prosody
daced16154fa
util/smqueue.lua

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util/smqueue.lua @ 12055:daced16154fa

util.smqueue: Abstract queue with acknowledgements and overflow Meant to be used in mod_smacks for XEP-0198 Meant to have a larger virtual size than actual number of items stored, on the theory that in most cases, the excess will be acked before needed for a resumption event.
author Kim Alvefur <zash@zash.se>
date Tue, 14 Dec 2021 19:58:53 +0100
child 12058:4860da718e87
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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12055
daced16154fa util.smqueue: Abstract queue with acknowledgements and overflow
Kim Alvefur <zash@zash.se>
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1 local queue = require("util.queue");
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2
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3 local lib = { smqueue = {} }
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4
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5 local smqueue = lib.smqueue;
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6
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7 function smqueue:push(v)
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8 self._head = self._head + 1;
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9
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10 assert(self._queue:push(v));
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11 end
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12
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13 function smqueue:ack(h)
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14 if h < self._tail then
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15 return nil, "tail"
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16 elseif h > self._head then
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17 return nil, "head"
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18 end
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19
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20 local acked = {};
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21 self._tail = h;
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22 local expect = self._head - self._tail;
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23 while expect < self._queue:count() do
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24 local v = self._queue:pop();
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25 if not v then return nil, "pop" end
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26 table.insert(acked, v);
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27 end
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28 return acked
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29 end
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30
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31 function smqueue:count_unacked() return self._head - self._tail end
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32
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33 function smqueue:count_acked() return self._tail end
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34
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35 function smqueue:resumable() return self._queue:count() >= (self._head - self._tail) end
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36
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37 function smqueue:resume() return self._queue:items() end
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38
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39 function smqueue:consume() return self._queue:consume() end
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40
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41 local compat_mt = {}
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42
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43 function compat_mt:__index(i)
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44 if i < self._queue._tail then return nil end
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45 return self._queue._queue._items[(i + self._queue._tail) % self._queue._queue.size]
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46 end
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47
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48 function compat_mt:__len() return self._queue:count_unacked() end
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49
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50 function smqueue:table() return setmetatable({ _queue = self }, compat_mt) end
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51
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52 local function freeze(q) return { head = q._head; tail = q._tail } end
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53
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54 local queue_mt = { __name = "smqueue"; __index = smqueue; __len = smqueue.count_unacked; __freeze = freeze }
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55
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56 function lib.new(size)
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57 assert(size > 0);
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58 return setmetatable({ _head = 0; _tail = 0; _queue = queue.new(size, true) }, queue_mt)
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59 end
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60
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61 return lib