Close promise thread on finalize and cancel

Closes #76

lib/init.lua

@@ -233,6 +233,9 @@ function Promise._new(traceback, callback, parent)
 	end
 
 	local self = {
+		-- The executor thread.
+		_thread = nil,
+
 		-- Used to locate where a promise was created
 		_source = traceback,
 
@@ -292,13 +295,15 @@ function Promise._new(traceback, callback, parent)
 		return self._status == Promise.Status.Cancelled
 	end
 
-	coroutine.wrap(function()
+	self._thread = coroutine.create(function()
 		local ok, _, result = runExecutor(self._source, callback, resolve, reject, onCancel)
 
 		if not ok then
 			reject(result[1])
 		end
-	end)()
+	end)
+
+	task.spawn(self._thread)
 
 	return self
 end
@@ -1385,6 +1390,8 @@ function Promise.prototype:cancel()
 		self._cancellationHook()
 	end
 
+	coroutine.close(self._thread)
+
 	if self._parent then
 		self._parent:_consumerCancelled(self)
 	end
@@ -1847,6 +1854,8 @@ function Promise.prototype:_finalize()
 		self._parent = nil
 		self._consumers = nil
 	end
+
+	task.defer(coroutine.close, self._thread)
 end
 
 --[=[

lib/init.spec.lua

@@ -218,6 +218,20 @@ return function()
 
 			expect(called).to.equal(true)
 		end)
+
+		itSKIP("should close the thread after resolve", function()
+			local count = 0
+			Promise.new(function(resolve)
+				count += 1
+				resolve()
+				Promise.delay(1):await()
+				count += 1
+			end)
+
+			task.wait(1)
+
+			expect(count).to.equal(1)
+		end)
 	end)
 
 	describe("Promise.defer", function()
@@ -627,6 +641,20 @@ return function()
 			expect(p1._status).to.equal(Promise.Status.Cancelled)
 			expect(p2._status).to.equal(Promise.Status.Cancelled)
 		end)
+
+		it("should close the promise thread", function()
+			local count = 0
+			local promise = Promise.new(function()
+				count += 1
+				Promise.delay(1):await()
+				count += 1
+			end)
+
+			promise:cancel()
+			advanceTime(2)
+
+			expect(count).to.equal(1)
+		end)
 	end)
 
 	describe("Promise:finally", function()