From dc2493e7525bb7633f697ef10f72b72b46222249 Mon Sep 17 00:00:00 2001
From: Andy Belle-Isle <drumsetmonkey@gmail.com>
Date: Fri, 30 Aug 2019 00:45:36 -0400
Subject: Forget what I said, I just need to change git attributes to mark for
 vendor

---
 lib/sol2/examples/source/docs/std_thread.cpp | 134 +++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 lib/sol2/examples/source/docs/std_thread.cpp

(limited to 'lib/sol2/examples/source/docs/std_thread.cpp')

diff --git a/lib/sol2/examples/source/docs/std_thread.cpp b/lib/sol2/examples/source/docs/std_thread.cpp
new file mode 100644
index 0000000..c610169
--- /dev/null
+++ b/lib/sol2/examples/source/docs/std_thread.cpp
@@ -0,0 +1,134 @@
+#define SOL_ALL_SAFETIES_ON 1
+#include <sol/sol.hpp>
+
+#include <mutex>
+#include <condition_variable>
+#include <thread>
+#include <variant>
+#include <cstddef>
+#include <iostream>
+
+struct worker_data {
+	std::mutex until_ready_mutex;
+	std::condition_variable until_ready_condition;
+	bool is_ready = false;
+	bool is_processed = false;
+	sol::state worker_lua;
+	sol::bytecode payload;
+	std::variant<double, std::vector<double>> return_payload;
+
+	worker_data() {
+		worker_lua.open_libraries(sol::lib::base);
+	}
+};
+
+void worker_thread(worker_data& data) {
+	for (std::uint64_t loops = 0; true; ++loops) {
+		// Wait until main() sends data
+		std::unique_lock<std::mutex> data_lock(data.until_ready_mutex);
+		data.until_ready_condition.wait(data_lock, [&data] { return data.is_ready; });
+
+		if (data.payload.size() == 0) {
+			// signaling we are done
+			return;
+		}
+
+		// just for easier typing
+		sol::state& lua = data.worker_lua;
+
+		// we own the lock now, do the work
+		std::variant<double, std::vector<double>> result = lua.safe_script(data.payload.as_string_view());
+
+		// store returning payload,
+		// clear current payload
+		data.return_payload = std::move(result);
+		data.payload.clear();
+
+		// Send result back to main
+		std::cout << "worker_thread data processing is completed: signaling & unlocking\n";
+		data.is_processed = true;
+		data.is_ready = false;
+		data_lock.unlock();
+		data.until_ready_condition.notify_one();
+	}
+}
+
+int main() {
+
+	// main lua state
+	sol::state lua;
+	lua.open_libraries(sol::lib::base);
+
+	// set up functions, etc. etc.
+	lua.script("function f () return 4.5 end");
+	lua.script("function g () return { 1.1, 2.2, 3.3 } end");
+
+	// kick off worker
+	worker_data data;
+	std::thread worker(worker_thread, std::ref(data));
+
+	// main Lua state
+	bool done_working = false;
+	for (std::uint64_t loops = 0; !done_working; ++loops) {
+		// finished working? send nothing
+		// even loop? use f
+		// otherwise, use g
+		if (loops >= 3) {
+			data.payload.clear();
+			done_working = true;
+		}
+		else if ((loops % 2) == 0) {
+			sol::function target = lua["f"];
+			data.payload = target.dump();
+		}
+		else {
+			sol::function target = lua["g"];
+			data.payload = target.dump();
+		}
+
+		// send data to the worker thread
+		{
+			std::lock_guard<std::mutex> lk(data.until_ready_mutex);
+			data.is_ready = true;
+			std::cout << "function serialized: sending to worker thread to execute on Lua state...\n";
+		}
+		data.until_ready_condition.notify_one();
+
+		if (done_working) {
+			break;
+		}
+		// wait for the worker
+		{
+			std::unique_lock<std::mutex> lock_waiting_for_worker(data.until_ready_mutex);
+			data.until_ready_condition.wait(lock_waiting_for_worker, [&data] { return data.is_processed; });
+			data.is_processed = false;
+		}
+		auto data_processor = [](auto& returned_data) {
+			using option_type = std::remove_cv_t<std::remove_reference_t<decltype(returned_data)>>;
+			if constexpr (std::is_same_v<option_type, double>) {
+				std::cout << "received a double: " << returned_data << "\n";
+			}
+			else if constexpr (std::is_same_v<option_type, std::vector<double>>) {
+				std::cout << "received a std::vector<double>: { ";
+				for (std::size_t i = 0; i < returned_data.size(); ++i) {
+					std::cout << returned_data[i];
+					if (i != static_cast<std::size_t>(returned_data.size() - 1)) {
+						std::cout << ", ";
+					}
+				}
+				std::cout << " }\n";
+			}
+			else {
+				std::cerr << "OH MY GOD YOU FORGOT TO HANDLE A TYPE OF DATA FROM A WORKER ABORT ABORT ABORT\n";
+				std::abort();
+			}
+		};
+		std::visit(data_processor, data.return_payload);
+	}
+
+	// join and wait for workers to come back
+	worker.join();
+
+	// workers are back, exit program
+	return 0;
+}
-- 
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