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mod_tombstones: Add caching to improve performance on busy servers (fixes #1728)

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This commit is contained in:
Matthew Wild 2022-03-28 11:08:18 +01:00
parent 1426d52e39
commit 4272c931ae
1 changed files with 42 additions and 11 deletions
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53
plugins/mod_tombstones.lua
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@ -2,12 +2,13 @@
-- e.g. via telnet or other admin interface
local datetime = require "util.datetime";
local errors = require "util.error";
local jid_split = require"util.jid".split;
local jid_node = require"util.jid".node;
local st = require "util.stanza";
-- Using a map store as key-value store so that removal of all user data
-- does not also remove the tombstone, which would defeat the point
local graveyard = module:open_store(nil, "map");
local graveyard_cache = require "util.cache".new(module:get_option_number("tombstone_cache_size", 1024));
local ttl = module:get_option_number("user_tombstone_expiry", nil);
-- Keep tombstones forever by default
@ -29,15 +30,40 @@ end);
-- Public API
function has_tombstone(username)
local tombstone, err = graveyard:get(nil, username);
local tombstone;
if err or not tombstone then return tombstone, err; end
-- Check cache
local cached_result = graveyard_cache:get(username);
if cached_result == false then
-- We cached that there is no tombstone for this user
return false;
elseif cached_result then
tombstone = cached_result;
else
local stored_result, err = graveyard:get(nil, username);
if not stored_result and not err then
-- Cache that there is no tombstone for this user
graveyard_cache:set(username, false);
return false;
elseif err then
-- Failed to check tombstone status
return nil, err;
end
-- We have a tombstone stored, so let's continue with that
tombstone = stored_result;
end
-- Check expiry
if ttl and tombstone + ttl < os.time() then
module:log("debug", "Tombstone for %s created at %s has expired", username, datetime.datetime(tombstone));
graveyard:set(nil, username, nil);
graveyard_cache:set(username, nil); -- clear cache entry (if any)
return nil;
end
-- Cache for the future
graveyard_cache:set(username, tombstone);
return tombstone;
end
@ -59,6 +85,8 @@ end);
module:hook("presence/bare", function(event)
local origin, presence = event.origin, event.stanza;
local local_username = jid_node(presence.attr.to);
if not local_username then return; end
-- We want to undo any left-over presence subscriptions and notify the former
-- contact that they're gone.
@ -66,14 +94,17 @@ module:hook("presence/bare", function(event)
-- FIXME This leaks that the user once existed. Hard to avoid without keeping
-- the contact list in some form, which we don't want to do for privacy
-- reasons. Bloom filter perhaps?
if has_tombstone(jid_split(presence.attr.to)) then
if presence.attr.type == "probe" then
origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
origin.send(st.presence({ type = "unsubscribed"; to = presence.attr.from; from = presence.attr.to }));
elseif presence.attr.type == nil or presence.attr.type == "unavailable" then
origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
origin.send(st.presence({ type = "unsubscribe"; to = presence.attr.from; from = presence.attr.to }));
end
local pres_type = presence.attr.type;
local is_probe = pres_type == "probe";
local is_normal = pres_type == nil or pres_type == "unavailable";
if is_probe and has_tombstone(local_username) then
origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
origin.send(st.presence({ type = "unsubscribed"; to = presence.attr.from; from = presence.attr.to }));
return true;
elseif is_normal and has_tombstone(local_username) then
origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
origin.send(st.presence({ type = "unsubscribe"; to = presence.attr.from; from = presence.attr.to }));
return true;
end
end, 1);