Improve database model conversion performance by caching extra data a…

…nd not force refreshing updated objects which affects Core Data row caches

Sources/StreamChat/Database/DTOs/ChannelDTO.swift

@@ -477,7 +477,7 @@ extension ChatChannel {
 
         let extraData: [String: RawJSON]
         do {
-            extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: dto.extraData)
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.extraData)
         } catch {
             log.error(
                 "Failed to decode extra data for Channel with cid: <\(dto.cid)>, using default value instead. "

Sources/StreamChat/Database/DTOs/CurrentUserDTO.swift

@@ -224,16 +224,12 @@ extension CurrentChatUser {
 
         let user = dto.user
 
-        var extraData = [String: RawJSON]()
-        if !dto.user.extraData.isEmpty {
-            do {
-                extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: dto.user.extraData)
-            } catch {
-                log.error(
-                    "Failed to decode extra data for user with id: <\(dto.user.id)>, using default value instead. "
-                        + "Error: \(error)"
-                )
-            }
+        let extraData: [String: RawJSON]
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.user.extraData)
+        } catch {
+            log.error("Failed to decode extra data for user with id: <\(dto.user.id)>, using default value instead. Error: \(error)")
+            extraData = [:]
         }
 
         let mutedUsers: [ChatUser] = try dto.mutedUsers.map { try $0.asModel() }

Sources/StreamChat/Database/DTOs/MemberModelDTO.swift

@@ -189,7 +189,7 @@ extension ChatChannelMember {
 
         let extraData: [String: RawJSON]
         do {
-            extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: dto.user.extraData)
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.user.extraData)
         } catch {
             log.error(
                 "Failed to decode extra data for user with id: <\(dto.user.id)>, using default value instead. "
@@ -198,13 +198,15 @@ extension ChatChannelMember {
             extraData = [:]
         }
 
-        var memberExtraData: [String: RawJSON] = [:]
-        if let dtoMemberExtraData = dto.extraData {
-            do {
-                memberExtraData = try JSONDecoder.default.decode([String: RawJSON].self, from: dtoMemberExtraData)
-            } catch {
-                memberExtraData = [:]
-            }
+        let memberExtraData: [String: RawJSON]
+        do {
+            memberExtraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.extraData)
+        } catch {
+            log.error(
+                "Failed to decode extra data for channel member with id: <\(dto.user.id)>, using default value instead. "
+                    + "Error: \(error)"
+            )
+            memberExtraData = [:]
         }
 
         let role = dto.channelRoleRaw.flatMap { MemberRole(rawValue: $0) } ?? .member

Sources/StreamChat/Database/DTOs/MessageDTO.swift

@@ -1275,20 +1275,12 @@ extension MessageDTO {
 
     /// Snapshots the current state of `MessageDTO` and returns its representation for the use in API calls.
     func asRequestBody() -> MessageRequestBody {
-        var decodedExtraData: [String: RawJSON]
-
-        if let extraData = self.extraData {
-            do {
-                decodedExtraData = try JSONDecoder.default.decode([String: RawJSON].self, from: extraData)
-            } catch {
-                log.assertionFailure(
-                    "Failed decoding saved extra data with error: \(error). This should never happen because"
-                        + "the extra data must be a valid JSON to be saved."
-                )
-                decodedExtraData = [:]
-            }
-        } else {
-            decodedExtraData = [:]
+        let extraData: [String: RawJSON]
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: self.extraData)
+        } catch {
+            log.assertionFailure("Failed decoding saved extra data with error: \(error). This should never happen because the extra data must be a valid JSON to be saved.")
+            extraData = [:]
         }
 
         let uploadedAttachments: [MessageAttachmentPayload] = attachments
@@ -1315,7 +1307,7 @@ extension MessageDTO {
             pinned: pinned,
             pinExpires: pinExpires?.bridgeDate,
             pollId: poll?.id,
-            extraData: decodedExtraData
+            extraData: extraData
         )
     }
 
@@ -1365,17 +1357,12 @@ private extension ChatMessage {
         moderationDetails = dto.moderationDetails.map { MessageModerationDetails(fromDTO: $0) }
         textUpdatedAt = dto.textUpdatedAt?.bridgeDate
 
-        if let extraData = dto.extraData, !extraData.isEmpty {
-            do {
-                self.extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: extraData)
-            } catch {
-                log
-                    .error(
-                        "Failed to decode extra data for Message with id: <\(dto.id)>, using default value instead. Error: \(error)"
-                    )
-                self.extraData = [:]
-            }
-        } else {
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.extraData)
+        } catch {
+            log.error(
+                "Failed to decode extra data for Message with id: <\(dto.id)>, using default value instead. Error: \(error)"
+            )
             extraData = [:]
         }
 

Sources/StreamChat/Database/DTOs/MessageReactionDTO.swift

@@ -207,17 +207,12 @@ extension MessageReactionDTO {
     func asModel() throws -> ChatMessageReaction {
         try isNotDeleted()
 
-        let decodedExtraData: [String: RawJSON]
-
-        if let extraData = self.extraData, !extraData.isEmpty {
-            do {
-                decodedExtraData = try JSONDecoder.default.decode([String: RawJSON].self, from: extraData)
-            } catch {
-                log.error("Failed decoding saved extra data with error: \(error)")
-                decodedExtraData = [:]
-            }
-        } else {
-            decodedExtraData = [:]
+        let extraData: [String: RawJSON]
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: self.extraData)
+        } catch {
+            log.error("Failed decoding saved extra data with error: \(error)")
+            extraData = [:]
         }
 
         return try .init(
@@ -227,7 +222,7 @@ extension MessageReactionDTO {
             createdAt: createdAt?.bridgeDate ?? .init(),
             updatedAt: updatedAt?.bridgeDate ?? .init(),
             author: user.asModel(),
-            extraData: decodedExtraData
+            extraData: extraData
         )
     }
 }

Sources/StreamChat/Database/DTOs/PollDTO.swift

@@ -88,11 +88,14 @@ extension PollDTO {
     func asModel() throws -> Poll {
         try isNotDeleted()
 
-        var extraData: [String: RawJSON] = [:]
-        if let custom,
-           !custom.isEmpty,
-           let decoded = try? JSONDecoder.default.decode([String: RawJSON].self, from: custom) {
-            extraData = decoded
+        let extraData: [String: RawJSON]
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: custom)
+        } catch {
+            log.error(
+                "Failed to decode extra data for poll with id: <\(id)>, using default value instead. Error: \(error)"
+            )
+            extraData = [:]
         }
 
         let optionsArray = (options.array as? [PollOptionDTO]) ?? []

Sources/StreamChat/Database/DTOs/PollOptionDTO.swift

@@ -60,11 +60,14 @@ extension PollOptionDTO {
     func asModel() throws -> PollOption {
         try isNotDeleted()
 
-        var extraData: [String: RawJSON] = [:]
-        if let custom,
-           !custom.isEmpty,
-           let decoded = try? JSONDecoder.default.decode([String: RawJSON].self, from: custom) {
-            extraData = decoded
+        let extraData: [String: RawJSON]
+        do {
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: custom)
+        } catch {
+            log.error(
+                "Failed to decode extra data for poll option with id: <\(id)>, using default value instead. Error: \(error)"
+            )
+            extraData = [:]
         }
         return PollOption(
             id: id,

Sources/StreamChat/Database/DTOs/ThreadDTO.swift

@@ -147,8 +147,11 @@ extension ThreadDTO {
 
         let extraData: [String: RawJSON]
         do {
-            extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: self.extraData)
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: self.extraData)
         } catch {
+            log.error(
+                "Failed to decode extra data for thread with id: <\(parentMessageId)>, using default value instead. Error: \(error)"
+            )
             extraData = [:]
         }
 

Sources/StreamChat/Database/DTOs/UserDTO.swift

@@ -191,7 +191,7 @@ extension UserDTO {
     func asRequestBody() -> UserRequestBody {
         let extraData: [String: RawJSON]
         do {
-            extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: self.extraData)
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: self.extraData)
         } catch {
             log.assertionFailure(
                 "Failed decoding saved extra data with error: \(error). This should never happen because"
@@ -235,7 +235,7 @@ extension ChatUser {
 
         let extraData: [String: RawJSON]
         do {
-            extraData = try JSONDecoder.default.decode([String: RawJSON].self, from: dto.extraData)
+            extraData = try JSONDecoder.stream.decodeCachedRawJSON(from: dto.extraData)
         } catch {
             log.error(
                 "Failed to decode extra data for user with id: <\(dto.id)>, using default value instead. "

Sources/StreamChat/Database/DatabaseContainer.swift

@@ -222,11 +222,6 @@ class DatabaseContainer: NSPersistentContainer, @unchecked Sendable {
                 try actions(self.writableContext)
                 FetchCache.clear()
 
-                // Refresh the state by merging persistent state and local state for avoiding optimistic locking failure
-                for object in self.writableContext.updatedObjects {
-                    self.writableContext.refresh(object, mergeChanges: true)
-                }
-
                 if self.writableContext.hasChanges {
                     log.debug("Context has changes. Saving.", subsystems: .database)
                     try self.writableContext.save()

Sources/StreamChat/Utils/Codable+Extensions.swift

@@ -9,6 +9,7 @@ import Foundation
 final class StreamJSONDecoder: JSONDecoder, @unchecked Sendable {
     let iso8601formatter: ISO8601DateFormatter
     let dateCache: NSCache<NSString, NSDate>
+    let rawJSONCache: RawJSONCache
 
     override convenience init() {
         let iso8601formatter = ISO8601DateFormatter()
@@ -17,12 +18,21 @@ final class StreamJSONDecoder: JSONDecoder, @unchecked Sendable {
         let dateCache = NSCache<NSString, NSDate>()
         dateCache.countLimit = 5000 // We cache at most 5000 dates, which gives good enough performance
 
-        self.init(dateFormatter: iso8601formatter, dateCache: dateCache)
+        self.init(
+            dateFormatter: iso8601formatter,
+            dateCache: dateCache,
+            rawJSONCache: RawJSONCache(countLimit: 500)
+        )
     }
 
-    init(dateFormatter: ISO8601DateFormatter, dateCache: NSCache<NSString, NSDate>) {
+    init(
+        dateFormatter: ISO8601DateFormatter,
+        dateCache: NSCache<NSString, NSDate>,
+        rawJSONCache: RawJSONCache
+    ) {
         iso8601formatter = dateFormatter
         self.dateCache = dateCache
+        self.rawJSONCache = rawJSONCache
 
         super.init()
 
@@ -50,6 +60,49 @@ final class StreamJSONDecoder: JSONDecoder, @unchecked Sendable {
     }
 }
 
+extension StreamJSONDecoder {
+    class RawJSONCache {
+        private let storage: NSCache<NSNumber, BoxedRawJSON>
+
+        init(countLimit: Int) {
+            storage = NSCache()
+            storage.countLimit = countLimit
+        }
+
+        func rawJSON(forKey key: Int) -> [String: RawJSON]? {
+            storage.object(forKey: key as NSNumber)?.value
+        }
+
+        func setRawJSON(_ value: [String: RawJSON], forKey key: Int) {
+            storage.setObject(BoxedRawJSON(value: value), forKey: key as NSNumber)
+        }
+
+        final class BoxedRawJSON {
+            let value: [String: RawJSON]
+
+            init(value: [String: RawJSON]) {
+                self.value = value
+            }
+        }
+    }
+
+    /// A convenience method returning decoded RawJSON dictionary with caching enabled.
+    ///
+    /// Extra data stored in models can be large, what can significantly slow
+    /// down DTO to model conversions. This function is a convenient way for
+    /// caching some of the data in DTO to model conversions.
+    func decodeCachedRawJSON(from data: Data?) throws -> [String: RawJSON] {
+        guard let data, !data.isEmpty else { return [:] }
+        let key = data.hashValue
+        if let value = rawJSONCache.rawJSON(forKey: key) {
+            return value
+        }
+        let rawJSON = try decode([String: RawJSON].self, from: data)
+        rawJSONCache.setRawJSON(rawJSON, forKey: key)
+        return rawJSON
+    }
+}
+
 extension JSONDecoder {
     /// A default `JSONDecoder`.
     static let `default`: JSONDecoder = stream

Tests/StreamChatTests/Utils/JSONDecoder_Tests.swift

@@ -148,7 +148,7 @@ final class JSONDecoder_Tests: XCTestCase {
         let dateFormatter = ISO8601DateFormatter_Spy()
         dateFormatter.formatOptions = [.withFractionalSeconds, .withInternetDateTime]
         let dateCache = NSCache_Spy()
-        let decoder = StreamJSONDecoder(dateFormatter: dateFormatter, dateCache: dateCache)
+        let decoder = StreamJSONDecoder(dateFormatter: dateFormatter, dateCache: dateCache, rawJSONCache: RawJSONCache_Spy())
 
         // When we decode a payload with repeated dates
         let repeatedDate = "2020-06-09T08:10:40.800912Z" // If you change this, make sure to change `actualDecodedDate` below
@@ -178,6 +178,33 @@ final class JSONDecoder_Tests: XCTestCase {
             XCTAssertEqual(value, actualDecodedDate)
         }
     }
+
+    func test_extraDataIsCached() throws {
+        let extraData1: [String: RawJSON] = [
+            "key": .string("value")
+        ]
+        let extraData2: [String: RawJSON] = [
+            "key2": .string("value2")
+        ]
+        let data1 = try JSONEncoder().encode(extraData1)
+        let data2 = try JSONEncoder().encode(extraData2)
+
+        let cacheSpy = RawJSONCache_Spy()
+        let decoder = StreamJSONDecoder(
+            dateFormatter: ISO8601DateFormatter(),
+            dateCache: NSCache(),
+            rawJSONCache: cacheSpy
+        )
+        let decoded1 = try decoder.decodeCachedRawJSON(from: data1)
+        let decoded2 = try decoder.decodeCachedRawJSON(from: data2)
+        let decoded1Again = try decoder.decodeCachedRawJSON(from: data1)
+
+        XCTAssertEqual(extraData1, decoded1)
+        XCTAssertEqual(extraData2, decoded2)
+        XCTAssertEqual(extraData1, decoded1Again)
+        XCTAssertEqual(3, cacheSpy.numberOfCalls(on: "rawJSON(forKey:)"), cacheSpy.recordedFunctions.joined(separator: " "))
+        XCTAssertEqual(2, cacheSpy.numberOfCalls(on: "setRawJSON(_:forKey:)"), cacheSpy.recordedFunctions.joined(separator: " "))
+    }
 
     // MARK: Helpers
 
@@ -251,3 +278,21 @@ final class JSONDecoder_Tests: XCTestCase {
         }
     }
 }
+
+private final class RawJSONCache_Spy: StreamJSONDecoder.RawJSONCache, Spy {
+    let spyState = SpyState()
+
+    init() {
+        super.init(countLimit: 3)
+    }
+
+    override func rawJSON(forKey key: Int) -> [String: RawJSON]? {
+        record()
+        return super.rawJSON(forKey: key)
+    }
+
+    override func setRawJSON(_ value: [String: RawJSON], forKey key: Int) {
+        record()
+        super.setRawJSON(value, forKey: key)
+    }
+}