implemented async_logger::sync()

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)
@@ -88,3 +90,35 @@ SPDLOG_INLINE std::shared_ptr<spdlog::logger> spdlog::async_logger::clone(std::s
     cloned->name_ = std::move(new_name);
     return cloned;
 }
+
+SPDLOG_INLINE bool spdlog::async_logger::sync(int intervalMs, int timeoutMs)
+{
+    using namespace std::chrono;
+
+    auto tp=thread_pool_.lock();
+    assert(tp);
+
+    if (tp->queue_size()==0)
+        return true;
+      
+    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=(tp->queue_size()==0);
+
+        if (!indef)
+        {
+            auto now=steady_clock::now();
+            auto passedMs=duration_cast<milliseconds>(now-start);
+            start=now;
+            timeoutMs-=passedMs.count();
+        }
+    } while ((!indef && timeoutMs>0 || indef) && !synced);
+    return synced;
+}

include/spdlog/async_logger.h

@@ -51,6 +51,14 @@ public:
 
     std::shared_ptr<logger> clone(std::string new_name) override;
 
+    /**
+     * @brief block until all messages in thread_pool_ are processed
+     * @param intervalMs check whether should return or not on every 'intervalMs' milliseconds
+     * @param timeoutMs timeout in milliseconds. -1 means to wait indefinitely
+     * @return true: all messages in thread_pool_ are processed, false: otherwise
+    */
+    bool sync(int intervalMs=100, int timeoutMs=-1);
+
 protected:
     void sink_it_(const details::log_msg &msg) override;
     void flush_() override;