Merge pull request #388 from nachoBonafonte/fix-metrics-thread-races

Fix potential thread race conditions that can happen if creating metrics while reporting.

Author: Ignacio Bonafonte

Examples/OTLP Exporter/main.swift

@@ -89,6 +89,8 @@ let meterProvider = MeterProviderSdk(metricProcessor: processor, metricExporter:
 OpenTelemetry.registerMeterProvider(meterProvider: meterProvider)
 
 
+let labels1 = ["dim1": "value1"]
+
 var meter = meterProvider.get(instrumentationName: "otlp_example_meter'")
 var exampleCounter = meter.createIntCounter(name: "otlp_example_counter")
 var exampleMeasure = meter.createIntMeasure(name: "otlp_example_measure")
@@ -100,11 +102,9 @@ var exampleObserver = meter.createIntObserver(name: "otlp_example_observation")
             task_info(mach_task_self_, task_flavor_t(MACH_TASK_BASIC_INFO), $0, &count)
         }
     }
-    labels1 = ["dim1": "value1"]
     observer.observe(value: Int(taskInfo.resident_size), labels: labels1)
 }
 
-var labels1 = ["dim1": "value1"]
 for _ in 1...3000 {
     exampleCounter.add(value: 1, labelset: meter.getLabelSet(labels: labels1))
     exampleMeasure.record(value: 100, labelset: meter.getLabelSet(labels: labels1))

Sources/OpenTelemetrySdk/Metrics/CounterMetricSdkBase.swift

@@ -7,7 +7,7 @@ import Foundation
 import OpenTelemetryApi
 
 class CounterMetricSdkBase<T>: CounterMetric {
-    private let bindUnbindLock = Lock()
+    let bindUnbindLock = Lock()
     public private(set) var boundInstruments = [LabelSet: BoundCounterMetricSdkBase<T>]()
     let metricName: String