Adding optional gzip compression for /track

Mixpanel-swift.podspec

@@ -21,7 +21,7 @@ Pod::Spec.new do |s|
     'Sources/Constants.swift', 'Sources/MixpanelType.swift', 'Sources/Mixpanel.swift', 'Sources/MixpanelInstance.swift',
     'Sources/Flush.swift','Sources/Track.swift', 'Sources/People.swift', 'Sources/AutomaticEvents.swift',
     'Sources/Group.swift',
-    'Sources/ReadWriteLock.swift', 'Sources/SessionMetadata.swift', 'Sources/MPDB.swift', 'Sources/MixpanelPersistence.swift']
+    'Sources/ReadWriteLock.swift', 'Sources/SessionMetadata.swift', 'Sources/MPDB.swift', 'Sources/MixpanelPersistence.swift', 'Sources/Data+Compression.swift']
   s.tvos.deployment_target = '11.0'
   s.tvos.frameworks = 'UIKit', 'Foundation'
   s.tvos.pod_target_xcconfig = {

Mixpanel.xcodeproj/project.pbxproj

@@ -45,6 +45,10 @@
 		86F86EF7224554B900B69832 /* Group.swift in Sources */ = {isa = PBXBuildFile; fileRef = 673ABE3921360CBE00B1784B /* Group.swift */; };
 		86F86F3622497F1200B69832 /* AutomaticEvents.swift in Sources */ = {isa = PBXBuildFile; fileRef = E151FA371E70DFB5002EF53D /* AutomaticEvents.swift */; };
 		86F86F3722497F2900B69832 /* AutomaticEvents.swift in Sources */ = {isa = PBXBuildFile; fileRef = E151FA371E70DFB5002EF53D /* AutomaticEvents.swift */; };
+		95ECF0682C9B851A006364D2 /* Data+Compression.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95ECF0662C9B83D8006364D2 /* Data+Compression.swift */; };
+		95ECF0692C9B851B006364D2 /* Data+Compression.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95ECF0662C9B83D8006364D2 /* Data+Compression.swift */; };
+		95ECF06A2C9B851B006364D2 /* Data+Compression.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95ECF0662C9B83D8006364D2 /* Data+Compression.swift */; };
+		95ECF06B2C9B851C006364D2 /* Data+Compression.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95ECF0662C9B83D8006364D2 /* Data+Compression.swift */; };
 		BB9614171F3BB87700C3EF3E /* ReadWriteLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = BB9614161F3BB87700C3EF3E /* ReadWriteLock.swift */; };
 		E10D118D1EC0F30900195CCD /* AutomaticEvents.swift in Sources */ = {isa = PBXBuildFile; fileRef = E151FA371E70DFB5002EF53D /* AutomaticEvents.swift */; };
 		E115948B1CFF1538007F8B4F /* Mixpanel.swift in Sources */ = {isa = PBXBuildFile; fileRef = E115948A1CFF1538007F8B4F /* Mixpanel.swift */; };
@@ -107,6 +111,7 @@
 		8625BEBA26D045CE0009BAA9 /* MPDB.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MPDB.swift; sourceTree = "<group>"; };
 		868550AB2699096F001FCDDC /* MixpanelPersistence.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MixpanelPersistence.swift; sourceTree = "<group>"; };
 		86F86E81224404BD00B69832 /* Mixpanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Mixpanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
+		95ECF0662C9B83D8006364D2 /* Data+Compression.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Data+Compression.swift"; sourceTree = "<group>"; };
 		BB9614161F3BB87700C3EF3E /* ReadWriteLock.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ReadWriteLock.swift; sourceTree = "<group>"; };
 		E115947D1CFF1491007F8B4F /* Mixpanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Mixpanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		E11594821CFF1491007F8B4F /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; name = Info.plist; path = ../Info.plist; sourceTree = "<group>"; };
@@ -254,6 +259,7 @@
 		E189D8FA1D5A692A007F3F29 /* Utilities */ = {
 			isa = PBXGroup;
 			children = (
+				95ECF0662C9B83D8006364D2 /* Data+Compression.swift */,
 				E11594981D01689F007F8B4F /* JSONHandler.swift */,
 				E1982BFE1D0AC2E2006B7330 /* Error.swift */,
 				E1D335CF1D3059A800E68E12 /* AutomaticProperties.swift */,
@@ -484,6 +490,7 @@
 				86F86EC522443A2C00B69832 /* People.swift in Sources */,
 				86F86EC422443A2300B69832 /* ReadWriteLock.swift in Sources */,
 				8625BEBE26D045CE0009BAA9 /* MPDB.swift in Sources */,
+				95ECF06B2C9B851C006364D2 /* Data+Compression.swift in Sources */,
 				86F86EC222443A1300B69832 /* Track.swift in Sources */,
 				86F86EC122443A0E00B69832 /* JSONHandler.swift in Sources */,
 				86F86EC022443A0800B69832 /* MixpanelType.swift in Sources */,
@@ -512,6 +519,7 @@
 				E11594971D006022007F8B4F /* Network.swift in Sources */,
 				E15FF7C81D0435670076CDE3 /* People.swift in Sources */,
 				673ABE3A21360CBE00B1784B /* Group.swift in Sources */,
+				95ECF0682C9B851A006364D2 /* Data+Compression.swift in Sources */,
 				E11594A11D01C597007F8B4F /* Track.swift in Sources */,
 				E11594991D01689F007F8B4F /* JSONHandler.swift in Sources */,
 				E1D335D01D3059A800E68E12 /* AutomaticProperties.swift in Sources */,
@@ -540,6 +548,7 @@
 				E12782BF1D4AB5CB0025FB05 /* MixpanelInstance.swift in Sources */,
 				E12782C11D4AB5CB0025FB05 /* Network.swift in Sources */,
 				8625BEBC26D045CE0009BAA9 /* MPDB.swift in Sources */,
+				95ECF0692C9B851B006364D2 /* Data+Compression.swift in Sources */,
 				E12782C21D4AB5CB0025FB05 /* JSONHandler.swift in Sources */,
 				E12782C31D4AB5CB0025FB05 /* Flush.swift in Sources */,
 				E12782C41D4AB5CB0025FB05 /* FlushRequest.swift in Sources */,
@@ -568,6 +577,7 @@
 				E1F15FD61E64B5FC00391AE3 /* FlushRequest.swift in Sources */,
 				E1F15FD71E64B60200391AE3 /* PrintLogging.swift in Sources */,
 				8625BEBD26D045CE0009BAA9 /* MPDB.swift in Sources */,
+				95ECF06A2C9B851B006364D2 /* Data+Compression.swift in Sources */,
 				E1F15FE21E64B60D00391AE3 /* Flush.swift in Sources */,
 				E1F15FD51E64B5F800391AE3 /* Network.swift in Sources */,
 				E1F15FDE1E64B60A00391AE3 /* MixpanelType.swift in Sources */,
@@ -805,7 +815,7 @@
 				HEADER_SEARCH_PATHS = "";
 				INFOPLIST_FILE = Info.plist;
 				INSTALL_PATH = "$(LOCAL_LIBRARY_DIR)/Frameworks";
-				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				OTHER_SWIFT_FLAGS = "";
 				PRODUCT_BUNDLE_IDENTIFIER = com.mixpanel.Mixpanel;
@@ -853,7 +863,7 @@
 				HEADER_SEARCH_PATHS = "";
 				INFOPLIST_FILE = Info.plist;
 				INSTALL_PATH = "$(LOCAL_LIBRARY_DIR)/Frameworks";
-				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				OTHER_SWIFT_FLAGS = "";
 				PRODUCT_BUNDLE_IDENTIFIER = com.mixpanel.Mixpanel;

MixpanelDemo/MixpanelDemoTests/MixpanelDemoTests.swift

@@ -1189,4 +1189,14 @@ class MixpanelDemoTests: MixpanelBaseTests {
             }
         }
     }
+
+    func testGzipCompressionInit() {
+        let testMixpanel = Mixpanel.initialize(token: randomId(), trackAutomaticEvents: false, useGzipCompression: true)
+        XCTAssertTrue(testMixpanel.useGzipCompression == true, "the init of GzipCompression failed")
+    }
+
+    func testGzipCompressionDefault() {
+        let testMixpanel = Mixpanel.initialize(token: randomId(), trackAutomaticEvents: false)
+        XCTAssertTrue(testMixpanel.useGzipCompression == false, "the default gzip option disabled failed")
+    }
 }

Sources/Constants.swift

@@ -27,6 +27,10 @@ struct BundleConstants {
     static let ID = "com.mixpanel.Mixpanel"
 }
 
+struct GzipSettings {
+    static let gzipHeaderOffset = Int32(16)
+}
+
 #if !os(OSX) && !os(watchOS) && !os(visionOS)
 extension UIDevice {
     var iPhoneX: Bool {

Sources/Data+Compression.swift

@@ -0,0 +1,93 @@
+//
+//  Data+Compression.swift
+//  MixpanelSessionReplay
+//
+//  Copyright © 2024 Mixpanel. All rights reserved.
+//
+
+import Foundation
+import zlib
+
+public enum GzipError: Swift.Error {
+    case stream
+    case data
+    case memory
+    case buffer
+    case version
+    case unknown(code: Int)
+
+    init(code: Int32) {
+        switch code {
+        case Z_STREAM_ERROR:
+            self = .stream
+        case Z_DATA_ERROR:
+            self = .data
+        case Z_MEM_ERROR:
+            self = .memory
+        case Z_BUF_ERROR:
+            self = .buffer
+        case Z_VERSION_ERROR:
+            self = .version
+        default:
+            self = .unknown(code: Int(code))
+        }
+    }
+}
+
+extension Data {
+    /// Compresses the data using gzip compression.
+    /// Adapted from: https://github.com/1024jp/GzipSwift/blob/main/Sources/Gzip/Data%2BGzip.swift
+    /// - Parameter level: Compression level.
+    /// - Returns: The compressed data.
+    /// - Throws: `GzipError` if compression fails.
+    public func gzipCompressed(level: Int32 = Z_DEFAULT_COMPRESSION) throws -> Data {
+        guard !self.isEmpty else {
+            Logger.warn(message: "Empty Data object cannot be compressed.")
+            return Data()
+        }
+
+        let originalSize = self.count
+
+        var stream = z_stream()
+        stream.next_in = UnsafeMutablePointer<Bytef>(mutating: (self as NSData).bytes.bindMemory(to: Bytef.self, capacity: self.count))
+        stream.avail_in = uint(self.count)
+
+        let windowBits = MAX_WBITS + GzipSettings.gzipHeaderOffset // Use gzip header instead of zlib header
+        let memLevel = MAX_MEM_LEVEL
+        let strategy = Z_DEFAULT_STRATEGY
+
+        var status = deflateInit2_(&stream, level, Z_DEFLATED, windowBits, memLevel, strategy, ZLIB_VERSION, Int32(MemoryLayout<z_stream>.size))
+        guard status == Z_OK else {
+            throw GzipError(code: status)
+        }
+
+        var compressedData = Data(count: self.count / 2)
+        repeat {
+            if Int(stream.total_out) >= compressedData.count {
+                compressedData.count += self.count / 2
+            }
+            stream.next_out = compressedData.withUnsafeMutableBytes { $0.baseAddress!.assumingMemoryBound(to: Bytef.self) }.advanced(by: Int(stream.total_out))
+            stream.avail_out = uint(compressedData.count) - uint(stream.total_out)
+
+            status = deflate(&stream, Z_FINISH)
+        } while stream.avail_out == 0 && status == Z_OK
+
+        guard status == Z_STREAM_END else {
+            throw GzipError(code: status)
+        }
+
+        deflateEnd(&stream)
+        compressedData.count = Int(stream.total_out)
+
+        let compressedSize = compressedData.count
+        let compressionRatio = Double(compressedSize) / Double(originalSize)
+        let compressionPercentage = (1 - compressionRatio) * 100
+
+        let roundedCompressionRatio = floor(compressionRatio * 1000) / 1000
+        let roundedCompressionPercentage = floor(compressionPercentage * 1000) / 1000
+
+        Logger.info(message: "Payload gzipped: original size = \(originalSize) bytes, compressed size = \(compressedSize) bytes, compression ratio = \(roundedCompressionRatio), compression percentage = \(roundedCompressionPercentage)%")
+
+        return compressedData
+    }
+}

Sources/Flush.swift

@@ -28,6 +28,7 @@ class Flush: AppLifecycle {
     private var _serverURL =  BasePath.DefaultMixpanelAPI
     private let flushRequestReadWriteLock: DispatchQueue
 
+    var useGzipCompression: Bool
 
     var serverURL: String {
         get {
@@ -68,8 +69,9 @@ class Flush: AppLifecycle {
         }
     }
 
-    required init(serverURL: String) {
+    required init(serverURL: String, useGzipCompression: Bool) {
         self.flushRequest = FlushRequest(serverURL: serverURL)
+        self.useGzipCompression = useGzipCompression
         _serverURL = serverURL
         flushRequestReadWriteLock = DispatchQueue(label: "com.mixpanel.flush_interval.lock", qos: .utility, attributes: .concurrent, autoreleaseFrequency: .workItem)
     }
@@ -135,7 +137,7 @@ class Flush: AppLifecycle {
                                                        type: type,
                                                        useIP: useIPAddressForGeoLocation,
                                                        headers: headers,
-                                                       queryItems: queryItems)
+                                                       queryItems: queryItems, useGzipCompression: useGzipCompression)
                 #if os(iOS)
                 if !MixpanelInstance.isiOSAppExtension() {
                     delegate?.updateNetworkActivityIndicator(false)

Sources/FlushRequest.swift

@@ -23,7 +23,8 @@ class FlushRequest: Network {
                      type: FlushType,
                      useIP: Bool,
                      headers: [String: String],
-                     queryItems: [URLQueryItem] = []) -> Bool {
+                     queryItems: [URLQueryItem] = [],
+                     useGzipCompression: Bool) -> Bool {
 
         let responseParser: (Data) -> Int? = { data in
             let response = String(data: data, encoding: String.Encoding.utf8)
@@ -33,14 +34,25 @@ class FlushRequest: Network {
             return nil
         }
 
-        let resourceHeaders: [String: String] = ["Content-Type": "application/json"].merging(headers) {(_,new) in new }
-
+        var resourceHeaders: [String: String] = ["Content-Type": "application/json"].merging(headers) {(_,new) in new }
+        var compressedData: Data? = nil
+
+        if useGzipCompression && type == .events {
+            if let requestDataRaw = requestData.data(using: .utf8) {
+                do {
+                    compressedData = try requestDataRaw.gzipCompressed()
+                    resourceHeaders["Content-Encoding"] = "gzip"
+                } catch {
+                    Logger.error(message: "Failed to compress data with gzip: \(error)")
+                }
+            }
+        }
         let ipString = useIP ? "1" : "0"
         var resourceQueryItems: [URLQueryItem] = [URLQueryItem(name: "ip", value: ipString)]
         resourceQueryItems.append(contentsOf: queryItems)
         let resource = Network.buildResource(path: type.rawValue,
                                              method: .post,
-                                             requestBody: requestData.data(using: .utf8),
+                                             requestBody: compressedData ?? requestData.data(using: .utf8),
                                              queryItems: resourceQueryItems,
                                              headers: resourceHeaders,
                                              parse: responseParser)