implemented async_logger::sync() to solve issue #1696

include/spdlog/async_logger-inl.h

@@ -13,6 +13,8 @@
 #include <memory>
 #include <string>
 
+#include <chrono>
+
 SPDLOG_INLINE spdlog::async_logger::async_logger(
  std::string logger_name, sinks_init_list sinks_list, std::weak_ptr<details::thread_pool> tp, async_overflow_policy overflow_policy)
  : async_logger(std::move(logger_name), sinks_list.begin(), sinks_list.end(), std::move(tp), overflow_policy)

include/spdlog/details/thread_pool-inl.h

@@ -85,6 +85,32 @@ size_t SPDLOG_INLINE thread_pool::queue_size()
  return q_.size();
 }
 
+SPDLOG_INLINE bool thread_pool::sync(int intervalMs, int timeoutMs)
+{
+ using namespace std::chrono;
+
+ auto start=steady_clock::now();
+ bool synced=false;
+ bool indef=(timeoutMs<=0);
+ do
+ {
+ if (!indef && intervalMs>timeoutMs)
+ intervalMs=timeoutMs; 
+
+ std::this_thread::sleep_for(milliseconds(intervalMs));
+ synced=(q_.size()==0);
+
+ if (!indef)
+ {
+ auto now=steady_clock::now();
+ auto passedMs=duration_cast<milliseconds>(now-start);
+ start=now;
+ timeoutMs-=static_cast<int>(passedMs.count());
+ }
+ } while (((!indef && timeoutMs>0) || indef) && !synced);
+ return synced;
+}
+
 void SPDLOG_INLINE thread_pool::post_async_msg_(async_msg &&new_msg, async_overflow_policy overflow_policy)
 {
  if (overflow_policy == async_overflow_policy::block)

include/spdlog/details/thread_pool.h

@@ -100,6 +100,9 @@ class SPDLOG_API thread_pool
  void reset_overrun_counter();
  size_t queue_size();
 
+ // block until all messages in thread pool are processed or the timer goes off.
+ bool sync(int intervalMs=100, int timeoutMs=-1);
+
 private:
  q_type q_;