RUMM-3151 feat: reduce number of view updates by filtering events fro…

BenchmarkTests/BenchmarkMocks.swift

@@ -14,14 +14,14 @@ extension PerformancePreset {
 struct FeatureRequestBuilderMock: FeatureRequestBuilder {
     let dataFormat = DataFormat(prefix: "", suffix: "", separator: "\n")
 
-    func request(for events: [Data], with context: DatadogContext) -> URLRequest {
+    func request(for events: [Event], with context: DatadogContext) -> URLRequest {
         let builder = URLRequestBuilder(
             url: .mockAny(),
             queryItems: [.ddtags(tags: ["foo:bar"])],
             headers: []
         )
 
-        let data = dataFormat.format(events)
+        let data = dataFormat.format(events.map { $0.data })
         return builder.uploadRequest(with: data)
     }
 }

BenchmarkTests/DataUpload/DataUploaderBenchmarkTests.swift

@@ -37,7 +37,7 @@ class DataUploaderBenchmarkTests: BenchmarkTests {
         measure(metrics: [XCTMemoryMetric()]) {
             // in each, 10 requests are done:
             try? (0..<10).forEach { _ in
-                let events = [Data(repeating: 0x41, count: 10 * 1_024 * 1_024)]
+                let events = [Event(data: Data(repeating: 0x41, count: 10 * 1_024 * 1_024))]
                 _ = try dataUploader.upload(events: events, context: context)
             }
             // After all, the baseline asserts `0kB` or less grow in Physical Memory.

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [IMPROVEMENT] Reduce number of view updates by filtering events from payload. See [#1328][]
+
 # 1.21.0 / 27-07-2023
 - [BUGFIX] Fix TracingUUID string format. See [#1311][] (Thanks [@changm4n][])
 - [BUGFIX] Rename _Datadog_Private to DatadogPrivate. See [#1331] (Thanks [@alexfanatics][])
@@ -472,6 +474,7 @@
 [#1311]: https://github.com/DataDog/dd-sdk-ios/pull/1311
 [#1315]: https://github.com/DataDog/dd-sdk-ios/pull/1315
 [#1331]: https://github.com/DataDog/dd-sdk-ios/pull/1331
+[#1328]: https://github.com/DataDog/dd-sdk-ios/pull/1328
 [@00fa9a]: https://github.com/00FA9A
 [@britton-earnin]: https://github.com/Britton-Earnin
 [@hengyu]: https://github.com/Hengyu

Datadog/Datadog.xcodeproj/project.pbxproj

@@ -7,6 +7,20 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		3C0D5DD72A543B3B00446CF9 /* Event.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DD62A543B3B00446CF9 /* Event.swift */; };
+		3C0D5DD82A543B3B00446CF9 /* Event.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DD62A543B3B00446CF9 /* Event.swift */; };
+		3C0D5DE22A543DC400446CF9 /* EventGeneratorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DDF2A543DAE00446CF9 /* EventGeneratorTests.swift */; };
+		3C0D5DE32A543DC900446CF9 /* EventGeneratorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DDF2A543DAE00446CF9 /* EventGeneratorTests.swift */; };
+		3C0D5DE42A543E3400446CF9 /* EventGenerator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DDC2A543D5D00446CF9 /* EventGenerator.swift */; };
+		3C0D5DE52A543E3500446CF9 /* EventGenerator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DDC2A543D5D00446CF9 /* EventGenerator.swift */; };
+		3C0D5DE92A543EA200446CF9 /* RUMViewEventsFilterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DE62A543E9700446CF9 /* RUMViewEventsFilterTests.swift */; };
+		3C0D5DEA2A543EA300446CF9 /* RUMViewEventsFilterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DE62A543E9700446CF9 /* RUMViewEventsFilterTests.swift */; };
+		3C0D5DEC2A54405A00446CF9 /* RUMViewEventsFilter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DEB2A54405A00446CF9 /* RUMViewEventsFilter.swift */; };
+		3C0D5DED2A54405A00446CF9 /* RUMViewEventsFilter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DEB2A54405A00446CF9 /* RUMViewEventsFilter.swift */; };
+		3C0D5DEF2A5442A900446CF9 /* EventMocks.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DEE2A5442A900446CF9 /* EventMocks.swift */; };
+		3C0D5DF02A5442A900446CF9 /* EventMocks.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DEE2A5442A900446CF9 /* EventMocks.swift */; };
+		3C0D5DF52A5443B100446CF9 /* DataFormatTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DF42A5443B100446CF9 /* DataFormatTests.swift */; };
+		3C0D5DF62A5443B100446CF9 /* DataFormatTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C0D5DF42A5443B100446CF9 /* DataFormatTests.swift */; };
 		3C41693C29FBF4D50042B9D2 /* DatadogWebViewTracking.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3CE119FE29F7BE0100202522 /* DatadogWebViewTracking.framework */; };
 		3C41694729FBF8CC0042B9D2 /* DatadogInternal.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = D2DA2385298D57AA00C6C7E6 /* DatadogInternal.framework */; };
 		3C74305C29FBC0480053B80F /* DatadogInternal.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = D2DA2385298D57AA00C6C7E6 /* DatadogInternal.framework */; };
@@ -1668,6 +1682,13 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		3C0D5DD62A543B3B00446CF9 /* Event.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Event.swift; sourceTree = "<group>"; };
+		3C0D5DDC2A543D5D00446CF9 /* EventGenerator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EventGenerator.swift; sourceTree = "<group>"; };
+		3C0D5DDF2A543DAE00446CF9 /* EventGeneratorTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = EventGeneratorTests.swift; sourceTree = "<group>"; };
+		3C0D5DE62A543E9700446CF9 /* RUMViewEventsFilterTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RUMViewEventsFilterTests.swift; sourceTree = "<group>"; };
+		3C0D5DEB2A54405A00446CF9 /* RUMViewEventsFilter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RUMViewEventsFilter.swift; sourceTree = "<group>"; };
+		3C0D5DEE2A5442A900446CF9 /* EventMocks.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EventMocks.swift; sourceTree = "<group>"; };
+		3C0D5DF42A5443B100446CF9 /* DataFormatTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DataFormatTests.swift; sourceTree = "<group>"; };
 		3C85D41429F7C59C00AFF894 /* WebViewTracking.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WebViewTracking.swift; sourceTree = "<group>"; };
 		3C85D41529F7C59C00AFF894 /* WebViewTrackingMessage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WebViewTrackingMessage.swift; sourceTree = "<group>"; };
 		3C85D41629F7C59C00AFF894 /* WKUserContentController+Datadog.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "WKUserContentController+Datadog.swift"; sourceTree = "<group>"; };
@@ -2860,6 +2881,7 @@
 				D29CDD3128211A2200F7DAA5 /* DataBlock.swift */,
 				D2DC4BF527F484AA00E4FB96 /* DataEncryption.swift */,
 				61133BA92423979B00786299 /* FilesOrchestrator.swift */,
+				3C0D5DDC2A543D5D00446CF9 /* EventGenerator.swift */,
 				D2A7841429A53B92003B03BB /* Files */,
 				613E79412577C08900DFCC17 /* Writing */,
 				613E79422577C09B00DFCC17 /* Reading */,
@@ -3043,6 +3065,7 @@
 		61133C272423990D00786299 /* Persistence */ = {
 			isa = PBXGroup;
 			children = (
+				3C0D5DDF2A543DAE00446CF9 /* EventGeneratorTests.swift */,
 				61133C2A2423990D00786299 /* FilesOrchestratorTests.swift */,
 				D2B3F0432823EE8300C2B5EE /* DataBlockTests.swift */,
 				619E16D42577C11B00B2516B /* Writing */,
@@ -4336,6 +4359,7 @@
 				D23039D4298D5235001A1FA3 /* DataCompression.swift */,
 				D23039D5298D5235001A1FA3 /* FeatureRequestBuilder.swift */,
 				D2D3199929E98D970004F169 /* DefaultJSONEncoder.swift */,
+				3C0D5DD62A543B3B00446CF9 /* Event.swift */,
 			);
 			path = Upload;
 			sourceTree = "<group>";
@@ -4459,6 +4483,7 @@
 				D2EBEE4729BA17C400B15732 /* NetworkInstrumentationMocks.swift */,
 				61C3646F243B5C8300C4D4E6 /* ServerMock.swift */,
 				D2160CF629C0EE2B00FAA9A5 /* UploadMocks.swift */,
+				3C0D5DEE2A5442A900446CF9 /* EventMocks.swift */,
 			);
 			path = Mocks;
 			sourceTree = "<group>";
@@ -4523,6 +4548,7 @@
 				D25FF2E729CC6B680063802D /* RUMFeature.swift */,
 				D25FF2ED29CC73240063802D /* RequestBuilder.swift */,
 				D25FF2F329CC88060063802D /* RUMBaggageKeys.swift */,
+				3C0D5DEB2A54405A00446CF9 /* RUMViewEventsFilter.swift */,
 			);
 			path = Feature;
 			sourceTree = "<group>";
@@ -4589,6 +4615,7 @@
 		D29A9F3F29DD84AB005C54A4 /* DatadogRUMTests */ = {
 			isa = PBXGroup;
 			children = (
+				3C0D5DE62A543E9700446CF9 /* RUMViewEventsFilterTests.swift */,
 				61C713AC2A3B793E00FA735A /* RUMMonitorProtocolTests.swift */,
 				61C713B52A3C600400FA735A /* RUMMonitorProtocol+ConvenienceTests.swift */,
 				61C713B22A3C3A0B00FA735A /* RUMMonitorProtocol+InternalTests.swift */,
@@ -4831,6 +4858,7 @@
 		D2F44FBA299AA2310074B0D9 /* Upload */ = {
 			isa = PBXGroup;
 			children = (
+				3C0D5DF42A5443B100446CF9 /* DataFormatTests.swift */,
 				D213532F270CA722000315AD /* DataCompressionTests.swift */,
 			);
 			path = Upload;
@@ -6397,6 +6425,7 @@
 				61D3E0D5277B23F1008BE766 /* KronosNTPPacket.swift in Sources */,
 				61133BCF2423979B00786299 /* FileWriter.swift in Sources */,
 				6179FFD3254ADB1700556A0B /* ObjcAppLaunchHandler.m in Sources */,
+				3C0D5DE42A543E3400446CF9 /* EventGenerator.swift in Sources */,
 				D2303A0A298D5412001A1FA3 /* AsyncWriter.swift in Sources */,
 				D29CDD3228211A2200F7DAA5 /* DataBlock.swift in Sources */,
 				D2553829288F0B2400727FAD /* LowPowerModePublisher.swift in Sources */,
@@ -6477,6 +6506,7 @@
 				D22743DC29DEB8B4001A7EF9 /* VitalRefreshRateReaderTests.swift in Sources */,
 				617B954224BF4E7600E6F443 /* RUMMonitorConfigurationTests.swift in Sources */,
 				61F9CABA2513A7F5000A5E61 /* RUMSessionMatcher.swift in Sources */,
+				3C0D5DE22A543DC400446CF9 /* EventGeneratorTests.swift in Sources */,
 				61C3638324361BE200C4D4E6 /* DatadogPrivateMocks.swift in Sources */,
 				D26C49AF2886DC7B00802B2D /* ApplicationStatePublisherTests.swift in Sources */,
 				6147989C2A459E2B0095CB02 /* DDTrace+apiTests.m in Sources */,
@@ -6855,6 +6885,7 @@
 				D23039FD298D5236001A1FA3 /* DataCompression.swift in Sources */,
 				D23039F0298D5236001A1FA3 /* AnyEncoder.swift in Sources */,
 				D2A783D429A5309F003B03BB /* SwiftExtensions.swift in Sources */,
+				3C0D5DD72A543B3B00446CF9 /* Event.swift in Sources */,
 				D22F06D929DAFD500026CC3C /* TimeInterval+Convenience.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -6902,6 +6933,7 @@
 				D23F8E7429DDCD28001CFAE8 /* RUMCommandSubscriber.swift in Sources */,
 				D23F8E7529DDCD28001CFAE8 /* RUMUserActionScope.swift in Sources */,
 				61C713A42A3B78F900FA735A /* RUMMonitorProtocol.swift in Sources */,
+				3C0D5DED2A54405A00446CF9 /* RUMViewEventsFilter.swift in Sources */,
 				D23F8E7629DDCD28001CFAE8 /* RUMConnectivityInfoProvider.swift in Sources */,
 				D23F8E7729DDCD28001CFAE8 /* UIKitRUMViewsPredicate.swift in Sources */,
 				61C713A62A3B78F900FA735A /* RUMMonitorProtocol+Internal.swift in Sources */,
@@ -6969,6 +7001,7 @@
 				D23F8EBF29DDCD38001CFAE8 /* URLSessionRUMResourcesHandlerTests.swift in Sources */,
 				D23F8EC029DDCD38001CFAE8 /* RUMEventSanitizerTests.swift in Sources */,
 				D23F8EC129DDCD38001CFAE8 /* RUMEventsMapperTests.swift in Sources */,
+				3C0D5DEA2A543EA300446CF9 /* RUMViewEventsFilterTests.swift in Sources */,
 				D23F8EC429DDCD38001CFAE8 /* RUMCommandTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -6998,6 +7031,7 @@
 				D24C9C6929A7CE06002057CF /* DDErrorMocks.swift in Sources */,
 				D2579558298ABB04008A1BE5 /* Encoding.swift in Sources */,
 				D2EBEE4829BA17C400B15732 /* NetworkInstrumentationMocks.swift in Sources */,
+				3C0D5DEF2A5442A900446CF9 /* EventMocks.swift in Sources */,
 				D24C9C5529A7C5F3002057CF /* RelativeDateProvider.swift in Sources */,
 				D2579559298ABB04008A1BE5 /* DDAssert.swift in Sources */,
 				D2579552298ABB04008A1BE5 /* FileWriterMock.swift in Sources */,
@@ -7031,6 +7065,7 @@
 				D24C9C6A29A7CE06002057CF /* DDErrorMocks.swift in Sources */,
 				D257957B298ABB83008A1BE5 /* Encoding.swift in Sources */,
 				D2EBEE4929BA17C400B15732 /* NetworkInstrumentationMocks.swift in Sources */,
+				3C0D5DF02A5442A900446CF9 /* EventMocks.swift in Sources */,
 				D24C9C5629A7C5F3002057CF /* RelativeDateProvider.swift in Sources */,
 				D257957C298ABB83008A1BE5 /* DDAssert.swift in Sources */,
 				D257957D298ABB83008A1BE5 /* FileWriterMock.swift in Sources */,
@@ -7151,6 +7186,7 @@
 				D29A9F5D29DD85BB005C54A4 /* RUMCommandSubscriber.swift in Sources */,
 				D29A9F6529DD85BB005C54A4 /* RUMUserActionScope.swift in Sources */,
 				61C713A32A3B78F900FA735A /* RUMMonitorProtocol.swift in Sources */,
+				3C0D5DEC2A54405A00446CF9 /* RUMViewEventsFilter.swift in Sources */,
 				D29A9F5829DD85BB005C54A4 /* RUMConnectivityInfoProvider.swift in Sources */,
 				D29A9F5E29DD85BB005C54A4 /* UIKitRUMViewsPredicate.swift in Sources */,
 				61C713A52A3B78F900FA735A /* RUMMonitorProtocol+Internal.swift in Sources */,
@@ -7218,6 +7254,7 @@
 				D29A9F9A29DDB483005C54A4 /* URLSessionRUMResourcesHandlerTests.swift in Sources */,
 				D29A9FA229DDB483005C54A4 /* RUMEventSanitizerTests.swift in Sources */,
 				D29A9FB929DDB483005C54A4 /* RUMEventsMapperTests.swift in Sources */,
+				3C0D5DE92A543EA200446CF9 /* RUMViewEventsFilterTests.swift in Sources */,
 				D29A9FA729DDB483005C54A4 /* RUMCommandTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -7306,6 +7343,7 @@
 				D2CB6E2927C50EAE00A62B57 /* KronosInternetAddress.swift in Sources */,
 				D2CB6E2C27C50EAE00A62B57 /* KronosNTPPacket.swift in Sources */,
 				D2CB6E3127C50EAE00A62B57 /* FileWriter.swift in Sources */,
+				3C0D5DE52A543E3500446CF9 /* EventGenerator.swift in Sources */,
 				D2EFA869286DA85700F1FAA6 /* DatadogContextProvider.swift in Sources */,
 				D2B3F04E282A85FD00C2B5EE /* DatadogCore.swift in Sources */,
 				D2303A0B298D5412001A1FA3 /* AsyncWriter.swift in Sources */,
@@ -7378,6 +7416,7 @@
 				D2EFA876286E011900F1FAA6 /* DatadogContextProviderTests.swift in Sources */,
 				614B78F2296D7B63009C6B92 /* LowPowerModePublisherTests.swift in Sources */,
 				D2CB6EEE27C520D400A62B57 /* DDErrorTests.swift in Sources */,
+				3C0D5DE32A543DC900446CF9 /* EventGeneratorTests.swift in Sources */,
 				D25CFAA229C8644E00E3A43D /* Casting+Tracing.swift in Sources */,
 				D2CB6EF227C520D400A62B57 /* KronosTimeStorageTests.swift in Sources */,
 				D2CB6EF427C520D400A62B57 /* FileWriterTests.swift in Sources */,
@@ -7622,6 +7661,7 @@
 				D2DA237D298D57AA00C6C7E6 /* DataCompression.swift in Sources */,
 				D2DA237E298D57AA00C6C7E6 /* AnyEncoder.swift in Sources */,
 				D2A783D529A530A0003B03BB /* SwiftExtensions.swift in Sources */,
+				3C0D5DD82A543B3B00446CF9 /* Event.swift in Sources */,
 				D22F06DA29DAFD500026CC3C /* TimeInterval+Convenience.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -7636,6 +7676,7 @@
 				D21AE6BC29E5EDAF0064BF29 /* TelemetryTests.swift in Sources */,
 				D2DA23A3298D58F400C6C7E6 /* AnyEncodableTests.swift in Sources */,
 				D263BCB429DB014900FA0E21 /* FixedWidthInteger+ConvenienceTests.swift in Sources */,
+				3C0D5DF52A5443B100446CF9 /* DataFormatTests.swift in Sources */,
 				D2EBEE4429BA168200B15732 /* TraceIDTests.swift in Sources */,
 				D2EBEE4329BA168200B15732 /* TraceIDGeneratorTests.swift in Sources */,
 				D2DA23A7298D58F400C6C7E6 /* AppStateHistoryTests.swift in Sources */,
@@ -7672,6 +7713,7 @@
 				D21AE6BD29E5EDAF0064BF29 /* TelemetryTests.swift in Sources */,
 				D2DA23B1298D59DC00C6C7E6 /* AnyEncodableTests.swift in Sources */,
 				D263BCB529DB014900FA0E21 /* FixedWidthInteger+ConvenienceTests.swift in Sources */,
+				3C0D5DF62A5443B100446CF9 /* DataFormatTests.swift in Sources */,
 				D2EBEE4629BA168400B15732 /* TraceIDTests.swift in Sources */,
 				D2EBEE4529BA168400B15732 /* TraceIDGeneratorTests.swift in Sources */,
 				D2DA23B2298D59DC00C6C7E6 /* AppStateHistoryTests.swift in Sources */,

DatadogCore/Sources/Core/Storage/DataBlock.swift

@@ -5,6 +5,7 @@
  */
 
 import Foundation
+import DatadogInternal
 
 /// Block size binary type
 internal typealias BlockSize = UInt32
@@ -14,7 +15,11 @@ private let MAX_DATA_LENGTH: UInt64 = 10 * 1_024 * 1_024
 
 /// Block type supported in data stream
 internal enum BlockType: UInt16 {
+    /// Represents an event
     case event = 0x00
+    /// Represents an event metadata associated with the previous event.
+    /// This block is optional and may be omitted.
+    case eventMetadata = 0x01
 }
 
 /// Reported errors while manipulating data blocks.

DatadogCore/Sources/Core/Storage/EventGenerator.swift

@@ -0,0 +1,60 @@
+/*
+ * 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
+import DatadogInternal
+
+/// Event generator that generates events from the given data blocks.
+internal struct EventGenerator: Sequence, IteratorProtocol {
+    private let dataBlocks: [DataBlock]
+    private var index: Int
+
+    init(dataBlocks: [DataBlock], index: Int = 0) {
+        self.dataBlocks = dataBlocks
+        self.index = index
+    }
+
+    /// Returns the next event.
+    ///
+    /// Data format
+    /// ```
+    /// [EVENT 1 METADATA] [EVENT 1] [EVENT 2 METADATA] [EVENT 2] [EVENT 3]
+    /// ```
+    ///
+    /// - Returns: The next event or `nil` if there are no more events.
+    /// - Note: a `DataBlock` with `.event` type marks the beginning of the event.
+    ///         It is either followed by another `DataBlock` with `.event` type or
+    ///         by a `DataBlock` with `.metadata` type.
+    mutating func next() -> Event? {
+        guard index < dataBlocks.count else {
+            return nil
+        }
+
+        var metadata: DataBlock? = nil
+        // If the next block is an event metadata, read it.
+        if dataBlocks[index].type == .eventMetadata {
+            metadata = dataBlocks[index]
+            index += 1
+        }
+
+        // If this is the last block, return nil.
+        // there cannot be a metadata block without an event block.
+        guard index < dataBlocks.count else {
+            return nil
+        }
+
+        // If the next block is an event, read it.
+        guard dataBlocks[index].type == .event else {
+            // this is safeguard against corrupted data.
+            // if there was a metadata block, it will be skipped.
+            return next()
+        }
+        let event = dataBlocks[index]
+        index += 1
+
+        return Event(data: event.data, metadata: metadata?.data)
+    }
+}