mod_presence_cache: Cache incoming presence broadcasts in order to get clients up to speed with who is online faster
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_presence_cache/README.markdown Mon Nov 16 18:19:25 2015 +0100
@@ -0,0 +1,45 @@
+---
+summary: Cache presence incoming presence
+...
+
+Introduction
+============
+
+This module stores presence from users contact even when they are
+offline, so that the client can see who is online faster when they sign
+in, and won't have to wait for remote servers to reply.
+
+Note that in its current form, the number of presence stanzas sent to a
+client is doubled, as the client would get both the cached stanzas and
+replies to presence probes. Also see [mod\_throttle\_presence].
+
+By default, only binary (online or offline) state is stored. It can
+optionally store the full presence but this requires much more memory.
+
+Configuration
+=============
+
+Just enable the module.
+
+ modules_enabled = {
+ -- more modules
+ "presence_cache";
+ }
+
+Advanced configuration
+======================
+
+To enable full stanza caching:
+
+ presence_cache_full = false
+
+TODO
+====
+
+- Deduplication, i.e don's send stanzas that are identical to the last
+ seen.
+- Cache invalidation or expiry, eg if a remote server goes down or is
+ gone a long time.
+- Sending probes at some interval to keep the cache reasonably fresh.
+
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_presence_cache/mod_presence_cache.lua Mon Nov 16 18:19:25 2015 +0100
@@ -0,0 +1,107 @@
+local is_contact_subscribed = require"core.rostermanager".is_contact_subscribed;
+local jid_split = require"util.jid".split;
+local jid_bare = require"util.jid".bare;
+local st = require"util.stanza";
+local datetime = require"util.datetime";
+
+local presence_cache = {}; -- Reload to empty
+
+local cache_full = module:get_option_boolean(module.name.."_full", false);
+
+local function cache_hook(event)
+ local origin, stanza = event.origin, event.stanza;
+ local typ = stanza.attr.type;
+ module:log("debug", "Cache hook, got %s from a %s", stanza:top_tag(), origin.type);
+ if origin.type:match"^s2s" and ( typ == nil or typ == "unavailable" ) then
+ local from_jid = stanza.attr.from;
+ local from_bare = jid_bare(from_jid);
+ local username = jid_split(stanza.attr.to);
+
+ if not is_contact_subscribed(username, module.host, from_bare) then
+ module:log("debug", "Not in their roster", origin.username);
+ return;
+ end
+
+ local user_presence_cache = presence_cache[username];
+ if not user_presence_cache then
+ user_presence_cache = {};
+ presence_cache[username] = user_presence_cache;
+ end
+
+ local contact_presence_cache = user_presence_cache[from_bare];
+ if not contact_presence_cache then
+ contact_presence_cache = {};
+ user_presence_cache[from_bare] = contact_presence_cache;
+ end
+
+ if typ == "unavailable" then
+ contact_presence_cache[from_jid] = nil;
+ if next(contact_presence_cache) == nil or from_jid == from_bare then
+ user_presence_cache[from_bare] = nil;
+ if next(user_presence_cache) == nil then
+ presence_cache[username] = nil;
+ end
+ end
+ elseif cache_full then
+ stanza = st.clone(stanza);
+ stanza:tag("delay", { xmlns = "urn:xmpp:delay", from = module.host, stamp = datetime.datetime() }):up();
+ contact_presence_cache[from_jid] = stanza;
+ else -- only cache binary state
+ contact_presence_cache[from_jid] = datetime.datetime();
+ end
+ end
+end
+
+module:hook("presence/bare", cache_hook, 10);
+-- module:hook("presence/full", cache_hook, 10);
+
+local function answer_probe_from_cache(event)
+ local origin, stanza = event.origin, event.stanza;
+ if stanza.attr.type ~= "probe" then return; end
+ local contact_bare = stanza.attr.to;
+
+ local user_presence_cache = presence_cache[origin.username];
+ if not user_presence_cache then return; end
+
+ local contact_presence_cache = user_presence_cache[contact_bare];
+ if not contact_presence_cache then return; end
+
+ local user_jid = stanza.attr.from;
+ for jid, presence in pairs(contact_presence_cache) do
+ module:log("debug", "Sending cached presence from %s", jid);
+ if presence == true then
+ presence = st.presence({ from = user_jid, from = jid });
+ elseif type(presence) == "string" then -- a timestamp
+ presence = st.presence({ from = user_jid, from = jid })
+ :tag("delay", { xmlns = "urn:xmpp:delay", from = module.host, stamp = presence }):up();
+ end
+ origin.send(presence);
+ end
+ if cache_full then
+ return true;
+ end
+end
+
+module:hook("pre-presence/bare", answer_probe_from_cache, 10);
+
+module:add_timer(3600, function (now)
+ local older = datetime.datetime(now - 7200);
+ for username, user_presence_cache in pairs(presence_cache) do
+ for contact, contact_presence_cache in pairs(user_presence_cache) do
+ for jid, presence in pairs(contact_presence_cache) do
+ if presence == true or (type(presence) == "string" and presence < older) then
+ contact_presence_cache[jid] = nil;
+ end
+ end
+ if next(contact_presence_cache) == nil then
+ user_presence_cache[contact] = nil;
+ end
+ end
+ if next(user_presence_cache) == nil then
+ presence_cache[username] = nil;
+ end
+ end
+ return 3600;
+end);
+
+module:log("info", "Loaded");