refactor and cleanup [skip ci]

submodules/Postbox/Sources/RatingTable.swift

@@ -0,0 +1,84 @@
+import Foundation
+
+protocol RatingTableItem {
+    static func emptyKey() -> ValueBoxKey
+    static func fromKey(key: ValueBoxKey) -> Self
+    func ratingKey(rating: Int32, sharedKey: ValueBoxKey) -> ValueBoxKey
+}
+
+extension PeerId: RatingTableItem {
+    static func emptyKey() -> ValueBoxKey {
+        return ValueBoxKey(length: 4 + 8)
+    }
+    
+    static func fromKey(key: ValueBoxKey) -> PeerId {
+        return PeerId(key.getInt64(4))
+    }
+    
+    func ratingKey(rating: Int32, sharedKey: ValueBoxKey) -> ValueBoxKey {
+        sharedKey.setInt32(0, value: rating)
+        sharedKey.setInt64(4, value: self.toInt64())
+        return sharedKey
+    }
+}
+
+final class RatingTable<T: RatingTableItem>: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .binary, compactValuesOnCreation: true)
+    }
+    
+    private var items: [T]?
+    
+    func get() -> [T] {
+        if let items = self.items {
+            return items
+        } else {
+            let lowerBound = T.emptyKey()
+            let upperBound = T.emptyKey()
+            memset(lowerBound.memory, 0, lowerBound.length)
+            memset(upperBound.memory, 0xff, upperBound.length)
+            
+            var result: [T] = []
+            self.valueBox.range(self.table, start: lowerBound, end: upperBound, keys: { key in
+                result.append(T.fromKey(key: key))
+                return true
+            }, limit: 0)
+            
+            self.items = result
+            return result
+        }
+    }
+    
+    func replace(items: [T]) {
+        var keys: [ValueBoxKey] = []
+        let lowerBound = T.emptyKey()
+        let upperBound = T.emptyKey()
+        memset(lowerBound.memory, 0, lowerBound.length)
+        memset(upperBound.memory, 0xff, upperBound.length)
+        self.valueBox.range(self.table, start: lowerBound, end: upperBound, keys: { key in
+            keys.append(key)
+            return true
+        }, limit: 0)
+        
+        for key in keys {
+            self.valueBox.remove(self.table, key: key, secure: false)
+        }
+        
+        let sharedKey = T.emptyKey()
+        var index: Int32 = 0
+        for item in items {
+            self.valueBox.set(self.table, key: item.ratingKey(rating: index, sharedKey: sharedKey), value: MemoryBuffer())
+            index += 1
+        }
+        
+        self.items = items
+    }
+    
+    override func clearMemoryCache() {
+        self.items = nil
+    }
+    
+    override func beforeCommit() {
+        
+    }
+}