public async Task EvaluateAsync(MetricQuery query, CancellationToken cancellation = default)
{
var options = _optionsProvider.Value;
var timeout = query.Timeout.GetValueOrDefault(options.Metrics.Evaluation.Timeout);
var interval = query.Interval.GetValueOrDefault(options.Metrics.Evaluation.Interval);
try
{
_logger.LogInformation("Starting evaluation of query '{Query}'", query.Name);
var result = await _queryExecutor.ExecuteAsync(query, timeout, cancellation);
await _metricsWriter.WriteAsync(query, result, cancellation);
}
catch (Exception e)
{
_logger.LogError(e, "Query '{Query}' evaluation failed with exception", query.Name);
}
finally
{
_logger.LogInformation("Query '{Query}' evaluated. Next evaluation on '{NextOccurence}'", query.Name, (DateTime.Now + interval));
// Re-schedule
_jobClient.Schedule <ScheduledMetricsEvaluator>(
e => e.EvaluateAsync(query, cancellation), interval);
}
}
public async Task Invoke(HttpContext context,
IMetricQueriesProvider queriesProvider,
IOptions <ExporterOptions> optionsProvider,
IMetricQueryExecutor queryExecutor,
IMetricsWriter metricsWriter,
ILogger <OndemandMetricsEvaluationMiddleware> logger)
{
var options = optionsProvider.Value;
var defaultMode = options.Metrics.Evaluation.Mode;
var queries = await queriesProvider.GetAsync(context.RequestAborted);
var tasks = queries.Select(q =>
{
if (q.EvaluationMode == MetricsEvaluationMode.Scheduled)
{
return(Task.CompletedTask);
}
if (!q.EvaluationMode.HasValue && defaultMode == MetricsEvaluationMode.Scheduled)
{
return(Task.CompletedTask);
}
return(Task.Run(async() =>
{
try
{
logger.LogInformation($"Executing on-demand query '{q.Name}'");
var timeout = q.Timeout.GetValueOrDefault(options.Metrics.Evaluation.Timeout);
var result = await queryExecutor.ExecuteAsync(q, timeout, context.RequestAborted);
await metricsWriter.WriteAsync(q, result, context.RequestAborted);
logger.LogInformation($"Executed on-demand query '{q.Name}'");
}
catch (OperationCanceledException)
{
// Ignore
}
catch (Exception e)
{
logger.LogError(e, $"Unable to write metric for query '{q.Name}'");
}
}, context.RequestAborted));
});
await Task.WhenAll(tasks);
await _next(context);
}