Merge pull request #262 from danielqsj/zipkin_sn

zipkin use configured serviceName at first span

ByDefault, TracerProviderSdk use EnvVarResource to generate serviceName from environment variables.
If we don't set the serviceName via environment variables, the default value will be unknown_service+processName.
In this scenario, for Zipkin exporter, the current implement will always clone the default serviceName to overwrite the configured serviceName via zipkin configuration. That's not what we want.

And, we have not use the localEndpointCache to replace the defaultLocalEndpoint yet.

This PR aims to fixes these two issues.

Author: Ignacio Bonafonte

Sources/Exporters/Zipkin/Implementation/ZipkinConversionExtension.swift

@@ -21,6 +21,8 @@ struct ZipkinConversionExtension {
     static var localEndpointCache = [String: ZipkinEndpoint]()
     static var remoteEndpointCache = [String: ZipkinEndpoint]()
 
+    static let defaultServiceName = "unknown_service:" + ProcessInfo.processInfo.processName
+
     struct AttributeEnumerationState {
         var tags = [String: String]()
         var RemoteEndpointServiceName: String?
@@ -44,11 +46,11 @@ struct ZipkinConversionExtension {
 
         var localEndpoint = defaultLocalEndpoint
 
-        if let serviceName = attributeEnumerationState.serviceName, !serviceName.isEmpty {
+        if let serviceName = attributeEnumerationState.serviceName, !serviceName.isEmpty, defaultServiceName != serviceName {
             if localEndpointCache[serviceName] == nil {
-                localEndpoint = defaultLocalEndpoint.clone(serviceName: serviceName)
-                localEndpointCache[serviceName] = localEndpoint
+                localEndpointCache[serviceName] = defaultLocalEndpoint.clone(serviceName: serviceName)
             }
+            localEndpoint = localEndpointCache[serviceName] ?? localEndpoint
         }
 
         if let serviceNamespace = attributeEnumerationState.serviceNamespace, !serviceNamespace.isEmpty {