【原创】有关Buffer使用，让你的日志类库解决IO高并发写

【本人原创】，欢迎交流和分享技术，转载请附上如下内容：

如果你觉得这篇文章对你有帮助，请记得帮我点赞， 谢谢！

作者:itshare 【转自】http://www.cnblogs.com/itshare/

     通常我们知道，当一个日志接口被外部程序多个线程请求后，如果没有使用Buffer和异步写入IO的处理。
CPU就会一直处于加锁和解锁的频繁切换，这样加上等待每次线程锁中的IO处理完毕的时间，
高并发调用日志接口的整个过程中响应和处理速度就会严重变慢，并且让CPU一直居高不下。

这里，Coding First，先看对比结果，最后我再附上LogBufferPool的代码实现。

下面我们分别做两组实验：时间单位为秒
100个线程，并发消费100000个请求。看下面每组实验的结果。

实验1：普通的日志接口，无Buffer缓冲池和异步写入IO的处理。

实验2：改造后日志接口，有Buffer缓冲池和异步写入IO的处理。

最后，在这里贴上我的代码实现：LogBufferPool

namespace ITS.Base.Comm.Logger_FastIO
{
    /// <summary>
    /// 日志缓冲池
    /// </summary>
    public class LogBufferPool :IDisposable
    {
        /// <summary>
        /// 工作日期
        /// </summary>
        private DateTime worktime
        {
            get;
            set;
        }

        /// <summary>
        /// 上一次写入时间
        /// </summary>
        private DateTime LastWriteTime
        {
            get;
            set;
        }

        /// <summary>
        /// 日志的文件路径
        /// </summary>
        private string fpath
        {
            get;
            set;
        }

        /// <summary>
        /// 最大行数 - write buffer
        /// </summary>
        public long MaxRows
        {
            get;
            private set;
        }

        /// <summary>
        /// 最大字数 - write buffer
        /// </summary>
        public long MaxSize
        {
            get;
            private set;
        }

        /// <summary>
        /// 当前字数 - write buffer
        /// </summary>
        public long CurrnetSize
        {
            get;
            private set;
        }
        /// <summary>
        /// 当前行数 - write buffer
        /// </summary>
        public long CurrnetRows
        {
            get;
            private set;
        }

        /// <summary>
        /// Lock of Buffer write
        /// </summary>
        private static object Lock_Write_IO = 1;
        /// <summary>
        /// Flag of last write Buffter
        /// </summary>
        private static bool IsLastWriteCompleted = true;
        /// <summary>
        /// Time of Buffer write
        /// </summary>
        static System.Threading.Timer timer_work = null;


        /// <summary>
        /// 文件流
        /// </summary>
        private Dictionary<int, FileStream> Dic_Stream = null;

        /// <summary>
        /// 日志消息
        /// </summary>
        private Dictionary<int, List<string>> Dic_MesgData = null;  

        /// <summary>
        /// 构造函数 - 日志缓冲池
        /// </summary>
        /// <param name="fpath">日志文件路径:logType</param>
        /// <param name="max_size">最大字数 - write buffer</param>
        /// <param name="max_rows">最大行数 - write buffer</param>
        public LogBufferPool(string fpath, long max_size = 50000, long max_rows = 1000)
        {
            this.worktime = DateTime.Now;
            this.LastWriteTime = DateTime.Now;
            this.fpath = fpath;
            this.MaxSize = max_size;
            this.MaxRows = max_rows;
            this.Dic_Stream = new Dictionary<int, FileStream>();
            this.Dic_MesgData = new Dictionary<int, List<string>>();

            IsLastWriteCompleted = true;
            if (timer_work == null)
            { 
                // 1*1000: 1秒后启动计时器
                // 执行计划：每隔开秒执行一次
                timer_work = new System.Threading.Timer(new System.Threading.TimerCallback(WriteBufferToFile), this, 1 * 1000, 5 * 1000);
            }
        }

        /// <summary>
        /// 写完日志后，再释放资源
        /// </summary>
        public void Dispose()
        {
            try
            {
                Dictionary<int, List<string>> dic = this.Dic_MesgData;
                if (dic != null && dic.Count > 0)
                {
                    foreach (KeyValuePair<int, List<string>> pair in this.Dic_MesgData)
                    {
                        WriteFile((LogTypeEnum)pair.Key, pair.Value);
                    }
                }
            }
            catch (Exception ex)
            {
                // log
            }
            finally
            {
                GC.Collect();
            }
        }

        /// <summary>
        /// 添加日志消息
        /// </summary>
        /// <param name="logType">日志类别</param>
        /// <param name="msg">日志内容</param>
        /// <returns></returns>
        public bool AddLog(LogTypeEnum logType, string msg)
        { 
            bool flag = false;
            List<string> list = null;
            int n = 0; // 写入IO的buffer文件个数
            List<int> keys = null; // 写入IO的buffer文件个数


            //long size_text = 0, row_text = 0;
            long index_row = 0, count_row = list != null ? list.Count : 0;


            try
            {
                if (!this.Dic_MesgData.TryGetValue((int)logType, out list))
                {
                    list = new List<string>();
                    this.Dic_MesgData.Add((int)logType, list);

                    //FileStream fs = File.Open(string.Format(fpath, logType), FileMode.Append, FileAccess.Write);
                    //// fs.WriteTimeout = 24 * 60 * 60;
                    //this.Dic_Stream.Add((int)logType, fs);
                } 

                // 添加日志消息
                list.Add(msg);
                index_row++;

                this.CurrnetSize += msg.Length;
                this.CurrnetRows++;

                // 根据缓冲池大小，定期清理和写入IO文件 
                //if ((this.CurrnetSize >= this.MaxSize 
                //    || this.CurrnetRows >= this.MaxRows)
                //    || (DateTime.Now - this.LastWriteTime).TotalSeconds > 10) 
                //{
                //    this.CurrnetSize = 0;
                //    this.CurrnetRows = 0;

                //    keys = Dic_MesgData.Keys.ToList();
                //    foreach (int key in keys)
                //    {
                //        List<string> list_old = this.Dic_MesgData[key]; 
                //        this.Dic_MesgData[key] = new List<string>();

                //        bool flag_write = this.WriteFile((LogTypeEnum)key, list_old); 
                //        if (flag_write)
                //        {
                //            n++;
                //        }
                //    } 
                //}

                //WriteBufferToFile(null);

                flag = true;

                // flag = keys != null && keys.Count > 0 ? n == keys.Count : true;
            }
            catch (Exception ex)
            {
                // log info 
            }  

            return flag;
        }

        private void WriteBufferToFile(object obj)
        {
            List<string> list = null;
            int n = 0; // 写入IO的buffer文件个数
            List<int> keys = null; // 写入IO的buffer文件个数

            lock (Lock_Write_IO)
            {
                if (IsLastWriteCompleted) // 判读上一次写入IO是否完成
                {
                    // 根据缓冲池大小，定期清理和写入IO文件 
                    if ((this.CurrnetSize >= this.MaxSize
                        || this.CurrnetRows >= this.MaxRows))
                    { 
                        IsLastWriteCompleted = false;

                        this.CurrnetSize = 0;
                        this.CurrnetRows = 0;

                        keys = Dic_MesgData.Keys.ToList();
                        foreach (int key in keys)
                        {
                            List<string> list_old = this.Dic_MesgData[key];
                            this.Dic_MesgData[key] = new List<string>();

                            bool flag_write = this.WriteFile((LogTypeEnum)key, list_old);
                            if (flag_write)
                            {
                                n++;
                            }
                        }

                        IsLastWriteCompleted = true;
                    }
                }
            }
        }

        /// <summary>
        /// 异步写入日志文件
        /// </summary>
        /// <param name="logType">日志类别</param>
        /// <param name="list">日志内容</param>
        /// <returns></returns>
        public bool WriteFile(LogTypeEnum logType, List<string> list)
        { 
            {
                bool flag = false;

                FileStream fs = null;
                StringBuilder sb = new StringBuilder();
                byte[] data = null;

                long size_text = 0, row_text = 0;
                long index_row = 0, count_row = list != null ? list.Count : 0;

                //if (!this.Dic_Stream.TryGetValue((int)logType, out fs))
                //{
                //    return false;
                //}



                try
                {
                    fs = File.Open(string.Format(fpath, logType), FileMode.Append, FileAccess.Write);

                    foreach (string item in list)
                    {
                        sb.Append(item);
                        index_row++; // 当前位置

                        size_text += item.Length;
                        row_text++;

                        if ((size_text >= 10 * 10000 || row_text >= 1000)
                            || (index_row == count_row && sb.Length > 0))
                        {
                            size_text = 0;
                            row_text = 0;

                            // wrire file   
                            data = Encoding.UTF8.GetBytes(sb.ToString());

                            #region 异步写入
                            //IAsyncResult asyc = fs.BeginWrite(data, 0, data.Length, (o) =>
                            //    {
                            //        object ret = o;
                            //    }, null);
                            //asyc.AsyncWaitHandle.WaitOne();
                            //fs.EndWrite(asyc);
                            #endregion

                            #region 同步写入
                            fs.Write(data, 0, data.Length); 
                            #endregion

                            fs.Flush(); // test code

                            size_text = 0;
                            row_text = 0;

                            data = null;
                            sb = null;
                            sb = new StringBuilder();
                        }
                    }

                    flag = index_row == count_row;
                }
                catch (Exception ex)
                {
                    // log info
                }
                finally
                {
                    if (sb != null)
                        sb = null;
                    if (data != null)
                        data = null;
                    if (list != null)
                        list = null;

                    if (fs != null)
                        fs.Dispose();
                }

                return flag;
            }
        }
    }
}