refactor and cleanup [skip ci]

submodules/Postbox/Sources/PeerNotificationSettingsBehaviorIndexTable.swift

@@ -0,0 +1,31 @@
+import Foundation
+
+final class PeerNotificationSettingsBehaviorIndexTable: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .int64, compactValuesOnCreation: true)
+    }
+    
+    private func key(peerId: PeerId) -> ValueBoxKey {
+        let key = ValueBoxKey(length: 8)
+        key.setInt64(0, value: peerId.toInt64())
+        return key
+    }
+    
+    func get(peerId: PeerId) -> Int32? {
+        if let value = self.valueBox.get(self.table, key: self.key(peerId: peerId)) {
+            var timestamp: Int32 = 0
+            value.read(&timestamp, offset: 0, length: 4)
+            return timestamp
+        } else {
+            return nil
+        }
+    }
+    
+    func set(peerId: PeerId, timestamp: Int32?) {
+        if var timestamp = timestamp {
+            self.valueBox.set(self.table, key: self.key(peerId: peerId), value: MemoryBuffer(memory: &timestamp, capacity: 4, length: 4, freeWhenDone: false))
+        } else {
+            self.valueBox.remove(self.table, key: self.key(peerId: peerId), secure: false)
+        }
+    }
+}