prosody
763bb2ce3f60
util/queue.lua

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util/queue.lua @ 10799:763bb2ce3f60

util.pposix,signal: Pass around various OS numbers as integers [Lua 5.3] Passing around PIDs, UIDs etc as integers makes it more sane in Lua 5.3. Getting 1234.0 as PID is silly. Shouldn't change any behavior as these are all integers on the C side and the integral floats are accepted as integers when passed back from Lua into C.
author Kim Alvefur <zash@zash.se>
date Mon, 04 May 2020 21:51:30 +0200
parent 9926:1bfd28e774db
child 10973:39991e40d1dc
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343ca80ceb36 util.queue: Small fast FIFO/ringbuffer/queue library
Matthew Wild <mwild1@gmail.com>
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1 -- Prosody IM
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2 -- Copyright (C) 2008-2015 Matthew Wild
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3 -- Copyright (C) 2008-2015 Waqas Hussain
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4 --
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5 -- This project is MIT/X11 licensed. Please see the
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6 -- COPYING file in the source package for more information.
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7 --
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8
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9 -- Small ringbuffer library (i.e. an efficient FIFO queue with a size limit)
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10 -- (because unbounded dynamically-growing queues are a bad thing...)
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11
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12 local have_utable, utable = pcall(require, "util.table"); -- For pre-allocation of table
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13
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14 local function new(size, allow_wrapping)
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15 -- Head is next insert, tail is next read
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16 local head, tail = 1, 1;
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17 local items = 0; -- Number of stored items
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18 local t = have_utable and utable.create(size, 0) or {}; -- Table to hold items
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19 --luacheck: ignore 212/self
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20 return {
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21 _items = t;
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22 size = size;
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23 count = function (self) return items; end;
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24 push = function (self, item)
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25 if items >= size then
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26 if allow_wrapping then
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27 tail = (tail%size)+1; -- Advance to next oldest item
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28 items = items - 1;
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29 else
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30 return nil, "queue full";
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31 end
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32 end
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33 t[head] = item;
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34 items = items + 1;
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35 head = (head%size)+1;
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36 return true;
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37 end;
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38 pop = function (self)
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39 if items == 0 then
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40 return nil;
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41 end
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42 local item;
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43 item, t[tail] = t[tail], 0;
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44 tail = (tail%size)+1;
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45 items = items - 1;
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46 return item;
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47 end;
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48 peek = function (self)
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49 if items == 0 then
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50 return nil;
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51 end
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52 return t[tail];
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53 end;
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54 items = function (self)
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55 return function (_, pos)
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56 if pos >= items then
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57 return nil;
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58 end
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59 local read_pos = tail + pos;
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60 if read_pos > self.size then
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61 read_pos = (read_pos%size);
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62 end
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63 return pos+1, t[read_pos];
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64 end, self, 0;
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65 end;
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66 consume = function (self)
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67 return self.pop, self;
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68 end;
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69 };
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70 end
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71
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72 return {
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73 new = new;
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74 };
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75