From 844bdc7e6f5c95f725ab306b4e3d5eec8527cef4 Mon Sep 17 00:00:00 2001
From: Mustafa Haddara <mustafa@honeycomb.io>
Date: Fri, 1 Nov 2024 12:17:46 -0400
Subject: [PATCH] add "real" instrumented view

---
 .../SmokeTest/SmokeTest/ContentView.swift     | 36 ++++--------
 .../Honeycomb/HoneycombInstrumentedView.swift | 55 +++++++++++++++++++
 2 files changed, 67 insertions(+), 24 deletions(-)
 create mode 100644 Sources/Honeycomb/HoneycombInstrumentedView.swift

diff --git a/Examples/SmokeTest/SmokeTest/ContentView.swift b/Examples/SmokeTest/SmokeTest/ContentView.swift
index fe09d6a..bb4d4f5 100644
--- a/Examples/SmokeTest/SmokeTest/ContentView.swift
+++ b/Examples/SmokeTest/SmokeTest/ContentView.swift
@@ -31,34 +31,18 @@ private func flush() {
     Thread.sleep(forTimeInterval: 3.0)
 }
 
-struct InstrumentedView<Content: View>: View {
-    private let creationDate: Date
-    private let content: () -> Content
-
-    init(@SwiftUICore.ViewBuilder _ content: @escaping () -> Content) {
-        self.creationDate = Date()
-        self.content = content
-    }
-
-    var body: some View {
-        content()
-            .onAppear {
-                let interval = Date().timeIntervalSince(creationDate)
-                print("render time: \(interval)")
-            }
-    }
-}
-
 struct ContentView: View {
     var body: some View {
-        InstrumentedView {
+        HoneycombInstrumentedView(name: "main view") {
             VStack(
                 alignment: .center,
                 spacing: 20.0
             ) {
-                Image(systemName: "globe")
-                    .imageScale(.large)
-                    .foregroundStyle(.tint)
+                HoneycombInstrumentedView(name: "home icon") {
+                    Image(systemName: "globe")
+                        .imageScale(.large)
+                        .foregroundStyle(.tint)
+                }
 
                 Text("This is a sample app.")
 
@@ -77,14 +61,18 @@ struct ContentView: View {
                 }
                 .buttonStyle(.bordered)
 
-                Text(String(timeConsumingCalculation()))
+                HoneycombInstrumentedView(name: "expensive text") {
+                    Text(String(timeConsumingCalculation()))
+                }
+
             }
             .padding()
         }
     }
 
     private func timeConsumingCalculation() -> Int {
-        (1...10_000_000).reduce(0, +)
+        print("starting time consuming calculation")
+        return (1...100_000_000).reduce(0, +)
     }
 }
 
diff --git a/Sources/Honeycomb/HoneycombInstrumentedView.swift b/Sources/Honeycomb/HoneycombInstrumentedView.swift
new file mode 100644
index 0000000..ebdfd27
--- /dev/null
+++ b/Sources/Honeycomb/HoneycombInstrumentedView.swift
@@ -0,0 +1,55 @@
+import OpenTelemetryApi
+import OpenTelemetrySdk
+import SwiftUI
+
+private let honeycombInstrumentedViewName = "@honeycombio/instrumentation-view"
+
+struct HoneycombInstrumentedView<Content: View>: View {
+    private let span: Span
+    private let content: () -> Content
+    private let name: String
+
+    init(name: String, @SwiftUICore.ViewBuilder _ content: @escaping () -> Content) {
+        self.name = name
+        self.content = content
+
+        span = getMetricKitTracer().spanBuilder(spanName: "ViewInstrumentation")
+            .setStartTime(time: Date())
+            .setAttribute(key: "ViewName", value: name)
+            .startSpan()
+
+        print("\(name) init")
+    }
+
+    var body: some View {
+        print("\(name) started rendering")
+        let start = Date()
+
+        let c = content()
+
+        print("\(name) finished rendering")
+        span.setAttribute(
+            key: "RenderTimeMicroSeconds",
+            value: Int(Date().timeIntervalSince(start).toMicroseconds)
+        )
+
+        return c.onAppear {
+            span.end(time: Date())
+        }
+    }
+}
+
+extension View {
+    func honeycombInstrumentedView(name: String) -> some View {
+        HoneycombInstrumentedView(name: name) {
+            self
+        }
+    }
+}
+
+func getViewTracer() -> Tracer {
+    return OpenTelemetry.instance.tracerProvider.get(
+        instrumentationName: honeycombInstrumentedViewName,
+        instrumentationVersion: honeycombLibraryVersion
+    )
+}