魔兽世界服务器Trinitycore分析三：日志模块
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=1,3,0
Appender.Server=2,2,0,Server.log,w
Logger.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')