147 lines
3.2 KiB
Lua
147 lines
3.2 KiB
Lua
--[[
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基于LRU算法的数据表
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]]
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local LRUMap = class("LRUMap")
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function LRUMap:ctor(maxLength)
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self.nodeMap = {} -- 通过key获得Node
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self.firstNode = nil
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self.lastNode = nil
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self.length = 0
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self.maxLength = maxLength or 10
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end
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function LRUMap:Get(key)
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local node = self.nodeMap[key]
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if not node then
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return nil
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end
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self:UpdateNode(node)
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return node.value or node.key
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end
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function LRUMap:Set(key, value)
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local node = self.nodeMap[key]
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if not node then
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return
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end
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node.value = value
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self:UpdateNode(node)
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end
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function LRUMap:Add(key, value)
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local node = self.nodeMap[key]
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if node then
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node.value = value
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self:UpdateNode(node)
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else
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while(self.length >= self.maxLength) do
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self:RemoveNode(self.firstNode)
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end
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node = { prev = nil, key = key, value = value, next = nil }
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self.nodeMap[key] = node
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self:AddNode(node)
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end
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end
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function LRUMap:Remove(key)
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local node = self.nodeMap[key]
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if node then
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self.nodeMap[key] = nil
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self:RemoveNode(node)
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return true
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end
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return false
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end
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function LRUMap:Clear()
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for key, node in pairs(self.nodeMap) do
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self:Remove(key)
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end
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self.nodeMap = {}
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self.firstNode = nil
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self.lastNode = nil
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self.length = 0
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end
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LRUMap.__tostring = function(self)
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local str = "{\n"
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local node = self.firstNode
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while node do
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local key = node.key
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local value = node.value
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if value then
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str = str .. key .. "=" .. Inspect(value) .. ",\n"
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else
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str = str .. Inspect(key) .. ",\n"
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end
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node = node.next
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end
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str = str .. "}"
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return str
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end
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---------------------------- 内部调用，理论上不在外部调用 Start -----------------------
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-- 增加节点
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function LRUMap:AddNode(node)
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self.length = self.length + 1
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self:AddNodeToLast(node)
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end
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-- 删除节点
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function LRUMap:RemoveNode(node)
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self:ExtractNode(node)
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node.key = nil
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node.value = nil
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node = nil
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self.length = self.length - 1
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end
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-- 更新节点
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-- 节点被访问，则需要把节点更新到末尾
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function LRUMap:UpdateNode(node)
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if self.lastNode == node then
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return
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end
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self:ExtractNode(node)
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self:AddNodeToLast(node)
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end
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function LRUMap:AddNodeToLast(node)
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if self.lastNode then
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self.lastNode.next = node
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node.prev = self.lastNode
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self.lastNode = node
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else
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self.firstNode = node
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self.lastNode = node
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end
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end
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-- 把节点从队列中提取出来
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function LRUMap:ExtractNode(node)
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local prev = node.prev
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local next = node.next
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if prev then
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prev.next = next
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end
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if next then
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next.prev = prev
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end
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node.prev = nil
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node.next = nil
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if self.firstNode == node then
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self.firstNode = next
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end
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if self.lastNode == node then
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self.lastNode = prev
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end
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end
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---------------------------- 内部调用，理论上不在外部调用 End -----------------------
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return LRUMap |