4.6.1. 基本¶

ets:tab2list(lager_config).

{parse_transform, lager_transform}

交流:

freenode:10 pm UTC,every third Thursday
https://github.com/erlang-lager/lager
其他backend
https://github.com/jbrisbin/lager_amqp_backend

Sink configuration:

lager:info  => lager_event
audit:info  => audit_lager_event
myCompanyName:debug  => myCompanyName_lager_event

// rebar.config
{lager_extra_sinks, [audit]}

Error logger integration:

error_logger_redirect   => true: //把系统error_logger转为lager的error_logger
error_logger_format_raw => true: //disable reformatting for OTP and Cowboy messages

Asynchronous mode:

% 小于20使用异步,超过20切换回同步,小于20-5再切换回异步
% 原因: 异步不可控,会把系统crash
{async_threshold, 20},
{async_threshold_window, 5}
% 如果想一直异步模式
{async_threshold, 20},

% 可设定每秒最大日志数
{error_logger_hwm, 50}

Event queue flushing:

% 超过戒备线,会flush all event notifications in the message queue
% 而这会对other handlers in the same event manager造成意外后果
% 默认是true,可以关闭
{error_logger_flush_queue, true | false}

%
{flush_queue, true | false}
% flush_queue为true时可以设置threshold
% 设定error_logger sink的阀值
{error_logger_flush_threshold, 1000}

%对所有的sinks
{flush_threshold, 1000}

Sink Killer:

// 有时你需要丢弃所有pending日志消息而不是让他耗光时间
// if the gen_event mailbox exceeds a configurable high water mark,
// the sink will be killed and reinstalled after a configurable cool down time

//例:
{killer_hwm, 1000},
{killer_reinstall_after, 5000}
% This means if the sink's mailbox size exceeds 1000 messages, kill the entire sink and reload it after 5000 milliseconds
% By default, the manager killer is not installed into any sink. If the killer_reinstall_after cool down time is not specified it defaults to 5000.

Runtime loglevel changes:

// 确定有哪几个event
gen_event:which_handlers(lager_event).
// 设定指定event到指定级别
lager:set_loglevel(lager_console_backend, debug).
lager:set_loglevel(lager_file_backend, "console.log", debug).