锁的封装 读写锁lock

Posted 2020-07-09 qqnihao

最近由于项目上面建议使用读写锁，而去除常见的lock锁。然后就按照需求封装了下锁。以简化锁的使用。但是开发C#的童鞋都知道lock关键字用起太方便了，但是lock关键字不支持超时处理。很无奈，为了实现类似lock的功能。于是通过使用using关键字和IDisposable实现了自己的锁方法

  class Program
    {
        static void Main(string[] args)
        {
            ReadWriteUtilTest();
            MonitorUtilTest();
            Console.ReadLine();
        }
        private static void MonitorUtilTest()
        {
            MonitorUtil util = new MonitorUtil();
            int num = 0;
            for (int index = 0; index < 20; index++)
            {
                var th = new Thread(new ThreadStart(() =>
                 {
                     Thread.Sleep(100);
                     for (int i = 0; i < 100; i++)
                     {
                         using (util.GetLock("hello"))
                         {
                             num++;
                             Console.WriteLine("num={0}", num);
                         }
                     }
                 }));

                th.Start();
            }
        }

        private static void ReadWriteUtilTest()
        {
            ReadWriteLockUtil utl = new ReadWriteLockUtil();
            Int32 num = 0;
            for (var i = 0; i < 10; i++)
            {
                Task.Factory.StartNew(() =>
                {
                    while (true)
                    {
                        using (utl.GetLock("hello", ReadWriteLockUtil.ReadWriteEnum.Read))
                        {
                            Console.WriteLine("num={0}", num);
                            Thread.Sleep(1000);
                        }
                    }
                });
            }
            Task.Factory.StartNew(() =>
            {
                while (true)
                {
                    using (utl.GetLock("hello", ReadWriteLockUtil.ReadWriteEnum.Write))
                    {
                        num++;
                        Thread.Sleep(5000);
                    }
                    Thread.Sleep(5000);
                }
            });
        }
    }

    /// <summary>
    /// 排他锁工具类
    /// </summary>
    public class MonitorUtil
    {
        /// <summary>
        /// 自定义锁对象
        /// </summary>
        internal class CustMonitor : IDisposable
        {
            /// <summary>
            /// 锁对象
            /// </summary>
            private Object lockObj = null;

            /// <summary>
            /// 构造函数
            /// </summary>
            /// <param name="lockObj">锁对象</param>
            public CustMonitor(Object lockObj)
            {
                this.lockObj = lockObj;
            }

            /// <summary>
            /// 锁释放
            /// </summary>
            public void Dispose()
            {
                try
                {
                    Monitor.Exit(this.lockObj);
                }
                catch
                {
                    // 当前线程如果没有获取到锁时，则会抛出异常。此处直接吞掉
                }
            }
        }

        /// <summary>
        /// 锁信息
        /// </summary>
        internal class LockInfo
        {
            /// <summary>
            /// 构造函数
            /// </summary>
            /// <param name="lockObj">锁实例</param>
            /// <param name="custMonitor">自定义锁对象</param>
            public LockInfo(Object lockObj, CustMonitor custMonitor)
            {
                this.CustMonitor = custMonitor;
                this.LockObj = lockObj;
            }

            /// <summary>
            /// 自定义锁对象
            /// </summary>
            public CustMonitor CustMonitor { get; private set; }

            /// <summary>
            /// 锁实例
            /// </summary>
            public Object LockObj { get; private set; }
        }

        /// <summary>
        /// 锁集合
        /// </summary>
        private ConcurrentDictionary<String, LockInfo> lockObjData = new ConcurrentDictionary<String, LockInfo>();

        /// <summary>
        /// lockObjData同步对象
        /// </summary>
        private Object custLockObj = new Object();

        /// <summary>
        /// 获取锁对象
        /// </summary>
        /// <param name="lockName">返回锁对象</param>
        /// <param name="waitTime">等待时间(单位：毫秒)</param>
        /// <returns>返回锁对象</returns>
        /// <exception cref="TimeoutException">获取锁对象超时时，抛出此异常</exception>
        public IDisposable GetLock(String lockName, Int32 waitTime = 10)
        {
            // 获取锁对象
            var lockObj = GetLockInfo(lockName);

            // 规范等待时间长
            if (waitTime <= 0)
            {
                // 进入锁
                Monitor.Enter(lockObj.LockObj);
            }
            else
            {
                // 进入锁
                if (Monitor.TryEnter(lockObj.LockObj, waitTime) == false)
                {
                    return lockObj.CustMonitor;
                    //throw new TimeoutException("等待锁超时");
                }
            }

            return lockObj.CustMonitor;
        }

        /// <summary>
        /// 获取锁对象信息
        /// </summary>
        /// <param name="lockName">锁名称</param>
        /// <returns>返回锁对象</returns>
        private LockInfo GetLockInfo(String lockName)
        {
            LockInfo lockObj = null;

            // 懒汉方式，先获取一次锁对象
            if (lockObjData.ContainsKey(lockName))
            {
                lockObj = lockObjData[lockName];
            }
            else
            {
                lock (custLockObj)
                {
                    if (lockObjData.ContainsKey(lockName))
                    {
                        lockObj = lockObjData[lockName];
                    }
                    else
                    {
                        // 如果获取不到锁，则创建一个锁对象

                        var lockInstance = new Object();
                        lockObj = new LockInfo(lockInstance, new CustMonitor(lockInstance));

                        lockObjData[lockName] = lockObj;
                    }
                }
            }

            return lockObj;
        }
    }

    /// <summary>
    /// 读写锁工具类
    /// </summary>
    public class ReadWriteLockUtil
    {
        /// <summary>
        /// 自定义锁对象
        /// </summary>
        internal class CustMonitor : IDisposable
        {
            /// <summary>
            /// 获取方式
            /// </summary>
            private ReadWriteEnum getType;

            /// <summary>
            /// 锁对象
            /// </summary>
            private ReaderWriterLockSlim lockObj = null;

            /// <summary>
            /// 构造函数
            /// </summary>
            /// <param name="lockObj">锁对象</param>
            /// <param name="getType">获取方式</param>
            public CustMonitor(ReaderWriterLockSlim lockObj, ReadWriteEnum getType)
            {
                this.lockObj = lockObj;
                this.getType = getType;
            }

            /// <summary>
            /// 锁释放
            /// </summary>
            public void Dispose()
            {
                if (getType == ReadWriteEnum.Read && lockObj.IsReadLockHeld)
                {
                    lockObj.ExitReadLock();
                }
                else if (getType == ReadWriteEnum.Write && lockObj.IsWriteLockHeld)
                {
                    lockObj.ExitWriteLock();
                }
            }
        }

        /// <summary>
        /// 读写枚举
        /// </summary>
        public enum ReadWriteEnum
        {
            /// <summary>
            /// 读
            /// </summary>
            Read,

            /// <summary>
            /// 写
            /// </summary>
            Write
        }

        /// <summary>
        /// 锁集合
        /// </summary>
        private ConcurrentDictionary<String, ReaderWriterLockSlim> lockObjData = new ConcurrentDictionary<String, ReaderWriterLockSlim>();

        /// <summary>
        /// lockObjData同步对象
        /// </summary>
        private Object custLockObj = new Object();

        /// <summary>
        /// 获取锁对象
        /// </summary>
        /// <param name="lockName">返回锁对象</param>
        /// <param name="getType">获取方式</param>
        /// <param name="waitTime">等待时间(单位：毫秒)，大于0，则等待指定时间，非正数，则死等</param>
        /// <returns>返回锁对象</returns>
        /// <exception cref="TimeoutException">获取锁对象超时时，抛出此异常</exception>
        public IDisposable GetLock(String lockName, ReadWriteEnum getType, Int32 waitTime = 10000)
        {
            // 获取锁对象
            var lockInfo = GetLockInfo(lockName);

            // 规范等待时间长
            if (waitTime <= 0)
            {
                // 进入锁
                return GetLockByInfiniteWait(lockName, getType);
            }

            // 进入锁
            if (getType == ReadWriteEnum.Read)
            {
                if (lockInfo.IsReadLockHeld || lockInfo.TryEnterReadLock(waitTime))
                {
                    return new CustMonitor(lockInfo, getType);
                }

                throw new TimeoutException("等待读锁超时");
            }
            else if (getType == ReadWriteEnum.Write)
            {
                if (lockInfo.IsWriteLockHeld || lockInfo.TryEnterWriteLock(waitTime))
                {
                    return new CustMonitor(lockInfo, getType);
                }

                throw new TimeoutException("等待写锁超时");
            }

            return null;
        }

        /// <summary>
        /// 获取锁对象，获取过程会死等。直到获取到锁对象
        /// </summary>
        /// <param name="lockName">锁名称</param>
        /// <param name="getType">获取方式</param>
        /// <returns>返回锁对象</returns>
        private IDisposable GetLockByInfiniteWait(String lockName, ReadWriteEnum getType)
        {
            // 获取锁对象
            var lockObj = GetLockInfo(lockName);

            // 进入锁
            if (getType == ReadWriteEnum.Read)
            {
                lockObj.EnterReadLock();

                return new CustMonitor(lockObj, getType);
            }
            else if (getType == ReadWriteEnum.Write)
            {
                lockObj.EnterWriteLock();

                return new CustMonitor(lockObj, getType);
            }

            return null;
        }

        /// <summary>
        /// 获取锁对象信息
        /// </summary>
        /// <param name="lockName">锁名称</param>
        /// <returns>返回锁对象</returns>
        private ReaderWriterLockSlim GetLockInfo(String lockName)
        {
            ReaderWriterLockSlim lockObj = null;

            // 懒汉方式，先获取一次锁对象
            if (lockObjData.ContainsKey(lockName))
            {
                lockObj = lockObjData[lockName];
            }
            else
            {
                lock (custLockObj)
                {
                    if (lockObjData.ContainsKey(lockName))
                    {
                        lockObj = lockObjData[lockName];
                    }
                    else
                    {
                        // 如果获取不到锁，则创建一个锁对象
                        lockObj = new ReaderWriterLockSlim();
                        lockObjData[lockName] = lockObj;
                    }
                }
            }

            return lockObj;
        }
    }