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README.md

@@ -188,10 +188,41 @@ public protocol XRayEmitter {
 }
 ```
 
-example:
+example of an emitter which logs emitted segments:
 
 ```swift
-let recorder = XRayRecorder(emitter: XRayNoopEmitter())
+public struct XRayLogEmitter: XRayEmitter {
+    private let logger: Logger
+
+    private let encoder: JSONEncoder = {
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = .prettyPrinted
+        return encoder
+    }()
+
+    public init(label: String? = nil) {
+        let label = label ?? "xray.log_emitter.\(String.random32())"
+        logger = Logger(label: label)
+    }
+
+    public func send(_ segment: XRayRecorder.Segment) {
+        do {
+            let document: String = try encoder.encode(segment)
+            logger.info("\n\(document)")
+        } catch {
+            logger.error("Failed to encode a segment: \(error)")
+        }
+    }
+
+    public func flush(_: @escaping (Error?) -> Void) {}
+}
+```
+
+
+The emitter has to be provided when creating an instance of `XRayRecorder`:
+
+```swift
+let recorder = XRayRecorder(emitter: XRayNoOpEmitter())
 ```
 
 ## References

Sources/AWSXRayRecorder/Config.swift

@@ -1,13 +1,7 @@
 import Logging
-import NIO // getenv
 
 // TODO: document
 
-private func env(_ name: String) -> String? {
-    guard let value = getenv(name) else { return nil }
-    return String(cString: value)
-}
-
 public extension XRayRecorder {
     struct Config {
         let enabled: Bool
@@ -46,3 +40,21 @@ internal extension XRayUDPEmitter {
         }
     }
 }
+
+#if canImport(Darwin)
+import Darwin
+#elseif canImport(Glibc)
+import Glibc
+#endif
+
+private func env(_ name: String) -> String? {
+    #if canImport(Darwin)
+    guard let value = getenv(name) else { return nil }
+    return String(cString: value)
+    #elseif canImport(Glibc)
+    guard let value = getenv(name) else { return nil }
+    return String(cString: value)
+    #else
+    return nil
+    #endif
+}

Sources/AWSXRayRecorder/Emitter.swift

@@ -5,7 +5,7 @@ public protocol XRayEmitter {
     func flush(_ callback: @escaping (Error?) -> Void)
 }
 
-public struct XRayNoopEmitter: XRayEmitter {
+public struct XRayNoOpEmitter: XRayEmitter {
     public func send(_: XRayRecorder.Segment) {}
     public func flush(_: @escaping (Error?) -> Void) {}
 

Sources/AWSXRayRecorder/LogEmitter/LogEmitter.swift

@@ -0,0 +1,38 @@
+import Logging
+
+import struct Foundation.Data
+import class Foundation.JSONEncoder
+
+private extension JSONEncoder {
+    func encode<T: Encodable>(_ value: T) throws -> String {
+        String(decoding: try encode(value), as: UTF8.self)
+    }
+}
+
+// TODO: document
+
+public struct XRayLogEmitter: XRayEmitter {
+    private let logger: Logger
+
+    private let encoder: JSONEncoder = {
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = .prettyPrinted
+        return encoder
+    }()
+
+    public init(label: String? = nil) {
+        let label = label ?? "xray.log_emitter.\(String.random32())"
+        logger = Logger(label: label)
+    }
+
+    public func send(_ segment: XRayRecorder.Segment) {
+        do {
+            let document: String = try encoder.encode(segment)
+            logger.info("\n\(document)")
+        } catch {
+            logger.error("Failed to encode a segment: \(error)")
+        }
+    }
+
+    public func flush(_: @escaping (Error?) -> Void) {}
+}

Sources/AWSXRayRecorder/Recorder.swift

@@ -23,7 +23,7 @@ public class XRayRecorder {
     public init(emitter: XRayEmitter, config: Config = Config()) {
         self.config = config
         if !config.enabled {
-            self.emitter = XRayNoopEmitter()
+            self.emitter = XRayNoOpEmitter()
         } else {
             self.emitter = emitter
         }
@@ -32,7 +32,7 @@ public class XRayRecorder {
 
     public convenience init(config: Config = Config(), eventLoopGroup: EventLoopGroup? = nil) {
         if !config.enabled {
-            self.init(emitter: XRayNoopEmitter(), config: config)
+            self.init(emitter: XRayNoOpEmitter(), config: config)
         } else {
             do {
                 let emitter = try XRayUDPEmitter(config: .init(config), eventLoopGroup: eventLoopGroup)
@@ -116,17 +116,19 @@ public class XRayRecorder {
             logger.debug("Segment \(id) parent has not been sent")
             return
         }
-        // mark it as emitted and pass responsibility to the emitter to actually do so
         do {
+            // mark it as emitted and pass responsibility to the emitter to actually do so
             try segment.emit()
+            // check if any of its subsegments are in progress and keep them in the recorder
+            let subsegments = segment.subsegmentsInProgress()
+            logger.debug("Segment \(id) has \(subsegments.count) subsegments \(Segment.State.inProgress)")
+            segmentsLock.withWriterLock {
+                subsegments.forEach { _segments[$0.id] = $0 }
+            }
+            // pass if the the emitter
+            emitter.send(segment)
         } catch {
             logger.error("Failed to emit Segment \(id): \(error)")
         }
-        // check if any of its subsegments are in progress and keep them in the recorder
-        let subsegments = segment.subsegmentsInProgress()
-        logger.debug("Segment \(id) has \(subsegments.count) subsegments \(Segment.State.inProgress)")
-        subsegments.forEach { _segments[$0.id] = $0 }
-        // pass if the the emitter
-        emitter.send(segment)
     }
 }