Shared/Logs: Improve log performances

Improve Log::ShouldLog() performances by saving the lowest log level across all loggers and discarding any log with lower level than that.

src/server/shared/Logging/Log.cpp

@@ -199,6 +199,9 @@ void Log::CreateLoggerFromConfig(std::string const& appenderName)
         return;
     }
 
+    if (level < lowestLogLevel)
+        lowestLogLevel = level;
+
     logger.Create(name, level);
     //fprintf(stdout, "Log::CreateLoggerFromConfig: Created Logger %s, Level %u\n", name.c_str(), level);
 
@@ -394,6 +397,7 @@ void Log::LoadFromConfig()
 {
     Close();
 
+    lowestLogLevel = LOG_LEVEL_FATAL;
     AppenderId = 0;
     m_logsDir = sConfigMgr->GetStringDefault("LogsDir", "");
     if (!m_logsDir.empty())

src/server/shared/Logging/Log.h

@@ -82,6 +82,7 @@ class Log
         AppenderMap appenders;
         LoggerMap loggers;
         uint8 AppenderId;
+        LogLevel lowestLogLevel;
 
         std::string m_logsDir;
         std::string m_logsTimestamp;
@@ -113,6 +114,10 @@ inline bool Log::ShouldLog(std::string const& type, LogLevel level) const
     // Speed up in cases where requesting "Type.sub1.sub2" but only configured
     // Logger "Type"
 
+    // Don't even look for a logger if the LogLevel is lower than lowest log levels across all loggers
+    if (level < lowestLogLevel)
+        return false;
+
     Logger const* logger = GetLoggerByType(type);
     if (!logger)
         return false;