add ThreadPool (#926)

* lib/std/collections: fix tab indentation

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

* lib/std/threads: add ThreadPool

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

* ats/lib/threads: add num_cpu()

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

---------

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

test/unit/stdlib/threads/pool.c3

@@ -0,0 +1,67 @@
+module thread_pool_test;
+import std::io;
+import std::thread;
+import std::thread::pool;
+
+def Pool = ThreadPool(<4>);
+
+fn void! init_destroy() @test
+{
+	for (usz i = 0; i < 20; i++)
+	{
+		Pool pool;
+		pool.init()!;
+		pool.destroy()!;
+	}
+}
+
+fn void! push_destroy() @test
+{
+	for (usz i = 0; i < 20; i++)
+	{
+		x = 0;
+		int y = 20;
+		Pool pool;
+		pool.init()!;
+		defer pool.destroy()!!;
+		work_done.lock()!!;
+		pool.push(&do_work, &y)!;
+		work_done.lock()!!;
+		assert(x == y, "%d: %d != %d", i, x, y);
+		work_done.unlock()!!;
+	}
+}
+
+fn void! push_stop() @test
+{
+	for (usz i = 0; i < 20; i++)
+	{
+		x = 0;
+		int y = 20;
+		Pool pool;
+		pool.init()!;
+		work_done.lock()!!;
+		pool.push(&do_work, &y)!;
+		pool.stop_and_destroy()!!;
+		assert(x == y, "%d: %d != %d", i, x, y);
+	}
+}
+
+int x;
+
+Mutex work_done;
+
+static initialize {
+	work_done.init()!!;
+}
+
+static finalize {
+	work_done.destroy()!!;
+}
+
+fn int do_work(void* arg)
+{
+	x = *(int*)arg;
+	work_done.unlock()!!;
+	return 0;
+}

test/unit/stdlib/threads/simple_thread.c3

@@ -63,10 +63,7 @@ fn void! testrun_mutex_timeout() @test
 	Mutex m;
 	m.init()!;
 	m.lock()!;
-	if (catch m.lock_timeout(100))
-	{
-	}
-	else
+	if (try m.lock_timeout(100))
 	{
 		assert(false, "lock_timeout should fail");
 	}