock(&Mutex_)) == 0) ||
    ((status == EBUSY) && (ThreadId_ == pthread_self())))
    {
    ThreadId_ = pthread_self();
    RefCount_++;
        if (refcount)
          *refcount=RefCount_;
    return(0);
    }
 
    // Otherwise, I wait for the lock.
    if ((status = pthread_mutex_lock(&Mutex_)) == 0)
    {
    assert(RefCount_ == 0);
    ThreadId_ = pthread_self();
    RefCount_++;
    }
    else
    {
    ERRMSG("pthread_mutex_lock: " << strerror(errno));
    }
 
    if (refcount)
      *refcount=RefCount_;
 
    return(status);
 #elif defined(_WIN32)
   // TOFIX update the refcount
   EnterCriticalSection(&CritSec_);
   return(0);
  #else
    #error Must define either _WIN32 or _UNIX
 #endif
}
 
// The "unlock" function release the critical section.
sint32 CritSec::unlock(void) RO 
{
 #ifdef _UNIX
    sint32    status = 0;
    
    assert(RefCount_ >= 0);
    if (RefCount_ <= 0)
    {
    //ERRMSG("unlocking unlocked mutex!");
    return(-1);
    }

    if (ThreadId_ != pthread_self())
    {
    WRNMSG("tried to unlock a mutex not owned by self");
        return(-1);
    }
 
    if (--RefCount_ == 0)
    {
    // Set thread id to zero -- we're going to release mutex
    ThreadId_ = (pthread_t)0;
    
    // Unlock the mutex.
    if ((status = pthread_mutex_unlock(&Mutex_)) != 0)
        ERRMSG("pthread_mutex_lock: " << strerror(errno));
    }
    return status;
 #elif defined(_WIN32)
    LeaveCriticalSection(&CritSec_);
    return(0);
 #endif
}