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util/async.lua @ 8616:a15c891c6232
util.async: ensure change in e77b37de482e applies after out-of-loop resume also
author | Matthew Wild <mwild1@gmail.com> |
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date | Sat, 17 Mar 2018 17:28:07 +0000 |
parent | 8615:e77b37de482e |
child | 8625:08bf4df6fdb7 |
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local log = require "util.logger".init("util.async"); local new_id = require "util.id".short; local function checkthread() local thread, main = coroutine.running(); if not thread or main then error("Not running in an async context, see https://prosody.im/doc/developers/util/async"); end return thread; end 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 log("warn", "unexpected async state: thread not suspended"); return false; end local ok, state, runner = coroutine.resume(thread); if not ok then local err = state; -- Running the coroutine failed, which means we have to find the runner manually, -- in order to inform the error handler local level = 0; -- Find the 'level' of the top-most function (0 == current level, 1 == caller, ...) while debug.getinfo(thread, level, "") do level = level + 1; end ok, runner = debug.getlocal(thread, level-1, 1); if ok ~= "self" or runner.thread ~= thread then log("warn", "unexpected async state: unable to locate runner during error handling, got %s", ok); return false; end local error_handler = runner.watchers.error; if error_handler then error_handler(runner, debug.traceback(thread, err)); end local ready_handler = runner.watchers.ready; runner.state, runner.thread = "ready", nil; return runner:run(); 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 = checkthread(); 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 = checkthread(); 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) -- luacheck: ignore 432/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, id = new_id() } , runner_mt); end -- Add a task item for the runner to process function runner_mt:run(input) if input ~= nil then table.insert(self.queue, input); self:log("debug", "queued new work item, %d items queued", #self.queue); end if self.state ~= "ready" then -- The runner is busy. Indicate that the task item has been -- queued, and return information about the current runner state return true, self.state, #self.queue; end local q, thread = self.queue, self.thread; if not thread or coroutine.status(thread) == "dead" then self:log("debug", "creating new coroutine"); -- Create a new coroutine for this runner thread = runner_create_thread(self.func, self); self.thread = thread; end -- Process task item(s) while the queue is not empty, and we're not blocked local n, state, err = #q, self.state, nil; self.state = "running"; self:log("debug", "running main loop"); while n > 0 and state == "ready" and not err do local consumed; -- Loop through queue items, and attempt to run them for i = 1,n do local queued_input = q[i]; local ok, new_state = coroutine.resume(thread, queued_input); if not ok then -- There was an error running the coroutine, save the error, mark runner as ready to begin again consumed, state, err = i, "ready", debug.traceback(thread, new_state); self.thread = nil; break; elseif new_state == "wait" then -- Runner is blocked on waiting for a task item to complete consumed, state = i, "waiting"; break; end end -- Loop ended - either queue empty because all tasks passed without blocking (consumed == nil) -- or runner is blocked/errored, and consumed will contain the number of tasks processed so far if not consumed then consumed = n; end -- Remove consumed items from the queue array if q[n+1] ~= nil then n = #q; end for i = 1, n do q[i] = q[consumed+i]; end n = #q; end -- Runner processed all items it can, so save current runner state self.state = state; if err or state ~= self.notified_state then self:log("debug", "changed state from %s to %s", self.notified_state, err and ("error ("..state..")") or state); if err then state = "error" else self.notified_state = state; end local handler = self.watchers[state]; if handler then handler(self, err); end end if n > 0 then return self:run(); end return true, state, n; end -- Add a task item to the queue without invoking the runner, even if it is idle function runner_mt:enqueue(input) table.insert(self.queue, input); self:log("debug", "queued new work item, %d items queued", #self.queue); end function runner_mt:log(level, fmt, ...) return log(level, "[runner %s] "..fmt, self.id, ...); end return { waiter = waiter, guarder = guarder, runner = runner };