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Publish Meter-based metrics to AppInsights SDK
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5 files changed

+431
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‎src/WebJobs.Script/Diagnostics/ApplicationInsightsMeterListener.cs‎

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// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the MIT License. See License.txt in the project root for license information.
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#nullable enable
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using System;
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using System.Collections.Generic;
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using System.Diagnostics.Metrics;
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using System.Threading;
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using System.Threading.Tasks;
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using Microsoft.ApplicationInsights;
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using Microsoft.ApplicationInsights.Extensibility;
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using Microsoft.ApplicationInsights.Metrics;
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using Microsoft.Extensions.Hosting;
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using Microsoft.Extensions.Options;
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using AIMetric = Microsoft.ApplicationInsights.Metric;
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namespace Microsoft.Azure.WebJobs.Script.Diagnostics
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{
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/// <summary>
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/// A meter listener which exports metrics to Application Insights.
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/// </summary>
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public sealed class ApplicationInsightsMeterListener : ITelemetryModule, IAsyncDisposable
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{
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private readonly MeterListener _listener;
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private readonly ApplicationInsightsMeterOptions _options;
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private readonly CancellationTokenSource _shutdown = new();
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private Task _exportTask = Task.CompletedTask;
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private TelemetryClient _client = null!;
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/// <summary>
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/// Initializes a new instance of the <see cref="ApplicationInsightsMeterListener"/> class.
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/// </summary>
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/// <param name="lifetime">The application lifetime.</param>
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/// <param name="options">The options.</param>
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public ApplicationInsightsMeterListener(
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IHostApplicationLifetime lifetime,
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IOptions<ApplicationInsightsMeterOptions> options)
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{
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ArgumentNullException.ThrowIfNull(options);
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ArgumentNullException.ThrowIfNull(lifetime);
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_shutdown = CancellationTokenSource.CreateLinkedTokenSource(lifetime.ApplicationStopping);
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_options = options.Value;
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_listener = new()
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{
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InstrumentPublished = (instrument, listener) =>
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{
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if (_options.ShouldListenTo(instrument))
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{
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listener.EnableMeasurementEvents(instrument, this);
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}
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},
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};
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// All of the supported instrument value types.
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_listener.SetMeasurementEventCallback(CreateCallback<byte>());
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_listener.SetMeasurementEventCallback(CreateCallback<short>());
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_listener.SetMeasurementEventCallback(CreateCallback<int>());
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_listener.SetMeasurementEventCallback(CreateCallback<long>());
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_listener.SetMeasurementEventCallback(CreateCallback<float>());
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_listener.SetMeasurementEventCallback(CreateCallback<double>());
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_listener.SetMeasurementEventCallback(CreateCallback<decimal>());
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}
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public void Initialize(TelemetryConfiguration configuration)
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{
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ArgumentNullException.ThrowIfNull(configuration);
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_client = new TelemetryClient(configuration);
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_exportTask = CollectAsync(_shutdown.Token);
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_listener.Start();
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}
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public async ValueTask DisposeAsync()
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{
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_listener.Dispose();
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await _shutdown.CancelNoThrowAsync();
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await _exportTask.ConfigureAwait(false);
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await _client.FlushAsync(default).ConfigureAwait(false);
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_shutdown.Dispose();
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}
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private static MeasurementCallback<T> CreateCallback<T>()
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where T : struct
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{
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return (instrument, value, tags, state) =>
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{
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if (state is not ApplicationInsightsMeterListener listener)
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{
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return;
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}
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listener.Publish(instrument, value, tags);
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};
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}
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private async Task CollectAsync(CancellationToken cancellation)
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{
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while (!cancellation.IsCancellationRequested)
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{
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try
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{
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_listener.RecordObservableInstruments();
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await Task.Delay(_options.CollectInterval, cancellation);
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}
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catch (Exception ex) when (!ex.IsFatal())
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{
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// swallow exceptions
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}
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}
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}
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private void Publish<T>(Instrument instrument, T value, ReadOnlySpan<KeyValuePair<string, object?>> tags)
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where T : struct
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{
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if (instrument is null)
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{
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return;
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}
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static bool TrackValue(AIMetric metric, double d)
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{
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metric.TrackValue(d);
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return true;
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}
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MetricIdentifier identifier = GetIdentifier(instrument, tags);
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AIMetric metric = _client.GetMetric(identifier);
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double d = MetricHelpers.ConvertToDouble(value);
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if (tags.Length == 0)
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{
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metric.TrackValue(d);
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return;
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}
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// All the calls are unrolled to avoid allocations.
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_ = tags.Length switch
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{
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0 => TrackValue(metric, d), // need to massage return type for switch.
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1 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0)),
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2 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1)),
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3 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2)),
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4 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3)),
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5 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4)),
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6 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4),
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GetValueOrDefault(tags, 5)),
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7 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4),
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GetValueOrDefault(tags, 5),
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GetValueOrDefault(tags, 6)),
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8 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4),
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GetValueOrDefault(tags, 5),
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GetValueOrDefault(tags, 6),
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GetValueOrDefault(tags, 7)),
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9 => metric.TrackValue(
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d,
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4),
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GetValueOrDefault(tags, 5),
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GetValueOrDefault(tags, 6),
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GetValueOrDefault(tags, 7),
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GetValueOrDefault(tags, 8)),
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_ => metric.TrackValue(
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d, /* only track first 10 dimensions */
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GetValueOrDefault(tags, 0),
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GetValueOrDefault(tags, 1),
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GetValueOrDefault(tags, 2),
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GetValueOrDefault(tags, 3),
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GetValueOrDefault(tags, 4),
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GetValueOrDefault(tags, 5),
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GetValueOrDefault(tags, 6),
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GetValueOrDefault(tags, 7),
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GetValueOrDefault(tags, 8),
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GetValueOrDefault(tags, 9)),
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};
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}
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private static MetricIdentifier GetIdentifier(
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Instrument instrument, ReadOnlySpan<KeyValuePair<string, object?>> tags)
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{
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// App insights only supports up to 10 dimensions. We also want to avoid any extra allocation here, so we
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// use the explicit ctor and not the IList<string> accepting one.
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return new MetricIdentifier(
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instrument.Meter.Name,
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instrument.Name,
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tags.Length > 0 ? tags[0].Key : null,
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tags.Length > 1 ? tags[1].Key : null,
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tags.Length > 2 ? tags[2].Key : null,
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tags.Length > 3 ? tags[3].Key : null,
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tags.Length > 4 ? tags[4].Key : null,
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tags.Length > 5 ? tags[5].Key : null,
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tags.Length > 6 ? tags[6].Key : null,
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tags.Length > 7 ? tags[7].Key : null,
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tags.Length > 8 ? tags[8].Key : null,
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tags.Length > 9 ? tags[9].Key : null);
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}
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private static string GetValueOrDefault(ReadOnlySpan<KeyValuePair<string, object?>> tags, int index)
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=> tags.Length > index && tags[index].Value != null
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? tags[index].Value?.ToString() ?? string.Empty : string.Empty;
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}
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}

‎src/WebJobs.Script/Diagnostics/ApplicationInsightsMeterOptions.cs‎

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// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the MIT License. See License.txt in the project root for license information.
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#nullable enable
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using System;
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using System.Collections.Generic;
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using System.Diagnostics.Metrics;
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namespace Microsoft.Azure.WebJobs.Script.Diagnostics
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{
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/// <summary>
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/// Options for <see cref="ApplicationInsightsMeterListener"/>.
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/// </summary>
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public class ApplicationInsightsMeterOptions
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{
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/// <summary>
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/// Gets the set of meter names to listen to.
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/// </summary>
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public ISet<string> Sources { get; } = new HashSet<string>(StringComparer.Ordinal);
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/// <summary>
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/// Gets or sets the interval to collect meter values. Default is 30 seconds.
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/// </summary>
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/// <remarks>
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/// This is the interval at which values for metrics will be tracked on the Application Insights SDK. This is
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/// NOT the export interval. Application Insights SDK will export tracked values based on its own internal
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/// schedule.
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/// </remarks>
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public TimeSpan CollectInterval { get; set; } = TimeSpan.FromSeconds(30);
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/// <summary>
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/// Determines if given instrument should be listened to.
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/// </summary>
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/// <param name="instrument">The instrument.</param>
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/// <returns><c>true</c> if should be listened to, <c>false</c> otherwise.</returns>
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public bool ShouldListenTo(Instrument instrument)
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{
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ArgumentNullException.ThrowIfNull(instrument);
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// TODO: consider allowing wildcards or regex
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// For now, just exact match on meter name
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return Sources.Contains(instrument.Meter.Name);
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}
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}
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}

‎src/WebJobs.Script/Diagnostics/MetricHelpers.cs‎

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// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the MIT License. See License.txt in the project root for license information.
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using System;
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namespace Microsoft.Azure.WebJobs.Script.Diagnostics
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{
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/// <summary>
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/// Helpers for metrics.
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/// </summary>
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internal static class MetricHelpers
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{
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/// <summary>
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/// Convert an unknown struct type to a double, avoiding boxing.
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/// </summary>
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/// <param name="value">The value to convert.</param>
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/// <typeparam name="TIn">The input type.</typeparam>
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/// <returns>The converted value.</returns>
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public static double ConvertToDouble<TIn>(TIn value)
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where TIn : struct
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{
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return value switch
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{
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byte b => Convert.ToDouble(b),
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short s => Convert.ToDouble(s),
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int i => Convert.ToDouble(i),
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long l => Convert.ToDouble(l),
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float f => Convert.ToDouble(f),
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double d => d,
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decimal d => Convert.ToDouble(d),
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_ => throw new ArgumentException($"Unsupported type: {typeof(TIn)}", nameof(value)),
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};
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}
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/// <summary>
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/// Convert an unknown struct type to a long, avoiding boxing.
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/// </summary>
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/// <param name="value">The value to convert.</param>
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/// <typeparam name="TIn">The input type.</typeparam>
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/// <returns>The converted value.</returns>
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public static long ConvertToLong<TIn>(TIn value)
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where TIn : struct
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{
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return value switch
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{
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byte b => Convert.ToInt64(b),
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short s => Convert.ToInt64(s),
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int i => Convert.ToInt64(i),
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long l => l,
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float f => Convert.ToInt64(f),
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double d => Convert.ToInt64(d),
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decimal d => Convert.ToInt64(d),
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_ => throw new ArgumentException($"Unsupported type: {typeof(TIn)}", nameof(value)),
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};
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}
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}
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}

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