fix an issue that ConsumeTasks() may end before end of the last task execution

core/CMakeLists.txt

@@ -12,6 +12,7 @@ target_sources(nf7_core
     version.cc
   PUBLIC
     luajit/context.hh
+    luajit/thread.hh
     version.hh
 )
 
@@ -20,6 +21,8 @@ target_sources(nf7_core_test
   PRIVATE
     luajit/context_test.cc
     luajit/context_test.hh
+    luajit/thread_test.cc
+    luajit/thread_test.hh
 )
 target_link_libraries(nf7_core_test
   PRIVATE

core/luajit/context.hh

@@ -47,9 +47,10 @@ class TaskContext final {
  public:
   friend class Context;
 
+  class Nil {};
+
   TaskContext() = delete;
-  explicit TaskContext(
-      std::shared_ptr<Context>&& ctx, lua_State* state) noexcept
+  TaskContext(const std::shared_ptr<Context>& ctx, lua_State* state) noexcept
       : ctx_(std::move(ctx)), state_(state) {
     assert(nullptr != state_);
   }
@@ -64,6 +65,39 @@ class TaskContext final {
   std::shared_ptr<Value> Register() noexcept;
   void Query(const Value&) noexcept;
 
+  template <typename T, typename... Args>
+  uint32_t PushAll(T&& v, Args&&... args) noexcept {
+    Push(v);
+    return 1 + PushAll(std::forward<Args>(args)...);
+  }
+  uint32_t PushAll() noexcept { return 0; }
+
+  void Push(Nil) noexcept {
+    lua_pushnil(state_);
+  }
+  void Push(bool v) noexcept {
+    lua_pushboolean(state_, v);
+  }
+  void Push(lua_Integer v) noexcept {
+    lua_pushinteger(state_, v);
+  }
+  void Push(lua_Number v) noexcept {
+    lua_pushnumber(state_, v);
+  }
+  void Push(std::string_view str) noexcept {
+    lua_pushlstring(state_, str.data(), str.size());
+  }
+  void Push(std::span<const uint8_t> ptr) noexcept {
+    lua_pushlstring(
+        state_, reinterpret_cast<const char*>(ptr.data()), ptr.size());
+  }
+  void Push(const std::shared_ptr<luajit::Value>& v) noexcept {
+    Query(*v);
+  }
+  void Push(const luajit::Value& v) noexcept {
+    Query(v);
+  }
+
   const std::shared_ptr<Context>& context() const noexcept { return ctx_; }
   lua_State* state() const noexcept { return state_; }
 

core/luajit/context_test.hh

@@ -9,6 +9,7 @@
 #include <cstdlib>
 #include <iostream>
 #include <memory>
+#include <thread>
 #include <utility>
 
 #include "iface/common/exception.hh"
@@ -21,43 +22,70 @@ namespace nf7::core::luajit::test {
 
 class ContextFixture : public ::testing::TestWithParam<Context::Kind> {
  private:
-  template <TaskLike T>
-  class Driver final {
+  class AsyncDriver final {
    public:
-    using Param = typename T::Param;
-    using Time  = typename T::Time;
+    explicit AsyncDriver(ContextFixture& parent) noexcept : parent_(parent) { }
 
-    explicit Driver(Param p) : param_(std::forward<Param>(p)) { }
-
-    Driver(const Driver&) = delete;
-    Driver(Driver&&) = delete;
-    Driver& operator=(const Driver&) = delete;
-    Driver& operator=(Driver&&) = delete;
-
-    void BeginBusy() noexcept { }
-    void EndBusy() noexcept { interrupt_ = true; }
-    void Drive(T&& task) noexcept {
+    void BeginBusy() noexcept { async_busy_ = true; }
+    void EndBusy() noexcept {
+      async_busy_ = false;
+      async_busy_.notify_all();
+    }
+    void Drive(AsyncTask&& task) noexcept {
       try {
         task(param_);
       } catch (const Exception& e) {
-        std::cout
-            << "unexpected exception while task execution: " << e.what()
+        std::cerr
+            << "unexpected exception while async task execution: " << e.what()
             << std::endl;
         std::abort();
       }
     }
-    Time tick() const noexcept {
+    AsyncTask::Time tick() const noexcept {
       const auto now = std::chrono::system_clock::now();
-      return std::chrono::time_point_cast<typename Time::duration>(now);
+      return std::chrono::time_point_cast<AsyncTask::Time::duration>(now);
+    }
+    bool nextIdleInterruption() const noexcept { return !parent_.alive_; }
+    bool nextTaskInterruption() const noexcept { return false; }
+
+    void Wait() { async_busy_.wait(true); }
+
+   private:
+    ContextFixture& parent_;
+    AsyncTaskContext param_;
+
+    std::atomic<bool> async_busy_ = false;
+  };
+
+  class SyncDriver final {
+   public:
+    void BeginBusy() noexcept { }
+    void EndBusy() noexcept { interrupt_ = true; }
+    void Drive(SyncTask&& task) noexcept {
+      try {
+        task(param_);
+      } catch (const Exception& e) {
+        std::cerr
+            << "unexpected exception while sync task execution: " << e.what()
+            << std::endl;
+        std::abort();
+      }
+    }
+    SyncTask::Time tick() const noexcept {
+      const auto now = std::chrono::system_clock::now();
+      return std::chrono::time_point_cast<SyncTask::Time::duration>(now);
     }
     bool nextIdleInterruption() const noexcept { return interrupt_; }
     bool nextTaskInterruption() const noexcept { return false; }
 
    private:
     bool interrupt_ = false;
-    Param param_;
+    SyncTaskContext param_;
   };
 
+ public:
+  ContextFixture() noexcept : async_driver_(*this) { }
+
  protected:
   void SetUp() override {
     syncq_  = std::make_shared<SimpleTaskQueue<SyncTask>>();
@@ -76,28 +104,46 @@ class ContextFixture : public ::testing::TestWithParam<Context::Kind> {
         },
       },
     });
+    thread_ = std::thread {[this]() { asyncq_->Drive(async_driver_); }};
   }
   void TearDown() override {
     ConsumeTasks();
-    env_    = std::nullopt;
+    env_ = std::nullopt;
+
+    WaitAsyncTasks(std::chrono::seconds(3));
+    alive_ = false;
+    asyncq_->Wake();
+    thread_.join();
+
     asyncq_ = nullptr;
     syncq_  = nullptr;
   }
 
   void ConsumeTasks() noexcept {
-    AsyncTaskContext async_ctx;
-    Driver<AsyncTask> async_driver {async_ctx};
-    asyncq_->Drive(async_driver);
-
-    SyncTaskContext sync_ctx;
-    Driver<SyncTask> sync_driver {sync_ctx};
+    SyncDriver sync_driver;
     syncq_->Drive(sync_driver);
+
+    WaitAsyncTasks(std::chrono::seconds(1));
+  }
+  void WaitAsyncTasks(auto dur) noexcept {
+    if (!asyncq_->WaitForEmpty(dur)) {
+      std::cerr << "timeout while waiting for task execution" << std::endl;
+      std::abort();
+    }
+    async_driver_.Wait();
   }
 
  protected:
   std::shared_ptr<SimpleTaskQueue<SyncTask>> syncq_;
   std::shared_ptr<SimpleTaskQueue<AsyncTask>> asyncq_;
   std::optional<SimpleEnv> env_;
+
+ private:
+  std::atomic<bool> alive_ = true;
+  uint32_t async_cycle_ = 0;
+
+  std::thread thread_;
+  AsyncDriver async_driver_;
 };
 
 }  // namespace nf7::core::luajit::test

core/luajit/thread.hh

@@ -0,0 +1,93 @@
+// No copyright
+#pragma once
+
+#include <cassert>
+#include <functional>
+#include <memory>
+#include <utility>
+
+#include <lua.hpp>
+
+#include "core/luajit/context.hh"
+
+namespace nf7::core::luajit {
+
+class Thread : public std::enable_shared_from_this<Thread> {
+ public:
+  struct DoNotCallConstructorDirectly { };
+
+  enum State : uint8_t {
+    kPaused,
+    kRunning,
+    kFinished,
+  };
+
+ public:
+  template <typename T = Thread>
+  static std::shared_ptr<T> Make(
+      TaskContext& lua, const std::shared_ptr<Value>& func) {
+    DoNotCallConstructorDirectly key;
+    auto th = std::make_shared<T>(lua, key);
+    th->taskContext(lua).Query(*func);
+    return th;
+  }
+
+ public:
+  Thread(TaskContext& t, DoNotCallConstructorDirectly&) noexcept
+      : context_(t.context()), th_(lua_newthread(*t)) {
+    assert(th_);
+  }
+
+ public:
+  // if this finished with state_ kPaused,
+  // a responsibility to resume is on one who yielded
+  template <typename... Args>
+  void Resume(TaskContext& lua, Args&&... args) noexcept {
+    assert(lua.context() == context_);
+
+    if (kFinished == state_) {
+      return;
+    }
+    assert(kPaused == state_);
+
+    auto thlua = taskContext(lua);
+    const auto narg = thlua.PushAll(std::forward<Args>(args)...);
+
+    state_ = kRunning;
+    const auto ret = lua_resume(*thlua, narg);
+    switch (ret) {
+    case 0:
+      state_ = kFinished;
+      onExited(thlua);
+      return;
+    case LUA_YIELD:
+      state_ = kPaused;
+      return;
+    default:
+      state_ = kFinished;
+      onAborted(thlua);
+      return;
+    }
+  }
+
+  const std::shared_ptr<Context>& context() const noexcept { return context_; }
+  State state() const noexcept { return state_; }
+
+ protected:
+  virtual void onExited(TaskContext&) noexcept { }
+  virtual void onAborted(TaskContext&) noexcept { }
+
+ private:
+  TaskContext taskContext(const TaskContext& t) const noexcept {
+    assert(t.context() == context_);
+    return TaskContext {context_, th_};
+  }
+
+ private:
+  const std::shared_ptr<Context> context_;
+  lua_State* const th_;
+
+  State state_ = kPaused;
+};
+
+}  // namespace nf7::core::luajit

core/luajit/thread_test.cc

@@ -0,0 +1,79 @@
+// No copyright
+#include "core/luajit/thread.hh"
+#include "core/luajit/thread_test.hh"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "core/luajit/context_test.hh"
+
+
+class LuaJIT_Thread : public nf7::core::luajit::test::ContextFixture {
+ public:
+  using ContextFixture::ContextFixture;
+
+  template <typename... Args>
+  void TestThread(
+      const auto& setup, const char* script, Args&&... args) {
+    auto lua    = nf7::core::luajit::Context::Create(*env_, GetParam());
+    auto called = uint32_t {0};
+    lua->Exec([&](auto& lua) {
+      const auto compile = luaL_loadstring(*lua, script);
+      ASSERT_EQ(compile, LUA_OK);
+
+      auto sut = nf7::core::luajit::Thread::Make<
+          nf7::core::luajit::test::ThreadMock>(lua, lua.Register());
+      setup(*sut);
+
+      sut->Resume(lua, std::forward<Args>(args)...);
+      ++called;
+    });
+    ConsumeTasks();
+    EXPECT_EQ(called, 1);
+  }
+};
+
+
+TEST_P(LuaJIT_Thread, ResumeWithSingleReturn) {
+  TestThread([](auto& sut) {
+    EXPECT_CALL(sut, onExited)
+      .WillOnce([](auto& lua) { EXPECT_EQ(lua_tointeger(*lua, 1), 6); });
+  },
+  "return 1+2+3");
+}
+
+TEST_P(LuaJIT_Thread, ResumeWithArgs) {
+  TestThread([](auto& sut) {
+    EXPECT_CALL(sut, onExited)
+      .WillOnce([](auto& lua) { EXPECT_EQ(lua_tointeger(*lua, 1), 60); });
+  },
+  "local x,y,z = ...\nreturn x+y+z",
+  lua_Integer {10}, lua_Integer {20}, lua_Integer {30});
+}
+
+TEST_P(LuaJIT_Thread, RunWithMultipleReturn) {
+  TestThread([](auto& sut) {
+    EXPECT_CALL(sut, onExited)
+      .WillOnce([](auto& lua) {
+        EXPECT_EQ(lua_gettop(*lua), 3);
+        EXPECT_EQ(lua_tointeger(*lua, 1), 1);
+        EXPECT_EQ(lua_tointeger(*lua, 2), 2);
+        EXPECT_EQ(lua_tointeger(*lua, 3), 3);
+      });
+  },
+  "return 1, 2, 3");
+}
+
+TEST_P(LuaJIT_Thread, RunAndError) {
+  TestThread([](auto& sut) {
+    EXPECT_CALL(sut, onAborted);
+  },
+  "return foo()");
+}
+
+
+INSTANTIATE_TEST_SUITE_P(
+    SyncOrAsync, LuaJIT_Thread,
+    testing::Values(
+        nf7::core::luajit::Context::kSync,
+        nf7::core::luajit::Context::kAsync));

core/luajit/thread_test.hh

@@ -0,0 +1,21 @@
+// No copyright
+#pragma once
+
+#include "core/luajit/thread.hh"
+
+#include <gmock/gmock.h>
+
+#include "core/luajit/context.hh"
+
+
+namespace nf7::core::luajit::test {
+
+class ThreadMock : public Thread {
+ public:
+  using Thread::Thread;
+
+  MOCK_METHOD(void, onExited, (TaskContext&), (noexcept, override));
+  MOCK_METHOD(void, onAborted, (TaskContext&), (noexcept, override));
+};
+
+}  // namespace nf7::core::luajit::test

iface/common/task.hh

@@ -233,6 +233,12 @@ class SimpleTaskQueue : public TaskQueue<T> {
     cv_.notify_all();
   }
 
+  // THREAD-SAFE
+  bool WaitForEmpty(auto dur) noexcept {
+    std::unique_lock<std::mutex> k {mtx_};
+    return cv_.wait_for(k, dur, [this]() { return tasks_.empty(); });
+  }
+
   template <TaskDriverLike<Item> Driver>
   void Drive(Driver& driver) {
     while (!driver.nextIdleInterruption()) {
@@ -257,6 +263,7 @@ class SimpleTaskQueue : public TaskQueue<T> {
 
       try {
         std::unique_lock<std::mutex> k{mtx_};
+        cv_.notify_all();
 
         const auto until = nextAwake();
         const auto pred  = [&]() {

iface/common/task_test.cc

@@ -281,3 +281,36 @@ TEST(SimpleTaskQueue, ChaoticPushAndDrive) {
     EXPECT_EQ(execCount, kPushPerThread);
   }
 }
+
+TEST(SimpleTaskQueue, WaitForEmpty) {
+  nf7::test::SimpleTaskQueueMock<nf7::Task<int32_t&>> sut;
+  EXPECT_CALL(sut, onErrorWhilePush).Times(0);
+
+  // use NiceMock to suppress annoying warnings that slowed unittests
+  ::testing::NiceMock<
+      nf7::test::SimpleTaskQueueDriverMock<nf7::Task<int32_t&>>> driver;
+
+  for (uint32_t i = 0; i < 1000; ++i) {
+    sut.Exec([](auto&){});
+  }
+
+  auto ctx = int32_t {0};
+  ON_CALL(driver, Drive)
+      .WillByDefault([&](auto&& task) { task(ctx); });
+
+  std::atomic<bool> exit = false;
+  ON_CALL(driver, nextIdleInterruption)
+      .WillByDefault([&]() -> bool { return exit; });
+
+  std::thread th {[&]() { sut.Drive(driver); }};
+  EXPECT_TRUE(sut.WaitForEmpty(1s));
+
+  exit = true;
+  sut.Wake();
+  th.join();
+}
+
+TEST(SimpleTaskQueue, WaitForEmptyWhenEmpty) {
+  nf7::test::SimpleTaskQueueMock<nf7::Task<int32_t&>> sut;
+  EXPECT_TRUE(sut.WaitForEmpty(1s));
+}