MLIBZ-2689: allow cache to be compacted during launch

.codebeatsettings

@@ -0,0 +1,6 @@
+{
+    "SWIFT": {
+        "ARITY": [8, 10, 14, 20],
+        "TOO_MANY_IVARS": [8, 10, 14, 20],
+    }
+}

Kinvey/Kinvey/Client.swift

@@ -165,6 +165,7 @@ open class Client: Credential {
         apiHostName: URL = Client.defaultApiHostName,
         authHostName: URL = Client.defaultAuthHostName,
         schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
         options: Options? = nil,
         completionHandler: ((Result<U?, Swift.Error>) -> Void)? = nil
     ) {
@@ -176,6 +177,7 @@ open class Client: Credential {
             apiHostName: apiHostName,
             authHostName: authHostName,
             schema: schema,
+            compactCacheOnLaunch: compactCacheOnLaunch,
             options: options
         ) { (result: Result<U?, Swift.Error>) in
             completionHandler?(result)
@@ -249,6 +251,7 @@ open class Client: Credential {
         authHostName: URL = Client.defaultAuthHostName,
         encrypted: Bool,
         schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
         options: Options? = nil,
         completionHandler: @escaping (Result<U?, Swift.Error>) -> Void
     ) {
@@ -269,22 +272,34 @@ open class Client: Credential {
             authHostName: authHostName,
             encryptionKey: encryptionKey,
             schema: Schema(version: schema?.version ?? 0, migrationHandler: schema?.migrationHandler),
+            compactCacheOnLaunch: compactCacheOnLaunch,
             options: options,
             completionHandler: completionHandler
         )
     }
 
     /// Initialize a `Client` instance with all the needed parameters.
     @available(*, deprecated: 3.17.0, message: "Please use Client.initialize(appKey:appSecret:accessGroup:apiHostName:authHostName:encryptionKey:schema:completionHandler:(Result<U?, Swift.Error>) -> Void) instead")
-    open func initialize<U: User>(appKey: String, appSecret: String, accessGroup: String? = nil, apiHostName: URL = Client.defaultApiHostName, authHostName: URL = Client.defaultAuthHostName, encryptionKey: Data? = nil, schema: Schema? = nil, completionHandler: @escaping User.UserHandler<U>) {
+    open func initialize<U: User>(
+        appKey: String,
+        appSecret: String,
+        accessGroup: String? = nil,
+        apiHostName: URL = Client.defaultApiHostName,
+        authHostName: URL = Client.defaultAuthHostName,
+        encryptionKey: Data? = nil,
+        schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
+        completionHandler: @escaping User.UserHandler<U>
+    ) {
         initialize(
             appKey: appKey,
             appSecret: appSecret,
             accessGroup: accessGroup,
             apiHostName: apiHostName,
             authHostName: authHostName,
             encryptionKey: encryptionKey,
-            schema: schema
+            schema: schema,
+            compactCacheOnLaunch: compactCacheOnLaunch
         ) { (result: Result<U?, Swift.Error>) in
             switch result {
             case .success(let user):
@@ -314,6 +329,7 @@ open class Client: Credential {
         accessGroup: String? = nil,
         encrypted: Bool,
         schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
         options: Options? = nil,
         completionHandler: @escaping (Result<U?, Swift.Error>) -> Void
     ) {
@@ -344,6 +360,7 @@ open class Client: Credential {
             authHostName: authHostName,
             encryptionKey: encryptionKey,
             schema: schema,
+            compactCacheOnLaunch: compactCacheOnLaunch,
             options: options,
             completionHandler: completionHandler
         )
@@ -368,6 +385,7 @@ open class Client: Credential {
         accessGroup: String? = nil,
         encryptionKey: Data? = nil,
         schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
         options: Options? = nil,
         completionHandler: @escaping (Result<U?, Swift.Error>) -> Void
     ) {
@@ -389,6 +407,7 @@ open class Client: Credential {
             authHostName: authHostName,
             encryptionKey: encryptionKey,
             schema: schema,
+            compactCacheOnLaunch: compactCacheOnLaunch,
             options: options,
             completionHandler: completionHandler
         )
@@ -407,6 +426,7 @@ open class Client: Credential {
         authHostName: URL = Client.defaultAuthHostName,
         encryptionKey: Data? = nil,
         schema: Schema? = nil,
+        compactCacheOnLaunch: Bool = true,
         options: Options? = nil,
         completionHandler: @escaping (Result<U?, Swift.Error>) -> Void
     ) {
@@ -421,7 +441,13 @@ open class Client: Credential {
         self.schemaVersion = schema?.version ?? 0
         self.options = options
 
-        Migration.performMigration(persistenceId: appKey, encryptionKey: encryptionKey, schemaVersion: schemaVersion, migrationHandler: schema?.migrationHandler)
+        Migration.performMigration(
+            persistenceId: appKey,
+            encryptionKey: encryptionKey,
+            schemaVersion: schemaVersion,
+            migrationHandler: schema?.migrationHandler,
+            compactCacheOnLaunch: compactCacheOnLaunch
+        )
 
         cacheManager = CacheManager(persistenceId: appKey, encryptionKey: encryptionKey as Data?, schemaVersion: schemaVersion)
         syncManager = SyncManager(persistenceId: appKey, encryptionKey: encryptionKey as Data?, schemaVersion: schemaVersion)

Kinvey/Kinvey/Migration.swift

@@ -24,8 +24,14 @@ open class Migration: NSObject {
         self.realmMigration = realmMigration
     }
 
-    internal class func performMigration(persistenceId: String, encryptionKey: Data? = nil, schemaVersion: CUnsignedLongLong = 0, migrationHandler: Migration.MigrationHandler? = nil) {
-        var realmBaseConfiguration = Realm.Configuration()
+    internal class func performMigration(
+        persistenceId: String,
+        encryptionKey: Data? = nil,
+        schemaVersion: CUnsignedLongLong = 0,
+        migrationHandler: Migration.MigrationHandler? = nil,
+        compactCacheOnLaunch: Bool = true
+    ) {
+        var realmBaseConfiguration = Realm.Configuration.defaultConfiguration
         if let encryptionKey = encryptionKey {
             realmBaseConfiguration.encryptionKey = encryptionKey
         }
@@ -38,23 +44,32 @@ open class Migration: NSObject {
         } else {
             realmBaseConfiguration.deleteRealmIfMigrationNeeded = true
         }
+        realmBaseConfiguration.shouldCompactOnLaunch = { totalBytes, usedBytes in
+            log.debug("Cache: \(usedBytes) bytes used in a total of \(totalBytes) bytes. Compact Cache on Launch: \(compactCacheOnLaunch)")
+            return compactCacheOnLaunch
+        }
         let baseFolderURL = Client.fileURL(appKey: persistenceId).deletingLastPathComponent()
         let fileManager = FileManager.default
         if let allFilesURL = try? fileManager.contentsOfDirectory(at: baseFolderURL, includingPropertiesForKeys: nil) {
             for realmFileURL in allFilesURL.filter({ $0.lastPathComponent.hasSuffix(".realm") }) {
                 var realmConfiguration = realmBaseConfiguration //copy
                 realmConfiguration.fileURL = realmFileURL
-                do {
-                    try Realm.performMigration(for: realmConfiguration)
-                } catch {
-                    log.error("Database migration failed: deleting local database.\nDetails of the failure: \(error)")
-                    realmConfiguration.deleteRealmIfMigrationNeeded = true
-                    try! Realm.performMigration(for: realmConfiguration)
-                }
+                performMigration(realmConfiguration: realmConfiguration)
             }
         }
     }
 
+    private class func performMigration(realmConfiguration: Realm.Configuration) {
+        var realmConfiguration = realmConfiguration //copy
+        do {
+            try Realm.performMigration(for: realmConfiguration)
+        } catch {
+            log.error("Database migration failed: deleting local database.\nDetails of the failure: \(error)")
+            realmConfiguration.deleteRealmIfMigrationNeeded = true
+            try! Realm.performMigration(for: realmConfiguration)
+        }
+    }
+
     /// Method that performs a migration in a specific collection.
     open func execute<T: Entity>(_ type: T.Type, oldClassName: String? = nil, migrationObjectHandler: MigrationObjectHandler? = nil) {
         let className = type.className()