/// 共享锁
public class ShareLock
{
    ReaderWriterLock Lock;
    IDisposable readLock, writeLock;

    public IDisposable ReadLock { get { Lock.AcquireReaderLock(-1); return readLock; } }
    public IDisposable WriteLock { get { Lock.AcquireWriterLock(-1); return writeLock; } }
    public IDisposable UpgradeLock { get { return new UpgraderLocked(Lock); } }
    /// 释放所有锁
    public void ReleaseLock() { Lock.ReleaseLock(); }

    public ShareLock()
    {
        this.Lock = new ReaderWriterLock();
        this.readLock = new Locked(Lock.ReleaseReaderLock);
        this.writeLock = new Locked(Lock.ReleaseWriterLock);
    }
    class Locked : IDisposable
    {
        ThreadStart ReleaseLock;
        public Locked(ThreadStart ReleaseLock) { this.ReleaseLock = ReleaseLock; }
        public void Dispose() { this.ReleaseLock(); }
    }
    class UpgraderLocked : IDisposable
    {
        delegate void ReleaseLockHandler(ref LockCookie lockCookie);

        ReleaseLockHandler ReleaseLock;
        LockCookie Cookie;
        public UpgraderLocked(ReaderWriterLock locker)
        {
            Cookie = locker.UpgradeToWriterLock(-1);
            this.ReleaseLock = locker.DowngradeFromWriterLock;
        }
        public void Dispose() { this.ReleaseLock(ref Cookie); }
    }
}