migrated io metrics from Counter to ObservableCounter instrument

src/EventStore.Core.XUnit.Tests/Index/IndexTrackerTests.cs

@@ -17,12 +17,11 @@ public class IndexTrackerTests : IDisposable {
 	public IndexTrackerTests() {
 		var meter = new Meter($"{typeof(IndexTrackerTests)}");
 		_listener = new TestMeterListener<long>(meter);
-
-		var eventMetric = meter.CreateCounter<long>("eventstore-io", unit: "events");
+
 		_sut = new IndexTracker(
-			new CounterSubMetric<long>(
-				eventMetric,
-				new KeyValuePair<string, object>("activity", "written")));
+			new FastCounterMetric(
+				meter, "eventstore-io",
+				new KeyValuePair<string, object>("activity", "written"), "events"));
 	}
 
 	public void Dispose() {
@@ -49,8 +48,6 @@ public class IndexTrackerTests : IDisposable {
 	}
 
 	private void AssertMeasurements(long expectedEventsWritten) {
-		_listener.Observe();
-
 		Assert.Collection(
 			_listener.RetrieveMeasurements("eventstore-io-events"),
 			m => {

src/EventStore.Core.XUnit.Tests/TransactionLog/Chunks/TFChunkTrackerTests.cs

@@ -17,13 +17,11 @@ public class TFChunkTrackerTests : IDisposable {
 	public TFChunkTrackerTests() {
 		var meter = new Meter($"{typeof(TFChunkTrackerTests)}");
 		_listener = new TestMeterListener<long>(meter);
-		var byteMetric = meter.CreateCounter<long>("eventstore-io", unit: "bytes");
-		var eventMetric = meter.CreateCounter<long>("eventstore-io", unit: "events");
 
 		var readTag = new KeyValuePair<string, object>("activity", "read");
 		_sut = new TFChunkTracker(
-			readBytes: new CounterSubMetric<long>(byteMetric, readTag),
-			readEvents: new CounterSubMetric<long>(eventMetric, readTag));
+			readBytes: new FastCounterMetric(meter, "eventstore-io", readTag, "bytes"),
+			readEvents: new FastCounterMetric(meter, "eventstore-io", readTag, "events"));
 	}
 
 	public void Dispose() {
@@ -49,8 +47,8 @@ public class TFChunkTrackerTests : IDisposable {
 		_sut.OnRead(system);
 		_listener.Observe();
 
-		AssertEventsRead(null);
-		AssertBytesRead(null);
+		AssertEventsRead(0);
+		AssertBytesRead(0);
 	}
 
 	[Fact]
@@ -59,8 +57,8 @@ public class TFChunkTrackerTests : IDisposable {
 		_sut.OnRead(system);
 		_listener.Observe();
 
-		AssertEventsRead(null);
-		AssertBytesRead(null);
+		AssertEventsRead(0);
+		AssertBytesRead(0);
 	}
 
 	private void AssertEventsRead(long? expectedEventsRead) =>
@@ -70,7 +68,6 @@ public class TFChunkTrackerTests : IDisposable {
 		AssertMeasurements("eventstore-io-bytes", expectedBytesRead);
 
 	private void AssertMeasurements(string instrumentName, long? expectedValue) {
-		_listener.Observe();
 		var actual = _listener.RetrieveMeasurements(instrumentName);
 
 		if (expectedValue is null) {

src/EventStore.Core/Index/IndexTracker.cs

@@ -9,9 +9,9 @@ public interface IIndexTracker {
 	}
 
 	public class IndexTracker : IIndexTracker {
-		private readonly CounterSubMetric<long> _indexedEvents;
+		private readonly FastCounterMetric _indexedEvents;
 
-		public IndexTracker(CounterSubMetric<long> indexedEvents) {
+		public IndexTracker(FastCounterMetric indexedEvents) {
 			_indexedEvents = indexedEvents;
 		}
 

src/EventStore.Core/MetricsBootstrapper.cs

@@ -71,8 +71,6 @@ public static class MetricsBootstrapper {
 		var gossipProcessingMetric = new DurationMetric(coreMeter, "eventstore-gossip-processing-duration");
 		var queueQueueingDurationMaxMetric = new DurationMaxMetric(coreMeter, "eventstore-queue-queueing-duration-max");
 		var queueProcessingDurationMetric = new DurationMetric(coreMeter, "eventstore-queue-processing-duration");
-		var byteMetric = coreMeter.CreateCounter<long>("eventstore-io", unit: "bytes");
-		var eventMetric = coreMeter.CreateCounter<long>("eventstore-io", unit: "events");
 
 		// incoming grpc calls
 		var enabledCalls = conf.IncomingGrpcCalls.Where(kvp => kvp.Value).Select(kvp => kvp.Key).ToArray();
@@ -84,15 +82,15 @@ public static class MetricsBootstrapper {
 		if (conf.Events.TryGetValue(Conf.EventTracker.Read, out var readEnabled) && readEnabled) {
 			var readTag = new KeyValuePair<string, object>("activity", "read");
 			trackers.TransactionFileTracker = new TFChunkTracker(
-				readBytes: new CounterSubMetric<long>(byteMetric, readTag),
-				readEvents: new CounterSubMetric<long>(eventMetric, readTag));
+				readBytes: new FastCounterMetric(coreMeter, "eventstore-io", readTag,  "bytes"),
+				readEvents: new FastCounterMetric(coreMeter, "eventstore-io", readTag, "events"));
 		}
 
 		// from a users perspective an event is written when it is indexed: thats when it can be read.
 		if (conf.Events.TryGetValue(Conf.EventTracker.Written, out var writtenEnabled) && writtenEnabled) {
-			trackers.IndexTracker = new IndexTracker(new CounterSubMetric<long>(
-				eventMetric,
-				new KeyValuePair<string, object>("activity", "written")));
+			trackers.IndexTracker = new IndexTracker(new FastCounterMetric(
+				coreMeter, "eventstore-io",
+				new KeyValuePair<string, object>("activity", "written"), "events"));
 		}
 
 		// gossip

src/EventStore.Core/Telemetry/FastCounterMetric.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using System.Diagnostics.Metrics;
+using System.Threading;
+
+namespace EventStore.Core.Telemetry {
+	public class FastCounterMetric {
+		private long _counter;
+
+		public FastCounterMetric(Meter meter, string name, KeyValuePair<string, object> tags, string unit = null) {
+			meter.CreateObservableCounter(name, () => new Measurement<long>(Interlocked.Read(ref _counter), tags), unit);
+		}
+
+		public void Add(int delta) {
+			Interlocked.Add(ref _counter, delta);
+		}
+	}
+}

src/EventStore.Core/TransactionLog/Chunks/TransactionFileTracker.cs

@@ -5,12 +5,12 @@
 namespace EventStore.Core.TransactionLog.Chunks;
 
 public class TFChunkTracker : ITransactionFileTracker {
-	private readonly CounterSubMetric<long> _readBytes;
-	private readonly CounterSubMetric<long> _readEvents;
+	private readonly FastCounterMetric _readBytes;
+	private readonly FastCounterMetric _readEvents;
 
 	public TFChunkTracker(
-		CounterSubMetric<long> readBytes,
-		CounterSubMetric<long> readEvents) {
+		FastCounterMetric readBytes,
+		FastCounterMetric readEvents) {
 
 		_readBytes = readBytes;
 		_readEvents = readEvents;