First byte and priority measurement (#53)

* Increase test timeout

* Add first byte & priority

* Formatting

* Spelling

Author: ladd

Sources/NautilusTelemetry/Tracing/Redaction.swift

@@ -5,7 +5,7 @@ import Foundation
 
 public enum Redaction {
 
-	// MARK: Public
+	static public let redacted = "REDACTED"
 
 	/// Provides a default implementation of URL redaction that hides common sensitive elements.
 	/// - Parameter url: A URL to redact
@@ -39,7 +39,4 @@ public enum Redaction {
 		return components.url?.absoluteString
 	}
 
-	// MARK: Internal
-
-	static public let redacted = "REDACTED"
 }

Sources/NautilusTelemetry/Tracing/Span+URLSession.swift

@@ -118,9 +118,11 @@ extension Span {
 
 			addAttribute("http.tls.duration", tlsDuration)
 		}
+
+		addAttribute("http.first_byte.duration", elapsedNanoseconds(metric.fetchStartDate, metric.responseStartDate))
 	}
 
-	/// Annotates the span with attributes from the task's URLRequest.
+	/// Annotates the span with attributes from the task and its URLRequest.
 	/// - Parameters:
 	///   - _:  the URLSession instance.
 	///   - task: the task.
@@ -135,6 +137,12 @@ extension Span {
 		if let request = task.currentRequest {
 			addRequestAttributes(request, captureHeaders: captureHeaders, urlRedaction: urlRedaction)
 		}
+
+		// No semantic convention available
+		// Reported in iOS's 0.0-1.0 range, but is translated inside the network stack,
+		// based on HTTP protocol version.
+		// https://blog.cloudflare.com/better-http-3-prioritization-for-a-faster-web/
+		addAttribute("http.priority", task.priority)
 	}
 
 	/// Annotates the span with attributes from the task's response.

Tests/NautilusTelemetryTests/Tracing/Span+URLSessionTests.swift

@@ -34,7 +34,7 @@ final class SpanURLSessionTests: XCTestCase {
 		let task = urlSession.dataTask(with: urlRequest)
 		span.urlSession(urlSession, didCreateTask: task, captureHeaders: Set(["content-type"]))
 
-		let attributes = try XCTUnwrap(span.attributes as? [String: String])
+		let attributes = try XCTUnwrap(span.attributes)
 		XCTAssertEqual(attributes["url.full"], url.absoluteString)
 		XCTAssertEqual(attributes["http.request.header.content-type"], "application/json")
 	}
@@ -171,7 +171,21 @@ final class SpanURLSessionTests: XCTestCase {
 
 		span.urlSession(urlSession, didCreateTask: task)
 
-		let attributes = try XCTUnwrap(span.attributes as? [String: String])
+		let attributes = try XCTUnwrap(span.attributes)
 		XCTAssertEqual(attributes["url.full"], "https://REDACTED:REDACTED@example.com/path")
 	}
+
+	func testUrlPriority() throws {
+		let span = tracer.startSpan(name: #function)
+		let url = try makeURL("/")
+		let urlRequest = URLRequest(url: url)
+		let task = urlSession.dataTask(with: urlRequest)
+
+		task.priority = 1.0
+		span.urlSession(urlSession, didCreateTask: task)
+
+		let attributes = try XCTUnwrap(span.attributes)
+		XCTAssertEqual(attributes["http.priority"], task.priority)
+	}
+
 }

Tests/NautilusTelemetryTests/Utilities/FlushTimerTests.swift

@@ -12,6 +12,8 @@ import XCTest
 
 final class FlushTimerTests: XCTestCase {
 
+	let timeout: TimeInterval = 10
+
 	func testFlushTimerInitialization() throws {
 		let expectation = XCTestExpectation(description: "Timer handler called")
 		var handlerCallCount = 0
@@ -24,7 +26,7 @@ final class FlushTimerTests: XCTestCase {
 		XCTAssertEqual(timer.flushInterval, 0.1)
 		XCTAssertNotNil(timer.flushTimer)
 
-		wait(for: [expectation], timeout: 1.0)
+		wait(for: [expectation], timeout: timeout)
 		XCTAssertGreaterThanOrEqual(handlerCallCount, 1)
 	}
 
@@ -40,7 +42,7 @@ final class FlushTimerTests: XCTestCase {
 		XCTAssertEqual(timer.flushInterval, 0.1)
 		XCTAssertNotNil(timer.flushTimer)
 
-		wait(for: [expectation], timeout: 1.0)
+		wait(for: [expectation], timeout: timeout)
 		XCTAssertGreaterThanOrEqual(handlerCallCount, 1)
 	}
 
@@ -58,7 +60,7 @@ final class FlushTimerTests: XCTestCase {
 			}
 		}
 
-		wait(for: [expectation1], timeout: 1.0)
+		wait(for: [expectation1], timeout: timeout)
 		XCTAssertEqual(handlerCallCount, 1)
 
 		// Check minimum enforced
@@ -78,7 +80,7 @@ final class FlushTimerTests: XCTestCase {
 			expectation.fulfill()
 		}
 
-		wait(for: [expectation], timeout: 1.0)
+		wait(for: [expectation], timeout: timeout)
 
 		XCTAssertNotNil(timer) // keep timer alive
 	}
@@ -110,7 +112,7 @@ final class FlushTimerTests: XCTestCase {
 
 		XCTAssertFalse(timer.suspended)
 
-		wait(for: [expectation2], timeout: 1.0)
+		wait(for: [expectation2], timeout: timeout)
 		XCTAssertEqual(handlerCallCount, 2)
 	}
 }