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module:set_global();
local async = require "util.async";
local datetime = require "util.datetime";
local record map_store<K,V>
-- TODO move to somewhere sensible
get : function (map_store<K,V>, string, K) : V
set : function (map_store<K,V>, string, K, V)
end
local enum frequency
"hourly"
"daily"
"weekly"
end
local record task_spec
id : string -- unique id
name : string -- name or short description
when : frequency
last : integer
run : function (task_spec, integer)
save : function (task_spec, integer)
end
local record task_event
source : module
item : task_spec
end
local periods : { frequency : integer } = { hourly = 3600, daily = 86400, weekly = 7*86400 }
local active_hosts : { string : boolean } = { }
function module.add_host(host_module : moduleapi)
local last_run_times = host_module:open_store("cron", "map") as map_store<string,integer>;
active_hosts[host_module.host] = true;
local function save_task(task : task_spec, started_at : integer)
last_run_times:set(nil, task.id, started_at);
end
local function task_added(event : task_event) : boolean
local task = event.item;
if task.name == nil then
task.name = task.when;
end
if task.id == nil then
task.id = event.source.name .. "/" .. task.name:gsub("%W", "_"):lower();
end
if task.last == nil then
task.last = last_run_times:get(nil, task.id);
end
task.save = save_task;
module:log("debug", "%s task %s added, last run %s", task.when, task.id,
task.last and datetime.datetime(task.last) or "never");
if task.last == nil then
-- initialize new tasks so e.g. daily tasks run at ~midnight UTC for now
local now = os.time();
task.last = now - now % periods[task.when];
end
return true;
end
local function task_removed(event : task_event) : boolean
local task = event.item;
host_module:log("debug", "Task %s removed", task.id);
return true;
end
host_module:handle_items("task", task_added, task_removed, true);
function host_module.unload()
active_hosts[host_module.host]=nil;
end
end
local function should_run(when : frequency, last : integer) : boolean
return not last or last + periods[when]*0.995 <= os.time();
end
local function run_task(task : task_spec)
local started_at = os.time();
task:run(started_at);
task.last = started_at;
task:save(started_at);
end
local task_runner = async.runner(run_task);
module:add_timer(1, function() : integer
module:log("info", "Running periodic tasks");
local delay = 3600;
for host in pairs(active_hosts) do
module:log("debug", "Running periodic tasks for host %s", host);
for _, task in ipairs(module:context(host):get_host_items("task") as { task_spec } ) do
module:log("debug", "Considering %s task %s (%s)", task.when, task.id, task.run);
if should_run(task.when, task.last) then task_runner:run(task); end
end
end
module:log("debug", "Wait %ds", delay);
return delay;
end);
-- TODO measure load, pick a good time to do stuff
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