private static async Task TasksWithScopedBuffer(int numTasksToStart, int parentTaskId)
{
using (LogBuffer.BeginScope(collapseOnTriggered: true))
{
var taskId = Interlocked.Increment(ref TaskCounter);
try
{
Log.Debug("Task {ParentTaskId}: Started the task {TaskId}", parentTaskId, taskId);
var failCounter = Interlocked.Decrement(ref FailCounter);
if (failCounter == 0)
{
// A single task will throw exception
Log.Debug("Task {TaskId} <-- was the one that failed", taskId);
throw new Exception("Failed");
}
if (failCounter < 0)
{
// Rest of the tasks end silently
return;
}
var tasks = Enumerable.Range(0, numTasksToStart)
.Select(
async x => {
await Task.Yield(); // yield first so we return the tasks before calling to make more
await TasksWithScopedBuffer(2, taskId);
}
);
await Task.WhenAll(tasks);
}
catch (Exception ex)
{
Log.Error(ex, "Task {TaskId}: Exception thrown and caught", taskId);
}
}
/* The output is (something like):
* [Error] #5E4 Task 1501: Exception thrown and caught
* [Debug] #2 Detailed trace of the task spawns (in order of occurrence):
* [Debug] #3 Task 0: Started the task 1
* [Debug] #4 Task 1: Started the task 2
* [Debug] #6 Task 2: Started the task 4
* [Debug] #B Task 4: Started the task 9
* [Debug] #14 Task 9: Started the task 18
* [Debug] #1E Task 18: Started the task 28
* [Debug] #34 Task 28: Started the task 49
* [Debug] #62 Task 49: Started the task 96
* [Debug] #C0 Task 96: Started the task 189
* [Debug] #17D Task 189: Started the task 377
* [Debug] #2F5 Task 377: Started the task 753
* [Debug] #5E4 Task 753: Started the task 1501
* [Debug] #5E4 Task 1501 <-- was the one that failed
* [Infor] #2 Total tasks started and ended: 3001
*/
}
/// <summary>
/// Use a LogBufferScope in the request pipeline for each request. The earlier in the pipeline
/// the middleware is added, the more debug information will be captured.
/// </summary>
public static void UseLogBufferScope(this IApplicationBuilder app)
{
app.Use(
async(context, next) => {
using (LogBuffer.BeginScope())
{
try
{
await next.Invoke();
}
catch (Exception ex)
{
Log.ForContext <Program>().Error(ex, "Exception details: {ExceptionMessage}", ex.Message);
throw;
}
}
}
);
}
private static void Main(string[] args)
{
var consoleOutputFormat =
$"[{{Level:u5}}] {{{LogBuffer.LogBufferContextPropertyName},-5}} {{Message:lj}}{{NewLine}}";
void LoggerConfig(LoggerConfiguration lc)
{
lc.WriteTo.Console(
formatProvider: new CultureInfo("en-US"), theme: AnsiConsoleTheme.Literate,
outputTemplate: consoleOutputFormat
);
}
Log.Logger = new LoggerConfiguration()
.UseLogBuffer(
(SourceToMatchOn: "*", MinLevelAlways: LogEventLevel.Information,
MinLevelOnDetailed: LogEventLevel.Debug)
)
.With(/* more options: log level switch, trigger level, buffer capacity */)
.WriteTo(LoggerConfig)
.CreateLogger();
Task.Run(
() => {
Console.WriteLine(
@"
----------
Simple task that errors and prints debug output:
----------
"
);
SimpleBufferExample();
}
)
.GetAwaiter()
.GetResult();
Task.Run(
async() => {
using (LogBuffer.BeginScope())
{
Console.WriteLine(
@"
----------
Collapsing scopes that print debug output from parents:
----------
"
);
Log.Debug("Detailed trace of the task spawns (in order of occurrence):");
await TasksWithScopedBuffer(2, 0);
Log.Information("Total tasks started and ended: {TaskCounter}", TaskCounter);
Log.Debug(" --> The parent scope does not *stay* triggered, so this is never printed");
}
}
)
.GetAwaiter()
.GetResult();
}
