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10007
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1 local hashring = require "util.hashring";
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2
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3 describe("util.hashring", function ()
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4
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5 local sha256 = require "util.hashes".sha256;
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6
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7 local ring = hashring.new(128, sha256);
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8
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9 it("should fail to get a node that does not exist", function ()
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10 assert.is_nil(ring:get_node("foo"))
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11 end);
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12
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13 it("should support adding nodes", function ()
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14 ring:add_node("node1");
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15 end);
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16
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17 it("should return a single node for all keys if only one node exists", function ()
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18 for i = 1, 100 do
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19 assert.is_equal("node1", ring:get_node(tostring(i)))
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20 end
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21 end);
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22
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23 it("should support adding a second node", function ()
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24 ring:add_node("node2");
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25 end);
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26
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27 it("should fail to remove a non-existent node", function ()
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28 assert.is_falsy(ring:remove_node("node3"));
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29 end);
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30
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31 it("should succeed to remove a node", function ()
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32 assert.is_truthy(ring:remove_node("node1"));
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33 end);
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34
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35 it("should return the only node for all keys", function ()
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36 for i = 1, 100 do
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37 assert.is_equal("node2", ring:get_node(tostring(i)))
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38 end
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39 end);
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40
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41 it("should support adding multiple nodes", function ()
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42 ring:add_nodes({ "node1", "node3", "node4", "node5" });
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43 end);
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44
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45 it("should disrupt a minimal number of keys on node removal", function ()
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46 local orig_ring = ring:clone();
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47 local node_tallies = {};
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48
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49 local n = 1000;
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50
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51 for i = 1, n do
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52 local key = tostring(i);
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53 local node = ring:get_node(key);
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54 node_tallies[node] = (node_tallies[node] or 0) + 1;
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55 end
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56
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57 --[[
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58 for node, key_count in pairs(node_tallies) do
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59 print(node, key_count, ("%.2f%%"):format((key_count/n)*100));
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60 end
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61 ]]
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62
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63 ring:remove_node("node5");
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64
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65 local disrupted_keys = 0;
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66 for i = 1, n do
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67 local key = tostring(i);
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68 if orig_ring:get_node(key) ~= ring:get_node(key) then
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69 disrupted_keys = disrupted_keys + 1;
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70 end
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71 end
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72 assert.is_equal(node_tallies["node5"], disrupted_keys);
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73 end);
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74
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75 it("should support removing multiple nodes", function ()
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76 ring:remove_nodes({"node2", "node3", "node4", "node5"});
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77 end);
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78
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79 it("should return a single node for all keys if only one node remains", function ()
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80 for i = 1, 100 do
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81 assert.is_equal("node1", ring:get_node(tostring(i)))
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82 end
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83 end);
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84
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85 end);
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