mod_mam,mod_muc_mam: Allow other work to be performed during archive cleanup (fixes #1504)

This lets Prosody handle socket related work between each step in the
cleanup in order to prevent the server from being completely blocked
during this.

An async storage backend would not need this but those are currently
rare.

1 files changed, 5 insertions, 1 deletions

diff --git a/plugins/mod_mam/mod_mam.lua b/plugins/mod_mam/mod_mam.lua
index 295d90e1..e7d89a95 100644
--- a/plugins/mod_mam/mod_mam.lua
+++ b/plugins/mod_mam/mod_mam.lua
@@ -362,7 +362,8 @@ if cleanup_after ~= "never" then
 		end
 	end
 
-	cleanup_runner = require "util.async".runner(function ()
+	local async = require "util.async";
+	cleanup_runner = async.runner(function ()
 		local users = {};
 		local cut_off = datestamp(os.time() - cleanup_after);
 		for date in cleanup_storage:users() do
@@ -391,6 +392,9 @@ if cleanup_after ~= "never" then
 				cleanup_map:set(cut_off, user, true);
 				module:log("error", "Could not delete messages for user '%s': %s", user, err);
 			end
+			local wait, done = async.waiter();
+			module:add_timer(0.01, done);
+			wait();
 		end
 		module:log("info", "Deleted %d expired messages for %d users", sum, num_users);
 	end);