From d52cf87d7127b3dad44f5ef1f888f8f006ab0e4e Mon Sep 17 00:00:00 2001
From: gabime <gmelman1@gmail.com>
Date: Tue, 17 Sep 2019 11:56:17 +0300
Subject: [PATCH] Avoid un necessary move when popping circular_q

---
 include/spdlog/details/backtracer-inl.h  |  6 +++---
 include/spdlog/details/circular_q.h      | 21 ++++++++++++++-------
 include/spdlog/details/mpmc_blocking_q.h |  3 ++-
 include/spdlog/sinks/daily_file_sink.h   |  4 ++--
 4 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/include/spdlog/details/backtracer-inl.h b/include/spdlog/details/backtracer-inl.h
index 910a7192..5d6de81c 100644
--- a/include/spdlog/details/backtracer-inl.h
+++ b/include/spdlog/details/backtracer-inl.h
@@ -65,9 +65,9 @@ SPDLOG_INLINE void backtracer::foreach_pop(std::function<void(const details::log
     std::lock_guard<std::mutex> lock{mutex_};
     while (!messages_.empty())
     {
-        log_msg_buffer popped;
-        messages_.pop_front(popped);
-        fun(popped);
+        auto &front_msg = messages_.front();
+        messages_.pop_front();
+        fun(front_msg);
     }
 }
 } // namespace details
diff --git a/include/spdlog/details/circular_q.h b/include/spdlog/details/circular_q.h
index c5e3d20b..5d15c8ab 100644
--- a/include/spdlog/details/circular_q.h
+++ b/include/spdlog/details/circular_q.h
@@ -60,15 +60,18 @@ public:
         }
     }
 
+    // Return reference to the front item.
+    // If there are no elements in the container, the behavior is undefined.
+    T& front()
+    {
+        return v_[head_];
+    }
+
     // Pop item from front.
     // If there are no elements in the container, the behavior is undefined.
-    void pop_front(T &popped_item)
+    void pop_front()
     {
-        if (max_items_ > 0)
-        {
-            popped_item = std::move(v_[head_]);
-            head_ = (head_ + 1) % max_items_;
-        }
+        head_ = (head_ + 1) % max_items_;
     }
 
     bool empty() const
@@ -79,7 +82,11 @@ public:
     bool full() const
     {
         // head is ahead of the tail by 1
-        return ((tail_ + 1) % max_items_) == head_;
+        if(max_items_ > 0)
+        {
+            return ((tail_ + 1) % max_items_) == head_;
+        }
+        return true;
     }
 
     size_t overrun_counter() const
diff --git a/include/spdlog/details/mpmc_blocking_q.h b/include/spdlog/details/mpmc_blocking_q.h
index d8a1efe2..1a0a303c 100644
--- a/include/spdlog/details/mpmc_blocking_q.h
+++ b/include/spdlog/details/mpmc_blocking_q.h
@@ -59,7 +59,8 @@ public:
             {
                 return false;
             }
-            q_.pop_front(popped_item);
+            popped_item = std::move(q_.front());
+            q_.pop_front();
         }
         pop_cv_.notify_one();
         return true;
diff --git a/include/spdlog/sinks/daily_file_sink.h b/include/spdlog/sinks/daily_file_sink.h
index 7dbc9916..59cf52d4 100644
--- a/include/spdlog/sinks/daily_file_sink.h
+++ b/include/spdlog/sinks/daily_file_sink.h
@@ -139,8 +139,8 @@ private:
         filename_t current_file = filename();
         if (filenames_q_.full())
         {
-            filename_t old_filename;
-            filenames_q_.pop_front(old_filename);
+            auto &old_filename = filenames_q_.front();
+            filenames_q_.pop_front();
             bool ok = remove_if_exists(old_filename) == 0;
             if (!ok)
             {