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local hashring = require "util.hashring"; |
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describe("util.hashring", function () |
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local sha256 = require "util.hashes".sha256; |
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local ring = hashring.new(128, sha256); |
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it("should fail to get a node that does not exist", function () |
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assert.is_nil(ring:get_node("foo")) |
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end); |
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it("should support adding nodes", function () |
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ring:add_node("node1"); |
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end); |
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it("should return a single node for all keys if only one node exists", function () |
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for i = 1, 100 do |
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assert.is_equal("node1", ring:get_node(tostring(i))) |
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end |
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end); |
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it("should support adding a second node", function () |
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ring:add_node("node2"); |
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end); |
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it("should fail to remove a non-existent node", function () |
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assert.is_falsy(ring:remove_node("node3")); |
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end); |
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it("should succeed to remove a node", function () |
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assert.is_truthy(ring:remove_node("node1")); |
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end); |
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it("should return the only node for all keys", function () |
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for i = 1, 100 do |
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assert.is_equal("node2", ring:get_node(tostring(i))) |
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end |
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end); |
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it("should support adding multiple nodes", function () |
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ring:add_nodes({ "node1", "node3", "node4", "node5" }); |
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end); |
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it("should disrupt a minimal number of keys on node removal", function () |
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local orig_ring = ring:clone(); |
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local node_tallies = {}; |
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local n = 1000; |
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for i = 1, n do |
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local key = tostring(i); |
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local node = ring:get_node(key); |
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node_tallies[node] = (node_tallies[node] or 0) + 1; |
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end |
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--[[ |
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for node, key_count in pairs(node_tallies) do |
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print(node, key_count, ("%.2f%%"):format((key_count/n)*100)); |
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end |
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]] |
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ring:remove_node("node5"); |
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local disrupted_keys = 0; |
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for i = 1, n do |
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local key = tostring(i); |
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if orig_ring:get_node(key) ~= ring:get_node(key) then |
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disrupted_keys = disrupted_keys + 1; |
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end |
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end |
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assert.is_equal(node_tallies["node5"], disrupted_keys); |
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end); |
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it("should support removing multiple nodes", function () |
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ring:remove_nodes({"node2", "node3", "node4", "node5"}); |
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end); |
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it("should return a single node for all keys if only one node remains", function () |
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for i = 1, 100 do |
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assert.is_equal("node1", ring:get_node(tostring(i))) |
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end |
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end); |
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end); |