[chore] refine

csrc/backend.cpp

@@ -53,12 +53,14 @@ void probe_asyncio(const std::string &backend)
 #else
             throw std::runtime_error("backend aio is not installed\n");
 #endif
-        } else {
+        } else if (backend == "pthread") {
 #ifndef DISABLE_PTHREAD
             aio.reset(new PthreadAsyncIO(2));
 #else
             throw std::runtime_error("backend pthread is not installed\n");
 #endif
+        } else {
+            throw std::runtime_error("unknown backend");
         }
 
         int fd = fileno(fp);
@@ -88,7 +90,7 @@ void probe_asyncio(const std::string &backend)
         for (int i = 0; i < n_loop; i++)
         {
             for (int j = 0; j < n_len; j++)
-            {   
+            {
                 assert(text[i][j] == new_text[i][j]);
             }
         }

csrc/pthread_backend.cpp

@@ -36,23 +36,21 @@ void PthreadAsyncIO::readv(int fd, const iovec *iov, unsigned int iovcnt, unsign
     this->read_fut.push_back(std::make_tuple(std::move(fut), callback));
 }
 
-
 void PthreadAsyncIO::get_event(WaitType wt) {
     if (wt == NOWAIT) return;
     this->sync_write_events();
     this->sync_read_events();
-
 }
 
 void PthreadAsyncIO::sync_write_events() {
     while (this->write_fut.size() > 0) {
         auto front = std::move(this->write_fut.front());
         this->write_fut.pop_front();
 
-        std::future<ssize_t> fut(std::move(std::get<0>(front)));
+        auto fut(std::move(std::get<0>(front)));
         fut.wait();
 
-        callback_t callback = std::get<1>(front);
+        auto callback = std::get<1>(front);
         if (callback != nullptr) {
             callback();
         }
@@ -64,10 +62,10 @@ void PthreadAsyncIO::sync_read_events() {
         auto front = std::move(this->read_fut.front());
         this->read_fut.pop_front();
 
-        std::future<ssize_t> fut(std::move(std::get<0>(front)));
+        auto fut(std::move(std::get<0>(front)));
         fut.wait();
 
-        callback_t callback = std::get<1>(front);
+        auto callback = std::get<1>(front);
         if (callback != nullptr) {
             callback();
         }

include/asyncio.h

@@ -8,7 +8,7 @@ using callback_t = std::function<void()>;
 enum IOType
 {
     WRITE,
-    READ,
+    READ
 };
 
 enum WaitType