Added Stable Metric Sample

Author: bryce-b

Examples/Stable Metric Sample/main.swift

@@ -0,0 +1,75 @@
+//
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+//
+
+
+import Foundation
+import OpenTelemetryApi
+import OpenTelemetrySdk
+import OpenTelemetryProtocolExporter
+import GRPC
+import NIO
+import NIOHPACK
+
+/*
+ Stable metrics is the working name for the otel-swift implementation of the current OpenTelemetry metrics specification.
+ The existing otel-swift metric implementation is old and out-of-spec. While Stable Metrics is in an experimental phase it will maintaion
+ the "stable" prefix, and can be expected to be present on overlapping constructs in the implementation.
+ Expected time line will be as follows:
+  Phase 1:
+    Provide access to Stable Metrics along side existing Metrics. Once Stable Metrics are considered stable we will move onto phase 2.
+  Phase 2:
+    Mark all existing Metric APIs as deprecated. This will maintained for a period TBD
+  Phase 3:
+    Remove deprecated metrics api and remove Stable prefix from Stable metrics.
+
+
+ Below is an example used the Stable Metrics API
+
+ */
+
+
+
+
+/*
+ Basic configuration for metrics
+ */
+func basicConfiguration() {
+  let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+  let exporterChannel =  ClientConnection.insecure(group: group)
+    .connect(host: "localhost", port: 8200)
+  
+  
+  // register view will process all instruments using `.*` regex
+  
+  OpenTelemetry.registerStableMeterProvider(meterProvider: StableMeterProviderBuilder()
+    .registerView(selector: InstrumentSelector.builder().setInstrument(name: ".*").build(), view: StableView.builder().build())
+    .registerMetricReader(reader:StablePeriodicMetricReaderBuilder(exporter: StableOtlpMetricExporter(channel: exporterChannel)).build())
+    .build()
+    )
+}
+
+
+func complexViewConfiguration() {
+  let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+  let exporterChannel =  ClientConnection.insecure(group: group)
+    .connect(host: "localhost", port: 8200)
+  
+  // The example registers a View that re-configures the Gauge instrument into a sum instrument named "GaugeSum"
+  
+  OpenTelemetry.registerStableMeterProvider(meterProvider: StableMeterProviderBuilder()
+    .registerView(selector: InstrumentSelector.builder().setInstrument(name: "Gauge").build(), view: StableView.builder().withName(name: "GaugeSum").withAggregation(aggregation: Aggregations.sum()).build())
+    .registerMetricReader(reader:StablePeriodicMetricReaderBuilder(exporter: StableOtlpMetricExporter(channel: exporterChannel)).build())
+    .build()
+    )
+}
+
+basicConfiguration()
+
+// creating a new meter & instrument
+let meter = OpenTelemetry.instance.stableMeterProvider?.meterBuilder(name: "MyMeter").build()
+var gaugeBuilder = meter!.gaugeBuilder(name: "Gauge")
+var gauge = gaugeBuilder.buildWithCallback({ ObservableDoubleMeasurement in
+  ObservableDoubleMeasurement.record(value: 1.0, attributes: ["test": AttributeValue.bool(true)])
+})

Package.swift

@@ -166,6 +166,10 @@ let package = Package(
                 dependencies: ["DatadogExporter"],
                 path: "Examples/Datadog Sample",
                 exclude: ["README.md"]),
+        .target(name: "StableMetricSample",
+                dependencies: ["OpenTelemetrySdk", "OpenTelemetryApi", "OpenTelemetryProtocolExporter", .product(name: "GRPC", package:  "grpc-swift")],
+                path: "Examples/Stable Metric Sample",
+                exclude: ["README.md"]),
         .target(name: "NetworkSample",
                 dependencies: ["URLSessionInstrumentation", "StdoutExporter"],
                 path: "Examples/Network Sample",

Sources/OpenTelemetrySdk/Metrics/Stable/InstrumentSelector.swift

@@ -13,7 +13,7 @@ public class InstrumentSelector {
     let meterVersion : String?
     let meterSchemaUrl : String?
 
-    static func builder() -> InstrumentSelectorBuilder {
+    static public func builder() -> InstrumentSelectorBuilder {
         return InstrumentSelectorBuilder()
     }
 

Sources/OpenTelemetrySdk/Metrics/Stable/MeterBuilderSdk.swift

@@ -28,7 +28,7 @@ public class MeterBuilderSdk : MeterBuilder {
         return self
     }
 
-    public func build() -> OpenTelemetryApi.StableMeter {
+    public func build() -> StableMeter {
         return registry.get(name: instrumentationScopeName, version: instrumentationVersion, schemaUrl: schemaUrl)
     }