Comment [WIP]

submodules/Postbox/Sources/PeerChatThreadInterfaceStateTable.swift

@@ -0,0 +1,80 @@
+import Foundation
+
+public struct PeerChatThreadId: Hashable {
+    public var peerId: PeerId
+    public var threadId: Int64
+
+    public init(peerId: PeerId, threadId: Int64) {
+        self.peerId = peerId
+        self.threadId = threadId
+    }
+}
+
+final class PeerChatThreadInterfaceStateTable: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .binary, compactValuesOnCreation: false)
+    }
+    
+    private var states: [PeerChatThreadId: PeerChatInterfaceState?] = [:]
+    private var peerIdsWithUpdatedStates = Set<PeerChatThreadId>()
+    
+    private let sharedKey = ValueBoxKey(length: 8 + 8)
+    
+    private func key(_ peerId: PeerChatThreadId, sharedKey: ValueBoxKey = ValueBoxKey(length: 8)) -> ValueBoxKey {
+        sharedKey.setInt64(0, value: peerId.peerId.toInt64())
+        sharedKey.setInt64(8, value: peerId.threadId)
+        return sharedKey
+    }
+    
+    func get(_ peerId: PeerChatThreadId) -> PeerChatInterfaceState? {
+        if let cachedValue = self.states[peerId] {
+            return cachedValue
+        } else if let value = self.valueBox.get(self.table, key: self.key(peerId, sharedKey: self.sharedKey)), let state = PostboxDecoder(buffer: value).decodeRootObject() as? PeerChatInterfaceState {
+            self.states[peerId] = state
+            return state
+        } else {
+            self.states[peerId] = nil
+            return nil
+        }
+    }
+    
+    func set(_ peerId: PeerChatThreadId, state: PeerChatInterfaceState?) -> Bool {
+        let currentState = self.get(peerId)
+        var updated = false
+        if let currentState = currentState, let state = state {
+            if !currentState.isEqual(to: state) {
+                updated = true
+            }
+        } else if (currentState != nil) != (state != nil) {
+            updated = true
+        }
+        if updated {
+            self.states[peerId] = state
+            self.peerIdsWithUpdatedStates.insert(peerId)
+        }
+        return updated
+    }
+    
+    override func clearMemoryCache() {
+        self.states.removeAll()
+        self.peerIdsWithUpdatedStates.removeAll()
+    }
+    
+    override func beforeCommit() {
+        if !self.peerIdsWithUpdatedStates.isEmpty {
+            let sharedEncoder = PostboxEncoder()
+            for peerId in self.peerIdsWithUpdatedStates {
+                if let state = self.states[peerId] {
+                    if let state = state {
+                    sharedEncoder.reset()
+                    sharedEncoder.encodeRootObject(state)
+                    self.valueBox.set(self.table, key: self.key(peerId, sharedKey: self.sharedKey), value: sharedEncoder.readBufferNoCopy())
+                    } else {
+                        self.valueBox.remove(self.table, key: self.key(peerId, sharedKey: self.sharedKey), secure: false)
+                    }
+                }
+            }
+            self.peerIdsWithUpdatedStates.removeAll()
+        }
+    }
+}