discard policies on queue overflow

include/spdlog/async_logger.h

@@ -38,6 +38,7 @@
 #include <functional>
 #include "common.h"
 #include "logger.h"
+#include "spdlog.h"
 
 
 namespace spdlog
@@ -52,9 +53,9 @@ class async_logger :public logger
 {
 public:
     template<class It>
-    async_logger(const std::string& name, const It& begin, const It& end, size_t queue_size, const std::function<void()>& worker_warmup_cb = nullptr);
-    async_logger(const std::string& logger_name, sinks_init_list sinks, size_t queue_size, const std::function<void()>& worker_warmup_cb = nullptr);
-    async_logger(const std::string& logger_name, sink_ptr single_sink, size_t queue_size, const std::function<void()>& worker_warmup_cb = nullptr);
+    async_logger(const std::string& name, const It& begin, const It& end, size_t queue_size, const async_queue_overflow_policy overflow_policy = async_queue_overflow_policy::block_retry, const std::function<void()>& worker_warmup_cb = nullptr);
+    async_logger(const std::string& logger_name, sinks_init_list sinks, size_t queue_size, const async_queue_overflow_policy overflow_policy = async_queue_overflow_policy::block_retry, const std::function<void()>& worker_warmup_cb = nullptr);
+    async_logger(const std::string& logger_name, sink_ptr single_sink, size_t queue_size, const async_queue_overflow_policy overflow_policy = async_queue_overflow_policy::block_retry, const std::function<void()>& worker_warmup_cb = nullptr);
 
 
 protected:

include/spdlog/details/async_log_helper.h

@@ -109,7 +109,7 @@ public:
     using clock = std::chrono::steady_clock;
 
 
-    async_log_helper(formatter_ptr formatter, const std::vector<sink_ptr>& sinks, size_t queue_size, const std::function<void()>& worker_warmup_cb = nullptr);
+    async_log_helper(formatter_ptr formatter, const std::vector<sink_ptr>& sinks, size_t queue_size, const async_queue_overflow_policy overflow_policy = async_queue_overflow_policy::block_retry, const std::function<void()>& worker_warmup_cb = nullptr);
     void log(const details::log_msg& msg);
 
     //Stop logging and join the back thread
@@ -126,6 +126,9 @@ private:
     // last exception thrown from the worker thread
     std::shared_ptr<spdlog_ex> _last_workerthread_ex;
 	
+	// overflow policy
+	const async_queue_overflow_policy _overflow_policy;
+
     // worker thread warmup callback - one can set thread priority, affinity, etc
     const std::function<void()> _worker_warmup_cb;
 
@@ -150,10 +153,11 @@ private:
 ///////////////////////////////////////////////////////////////////////////////
 // async_sink class implementation
 ///////////////////////////////////////////////////////////////////////////////
-inline spdlog::details::async_log_helper::async_log_helper(formatter_ptr formatter, const std::vector<sink_ptr>& sinks, size_t queue_size, const std::function<void()>& worker_warmup_cb):
+inline spdlog::details::async_log_helper::async_log_helper(formatter_ptr formatter, const std::vector<sink_ptr>& sinks, size_t queue_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb):
     _formatter(formatter),
     _sinks(sinks),
     _q(queue_size),
+	_overflow_policy(overflow_policy),
     _worker_warmup_cb(worker_warmup_cb),
     _worker_thread(&async_log_helper::worker_loop, this)
 {}
@@ -178,7 +182,7 @@ inline void spdlog::details::async_log_helper::log(const details::log_msg& msg)
 {
     throw_if_bad_worker();
     async_msg new_msg(msg);
-    if (!_q.enqueue(std::move(new_msg)))
+    if (!_q.enqueue(std::move(new_msg)) && _overflow_policy != async_queue_overflow_policy::discard_log_msg)
     {
         auto last_op_time = clock::now();
         do

include/spdlog/details/async_logger_impl.h

@@ -34,17 +34,17 @@
 
 
 template<class It>
-inline spdlog::async_logger::async_logger(const std::string& logger_name, const It& begin, const It& end, size_t queue_size, const std::function<void()>& worker_warmup_cb) :
+inline spdlog::async_logger::async_logger(const std::string& logger_name, const It& begin, const It& end, size_t queue_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb) :
     logger(logger_name, begin, end),
-    _async_log_helper(new details::async_log_helper(_formatter, _sinks, queue_size, worker_warmup_cb))
+    _async_log_helper(new details::async_log_helper(_formatter, _sinks, queue_size, overflow_policy, worker_warmup_cb))
 {
 }
 
-inline spdlog::async_logger::async_logger(const std::string& logger_name, sinks_init_list sinks, size_t queue_size, const std::function<void()>& worker_warmup_cb) :
-    async_logger(logger_name, sinks.begin(), sinks.end(), queue_size, worker_warmup_cb) {}
+inline spdlog::async_logger::async_logger(const std::string& logger_name, sinks_init_list sinks, size_t queue_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb) :
+    async_logger(logger_name, sinks.begin(), sinks.end(), queue_size, overflow_policy, worker_warmup_cb) {}
 
-inline spdlog::async_logger::async_logger(const std::string& logger_name, sink_ptr single_sink, size_t queue_size, const std::function<void()>& worker_warmup_cb) :
-    async_logger(logger_name, { single_sink }, queue_size, worker_warmup_cb) {}
+inline spdlog::async_logger::async_logger(const std::string& logger_name, sink_ptr single_sink, size_t queue_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb) :
+    async_logger(logger_name, { single_sink }, queue_size, overflow_policy, worker_warmup_cb) {}
 
 
 inline void spdlog::async_logger::_set_formatter(spdlog::formatter_ptr msg_formatter)

include/spdlog/details/registry.h

@@ -62,7 +62,7 @@ public:
             return found->second;
         std::shared_ptr<logger> new_logger;
         if (_async_mode)
-            new_logger = std::make_shared<async_logger>(logger_name, sinks_begin, sinks_end, _async_q_size, _worker_warmup_cb);
+            new_logger = std::make_shared<async_logger>(logger_name, sinks_begin, sinks_end, _async_q_size, _overflow_policy, _worker_warmup_cb);
         else
             new_logger = std::make_shared<logger>(logger_name, sinks_begin, sinks_end);
 
@@ -120,11 +120,12 @@ public:
             l.second->set_level(log_level);
     }
 
-    void set_async_mode(size_t q_size, const std::function<void()>& worker_warmup_cb = nullptr)
+    void set_async_mode(size_t q_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb)
     {
         std::lock_guard<std::mutex> lock(_mutex);
         _async_mode = true;
         _async_q_size = q_size;
+		_overflow_policy = overflow_policy;
 		_worker_warmup_cb = worker_warmup_cb;
     }
 
@@ -151,6 +152,7 @@ private:
     level::level_enum _level = level::info;
     bool _async_mode = false;
     size_t _async_q_size = 0;
+	async_queue_overflow_policy _overflow_policy = async_queue_overflow_policy::block_retry;
 	std::function<void()> _worker_warmup_cb = nullptr;
 };
 }

include/spdlog/details/spdlog_impl.h

@@ -132,9 +132,9 @@ inline void spdlog::set_level(level::level_enum log_level)
 }
 
 
-inline void spdlog::set_async_mode(size_t queue_size, const std::function<void()>& worker_warmup_cb)
+inline void spdlog::set_async_mode(size_t queue_size, const async_queue_overflow_policy overflow_policy, const std::function<void()>& worker_warmup_cb)
 {
-    details::registry::instance().set_async_mode(queue_size, worker_warmup_cb);
+    details::registry::instance().set_async_mode(queue_size, overflow_policy, worker_warmup_cb);
 }
 
 inline void spdlog::set_sync_mode()

include/spdlog/spdlog.h

@@ -61,9 +61,14 @@ void set_level(level::level_enum log_level);
 // Async mode - off by default.
 //
 
+enum class async_queue_overflow_policy {
+	block_retry, // Block / yield / sleep until message can be enqueued
+	discard_log_msg // Discard the message it enqueue fails
+};
+
 // Turn on async mode and set the queue size for each async_logger
 
-void set_async_mode(size_t queue_size, const std::function<void()>& worker_warmup_cb = nullptr);
+void set_async_mode(size_t queue_size, const async_queue_overflow_policy overflow_policy = async_queue_overflow_policy::block_retry, const std::function<void()>& worker_warmup_cb = nullptr);
 // Turn off async mode
 void set_sync_mode();