RUMM-1272 Implement a VitalObserver

CONTRIBUTING.md

@@ -52,6 +52,14 @@ The workspace for SDK development and integration (tests, benchmarks, example ap
 
 `DatadogTests` (unit tests), `DatadogIntegrationTests` (integration tests), and `DatadogBenchmarkTests` (benchmarks) source files
 
+#### Lint
+
+We're using swiftlint to ensure our codebase follows Swift standard syntax. You can run the lint with our custom rules with the following command line:
+
+```shell
+$ ./tools/lint/run-linter.sh
+```
+
 #### Dependency manager tests
 
 Isolated example apps using `cocoapods`, `carthage` and `spm` to ensure SDK is well integrated with all supported dependency managers.

Datadog/Datadog.xcodeproj/project.pbxproj

@@ -439,6 +439,10 @@
 		9EEA4871258B76A100EBDA9D /* Global+objc.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9EEA4870258B76A100EBDA9D /* Global+objc.swift */; };
 		9EF963E82537556300235F98 /* DDURLSessionDelegateAsSuperclassTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9EF963E72537556300235F98 /* DDURLSessionDelegateAsSuperclassTests.swift */; };
 		9EFD112C24B32D29003A1A2B /* FirstPartyURLsFilter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9EFD112B24B32D29003A1A2B /* FirstPartyURLsFilter.swift */; };
+		B3FC3C0926526F0000DEED9E /* VitalInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = B3FC3C0626526EFF00DEED9E /* VitalInfo.swift */; };
+		B3FC3C0A26526F0000DEED9E /* VitalObserver.swift in Sources */ = {isa = PBXBuildFile; fileRef = B3FC3C0726526F0000DEED9E /* VitalObserver.swift */; };
+		B3FC3C332652AE1400DEED9E /* VitalListener.swift in Sources */ = {isa = PBXBuildFile; fileRef = B3FC3C322652AE1400DEED9E /* VitalListener.swift */; };
+		B3FC3C3C2653A97700DEED9E /* VitalObserverTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = B3FC3C3B2653A97700DEED9E /* VitalObserverTest.swift */; };
 		E132727B24B333C700952F8B /* TracingBenchmarkTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = E132727A24B333C700952F8B /* TracingBenchmarkTests.swift */; };
 		E132727D24B35B5F00952F8B /* TracingStorageBenchmarkTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = E132727C24B35B5F00952F8B /* TracingStorageBenchmarkTests.swift */; };
 		E13A880C257922EC004FB174 /* EnvironmentSpanIntegration.swift in Sources */ = {isa = PBXBuildFile; fileRef = E13A880B257922EC004FB174 /* EnvironmentSpanIntegration.swift */; };
@@ -982,6 +986,10 @@
 		9EF49F17244770AD004F2CA0 /* DatadogIntegrationTests.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = DatadogIntegrationTests.xcconfig; sourceTree = "<group>"; };
 		9EF963E72537556300235F98 /* DDURLSessionDelegateAsSuperclassTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DDURLSessionDelegateAsSuperclassTests.swift; sourceTree = "<group>"; };
 		9EFD112B24B32D29003A1A2B /* FirstPartyURLsFilter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FirstPartyURLsFilter.swift; sourceTree = "<group>"; };
+		B3FC3C0626526EFF00DEED9E /* VitalInfo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = VitalInfo.swift; sourceTree = "<group>"; };
+		B3FC3C0726526F0000DEED9E /* VitalObserver.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = VitalObserver.swift; sourceTree = "<group>"; };
+		B3FC3C322652AE1400DEED9E /* VitalListener.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = VitalListener.swift; sourceTree = "<group>"; };
+		B3FC3C3B2653A97700DEED9E /* VitalObserverTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = VitalObserverTest.swift; sourceTree = "<group>"; };
 		E132727A24B333C700952F8B /* TracingBenchmarkTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TracingBenchmarkTests.swift; sourceTree = "<group>"; };
 		E132727C24B35B5F00952F8B /* TracingStorageBenchmarkTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TracingStorageBenchmarkTests.swift; sourceTree = "<group>"; };
 		E13A880B257922EC004FB174 /* EnvironmentSpanIntegration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EnvironmentSpanIntegration.swift; sourceTree = "<group>"; };
@@ -2525,6 +2533,7 @@
 		61E5332A24B75C3B003D6C4E /* RUM */ = {
 			isa = PBXGroup;
 			children = (
+				B3FC3C0426526EE900DEED9E /* RUMVitals */,
 				61E5332B24B75C51003D6C4E /* RUMFeature.swift */,
 				61E5333224B7A504003D6C4E /* DataModels */,
 				61C3E63124BF143C008053F2 /* RUMMonitor */,
@@ -2542,6 +2551,7 @@
 		61E5332D24B75DC7003D6C4E /* RUM */ = {
 			isa = PBXGroup;
 			children = (
+				B3FC3C1226526F4100DEED9E /* RUMVitals */,
 				61E5332E24B75DE2003D6C4E /* RUMFeatureTests.swift */,
 				618715FA24DC5EE700FC0F69 /* DataModels */,
 				617B953B24BF4D7300E6F443 /* RUMMonitor */,
@@ -2842,6 +2852,24 @@
 			path = DatadogIntegrationTests;
 			sourceTree = "<group>";
 		};
+		B3FC3C0426526EE900DEED9E /* RUMVitals */ = {
+			isa = PBXGroup;
+			children = (
+				B3FC3C0626526EFF00DEED9E /* VitalInfo.swift */,
+				B3FC3C0726526F0000DEED9E /* VitalObserver.swift */,
+				B3FC3C322652AE1400DEED9E /* VitalListener.swift */,
+			);
+			path = RUMVitals;
+			sourceTree = "<group>";
+		};
+		B3FC3C1226526F4100DEED9E /* RUMVitals */ = {
+			isa = PBXGroup;
+			children = (
+				B3FC3C3B2653A97700DEED9E /* VitalObserverTest.swift */,
+			);
+			path = RUMVitals;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXHeadersBuildPhase section */
@@ -3351,6 +3379,7 @@
 				61C5A88E24509A1F00DA608C /* Tracer.swift in Sources */,
 				61E909EE24A24DD3005EA2DE /* OTFormat.swift in Sources */,
 				9E26E6B924C87693000B3270 /* RUMDataModels.swift in Sources */,
+				B3FC3C0A26526F0000DEED9E /* VitalObserver.swift in Sources */,
 				613E793B2577B6EE00DFCC17 /* DataReader.swift in Sources */,
 				614B0A5324EBFE5500A2A780 /* DDRUMMonitor.swift in Sources */,
 				61133BE32423979B00786299 /* UserInfoProvider.swift in Sources */,
@@ -3380,10 +3409,12 @@
 				61133BD72423979B00786299 /* DataUploadWorker.swift in Sources */,
 				61133BD12423979B00786299 /* FilesOrchestrator.swift in Sources */,
 				61133BCD2423979B00786299 /* NetworkConnectionInfoProvider.swift in Sources */,
+				B3FC3C332652AE1400DEED9E /* VitalListener.swift in Sources */,
 				61FF282424B8A1C3000B3D9B /* RUMEventFileOutput.swift in Sources */,
 				61B22E5A24F3E6B700DC26D2 /* RUMDebugging.swift in Sources */,
 				61C5A88B24509A0C00DA608C /* SpanOutput.swift in Sources */,
 				61133BE42423979B00786299 /* LogEncoder.swift in Sources */,
+				B3FC3C0926526F0000DEED9E /* VitalInfo.swift in Sources */,
 				613E81F025A740140084B751 /* RUMEventsMapper.swift in Sources */,
 				61D980BA24E28D0100E03345 /* RUMIntegrations.swift in Sources */,
 				61C5A88424509A0C00DA608C /* DDSpan.swift in Sources */,
@@ -3511,6 +3542,7 @@
 				61C1510D25AC8C1B00362D4B /* RUMViewIdentityTests.swift in Sources */,
 				613E820525A879AF0084B751 /* RUMDataModelMocks.swift in Sources */,
 				61133C492423990D00786299 /* DDLoggerBuilderTests.swift in Sources */,
+				B3FC3C3C2653A97700DEED9E /* VitalObserverTest.swift in Sources */,
 				61133C4B2423990D00786299 /* DDLoggerTests.swift in Sources */,
 				618715FC24DC5F0800FC0F69 /* RUMDataModelsMappingTests.swift in Sources */,
 				61C5A89624509BF600DA608C /* TracerTests.swift in Sources */,

Sources/Datadog/RUM/RUMVitals/VitalInfo.swift

@@ -0,0 +1,21 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2019-Present Datadog, Inc.
+ */
+
+import Foundation
+
+internal struct VitalInfo {
+    /// Number of sample for this info
+    internal let sampleCount: Int
+
+    /// Minimum value across all samples
+    internal let minValue: Double
+
+    /// Maximum value across all samples
+    internal let maxValue: Double
+
+    /// Average value across all samples
+    internal let meanValue: Double
+}

Sources/Datadog/RUM/RUMVitals/VitalListener.swift

@@ -0,0 +1,12 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2019-Present Datadog, Inc.
+ */
+
+import Foundation
+
+/// A listener getting aggregated information from a VitalObserver
+internal protocol VitalListener {
+    func onVitalInfo(info: VitalInfo)
+}

Sources/Datadog/RUM/RUMVitals/VitalObserver.swift

@@ -0,0 +1,43 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2019-Present Datadog, Inc.
+ */
+
+import Foundation
+
+/// Provides interface for observing Vital info from a producer
+internal class VitalObserver: ValueObserver {
+    let listener: VitalListener
+
+    private var vitalInfo = VitalInfo(
+        sampleCount: 0,
+        minValue: Double.greatestFiniteMagnitude,
+        maxValue: -Double.greatestFiniteMagnitude,
+        meanValue: 0.0
+    )
+
+    init(listener: VitalListener) {
+        self.listener = listener
+    }
+
+    // MARK: - ValueObserver
+    final func onValueChanged(oldValue: Double, newValue: Double) {
+        let newSampleCount = vitalInfo.sampleCount + 1
+        // Assuming M(n) is the mean value of the first n samples
+        // M(n) = ∑ sample(n) / n
+        // n⨉M(n) = ∑ sample(n)
+        // M(n+1) = ∑ sample(n+1) / (n+1)
+        //        = [ sample(n+1) + ∑ sample(n) ] / (n+1)
+        //        = (sample(n+1) + n⨉M(n)) / (n+1)
+        let newMeanValue = (newValue + (Double(vitalInfo.sampleCount) * vitalInfo.meanValue)) / Double(newSampleCount)
+        let newVitalInfo = VitalInfo(
+            sampleCount: newSampleCount,
+            minValue: min(vitalInfo.minValue, newValue),
+            maxValue: max(vitalInfo.maxValue, newValue),
+            meanValue: newMeanValue
+        )
+        vitalInfo = newVitalInfo
+        listener.onVitalInfo(info: newVitalInfo)
+    }
+}

Tests/DatadogTests/Datadog/Mocks/RUMFeatureMocks.swift

@@ -671,3 +671,11 @@ class UIKitRUMUserActionsHandlerMock: UIKitRUMUserActionsHandlerType {
         onSendEvent?(application, event)
     }
 }
+
+class VitalListenerMock: VitalListener {
+    var onVitalInfoUpdate: ((VitalInfo) -> Void)?
+
+    func onVitalInfo(info: VitalInfo) {
+        onVitalInfoUpdate?(info)
+    }
+}

Tests/DatadogTests/Datadog/RUM/RUMVitals/VitalObserverTest.swift

@@ -0,0 +1,72 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2019-Present Datadog, Inc.
+ */
+
+import XCTest
+@testable import Datadog
+
+class VitalObserverTest: XCTestCase {
+    func testItUpdatesVitalInfoOnFirstValue() {
+        let randomOldValue = Double.random(in: -65_536.0...65_536.0)
+        let randomValue = Double.random(in: -65_536.0...65_536.0)
+        let notifyExpectation = expectation(description: "Notify vital info")
+        let mockListener = VitalListenerMock()
+        let testedObserver = VitalObserver(listener: mockListener)
+        mockListener.onVitalInfoUpdate = { vitalInfo in
+            XCTAssertEqual(vitalInfo.minValue, randomValue)
+            XCTAssertEqual(vitalInfo.maxValue, randomValue)
+            XCTAssertEqual(vitalInfo.meanValue, randomValue)
+            XCTAssertEqual(vitalInfo.sampleCount, 1)
+            notifyExpectation.fulfill()
+        }
+
+        // When
+        testedObserver.onValueChanged(oldValue: randomOldValue, newValue: randomValue)
+
+        // Then
+        wait(for: [notifyExpectation], timeout: 0.5, enforceOrder: true)
+    }
+
+    func testItUpdatesVitalInfoOnMultipleValue() {
+        let randomOldValue = Double.random(in: -65_536.0...65_536.0)
+        let randomValue1 = Double.random(in: -65_536.0...65_536.0)
+        let randomValue2 = Double.random(in: -65_536.0...65_536.0)
+        let randomValue3 = Double.random(in: -65_536.0...65_536.0)
+        let notifyExpectation1 = expectation(description: "Notify vital info 1")
+        let notifyExpectation2 = expectation(description: "Notify vital info 2")
+        let notifyExpectation3 = expectation(description: "Notify vital info 3")
+        let mockListener = VitalListenerMock()
+        let testedObserver = VitalObserver(listener: mockListener)
+
+        // When
+        mockListener.onVitalInfoUpdate = { vitalInfo in
+            XCTAssertEqual(vitalInfo.minValue, randomValue1)
+            XCTAssertEqual(vitalInfo.maxValue, randomValue1)
+            XCTAssertEqual(vitalInfo.meanValue, randomValue1)
+            XCTAssertEqual(vitalInfo.sampleCount, 1)
+            notifyExpectation1.fulfill()
+        }
+        testedObserver.onValueChanged(oldValue: randomOldValue, newValue: randomValue1)
+        mockListener.onVitalInfoUpdate = { vitalInfo in
+            XCTAssertEqual(vitalInfo.minValue, min(randomValue1, randomValue2))
+            XCTAssertEqual(vitalInfo.maxValue, max(randomValue1, randomValue2))
+            XCTAssertEqual(vitalInfo.meanValue, (randomValue1 + randomValue2) / 2.0)
+            XCTAssertEqual(vitalInfo.sampleCount, 2)
+            notifyExpectation2.fulfill()
+        }
+        testedObserver.onValueChanged(oldValue: randomValue1, newValue: randomValue2)
+        mockListener.onVitalInfoUpdate = { vitalInfo in
+            XCTAssertEqual(vitalInfo.minValue, min(randomValue1, min(randomValue2, randomValue3)))
+            XCTAssertEqual(vitalInfo.maxValue, max(randomValue1, max(randomValue2, randomValue3)))
+            XCTAssertEqual(vitalInfo.meanValue, (randomValue1 + randomValue2 + randomValue3) / 3.0)
+            XCTAssertEqual(vitalInfo.sampleCount, 3)
+            notifyExpectation3.fulfill()
+        }
+        testedObserver.onValueChanged(oldValue: randomValue2, newValue: randomValue3)
+
+        // Then
+        wait(for: [notifyExpectation1, notifyExpectation2, notifyExpectation3], timeout: 0.5, enforceOrder: true)
+    }
+}