prosody-modules
f24b02e0d706
mod_presence_dedup/mod_presence_dedup.lua

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mod_presence_dedup/mod_presence_dedup.lua @ 2155:f24b02e0d706

mod_presence_dedup: Attempt at saving bandwith by deduplicating presence stanzas
author Kim Alvefur <zash@zash.se>
date Sun, 03 Apr 2016 17:09:03 +0200
child 3445:19924a2c4a48
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2154:ada71b81425a 2155:f24b02e0d706
1 local st = require "util.stanza";
2 local cache = require "util.cache";
3 local add_filter = require "util.filters".add_filter;
4
5 local cache_size = module:get_option_number("presence_dedup_cache_size", 100);
6
7 -- stanza equality tests
8 local function attr_eq(a, b)
9 if a == b then return true; end -- unlikely but not impossible
10 for k,v in pairs(a) do if b[k] ~= v then return false; end end
11 for k,v in pairs(b) do if a[k] ~= v then return false; end end
12 return true;
13 end
14
15 local function st_eq(a, b)
16 if a == b then return true; end
17 if type(b) ~= "table" then return false; end
18 if getmetatable(b) ~= st.stanza_mt then return false; end
19 if a.name ~= b.name then return false; end
20 if #a ~= #b then return false; end
21 if not attr_eq(a.attr, b.attr) then return false; end
22 for i = 1, #a do if not st_eq(a[i], b[i]) then return false; end end
23 return true;
24 end
25
26 local function dedup_presence(stanza, session)
27 if session.presence_cache and session.presence
28 and getmetatable(stanza) == st.stanza_mt and stanza.name == "presence"
29 and stanza.attr.xmlns == nil and stanza.attr.from then
30 local cached = session.presence_cache:get(stanza.attr.from);
31 if st_eq(stanza, cached) then
32 return nil;
33 else
34 session.presence_cache:set(stanza.attr.from, st.clone(stanza));
35 end
36 end
37 return stanza;
38 end
39
40 module:hook("presence/initial", function (event)
41 local session, stanza = event.origin, event.stanza;
42 session.presence_cache = cache.new(cache_size);
43 add_filter(session, "stanzas/out", dedup_presence, 90);
44 end);