Proposal for fixing the issue skypjack#292

Signed-off-by: Fiorentino, Stefano <stefano.fiorentino@adesso.ch>

src/uvw/thread.cpp

@@ -9,7 +9,8 @@ namespace uvw {
 UVW_INLINE thread::thread(loop::token token, std::shared_ptr<loop> ref, task t, std::shared_ptr<void> d) noexcept
     : uv_type{token, std::move(ref)},
       data{std::move(d)},
-      func{std::move(t)} {}
+      func{std::move(t)},
+      joined{false} {}
 
 UVW_INLINE void thread::create_callback(void *arg) {
     thread &curr = *(static_cast<thread *>(arg));
@@ -42,7 +43,11 @@ UVW_INLINE bool thread::run(create_flags opts, std::size_t stack) noexcept {
 }
 
 UVW_INLINE bool thread::join() noexcept {
-    return (0 == uv_thread_join(raw()));
+    if(!joined && 0 == uv_thread_join(raw())) {
+        joined = true;
+        return joined;
+    }
+    return false;
 }
 
 UVW_INLINE thread_local_storage::thread_local_storage(loop::token token, std::shared_ptr<loop> ref) noexcept

src/uvw/thread.h

@@ -106,6 +106,7 @@ class thread final: public uv_type<uv_thread_t> {
 private:
     std::shared_ptr<void> data;
     task func;
+    bool joined;
 };
 
 /**

test/uvw/thread.cpp

@@ -19,6 +19,17 @@ TEST(Thread, Run) {
     loop->run();
 }
 
+TEST(Thread, Join) {
+    auto loop = uvw::loop::get_default();
+    auto cb = [](std::shared_ptr<void> d) -> void {
+    };
+
+    auto handle = loop->resource<uvw::thread>(cb);
+    handle->run();
+    ASSERT_TRUE(handle->join());
+    ASSERT_FALSE(handle->join());
+}
+
 TEST(ThreadLocalStorage, SetGet) {
     auto loop = uvw::loop::get_default();
     auto localStorage = loop->resource<uvw::thread_local_storage>();