一：日志接口
TrinityCore的日志有六个级别：Trace，Debug，Info，Warn，Error，Fatal
它们分别对应以下这六个接口，（filterType__也是在配置文件中指定的）
#define TC_LOG_TRACE(filterType__, ...)#define TC_LOG_DEBUG(filterType__, ...)#define TC_LOG_INFO(filterType__, ...)#define TC_LOG_WARN(filterType__, ...)#define TC_LOG_ERROR(filterType__, ...)#define TC_LOG_FATAL(filterType__, ...)
二：日志类型与Appender
说明：这个在配置文件的注释中说得很详细，直接帖两段吧
Appender配置：
# Appender config values: Given a appender "name"# Appender.name# Description: Defines 'where to log'# Format:Type,LogLevel,Flags,optional1,optional2,optional3## Type#0 - (None)#1 - (Console)#2 - (File)#3 - (DB)## LogLevel#0 - (Disabled)#1 - (Trace)#2 - (Debug)#3 - (Info)#4 - (Warn)#5 - (Error)#6 - (Fatal)## Flags:#0 - None#1 - Prefix Timestamp to the text#2 - Prefix Log Level to the text#4 - Prefix Log Filter type to the text#8 - Append timestamp to the log file name. Format: YYYY-MM-DD_HH-MM-SS (Only used with Type = 2)# 16 - Make a backup of existing file before overwrite (Only used with Mode = w)## Colors (read as optional1 if Type = Console)#Format: "fatal error warn info debug trace"#0 - BLACK#1 - RED#2 - GREEN#3 - BROWN#4 - BLUE#5 - MAGENTA#6 - CYAN#7 - GREY#8 - YELLOW#9 - LRED# 10 - LGREEN# 11 - LBLUE# 12 - LMAGENTA# 13 - LCYAN# 14 - WHITE## File: Name of the file (read as optional1 if Type = File)#Allows to use one "%s" to create dynamic files## Mode: Mode to open the file (read as optional2 if Type = File)#a - (Append)#w - (Overwrite)## MaxFileSize: Maximum file size of the log file before creating a new log file
日志配置：
# Appender config values: Given a appender "name"# Appender.name# Description: Defines 'where to log'# Format:Type,LogLevel,Flags,optional1,optional2,optional3## Type#0 - (None)#1 - (Console)#2 - (File)#3 - (DB)## LogLevel#0 - (Disabled)#1 - (Trace)#2 - (Debug)#3 - (Info)#4 - (Warn)#5 - (Error)#6 - (Fatal)## Flags:#0 - None#1 - Prefix Timestamp to the text#2 - Prefix Log Level to the text#4 - Prefix Log Filter type to the text#8 - Append timestamp to the log file name. Format: YYYY-MM-DD_HH-MM-SS (Only used with Type = 2)# 16 - Make a backup of existing file before overwrite (Only used with Mode = w)## Colors (read as optional1 if Type = Console)#Format: "fatal error warn info debug trace"#0 - BLACK#1 - RED#2 - GREEN#3 - BROWN#4 - BLUE#5 - MAGENTA#6 - CYAN#7 - GREY#8 - YELLOW#9 - LRED# 10 - LGREEN# 11 - LBLUE# 12 - LMAGENTA# 13 - LCYAN# 14 - WHITE## File: Name of the file (read as optional1 if Type = File)#Allows to use one "%s" to create dynamic files## Mode: Mode to open the file (read as optional2 if Type = File)#a - (Append)#w - (Overwrite)## MaxFileSize: Maximum file size of the log file before creating a new log file
三：配置例子：
Appender.Console=1,3,0Appender.Server=2,2,0,Server.log,wLogger.root=2,Console Server
以上这三句，定义了两个Appender:Console, Server，一个log type:root
Appender.Console说明将日志输出到终端上，最低输出级别是Info，输出字体颜色是黑色（因终端的不同而不同）
Appender.Server说明将日志输出到文件，最低输出级别是Debug，输出文件是（Server.log），以重写（非添加）的方式写入
Logger.root最低输出级别是Info，使用Console和Server的配置
四，底层实现
这里简单地说一下，就不太深入了
以TC_LOG_INFO("qch", "Hello, world");为例子
这句实现上是调用了
if(Log::instance()::ShouldLog("qch", LOG_LEVEL_INFO) )Log::instance()::outMessage ("qch", LOG_LEVEL_INFO, "Hello,world");
ShouldLog比较好理解，直接将配置文件中的最低日志输出级别和LOG_LEVEL_INFO一比较就搞定。
outMessage就比较麻烦了，层层调用，有兴趣的可以去看看，这里就不多作解释了。
如果把Appender的Type设为3（DB），那每写一条日志，就是在auth库的logs表中插入一条记录：
INSERT INTO logs (time, realm, type, level, string) VALUES (1409544332, 0, 'qch', 3,'Hello, world\n')
