prosody
0b0a42542456
util/hashring.lua

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util/hashring.lua @ 11056:0b0a42542456

util.jid: Fix special escaping of '\' per XEP-0106 From XEP-0106 §2. Requirements: > in certain circumstances, the escaping character itself ("\") might > also be escaped Later in §4.2 Address Transformation Algorithm it is stated that the backslash would only be escaped if it forms an escape sequence. Thus '\foo' is unaltered but '\20' must be escaped into '\5c20'. Thanks to lovetox and jonas’ for brining up.
author Kim Alvefur <zash@zash.se>
date Fri, 28 Aug 2020 18:44:02 +0200
parent 10005:409ff72c501c
child 11208:96429946a742
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rev   line source
10005
409ff72c501c util.hashring: Implementation of hashring data structure
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1 local function generate_ring(nodes, num_replicas, hash)
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2 local new_ring = {};
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3 for _, node_name in ipairs(nodes) do
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4 for replica = 1, num_replicas do
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5 local replica_hash = hash(node_name..":"..replica);
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6 new_ring[replica_hash] = node_name;
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7 table.insert(new_ring, replica_hash);
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8 end
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9 end
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10 table.sort(new_ring);
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11 return new_ring;
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12 end
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13
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14 local hashring_methods = {};
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15 local hashring_mt = {
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16 __index = function (self, k)
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17 -- Automatically build self.ring if it's missing
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18 if k == "ring" then
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19 local ring = generate_ring(self.nodes, self.num_replicas, self.hash);
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20 rawset(self, "ring", ring);
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21 return ring;
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22 end
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23 return rawget(hashring_methods, k);
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24 end
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25 };
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26
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27 local function new(num_replicas, hash_function)
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28 return setmetatable({ nodes = {}, num_replicas = num_replicas, hash = hash_function }, hashring_mt);
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29 end;
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30
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31 function hashring_methods:add_node(name)
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32 self.ring = nil;
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33 self.nodes[name] = true;
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34 table.insert(self.nodes, name);
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35 return true;
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36 end
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37
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38 function hashring_methods:add_nodes(nodes)
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39 self.ring = nil;
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40 for _, node_name in ipairs(nodes) do
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41 if not self.nodes[node_name] then
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42 self.nodes[node_name] = true;
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43 table.insert(self.nodes, node_name);
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44 end
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45 end
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46 return true;
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47 end
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48
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49 function hashring_methods:remove_node(node_name)
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50 self.ring = nil;
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51 if self.nodes[node_name] then
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52 for i, stored_node_name in ipairs(self.nodes) do
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53 if node_name == stored_node_name then
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54 self.nodes[node_name] = nil;
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55 table.remove(self.nodes, i);
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56 return true;
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57 end
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58 end
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59 end
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60 return false;
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61 end
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62
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63 function hashring_methods:remove_nodes(nodes)
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64 self.ring = nil;
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65 for _, node_name in ipairs(nodes) do
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66 self:remove_node(node_name);
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67 end
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68 end
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69
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70 function hashring_methods:clone()
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71 local clone_hashring = new(self.num_replicas, self.hash);
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72 clone_hashring:add_nodes(self.nodes);
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73 return clone_hashring;
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74 end
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75
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76 function hashring_methods:get_node(key)
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77 local key_hash = self.hash(key);
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78 for _, replica_hash in ipairs(self.ring) do
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79 if key_hash < replica_hash then
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80 return self.ring[replica_hash];
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81 end
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82 end
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83 return self.ring[self.ring[1]];
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84 end
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85
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86 return {
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87 new = new;
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88 }