File

+
−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;
+
−}