delay the release mutex in the async queue only for mingw

include/spdlog/details/mpmc_blocking_q.h

@@ -30,26 +30,32 @@ public:
     {
     }
 
+#ifndef __MINGW32__
     // try to enqueue and block if no room left
     void enqueue(T &&item)
+    {
         {
             std::unique_lock<std::mutex> lock(queue_mutex_);
             pop_cv_.wait(lock, [this] { return !this->q_.full(); });
             q_.push_back(std::move(item));
+        }
         push_cv_.notify_one();
     }
 
     // enqueue immediately. overrun oldest message in the queue if no room left.
     void enqueue_nowait(T &&item)
+    {
         {
             std::unique_lock<std::mutex> lock(queue_mutex_);
             q_.push_back(std::move(item));
+        }
         push_cv_.notify_one();
     }
 
     // try to dequeue item. if no item found. wait upto timeout and try again
     // Return true, if succeeded dequeue item, false otherwise
     bool dequeue_for(T &popped_item, std::chrono::milliseconds wait_duration)
+    {
         {
             std::unique_lock<std::mutex> lock(queue_mutex_);
             if (!push_cv_.wait_for(lock, wait_duration, [this] { return !this->q_.empty(); }))
@@ -57,10 +63,48 @@ public:
                 return false;
             }
             q_.pop_front(popped_item);
+        }
         pop_cv_.notify_one();
         return true;
     }
 
+#else
+    // apparently mingw deadlocks if the mutex is released before cv.notify_one(),
+    // so release the mutex at the very end each function.
+
+    // try to enqueue and block if no room left
+    void enqueue(T &&item)
+    {
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        pop_cv_.wait(lock, [this] { return !this->q_.full(); });
+        q_.push_back(std::move(item));
+        push_cv_.notify_one();
+    }
+
+    // enqueue immediately. overrun oldest message in the queue if no room left.
+    void enqueue_nowait(T &&item)
+    {
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        q_.push_back(std::move(item));
+        push_cv_.notify_one();
+    }
+
+    // try to dequeue item. if no item found. wait upto timeout and try again
+    // Return true, if succeeded dequeue item, false otherwise
+    bool dequeue_for(T &popped_item, std::chrono::milliseconds wait_duration)
+    {
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        if (!push_cv_.wait_for(lock, wait_duration, [this] { return !this->q_.empty(); }))
+        {
+            return false;
+        }
+        q_.pop_front(popped_item);
+        pop_cv_.notify_one();
+        return true;
+    }
+
+#endif
+
 private:
     std::mutex queue_mutex_;
     std::condition_variable push_cv_;