Review visibility of classes and methods, some of them could not be used properly outside of the library (#81)

Convert some Metrics classes to structs, since are not meant to be inherited
Modify tests import so only those files needing non public access import libraries as `@testable`
Code styling done to the modified files

Author: Ignacio Bonafonte

Sources/OpenTelemetryApi/Context/Propagation/DefaultContextPropagators.swift

@@ -21,11 +21,11 @@ import Foundation
 public struct DefaultContextPropagators: ContextPropagators {
     public var httpTextFormat: HTTPTextFormattable
 
-    init() {
+    public init() {
         httpTextFormat = NoopHttpTextFormat()
     }
 
-    init(textPropagators: [HTTPTextFormattable]) {
+    public init(textPropagators: [HTTPTextFormattable]) {
         httpTextFormat = MultiHttpTextFormat(textPropagators: textPropagators)
     }
 
@@ -76,8 +76,7 @@ public struct DefaultContextPropagators: ContextPropagators {
     struct NoopHttpTextFormat: HTTPTextFormattable {
         public var fields = Set<String>()
 
-        public func inject<S>(spanContext: SpanContext, carrier: inout [String: String], setter: S) where S: Setter {
-        }
+        public func inject<S>(spanContext: SpanContext, carrier: inout [String: String], setter: S) where S: Setter {}
 
         public func extract<G>(spanContext: SpanContext?, carrier: [String: String], getter: G) -> SpanContext? where G: Getter {
             return spanContext

Sources/OpenTelemetryApi/CorrelationContext/DefaultCorrelationContextManager.swift

@@ -19,7 +19,7 @@ import Foundation
 public class DefaultCorrelationContextManager: CorrelationContextManager {
     ///  Returns a CorrelationContextManager singleton that is the default implementation for
     ///  CorrelationContextManager.
-    static var instance = DefaultCorrelationContextManager()
+    public static var instance = DefaultCorrelationContextManager()
 
     private init() {}
 

Sources/OpenTelemetryApi/CorrelationContext/EntryMetadata.swift

@@ -38,7 +38,7 @@ public enum EntryTtl: Equatable {
 }
 
 public struct EntryMetadata: Equatable {
-    var entryTtl: EntryTtl
+    public var entryTtl: EntryTtl
 
     public init(entryTtl: EntryTtl) {
         self.entryTtl = entryTtl

Sources/OpenTelemetryApi/Metrics/CounterMetric.swift

@@ -76,18 +76,18 @@ public struct AnyCounterMetric<T>: CounterMetric {
     }
 }
 
-struct NoopCounterMetric<T>: CounterMetric {
-    func add(value: T, labelset: LabelSet) {
-    }
+public struct NoopCounterMetric<T>: CounterMetric {
+    public init() {}
 
-    func add(value: T, labels: [String: String]) {
-    }
+    public func add(value: T, labelset: LabelSet) {}
+
+    public func add(value: T, labels: [String: String]) {}
 
-    func bind(labelset: LabelSet) -> BoundCounterMetric<T> {
+    public func bind(labelset: LabelSet) -> BoundCounterMetric<T> {
         return BoundCounterMetric<T>()
     }
 
-    func bind(labels: [String: String]) -> BoundCounterMetric<T> {
+    public func bind(labels: [String: String]) -> BoundCounterMetric<T> {
         return BoundCounterMetric<T>()
     }
 }

Sources/OpenTelemetryApi/Metrics/DefaultMeterProvider.swift

@@ -15,15 +15,15 @@
 
 import Foundation
 
-class DefaultMeterProvider: MeterProvider {
-    static var instance: MeterProvider = DefaultMeterProvider()
+public class DefaultMeterProvider: MeterProvider {
+    public static var instance: MeterProvider = DefaultMeterProvider()
 
     static var proxyMeter = ProxyMeter()
     static var initialized = false
 
-    public init() {}
+    init() {}
 
-    static func setDefault(meterFactory: MeterProvider) {
+    public static func setDefault(meterFactory: MeterProvider) {
         guard !initialized else {
             return
         }
@@ -32,7 +32,7 @@ class DefaultMeterProvider: MeterProvider {
         initialized = true
     }
 
-    func get(instrumentationName: String, instrumentationVersion: String? = nil) -> Meter {
+    public func get(instrumentationName: String, instrumentationVersion: String? = nil) -> Meter {
         return DefaultMeterProvider.initialized ? DefaultMeterProvider.instance.get(instrumentationName: instrumentationName, instrumentationVersion: instrumentationVersion) : DefaultMeterProvider.proxyMeter
     }
 

Sources/OpenTelemetryApi/Metrics/DoubleObserverMetric.swift

@@ -16,7 +16,7 @@
 import Foundation
 
 /// Observer instrument for Double values.
-public protocol DoubleObserverMetric: AnyObject {
+public protocol DoubleObserverMetric {
     /// Observes a value.
     /// - Parameters:
     ///   - value: value to observe.
@@ -31,10 +31,10 @@ public protocol DoubleObserverMetric: AnyObject {
     func observe(value: Double, labels: [String: String])
 }
 
-class NoopDoubleObserverMetric: DoubleObserverMetric {
-    func observe(value: Double, labelset: LabelSet) {
-    }
+public struct NoopDoubleObserverMetric: DoubleObserverMetric {
+    public init() {}
 
-    func observe(value: Double, labels: [String: String]) {
-    }
+    public func observe(value: Double, labelset: LabelSet) {}
+
+    public func observe(value: Double, labels: [String: String]) {}
 }

Sources/OpenTelemetryApi/Metrics/IntObserverMetric.swift

@@ -16,7 +16,7 @@
 import Foundation
 
 /// Observer instrument for Int values.
-public protocol IntObserverMetric: AnyObject {
+public protocol IntObserverMetric {
     /// Observes a value.
     /// - Parameters:
     ///   - value: value to observe.
@@ -31,10 +31,10 @@ public protocol IntObserverMetric: AnyObject {
     func observe(value: Int, labels: [String: String])
 }
 
-class NoopIntObserverMetric: IntObserverMetric {
-    func observe(value: Int, labelset: LabelSet) {
-    }
+public struct NoopIntObserverMetric: IntObserverMetric {
+    public init() {}
 
-    func observe(value: Int, labels: [String: String]) {
-    }
+    public func observe(value: Int, labelset: LabelSet) {}
+
+    public func observe(value: Int, labels: [String: String]) {}
 }

Sources/OpenTelemetryApi/Metrics/MeasureMetric.swift

@@ -68,12 +68,14 @@ public struct AnyMeasureMetric<T>: MeasureMetric {
     }
 }
 
-struct NoopMeasureMetric<T>: MeasureMetric {
-    func bind(labelset: LabelSet) -> BoundMeasureMetric<T> {
+public struct NoopMeasureMetric<T>: MeasureMetric {
+    public init() {}
+
+    public func bind(labelset: LabelSet) -> BoundMeasureMetric<T> {
         BoundMeasureMetric<T>()
     }
 
-    func bind(labels: [String: String]) -> BoundMeasureMetric<T> {
+    public func bind(labels: [String: String]) -> BoundMeasureMetric<T> {
         BoundMeasureMetric<T>()
     }
 }

Sources/OpenTelemetryApi/Metrics/Meter.swift

@@ -16,7 +16,7 @@
 import Foundation
 
 /// Main interface to obtain metric instruments.
-public protocol Meter: AnyObject {
+public protocol Meter {
     /// Creates Int counter with given name.
     /// - Parameters:
     ///   - name: The name of the counter.

Sources/OpenTelemetryApi/Metrics/ProxyMeter.swift

@@ -16,38 +16,38 @@
 import Foundation
 
 /// Proxy Meter which act as a No-Op Meter, until real meter is provided.
-class ProxyMeter: Meter {
+public struct ProxyMeter: Meter {
     private var realMeter: Meter?
 
-    func getLabelSet(labels: [String: String]) -> LabelSet {
+    public func getLabelSet(labels: [String: String]) -> LabelSet {
         return realMeter?.getLabelSet(labels: labels) ?? LabelSet.empty
     }
 
-    func createIntCounter(name: String, monotonic: Bool) -> AnyCounterMetric<Int> {
+    public func createIntCounter(name: String, monotonic: Bool) -> AnyCounterMetric<Int> {
         return realMeter?.createIntCounter(name: name, monotonic: monotonic) ?? AnyCounterMetric<Int>(NoopCounterMetric<Int>())
     }
 
-    func createDoubleCounter(name: String, monotonic: Bool) -> AnyCounterMetric<Double> {
+    public func createDoubleCounter(name: String, monotonic: Bool) -> AnyCounterMetric<Double> {
         return realMeter?.createDoubleCounter(name: name, monotonic: monotonic) ?? AnyCounterMetric<Double>(NoopCounterMetric<Double>())
     }
 
-    func createIntMeasure(name: String, absolute: Bool) -> AnyMeasureMetric<Int> {
+    public func createIntMeasure(name: String, absolute: Bool) -> AnyMeasureMetric<Int> {
         return realMeter?.createIntMeasure(name: name, absolute: absolute) ?? AnyMeasureMetric<Int>(NoopMeasureMetric<Int>())
     }
 
-    func createDoubleMeasure(name: String, absolute: Bool) -> AnyMeasureMetric<Double> {
+    public func createDoubleMeasure(name: String, absolute: Bool) -> AnyMeasureMetric<Double> {
         return realMeter?.createDoubleMeasure(name: name, absolute: absolute) ?? AnyMeasureMetric<Double>(NoopMeasureMetric<Double>())
     }
 
-    func createIntObserver(name: String, absolute: Bool, callback: @escaping (IntObserverMetric) -> Void) -> IntObserverMetric {
+    public func createIntObserver(name: String, absolute: Bool, callback: @escaping (IntObserverMetric) -> Void) -> IntObserverMetric {
         return realMeter?.createIntObserver(name: name, absolute: absolute, callback: callback) ?? NoopIntObserverMetric()
     }
 
-    func createDoubleObserver(name: String, absolute: Bool, callback: @escaping (DoubleObserverMetric) -> Void) -> DoubleObserverMetric {
+    public func createDoubleObserver(name: String, absolute: Bool, callback: @escaping (DoubleObserverMetric) -> Void) -> DoubleObserverMetric {
         return realMeter?.createDoubleObserver(name: name, absolute: absolute, callback: callback) ?? NoopDoubleObserverMetric()
     }
 
-    func updateMeter(realMeter: Meter) {
+    mutating func updateMeter(realMeter: Meter) {
         guard self.realMeter == nil else {
             return
         }