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spec/util_hashring_spec.lua @ 13134:638f627e707f
util.datamanager: Add O(1) list indexing with on-disk index
Index file contains offsets and lengths of each item() which allows
seeking directly to each item and reading it without parsing the entire
file.
Also allows tricks like binary search, assuming items have some defined
order.
We take advantage of the 1-based indexing in tables to store a magic
header in the 0 position, so that table index 1 ends up at file index 1.
author | Kim Alvefur <zash@zash.se> |
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date | Tue, 11 May 2021 02:09:56 +0200 |
parent | 12795:87424cbedc55 |
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local hashring = require "util.hashring"; describe("util.hashring", function () randomize(false); local sha256 = require "util.hashes".sha256; local ring = hashring.new(128, sha256); it("should fail to get a node that does not exist", function () assert.is_nil(ring:get_node("foo")) end); it("should support adding nodes", function () ring:add_node("node1"); end); it("should return a single node for all keys if only one node exists", function () for i = 1, 100 do assert.is_equal("node1", ring:get_node(tostring(i))) end end); it("should support adding a second node", function () ring:add_node("node2"); end); it("should fail to remove a non-existent node", function () assert.is_falsy(ring:remove_node("node3")); end); it("should succeed to remove a node", function () assert.is_truthy(ring:remove_node("node1")); end); it("should return the only node for all keys", function () for i = 1, 100 do assert.is_equal("node2", ring:get_node(tostring(i))) end end); it("should support adding multiple nodes", function () ring:add_nodes({ "node1", "node3", "node4", "node5" }); end); it("should disrupt a minimal number of keys on node removal", function () local orig_ring = ring:clone(); local node_tallies = {}; local n = 1000; for i = 1, n do local key = tostring(i); local node = ring:get_node(key); node_tallies[node] = (node_tallies[node] or 0) + 1; end --[[ for node, key_count in pairs(node_tallies) do print(node, key_count, ("%.2f%%"):format((key_count/n)*100)); end ]] ring:remove_node("node5"); local disrupted_keys = 0; for i = 1, n do local key = tostring(i); if orig_ring:get_node(key) ~= ring:get_node(key) then disrupted_keys = disrupted_keys + 1; end end assert.is_equal(node_tallies["node5"], disrupted_keys); end); it("should support removing multiple nodes", function () ring:remove_nodes({"node2", "node3", "node4", "node5"}); end); it("should return a single node for all keys if only one node remains", function () for i = 1, 100 do assert.is_equal("node1", ring:get_node(tostring(i))) end end); it("should support values associated with nodes", function () local r = hashring.new(128, sha256); r:add_node("node1", { a = 1 }); local node, value = r:get_node("foo"); assert.is_equal("node1", node); assert.same({ a = 1 }, value); end); end);