Jared Kells 描述的方法
在 Net Core 下不起作用，因为不能保证会调用终结器。而且，事实上，上面的代码并没有调用它。请看：
Why does the Finalize/Destructor example not work in .NET Core?
https://github.com/dotnet/runtime/issues/16028
https://github.com/dotnet/runtime/issues/17836
https://github.com/dotnet/runtime/issues/24623
所以，根据上面的好答案，这就是我最终做的事情（根据需要替换保存到文件）：
public class DatabaseCommandInterceptor : IDbCommandInterceptor
{
private static ConcurrentDictionary<DbCommand, DateTime> StartTime { get; } = new();
public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) => Log(command, interceptionContext);
public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) => Log(command, interceptionContext);
public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext) => Log(command, interceptionContext);
private static void Log<T>(DbCommand command, DbCommandInterceptionContext<T> interceptionContext)
{
var parameters = new StringBuilder();
foreach (DbParameter param in command.Parameters)
{
if (parameters.Length > 0) parameters.Append(", ");
parameters.Append($"{param.ParameterName}:{param.DbType} = {param.Value}");
}
var data = new DatabaseCommandInterceptorData
{
CommandText = command.CommandText,
CommandType = $"{command.CommandType}",
Parameters = $"{parameters}",
Duration = StartTime.TryRemove(command, out var startTime) ? DateTime.Now - startTime : TimeSpan.Zero,
Exception = interceptionContext.Exception,
};
DbInterceptorFixture.Current.LogDatabaseCall(data);
}
public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) => OnStart(command);
public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) => OnStart(command);
public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext) => OnStart(command);
private static void OnStart(DbCommand command) => StartTime.TryAdd(command, DateTime.Now);
}
public class DatabaseCommandInterceptorData
{
public string CommandText { get; set; }
public string CommandType { get; set; }
public string Parameters { get; set; }
public TimeSpan Duration { get; set; }
public Exception Exception { get; set; }
}
/// <summary>
/// All times are in milliseconds.
/// </summary>
public record DatabaseCommandStatisticalData
{
public string CommandText { get; }
public int CallCount { get; init; }
public int ExceptionCount { get; init; }
public double Min { get; init; }
public double Max { get; init; }
public double Mean { get; init; }
public double StdDev { get; init; }
public DatabaseCommandStatisticalData(string commandText)
{
CommandText = commandText;
CallCount = 0;
ExceptionCount = 0;
Min = 0;
Max = 0;
Mean = 0;
StdDev = 0;
}
/// <summary>
/// Calculates k-th moment for n + 1 values: M_k(n + 1)
/// based on the values of k, n, mkn = M_k(N), and x(n + 1).
/// The sample adjustment (replacement of n -> (n - 1)) is NOT performed here
/// because it is not needed for this function.
/// Note that k-th moment for a vector x will be calculated in Wolfram as follows:
/// Sum[x[[i]]^k, {i, 1, n}] / n
/// </summary>
private static double MknPlus1(int k, int n, double mkn, double xnp1) =>
(n / (n + 1.0)) * (mkn + (1.0 / n) * Math.Pow(xnp1, k));
public DatabaseCommandStatisticalData Updated(DatabaseCommandInterceptorData data) =>
CallCount == 0
? this with
{
CallCount = 1,
ExceptionCount = data.Exception == null ? 0 : 1,
Min = data.Duration.TotalMilliseconds,
Max = data.Duration.TotalMilliseconds,
Mean = data.Duration.TotalMilliseconds,
StdDev = 0.0,
}
: this with
{
CallCount = CallCount + 1,
ExceptionCount = ExceptionCount + (data.Exception == null ? 0 : 1),
Min = Math.Min(Min, data.Duration.TotalMilliseconds),
Max = Math.Max(Max, data.Duration.TotalMilliseconds),
Mean = MknPlus1(1, CallCount, Mean, data.Duration.TotalMilliseconds),
StdDev = Math.Sqrt(
MknPlus1(2, CallCount, Math.Pow(StdDev, 2) + Math.Pow(Mean, 2), data.Duration.TotalMilliseconds)
- Math.Pow(MknPlus1(1, CallCount, Mean, data.Duration.TotalMilliseconds), 2)),
};
public static string Header { get; } =
string.Join(TextDelimiter.VerticalBarDelimiter.Key,
new[]
{
nameof(CommandText),
nameof(CallCount),
nameof(ExceptionCount),
nameof(Min),
nameof(Max),
nameof(Mean),
nameof(StdDev),
});
public override string ToString() =>
string.Join(TextDelimiter.VerticalBarDelimiter.Key,
new[]
{
$"\"{CommandText.Replace("\"", "\"\"")}\"",
$"{CallCount}",
$"{ExceptionCount}",
$"{Min}",
$"{Max}",
$"{Mean}",
$"{StdDev}",
});
}
public class DbInterceptorFixture
{
public static readonly DbInterceptorFixture Current = new();
private bool _disposedValue;
private ConcurrentDictionary<string, DatabaseCommandStatisticalData> DatabaseCommandData { get; } = new();
private static IMasterLogger Logger { get; } = new MasterLogger(typeof(DbInterceptorFixture));
/// <summary>
/// Will run once at start up.
/// </summary>
private DbInterceptorFixture()
{
AssemblyLoadContext.Default.Unloading += Unloading;
}
/// <summary>
/// A dummy method to call in order to ensure that static constructor is called
/// at some more or less controlled time.
/// </summary>
public void Ping()
{
}
public void LogDatabaseCall(DatabaseCommandInterceptorData data) =>
DatabaseCommandData.AddOrUpdate(
data.CommandText,
_ => new DatabaseCommandStatisticalData(data.CommandText).Updated(data),
(_, d) => d.Updated(data));
private void Unloading(AssemblyLoadContext context)
{
if (_disposedValue) return;
GC.SuppressFinalize(this);
_disposedValue = true;
SaveData();
}
private void SaveData()
{
try
{
File.WriteAllLines(
@"C:\Temp\Test.txt",
DatabaseCommandData
.Select(e => $"{e.Value}")
.Prepend(DatabaseCommandStatisticalData.Header));
}
catch (Exception e)
{
Logger.LogError(e);
}
}
}
然后在测试的某个地方注册一次DatabaseCommandInterceptor：
DbInterception.Add(new DatabaseCommandInterceptor());
我也更喜欢在基础测试类中调用DbInterceptorFixture.Current.Ping()，尽管我不认为这是必要的。
接口IMasterLogger 只是log4net 的强类型包装器，因此只需将其替换为您喜欢的接口即可。
TextDelimiter.VerticalBarDelimiter.Key 的值就是'|'，它位于我们所说的闭集内。
PS 如果我搞砸了统计数据，请发表评论，我会更新答案。