--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/scansion/async.lua Sat Sep 05 23:20:17 2015 +0100
@@ -0,0 +1,158 @@
+--local log = require "util.logger".init("util.async");
+
+local function runner_continue(thread)
+ -- ASSUMPTION: runner is in 'waiting' state (but we don't have the runner to know for sure)
+ if coroutine.status(thread) ~= "suspended" then -- This should suffice
+ return false;
+ end
+ local ok, state, runner = coroutine.resume(thread);
+ if not ok then
+ local level = 0;
+ while debug.getinfo(thread, level, "") do level = level + 1; end
+ ok, runner = debug.getlocal(thread, level-1, 1);
+ local error_handler = runner.watchers.error;
+ if error_handler then error_handler(runner, debug.traceback(thread, state)); end
+ elseif state == "ready" then
+ -- If state is 'ready', it is our responsibility to update runner.state from 'waiting'.
+ -- We also have to :run(), because the queue might have further items that will not be
+ -- processed otherwise. FIXME: It's probably best to do this in a nexttick (0 timer).
+ runner.state = "ready";
+ runner:run();
+ end
+ return true;
+end
+
+local function waiter(num)
+ local thread = coroutine.running();
+ if not thread then
+ error("Not running in an async context, see http://prosody.im/doc/developers/async");
+ end
+ num = num or 1;
+ local waiting;
+ return function ()
+ if num == 0 then return; end -- already done
+ waiting = true;
+ coroutine.yield("wait");
+ end, function ()
+ num = num - 1;
+ if num == 0 and waiting then
+ runner_continue(thread);
+ elseif num < 0 then
+ error("done() called too many times");
+ end
+ end;
+end
+
+local function guarder()
+ local guards = {};
+ return function (id, func)
+ local thread = coroutine.running();
+ if not thread then
+ error("Not running in an async context, see http://prosody.im/doc/developers/async");
+ end
+ local guard = guards[id];
+ if not guard then
+ guard = {};
+ guards[id] = guard;
+ --log("debug", "New guard!");
+ else
+ table.insert(guard, thread);
+ --log("debug", "Guarded. %d threads waiting.", #guard)
+ coroutine.yield("wait");
+ end
+ local function exit()
+ local next_waiting = table.remove(guard, 1);
+ if next_waiting then
+ --log("debug", "guard: Executing next waiting thread (%d left)", #guard)
+ runner_continue(next_waiting);
+ else
+ --log("debug", "Guard off duty.")
+ guards[id] = nil;
+ end
+ end
+ if func then
+ func();
+ exit();
+ return;
+ end
+ return exit;
+ end;
+end
+
+local runner_mt = {};
+runner_mt.__index = runner_mt;
+
+local function runner_create_thread(func, self)
+ local thread = coroutine.create(function (self)
+ while true do
+ func(coroutine.yield("ready", self));
+ end
+ end);
+ assert(coroutine.resume(thread, self)); -- Start it up, it will return instantly to wait for the first input
+ return thread;
+end
+
+local empty_watchers = {};
+local function runner(func, watchers, data)
+ return setmetatable({ func = func, thread = false, state = "ready", notified_state = "ready",
+ queue = {}, watchers = watchers or empty_watchers, data = data }
+ , runner_mt);
+end
+
+function runner_mt:run(input)
+ if input ~= nil then
+ table.insert(self.queue, input);
+ end
+ if self.state ~= "ready" then
+ return true, self.state, #self.queue;
+ end
+
+ local q, thread = self.queue, self.thread;
+ if not thread or coroutine.status(thread) == "dead" then
+ thread = runner_create_thread(self.func, self);
+ self.thread = thread;
+ end
+
+ local n, state, err = #q, self.state, nil;
+ self.state = "running";
+ while n > 0 and state == "ready" do
+ local consumed;
+ for i = 1,n do
+ local input = q[i];
+ local ok, new_state = coroutine.resume(thread, input);
+ if not ok then
+ consumed, state, err = i, "ready", debug.traceback(thread, new_state);
+ self.thread = nil;
+ break;
+ elseif new_state == "wait" then
+ consumed, state = i, "waiting";
+ break;
+ end
+ end
+ if not consumed then consumed = n; end
+ if q[n+1] ~= nil then
+ n = #q;
+ end
+ for i = 1, n do
+ q[i] = q[consumed+i];
+ end
+ n = #q;
+ end
+ self.state = state;
+ if err or state ~= self.notified_state then
+ if err then
+ state = "error"
+ else
+ self.notified_state = state;
+ end
+ local handler = self.watchers[state];
+ if handler then handler(self, err); end
+ end
+ return true, state, n;
+end
+
+function runner_mt:enqueue(input)
+ table.insert(self.queue, input);
+end
+
+return { waiter = waiter, guarder = guarder, runner = runner };