prosody
495de404a8ae
util/queue.lua

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util/queue.lua @ 7567:495de404a8ae

ejabberdsql2prosody: rename variable 'host' to prevent shadowing upvalue [luacheck] Functions roster(), roster_pending(), roster_group(), private_storage() and offline_msg() have argument named "host", which used to shadow upvalue of this variable before this change. Instead of renaming this argument, let's rename the variable to match what the script says in usage: Usage: ejabberdsql2prosody.lua filename.txt hostname
author Anton Shestakov <av6@dwimlabs.net>
date Fri, 12 Aug 2016 13:44:47 +0800
parent 6912:cb5b14c95b7b
child 9901:c8b75239846c
child 11103:73b8aaf55775
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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 --luacheck: ignore 431/t
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56 return function (t, pos)
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57 if pos >= t:count() then
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58 return nil;
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59 end
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60 local read_pos = tail + pos;
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61 if read_pos > t.size then
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62 read_pos = (read_pos%size);
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63 end
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64 return pos+1, t._items[read_pos];
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65 end, self, 0;
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66 end;
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67 };
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68 end
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69
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70 return {
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71 new = new;
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72 };
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73