From 78cafe656684be32022bc9202628f9d3633e216d Mon Sep 17 00:00:00 2001
From: Alberto Torres <kungfoobar@gmail.com>
Date: Thu, 29 Aug 2024 00:19:52 +0200
Subject: [PATCH] Add threading support to `LoadableResource`.

---
 libs/loadable/loadable.nim | 70 +++++++++++++++++++++++++++++++-------
 src/myou_engine.nim        |  2 ++
 2 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/libs/loadable/loadable.nim b/libs/loadable/loadable.nim
index 3db1886..f2d2e3c 100644
--- a/libs/loadable/loadable.nim
+++ b/libs/loadable/loadable.nim
@@ -58,12 +58,14 @@ type LoadableResource* = ref object of RootObj
     done_func: proc()
     cancel_func: proc()
     str*: proc(): string
+    use_threads: bool
     result: ref Result # only to be used with loadAll
 
 proc newLoadableResource*[T: LoadableResource](
         start: proc(self: LoadableResource),
         done: proc() = nil,
         str: proc(): string = nil,
+        use_threads = false,
     ): T =
     new(result)
     result.start_func = start
@@ -71,10 +73,28 @@ proc newLoadableResource*[T: LoadableResource](
     result.str = str
     if str == nil:
         result.str = proc(): string = ""
+    result.use_threads = use_threads
+
+# main -> thread  channels
+var to_start: Channel[LoadableResource]
+# main <- thread  channels
+var to_return: Channel[(LoadableResource, bool, string, pointer, int)]
+var to_done: Channel[LoadableResource]
 
 proc start*[T: LoadableResource](self: T) =
     self.status = Started
-    self.start_func(self)
+    if self.use_threads:
+        to_start.send self
+    else:
+        self.start_func(self)
+
+proc doneImpl*[T: LoadableResource](self: T) =
+    if self.status == Started:
+        self.cancel()
+    else:
+        self.status = NotStarted
+        if self.done_func != nil:
+            self.done_func()
 
 proc `onload=`*[T: LoadableResource](self: T, onload_func: proc(ok: bool, err: string, p: pointer, len: int)) =
     self.onload_func = onload_func
@@ -85,25 +105,24 @@ proc onload*[T: LoadableResource](self: T, ok: bool, err: string, p: pointer, le
         if self.result != nil:
             self.result[] = (ok, err, p, len)
         if self.onload_func != nil:
-            self.onload_func(ok, err, p, len)
+            if self.use_threads:
+                to_return.send((self.LoadableResource, ok, err, p, len))
+            else:
+                self.onload_func(ok, err, p, len)
     else: # cancelled
-        self.status = NotStarted
-        if self.done_func != nil:
-            self.done_func()
+        self.doneImpl()
 
 # TODO: check if we can always use destructors instead of calling this
 proc done*[T: LoadableResource](self: T) =
-    if self.status == Started:
-        self.cancel()
+    if self.use_threads:
+        to_done.send self
     else:
-        self.status = NotStarted
-        if self.done_func != nil:
-            self.done_func()
+        self.doneImpl()
 
 proc cancel*[T: LoadableResource](self: T) =
     if self.status != Started:
         return
-    if self.cancel_func != nil:
+    if self.cancel_func == nil:
         # self.`onload=`(proc(ok, err, p, len: auto) =
         #     self.done())
         self.onload_func = proc(ok: bool, err: string, p: pointer, len: int) =
@@ -128,6 +147,31 @@ proc cancel*[T: LoadableResource](self: T) =
 #             results.add res.result[]
 #             res.result = nil
 
+var worker: Thread[void]
+proc workerThreadProc() {.thread.} =
+    while true:
+        let res = to_start.recv()
+        if res == nil:
+            break
+        cast[proc(self: LoadableResource) {.gcsafe.}](res.start_func)(res)
+
+worker.createThread(workerThreadProc)
+to_start.open()
+to_return.open()
+to_done.open()
+
+proc updateLoadableWorkerThreads*() =
+    while true:
+        let tried = to_return.tryRecv()
+        if not tried.dataAvailable:
+            break
+        let (res, ok, err, p, len) = tried.msg
+        res.onload_func(ok, err, p, len)
+    while true:
+        let tried = to_done.tryRecv()
+        if not tried.dataAvailable:
+            break
+        tried.msg.done_func()
 
 type Fetch* = ref object of LoadableResource
     custom: pointer
@@ -226,6 +270,7 @@ proc loadUri*(
     var done_func: proc()
     var self: Fetch
     var uri = uri
+    var use_threads = false
     when not defined(onlyLocalFiles):
         when defined(emscripten):
             const is_remote = true
@@ -261,6 +306,7 @@ proc loadUri*(
                         discard emscripten_fetch_close(cast[ptr emscripten_fetch_t](self.custom))
                         self.custom = nil
             else:
+                use_threads = true
                 var client = newHttpClient()
                 var response: string
                 start_func = proc(self: LoadableResource) =
@@ -298,7 +344,7 @@ proc loadUri*(
             if cast[Fetch](self).auto_done:
                 self.done()
     proc str(): string = uri
-    self = newLoadableResource[Fetch](start_func, done_func, str)
+    self = newLoadableResource[Fetch](start_func, done_func, str, use_threads=use_threads)
     self.onload_func = onload_func
     self.auto_done = auto_done
     if auto_start:
diff --git a/src/myou_engine.nim b/src/myou_engine.nim
index 70ed184..edb81d2 100644
--- a/src/myou_engine.nim
+++ b/src/myou_engine.nim
@@ -77,6 +77,7 @@ import ./screen
 import ./platform/platform
 import ./loaders/blend
 import ./util
+from loadable import updateLoadableWorkerThreads
 import arr_ref
 
 export arr_ref
@@ -165,6 +166,7 @@ proc myou_main_loop*(self: MyouEngine) =
     ##
     ## You usually don't need to call this. Use `run <#run,MyouEngine>`_
     ## instead.
+    updateLoadableWorkerThreads()
     # TODO: make a table object that can be iterated while changing, e.g. with a
     # seq and a dirty flag to update the seq
     if self.new_scenes.len != 0: