Log stable filename (#2534)

* Support stable log filename on rotation

* Add to toml test

nano/core_test/toml.cpp

@@ -202,6 +202,7 @@ TEST (toml, daemon_config_deserialize_defaults)
 	ASSERT_EQ (conf.node.logging.network_telemetry_logging_value, defaults.node.logging.network_telemetry_logging_value);
 	ASSERT_EQ (conf.node.logging.rotation_size, defaults.node.logging.rotation_size);
 	ASSERT_EQ (conf.node.logging.single_line_record_value, defaults.node.logging.single_line_record_value);
+	ASSERT_EQ (conf.node.logging.stable_log_filename, defaults.node.logging.stable_log_filename);
 	ASSERT_EQ (conf.node.logging.timing_logging_value, defaults.node.logging.timing_logging_value);
 	ASSERT_EQ (conf.node.logging.active_update_value, defaults.node.logging.active_update_value);
 	ASSERT_EQ (conf.node.logging.upnp_details_logging_value, defaults.node.logging.upnp_details_logging_value);
@@ -467,6 +468,7 @@ TEST (toml, daemon_config_deserialize_no_defaults)
 	node_lifetime_tracing = true
 	rotation_size = 999
 	single_line_record = true
+	stable_log_filename = true
 	timing = true
 	active_update = true
 	upnp_details = true
@@ -598,6 +600,7 @@ TEST (toml, daemon_config_deserialize_no_defaults)
 	ASSERT_NE (conf.node.logging.node_lifetime_tracing_value, defaults.node.logging.node_lifetime_tracing_value);
 	ASSERT_NE (conf.node.logging.rotation_size, defaults.node.logging.rotation_size);
 	ASSERT_NE (conf.node.logging.single_line_record_value, defaults.node.logging.single_line_record_value);
+	ASSERT_NE (conf.node.logging.stable_log_filename, defaults.node.logging.stable_log_filename);
 	ASSERT_NE (conf.node.logging.timing_logging_value, defaults.node.logging.timing_logging_value);
 	ASSERT_NE (conf.node.logging.active_update_value, defaults.node.logging.active_update_value);
 	ASSERT_NE (conf.node.logging.upnp_details_logging_value, defaults.node.logging.upnp_details_logging_value);

nano/node/logging.cpp

@@ -68,9 +68,48 @@ void nano::logging::init (boost::filesystem::path const & application_path_a)
 #endif
 		}
 
-		auto path = application_path_a / "log";
+//clang-format off
-		file_sink = boost::log::add_file_log (boost::log::keywords::target = path, boost::log::keywords::file_name = path / "log_%Y-%m-%d_%H-%M-%S.%N.log", boost::log::keywords::rotation_size = rotation_size, boost::log::keywords::auto_flush = flush, boost::log::keywords::scan_method = boost::log::sinks::file::scan_method::scan_matching, boost::log::keywords::max_size = max_size, boost::log::keywords::format = format_with_timestamp);
+#if BOOST_VERSION < 107000
+		if (stable_log_filename)
+		{
+			stable_log_filename = false;
+			std::cerr << "The stable_log_filename config setting is only available when building with Boost 1.70 or later. Reverting to old behavior." << std::endl;
 		}
+#endif
+
+		auto path = application_path_a / "log";
+		if (stable_log_filename)
+		{
+#if BOOST_VERSION >= 107000
+			// Logging to node.log and node_<pattern> instead of log_<pattern>.log is deliberate. This way,
+			// existing log monitoring scripts expecting the old logfile structure will fail immediately instead
+			// of reading only rotated files with old entries.
+			file_sink = boost::log::add_file_log (boost::log::keywords::target = path,
+			boost::log::keywords::file_name = path / "node.log",
+			boost::log::keywords::target_file_name = path / "node_%Y-%m-%d_%H-%M-%S.%N.log",
+			boost::log::keywords::open_mode = std::ios_base::out | std::ios_base::app, // append to node.log if it exists
+			boost::log::keywords::enable_final_rotation = false, // for stable log filenames, don't rotate on destruction
+			boost::log::keywords::rotation_size = rotation_size, // max file size in bytes before rotation
+			boost::log::keywords::auto_flush = flush,
+			boost::log::keywords::scan_method = boost::log::sinks::file::scan_method::scan_matching,
+			boost::log::keywords::max_size = max_size, // max total size in bytes of all log files
+			boost::log::keywords::format = format_with_timestamp);
+#else
+			assert (false);
+#endif
+		}
+		else
+		{
+			file_sink = boost::log::add_file_log (boost::log::keywords::target = path,
+			boost::log::keywords::file_name = path / "log_%Y-%m-%d_%H-%M-%S.%N.log",
+			boost::log::keywords::rotation_size = rotation_size,
+			boost::log::keywords::auto_flush = flush,
+			boost::log::keywords::scan_method = boost::log::sinks::file::scan_method::scan_matching,
+			boost::log::keywords::max_size = max_size,
+			boost::log::keywords::format = format_with_timestamp);
+		}
+	}
+	//clang-format on
 }
 
 void nano::logging::release_file_sink ()
@@ -109,6 +148,7 @@ nano::error nano::logging::serialize_toml (nano::tomlconfig & toml) const
 	toml.put ("flush", flush, "If enabled, immediately flush new entries to log file.\nWarning: this may negatively affect logging performance.\ntype:bool");
 	toml.put ("min_time_between_output", min_time_between_log_output.count (), "Minimum time that must pass for low priority entries to be logged.\nWarning: decreasing this value may result in a very large amount of logs.\ntype:milliseconds");
 	toml.put ("single_line_record", single_line_record_value, "Keep log entries on single lines.\ntype:bool");
+	toml.put ("stable_log_filename", stable_log_filename, "Append to log/node.log without a timestamp in the filename.\nThe file is not emptied on startup if it exists, but appended to.\ntype:bool");
 
 	return toml.get_error ();
 }
@@ -142,6 +182,7 @@ nano::error nano::logging::deserialize_toml (nano::tomlconfig & toml)
 	auto min_time_between_log_output_l = min_time_between_log_output.count ();
 	toml.get ("min_time_between_output", min_time_between_log_output_l);
 	min_time_between_log_output = std::chrono::milliseconds (min_time_between_log_output_l);
+	toml.get ("stable_log_filename", stable_log_filename);
 
 	return toml.get_error ();
 }

nano/node/logging.hpp

@@ -89,6 +89,7 @@ public:
 	bool flush{ true };
 	uintmax_t max_size{ 128 * 1024 * 1024 };
 	uintmax_t rotation_size{ 4 * 1024 * 1024 };
+	bool stable_log_filename{ false };
 	std::chrono::milliseconds min_time_between_log_output{ 5 };
 	bool single_line_record_value{ false };
 	static void release_file_sink ();