/// <summary>
/// 申请写入锁
/// </summary>
/// <param name="rwlock">读写锁</param>
/// <returns>Cookie对象</returns>
public static IntelligentLockCookie WriterLock(ReaderWriterLock rwlock)
{
IntelligentLockCookie ilc = new IntelligentLockCookie();
ilc.upgrade = false;
if (rwlock.IsWriterLockHeld)
{
ilc.locked = false;
ilc.upgrade = false;
}
else
{
if (rwlock.IsReaderLockHeld)
{
//注意: 在线程调用 UpgradeToWriterLock 时，不管锁计数为多少都将释放读线程锁，并且线程将转到写线程锁队列的末尾。因此，在请求升级的线程被授予写线程锁之前，其他线程可以写入资源。
//此操作相当危险所以暂时不使用
throw new AbandonedMutexException("ReaderWriterLock.UpgradeToWriterLock is dangerous method!");
//ilc.lc = rwlock.UpgradeToWriterLock(Timeout.Infinite);
//ilc.locked = true;
//ilc.upgrade = true;
}
else
{
rwlock.AcquireWriterLock(Timeout.Infinite);
ilc.locked = true;
ilc.upgrade = false;
}
}
return(ilc);
}
/// <summary>
/// 解除写入锁
/// </summary>
/// <param name="rwlock">读写锁</param>
/// <param name="ilc">Cookie对象</param>
public static void ReleaseWriterLock(ReaderWriterLock rwlock, IntelligentLockCookie ilc)
{
if (true == ilc.locked)
{
if (true == ilc.upgrade)
{
LockCookie lc = ilc.lc;
rwlock.DowngradeFromWriterLock(ref lc);
}
else
{
rwlock.ReleaseWriterLock();
}
}
}