File

util/hashring.lua @ 10066:216ae100c04a

mod_pep: Only log when creating new pubsub services Once upon a time get_pep_service() would get called with random bare JIDs and remote hostnames, which is why it was logged this way. This seems to have been fixed, so it's not as useful anymore. It's still useful to know when it creates a new service object.
author Kim Alvefur <zash@zash.se>
date Tue, 09 Jul 2019 15:12:32 +0200
parent 10005:409ff72c501c
child 11208:96429946a742
line wrap: on
line source

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;
}