(ns pixie.stacklets

(:require [pixie.uv :as uv]

[pixie.ffi :as ffi]))

;; If we don't do this, compiling this file doesn't work since the def will clear out

;; the existing value.

(when (undefined? (var stacklet-loop-h))

(def stacklet-loop-h (atom nil))

(def running-threads (atom 0))

(def main-loop-running? (atom false))

(def main-loop-lock (-create-lock))

(-acquire-lock main-loop-lock true))

;; Yield

(defrecord ThrowException [ex])

(defn run-and-process

([k]

(run-and-process k nil))

([k val]

(let [[h f] (k val)]

(f h))))

(defn exception-on-uv-error [result]

(when (neg? result)

(->ThrowException (str "UV Error: " (uv/uv_err_name result)))))

(defn call-cc [f]

(let [frames (-get-current-var-frames nil)

[h val] (@stacklet-loop-h f)]

(reset! stacklet-loop-h h)

(-set-current-var-frames nil frames)

(if (instance? ThrowException val)

(throw (:ex val))

val)))

(defn -run-later [f]

(let [a (uv/uv_async_t)

cb (atom nil)]

(reset! cb (ffi/ffi-prep-callback uv/uv_async_cb

(fn [handle]

(try

(uv/uv_close a close_cb)

(-dispose! @cb)

(f)

(catch ex (println ex))))))

(uv/uv_async_init (uv/uv_default_loop) a @cb)

(uv/uv_async_send a)

(when (not @main-loop-running?)

(reset! main-loop-running? true)

(-release-lock main-loop-lock))

nil))

(defn yield-control []

(call-cc (fn [k]

(-run-later (partial run-and-process k)))))

(def close_cb (ffi/ffi-prep-callback uv/uv_close_cb

pixie.ffi/dispose!))

;;; Sleep

(defn sleep [ms]

(let [f (fn [k]

(let [cb (atom nil)

timer (uv/uv_timer_t)]

(reset! cb (ffi/ffi-prep-callback uv/uv_timer_cb

(fn [handle]

(try

(run-and-process k)

(uv/uv_timer_stop timer)

(-dispose! @cb)

(catch ex

(println ex))))))

(uv/uv_timer_init (uv/uv_default_loop) timer)

(uv/uv_timer_start timer @cb ms 0)))]

(call-cc f)))

;; Spawn

(defn -spawn [start-fn]

(call-cc (fn [k]

(-run-later (fn []

(run-and-process (new-stacklet start-fn))))

(-run-later (partial run-and-process k)))))

(defmacro spawn [& body]

`(let [frames (-get-current-var-frames nil)]

(-spawn (fn [h# _]

(-set-current-var-frames nil frames)

(try

(swap! running-threads inc)

(reset! stacklet-loop-h h#)

(let [result# (do ~@body)]

(swap! running-threads dec)

(call-cc (fn [_] nil)))

(catch e

(println e)))))))

(defn spawn-from-non-stacklet [f]

(let [s (new-stacklet (fn [h _]

(try

(reset! stacklet-loop-h h)

(swap! running-threads inc)

(f)

(swap! running-threads dec)

(call-cc (fn [_] nil))

(catch e

(println e)))))]

(-run-later

(fn []

(run-and-process s)))))

(defn -with-stacklets [fn]

(swap! running-threads inc)

(reset! main-loop-running? true)

(let [[h f] ((new-stacklet fn) nil)]

(f h)

(loop []

(uv/uv_run (uv/uv_default_loop) uv/UV_RUN_DEFAULT)

(when (> @running-threads 0)

(reset! main-loop-running? false)

(-acquire-lock main-loop-lock true)

(recur)))))

(defmacro with-stacklets [& body]

`(-with-stacklets

(fn [h# _]

(try

(reset! stacklet-loop-h h#)

(let [result# (do ~@body)]

(swap! running-threads dec)

(call-cc (fn [_] nil)))

(catch e

(println e))))))

(defn run-with-stacklets [f]

(with-stacklets

(f)))

(defprotocol IThreadPool

(-execute [this work-fn]))

;; Super basic Thread Pool, yes, this should be improved

(deftype ThreadPool []

IThreadPool

(-execute [this work-fn]

(-thread (fn [] (work-fn)))))

(def basic-thread-pool (->ThreadPool))

(defn -run-in-other-thread [work-fn]

(-execute basic-thread-pool work-fn))

(defn apply-blocking [f & args]

(call-cc (fn [k]

(-run-in-other-thread

(fn []

(let [result (apply f args)]

(-run-later (fn [] (run-and-process k result)))))))))