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util/hashring.lua @ 11366:618ab9bba1c2
util.cache: Add test for :table (fails on Lua 5.1)
author | Kim Alvefur <zash@zash.se> |
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date | Fri, 05 Feb 2021 16:14:06 +0100 |
parent | 11208:96429946a742 |
child | 12795:87424cbedc55 |
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local function generate_ring(nodes, num_replicas, hash) local new_ring = {}; for _, node_name in ipairs(nodes) do for replica = 1, num_replicas do local replica_hash = hash(node_name..":"..replica); new_ring[replica_hash] = node_name; table.insert(new_ring, replica_hash); end end table.sort(new_ring); return new_ring; end local hashring_methods = {}; local hashring_mt = { __index = function (self, k) -- Automatically build self.ring if it's missing if k == "ring" then local ring = generate_ring(self.nodes, self.num_replicas, self.hash); rawset(self, "ring", ring); return ring; end return rawget(hashring_methods, k); end }; local function new(num_replicas, hash_function) return setmetatable({ nodes = {}, num_replicas = num_replicas, hash = hash_function }, hashring_mt); end; function hashring_methods:add_node(name) self.ring = nil; self.nodes[name] = true; table.insert(self.nodes, name); return true; end function hashring_methods:add_nodes(nodes) self.ring = nil; for _, node_name in ipairs(nodes) do if not self.nodes[node_name] then self.nodes[node_name] = true; table.insert(self.nodes, node_name); end end return true; end function hashring_methods:remove_node(node_name) self.ring = nil; if self.nodes[node_name] then for i, stored_node_name in ipairs(self.nodes) do if node_name == stored_node_name then self.nodes[node_name] = nil; table.remove(self.nodes, i); return true; end end end return false; end function hashring_methods:remove_nodes(nodes) self.ring = nil; for _, node_name in ipairs(nodes) do self:remove_node(node_name); end end function hashring_methods:clone() local clone_hashring = new(self.num_replicas, self.hash); clone_hashring:add_nodes(self.nodes); return clone_hashring; end function hashring_methods:get_node(key) local key_hash = self.hash(key); for _, replica_hash in ipairs(self.ring) do if key_hash < replica_hash then return self.ring[replica_hash]; end end return self.ring[self.ring[1]]; end return { new = new; }