Move ringbuffer_sink to spdlog::details::circular_q, enhance its API:…

… size(), at(i)

include/spdlog/details/circular_q.h

@@ -72,6 +72,20 @@ class circular_q
         return v_[head_];
     }
 
+    // Return number of elements actually stored
+    size_t size() const
+    {
+        return (tail_ - head_) % max_items_;
+    }
+
+    // Return const reference to item by index.
+    // If index is out of range 0…size()-1, the behavior is undefined.
+    const T &at(size_t i) const
+    {
+        assert(i < size());
+        return v_[(head_+ i) % max_items_];
+    }
+
     // Pop item from front.
     // If there are no elements in the container, the behavior is undefined.
     void pop_front()

include/spdlog/sinks/ringbuffer_sink-inl.h

@@ -10,23 +10,21 @@
 #include "spdlog/common.h"
 #include "spdlog/details/os.h"
 
-#include<boost/circular_buffer.hpp>
-
 namespace spdlog {
 namespace sinks {
 
 template<typename Mutex>
 SPDLOG_INLINE ringbuffer_sink<Mutex>::ringbuffer_sink(size_t buf_size)
 {
-    buf.set_capacity(buf_size);
+    buf=details::circular_q<std::string>(buf_size);
 }
 
 template<typename Mutex>
 SPDLOG_INLINE void ringbuffer_sink<Mutex>::sink_it_(const details::log_msg &msg)
 {
     memory_buf_t formatted;
     base_sink<Mutex>::formatter_->format(msg, formatted);
-    buf.push_front(fmt::to_string(formatted));
+    buf.push_back(fmt::to_string(formatted));
 }
 
 template<typename Mutex>
@@ -36,9 +34,9 @@ SPDLOG_INLINE std::vector<std::string> ringbuffer_sink<Mutex>::last(size_t lim)
     std::vector<std::string> ret;
     ret.reserve(lim);
     size_t num=0;
-    for(const std::string& msg: buf){
+    for(size_t i=0; i<buf.size(); i++){
         num++;
-        ret.push_back(msg);
+        ret.push_back(buf.at(i));
         if(lim>0 && num==lim) break;
     }
     return ret;

include/spdlog/sinks/ringbuffer_sink.h

@@ -6,13 +6,12 @@
 #include "spdlog/details/null_mutex.h"
 #include "spdlog/sinks/base_sink.h"
 #include "spdlog/details/synchronous_factory.h"
+#include "spdlog/details/circular_q.h"
 
 #include <mutex>
 #include <string>
 #include <vector>
 
-#include<boost/circular_buffer.hpp>
-
 namespace spdlog {
 namespace sinks {
 /*
@@ -30,7 +29,7 @@ class ringbuffer_sink final : public base_sink<Mutex>
     void flush_() override {};
 
 private:
-    boost::circular_buffer<std::string> buf;
+    details::circular_q<std::string> buf;
 };
 
 using ringbuffer_sink_mt = ringbuffer_sink<std::mutex>;