refactor and cleanup [skip ci]

submodules/Postbox/Sources/CachedPeerDataTable.swift

@@ -0,0 +1,58 @@
+import Foundation
+
+final class CachedPeerDataTable: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .int64, compactValuesOnCreation: false)
+    }
+    
+    private let sharedEncoder = PostboxEncoder()
+    private let sharedKey = ValueBoxKey(length: 8)
+    
+    private var cachedDatas: [PeerId: CachedPeerData] = [:]
+    private var updatedPeerIds = Set<PeerId>()
+    
+    override init(valueBox: ValueBox, table: ValueBoxTable) {
+        super.init(valueBox: valueBox, table: table)
+    }
+    
+    private func key(_ id: PeerId) -> ValueBoxKey {
+        self.sharedKey.setInt64(0, value: id.toInt64())
+        return self.sharedKey
+    }
+    
+    func set(id: PeerId, data: CachedPeerData) {
+        self.cachedDatas[id] = data
+        self.updatedPeerIds.insert(id)
+    }
+    
+    func get(_ id: PeerId) -> CachedPeerData? {
+        if let status = self.cachedDatas[id] {
+            return status
+        }
+        if let value = self.valueBox.get(self.table, key: self.key(id)) {
+            if let data = PostboxDecoder(buffer: value).decodeRootObject() as? CachedPeerData {
+                self.cachedDatas[id] = data
+                return data
+            }
+        }
+        return nil
+    }
+    
+    override func clearMemoryCache() {
+        self.cachedDatas.removeAll()
+        self.updatedPeerIds.removeAll()
+    }
+    
+    override func beforeCommit() {
+        for peerId in self.updatedPeerIds {
+            if let data = self.cachedDatas[peerId] {
+                self.sharedEncoder.reset()
+                self.sharedEncoder.encodeRootObject(data)
+                
+                self.valueBox.set(self.table, key: self.key(peerId), value: self.sharedEncoder.readBufferNoCopy())
+            }
+        }
+        
+        self.updatedPeerIds.removeAll()
+    }
+}