Merge pull request #160 from nachoBonafonte/Context-handling-rework

Reworked context handling in the library:
Add initial support for implementing a different contextProvider, by default uses a contextProvider based on Activity.framework
Removed Scope concept from the library
Now context is handled in OpenTelemetry.instance.contextProvider, which uses the desired ContextProvider
This rework also implied modifiying the default Baggage, whihch is now an optional set to nil instead of an EmptyBaggage instance, these empty classes are not public anymore.
Some more cleaning can be done in Baggage handling, but the PR is big enough
Fixes #126, Fixes #154, partially improves #141
Some changes ease development for #38

Author: Ignacio Bonafonte

Examples/Datadog Sample/main.swift

@@ -71,7 +71,7 @@ func simpleSpan() {
 func childSpan() {
     let span = tracer.spanBuilder(spanName: "parentSpan").setSpanKind(spanKind: .client).startSpan()
     span.setAttribute(key: sampleKey, value: sampleValue)
-    OpenTelemetryContext.setActiveSpan(span)
+    OpenTelemetry.instance.contextProvider.setActiveSpan(span)
     let childSpan = tracer.spanBuilder(spanName: "childSpan").setSpanKind(spanKind: .client).startSpan()
     childSpan.setAttribute(key: sampleKey, value: sampleValue)
     childSpan.end()

Examples/Logging Tracer/LoggingSpan.swift

@@ -22,7 +22,6 @@ class LoggingSpan: Span {
     var context: SpanContext
     var isRecording: Bool = true
     var status: Status = .unset
-    var scope: Scope?
 
     public init(name: String, kind: SpanKind) {
         self.name = name

Examples/Logging Tracer/LoggingTracer.swift

@@ -18,9 +18,6 @@ import OpenTelemetryApi
 
 class LoggingTracer: Tracer {
     let tracerName = "LoggingTracer"
-    public var activeSpan: Span? {
-        return OpenTelemetryContext.activeSpan
-    }
 
     var binaryFormat: BinaryFormattable = LoggingBinaryFormat()
     var textFormat: TextMapPropagator = W3CTraceContextPropagator()
@@ -42,7 +39,7 @@ class LoggingTracer: Tracer {
 
         func startSpan() -> Span {
             if spanContext == nil, !isRootSpan {
-                spanContext = OpenTelemetryContext.activeSpan?.context
+                spanContext = OpenTelemetry.instance.contextProvider.activeSpan?.context
             }
             if spanContext != nil {
                 return LoggingSpan(name: name, kind: .client)

Examples/Logging Tracer/main.swift

@@ -22,14 +22,18 @@ OpenTelemetry.registerTracerProvider(tracerProvider: LoggingTracerProvider())
 
 var tracer = OpenTelemetry.instance.tracerProvider.get(instrumentationName: "ConsoleApp", instrumentationVersion: "semver:1.0.0")
 
-let scope = OpenTelemetryContext.setActiveSpan(tracer.spanBuilder(spanName: "Main (span1)").startSpan())
+
+let span1 = tracer.spanBuilder(spanName: "Main (span1)").startSpan()
+OpenTelemetry.instance.contextProvider.setActiveSpan(span1)
 let semaphore = DispatchSemaphore(value: 0)
 DispatchQueue.global().async {
-    var scope2 = OpenTelemetryContext.setActiveSpan(tracer.spanBuilder(spanName: "Main (span2)").startSpan())
-    OpenTelemetryContext.activeSpan?.setAttribute(key: "myAttribute", value: "myValue")
+    let span2 = tracer.spanBuilder(spanName: "Main (span2)").startSpan()
+    OpenTelemetry.instance.contextProvider.setActiveSpan(span2)
+    OpenTelemetry.instance.contextProvider.activeSpan?.setAttribute(key: "myAttribute", value: "myValue")
     sleep(1)
     semaphore.signal()
-    scope2.close()
+    span2.end()
 }
+span1.end()
 
 semaphore.wait()

Examples/Simple Exporter/main.swift

@@ -39,7 +39,7 @@ func simpleSpan() {
 func childSpan() {
     let span = tracer.spanBuilder(spanName: "parentSpan").setSpanKind(spanKind: .client).startSpan()
     span.setAttribute(key: sampleKey, value: sampleValue)
-    OpenTelemetryContext.setActiveSpan(span)
+    OpenTelemetry.instance.contextProvider.setActiveSpan(span)
     let childSpan = tracer.spanBuilder(spanName: "childSpan").setSpanKind(spanKind: .client).startSpan()
     childSpan.setAttribute(key: sampleKey, value: sampleValue)
     childSpan.end()

Sources/OpenTelemetryApi/Baggage/BaggageBuilder.swift

@@ -24,7 +24,7 @@ public protocol BaggageBuilder: AnyObject {
     ///  propagation is used.
     ///  If called multiple times, only the last specified value will be used.
     /// - Parameter parent: the Baggage used as parent
-    @discardableResult func setParent(_ parent: Baggage) -> Self
+    @discardableResult func setParent(_ parent: Baggage?) -> Self
 
     /// Sets the option to become a root Baggage with no parent. If not
     /// called, the value provided using setParent(Baggage) or otherwise
@@ -43,6 +43,6 @@ public protocol BaggageBuilder: AnyObject {
     /// - Parameter key: the EntryKey which will be removed.
     @discardableResult func remove(key: EntryKey) -> Self
 
-    /// Creates a Baggage from this builder.
+    /// Creates a Baggage from this builder. 
     func build() -> Baggage
 }

Sources/OpenTelemetryApi/Baggage/BaggageManager.swift

@@ -23,15 +23,6 @@ import Foundation
 /// own subtypes. This means callers cannot assume the getCurrentContext()
 /// is the same instance as the one withContext() placed into scope.
 public protocol BaggageManager: AnyObject {
-    /// Returns the current Baggage
-    func getCurrentBaggage() -> Baggage
-
     /// Returns a new ContextBuilder.
     func baggageBuilder() -> BaggageBuilder
-
-    /// Enters the scope of code where the given Baggage is in the current context
-    /// (replacing the previous Baggage) and returns an object that represents that
-    /// scope. The scope is exited when the returned object is closed.
-    /// - Parameter baggage: the Baggage to be set as the current context.
-    func withContext(baggage: Baggage) -> Scope
 }

Sources/OpenTelemetryApi/Baggage/DefaultBaggageBuilder.swift

@@ -22,7 +22,7 @@ public class DefaultBaggageBuilder: BaggageBuilder {
 
     public init() {}
 
-    @discardableResult public func setParent(_ parent: Baggage) -> Self {
+    @discardableResult public func setParent(_ parent: Baggage?) -> Self {
         self.parent = parent
         return self
     }
@@ -60,7 +60,7 @@ public class DefaultBaggageBuilder: BaggageBuilder {
     public func build() -> Baggage {
         var parentCopy = parent
         if parent == nil, !noImplicitParent {
-            parentCopy = OpenTelemetry.instance.baggageManager.getCurrentBaggage()
+            parentCopy = OpenTelemetry.instance.contextProvider.activeBaggage
         }
 
         var combined = entries

Sources/OpenTelemetryApi/Baggage/DefaultBaggageManager.swift

@@ -27,11 +27,7 @@ public class DefaultBaggageManager: BaggageManager {
         return DefaultBaggageBuilder()
     }
 
-    public func getCurrentBaggage() -> Baggage {
-        return OpenTelemetryContext.activeBaggage ?? EmptyBaggage.instance
-    }
-
-    public func withContext(baggage: Baggage) -> Scope {
-        return OpenTelemetryContext.setActiveBaggage(baggage)
+    public func getCurrentBaggage() -> Baggage? {
+        return OpenTelemetry.instance.contextProvider.activeBaggage
     }
 }

Sources/OpenTelemetryApi/Baggage/EmptyBaggage.swift

@@ -16,21 +16,21 @@
 import Foundation
 
 /// An immutable implementation of the Baggage that does not contain any entries.
-public class EmptyBaggage: Baggage {
+ class EmptyBaggage: Baggage {
     private init() {}
 
     /// Returns the single instance of the EmptyBaggage class.
-    public static var instance = EmptyBaggage()
+    static var instance = EmptyBaggage()
 
-    public static func baggageBuilder() -> BaggageBuilder {
+    static func baggageBuilder() -> BaggageBuilder {
         return EmptyBaggageBuilder()
     }
 
-    public func getEntries() -> [Entry] {
+    func getEntries() -> [Entry] {
         return [Entry]()
     }
 
-    public func getEntryValue(key: EntryKey) -> EntryValue? {
+    func getEntryValue(key: EntryKey) -> EntryValue? {
         return nil
     }
 }