MVC 中dapper的日志功能+程序报错修改

由于之前的项目说最好要有日志功能，正好之前看过几篇这方面的文章就弄了点东西。

这是EF日志受启发很大的一个原文：

http://www.cnblogs.com/GuZhenYin/p/5556732.html

下面说开发经历~

由于之前有一个开发了一半的.net core的项目M，这个项目的框架都是由一个大牛来搭起来的。期中有几个比较好的功能，一个是报错拦截和日志记录功能。但是现在开发的项目C是没有上面的两个功能的，然后项目C的前辈说最好C也能实现这几个功能，正好我又看了上面的那个文章，就想着来自己搞一下~。

（下面说的内容如果没有看过上面EF日志的文章可能会看不懂）

最初：

一开始我想先把项目的SQL日志给完成了，但是项目C使用的ORM是dapper，之前文章里面用的是EF（这里不得不吐槽一下，一开始项目C都是没有ORM的，就有一个SqlHelper简单封装了一下，其实几乎就是ado.net了），我“天真”的以为直接下一个DatabaseLogger然后在Global.asax里面注入一下就可以了，但是注入好之后发现根本没有起任何作用。最后在一个Chloe.ORM的作者的提醒下发现了这个错误原因：

 这个注入的方法是EF空间下的，明显就是EF的功能，对dapper当然没有用了。然后查了一下发现dapper原生的是没有这个功能的，只能自己写~（囧），然后我就对照着Chloe.ORM的写法，自己在dapper的源码里面修改了几个方法（只要修改sqlmapper.cs里面的代码就可以了）

private static int ExecuteImpl(this IDbConnection cnn, ref CommandDefinition command)
        {
            object param = command.Parameters;
            IEnumerable multiExec = GetMultiExec(param);
            Identity identity;
            CacheInfo info = null;
            IDbCommandInterceptor[] log = DbInterception.GetInterceptors();
            IDbCommand cmd = null;
            DbCommandInterceptionContext<IDataReader> dbCommandInterceptionContext = new DbCommandInterceptionContext<IDataReader>();
            if (multiExec != null)
            {
#if ASYNC
                if((command.Flags & CommandFlags.Pipelined) != 0)
                {
                    // this includes all the code for concurrent/overlapped query
                    return ExecuteMultiImplAsync(cnn, command, multiExec).Result;
                }
#endif          
                bool isFirst = true;
                int total = 0;
                bool wasClosed = cnn.State == ConnectionState.Closed;
                try
                {
                    if (wasClosed) cnn.Open();
                    using (cmd = command.SetupCommand(cnn, null))
                    {
                        foreach (var l in log)
                        {
                            l.ReaderExecuting(cmd, dbCommandInterceptionContext);
                        }                     
                        string masterSql = null;
                        foreach (var obj in multiExec)
                        {
                            if (isFirst)
                            {
                                masterSql = cmd.CommandText;
                                isFirst = false;
                                identity = new Identity(command.CommandText, cmd.CommandType, cnn, null, obj.GetType(), null);
                                info = GetCacheInfo(identity, obj, command.AddToCache);
                            }
                            else
                            {
                                cmd.CommandText = masterSql; // because we do magic replaces on "in" etc
                                cmd.Parameters.Clear(); // current code is Add-tastic
                            }
                            info.ParamReader(cmd, obj);
                            total += cmd.ExecuteNonQuery();
                        }
                    }
                    command.OnCompleted();
                }
                catch (Exception e)
                {
                    dbCommandInterceptionContext.Exception = e;
                    foreach (var l in log)
                    {
                        l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                    }
                    
                }
                finally
                {
                    foreach (var l in log)
                    {
                        l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                    }
                    if (wasClosed) cnn.Close();
                }
                return total;
            }

            // nice and simple
            if (param != null)
            {
                identity = new Identity(command.CommandText, command.CommandType, cnn, null, param.GetType(), null);
                info = GetCacheInfo(identity, param, command.AddToCache);
            }
            return ExecuteCommand(cnn, ref command, param == null ? null : info.ParamReader);
        }

private static IEnumerable<T> QueryImpl<T>(this IDbConnection cnn, CommandDefinition command, Type effectiveType)
        {
            object param = command.Parameters;
            var identity = new Identity(command.CommandText, command.CommandType, cnn, effectiveType, param?.GetType(), null);
            var info = GetCacheInfo(identity, param, command.AddToCache);
            List<T> temp = new List<T>();
            IDbCommand cmd = null;
            IDataReader reader = null;
            IDbCommandInterceptor[] log = DbInterception.GetInterceptors();
            bool wasClosed = cnn.State == ConnectionState.Closed;
            DbCommandInterceptionContext<IDataReader> dbCommandInterceptionContext = new DbCommandInterceptionContext<IDataReader>();
            try
            {    
                
                cmd = command.SetupCommand(cnn, info.ParamReader);
                foreach (var l in log)
                    l.ReaderExecuting(cmd, dbCommandInterceptionContext);
                if (wasClosed) cnn.Open();
                reader = ExecuteReaderWithFlagsFallback(cmd, wasClosed, CommandBehavior.SequentialAccess | CommandBehavior.SingleResult);
                wasClosed = false; // *if* the connection was closed and we got this far, then we now have a reader
                // with the CloseConnection flag, so the reader will deal with the connection; we
                // still need something in the "finally" to ensure that broken SQL still results
                // in the connection closing itself
                var tuple = info.Deserializer;
                int hash = GetColumnHash(reader);
                if (tuple.Func == null || tuple.Hash != hash)
                {
                    if (reader.FieldCount == 0) //https://code.google.com/p/dapper-dot-net/issues/detail?id=57
                        return null;
                    tuple = info.Deserializer = new DeserializerState(hash, GetDeserializer(effectiveType, reader, 0, -1, false));
                    if (command.AddToCache) SetQueryCache(identity, info);
                }

                var func = tuple.Func;
                var convertToType = Nullable.GetUnderlyingType(effectiveType) ?? effectiveType;
                while (reader.Read())
                {
                    object val = func(reader);
                    if (val == null || val is T)
                    {
                        temp.Add((T)val);
                        //return (T)val;
                    }
                    else
                    {
                        temp.Add((T)Convert.ChangeType(val, convertToType, CultureInfo.InvariantCulture));
                    }
                }
                while (reader.NextResult()) { }
                // happy path; close the reader cleanly - no
                // need for "Cancel" etc
                reader.Dispose();
                reader = null;

                command.OnCompleted();
                return temp;
            }
            catch(Exception e)
            {
                dbCommandInterceptionContext.Exception = e;
                foreach (var l in log)
                    l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                return new List<T>();
            }
            finally
            {
                foreach (var l in log)
                    l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                if (reader != null)
                {
                    if (!reader.IsClosed) try { cmd.Cancel(); }
                        catch { /* don't spoil the existing exception */ }
                    reader.Dispose();
                }
                if (wasClosed) cnn.Close();
                cmd?.Dispose();
            }
        }

 private static T QueryRowImpl<T>(IDbConnection cnn, Row row, ref CommandDefinition command, Type effectiveType)
        {
            object param = command.Parameters;
            var identity = new Identity(command.CommandText, command.CommandType, cnn, effectiveType, param?.GetType(), null);
            var info = GetCacheInfo(identity, param, command.AddToCache);

            IDbCommand cmd = null;
            IDataReader reader = null;
            IDbCommandInterceptor[] log = DbInterception.GetInterceptors();
            bool wasClosed = cnn.State == ConnectionState.Closed;
            DbCommandInterceptionContext<IDataReader> dbCommandInterceptionContext = new DbCommandInterceptionContext<IDataReader>();
            try
            {
                cmd = command.SetupCommand(cnn, info.ParamReader);
                foreach (var l in log)
                    l.ReaderExecuting(cmd, dbCommandInterceptionContext);
                if (wasClosed) cnn.Open();
                reader = ExecuteReaderWithFlagsFallback(cmd, wasClosed, (row & Row.Single) != 0
                    ? CommandBehavior.SequentialAccess | CommandBehavior.SingleResult // need to allow multiple rows, to check fail condition
                    : CommandBehavior.SequentialAccess | CommandBehavior.SingleResult | CommandBehavior.SingleRow);
                wasClosed = false; // *if* the connection was closed and we got this far, then we now have a reader

                T result = default(T);
                if (reader.Read() && reader.FieldCount != 0)
                {
                    // with the CloseConnection flag, so the reader will deal with the connection; we
                    // still need something in the "finally" to ensure that broken SQL still results
                    // in the connection closing itself
                    var tuple = info.Deserializer;
                    int hash = GetColumnHash(reader);
                    if (tuple.Func == null || tuple.Hash != hash)
                    {
                        tuple = info.Deserializer = new DeserializerState(hash, GetDeserializer(effectiveType, reader, 0, -1, false));
                        if (command.AddToCache) SetQueryCache(identity, info);
                    }

                    var func = tuple.Func;
                    object val = func(reader);
                    if (val == null || val is T)
                    {
                        result = (T)val;
                    }
                    else
                    {
                        var convertToType = Nullable.GetUnderlyingType(effectiveType) ?? effectiveType;
                        result = (T)Convert.ChangeType(val, convertToType, CultureInfo.InvariantCulture);
                    }
                    if ((row & Row.Single) != 0 && reader.Read()) ThrowMultipleRows(row);
                    while (reader.Read()) { }
                }
                else if ((row & Row.FirstOrDefault) == 0) // demanding a row, and don't have one
                {
                    ThrowZeroRows(row);
                }
                while (reader.NextResult()) { }
                // happy path; close the reader cleanly - no
                // need for "Cancel" etc
                reader.Dispose();
                reader = null;

                command.OnCompleted();
                return result;
            }
            catch (Exception e)
            {
                dbCommandInterceptionContext.Exception = e;
                foreach (var l in log)
                    l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                return default(T);
            }
            finally
            {
                foreach (var l in log)
                    l.ReaderExecuted(cmd, dbCommandInterceptionContext);
                if (reader != null)
                {
                    if (!reader.IsClosed) try { cmd.Cancel(); }
                        catch { /* don't spoil the existing exception */ }
                    reader.Dispose();
                }
                if (wasClosed) cnn.Close();
                cmd?.Dispose();
            }
        }

这个就是在dapper数据操作的时候记录日志的，为了体现DI的思想，还要新增一个类

public static class DbInterception
    {
        static volatile List<IDbCommandInterceptor> _interceptors = new List<IDbCommandInterceptor>();
        static readonly object _lockObject = new object();
        public static void Add(IDbCommandInterceptor interceptor)
        {
            lock (_lockObject)
            {
                List<IDbCommandInterceptor> newList = _interceptors.ToList();
                newList.Add(interceptor);
                newList.TrimExcess();
                _interceptors = newList;
            }
        }
        public static void Remove(IDbCommandInterceptor interceptor)
        {
            lock (_lockObject)
            {
                List<IDbCommandInterceptor> newList = _interceptors.ToList();
                newList.Remove(interceptor);
                newList.TrimExcess();
                _interceptors = newList;
            }
        }

        public static IDbCommandInterceptor[] GetInterceptors()
        {
            return _interceptors.ToArray();
        }
    }

这样子当要注入日志操作的时候只要在Global.asax中向DbInterception插入实现IDbCommandInterceptor的类就可以了。

由于篇幅过长，关于程序报错的日志处理就稍后发表了。