Nodejs 一个简单的日志module

一个简单的日志module, 功能如下 <ul> <li>时间显示</li> <li>调用log的文件名与行号显示</li> <li>不同日志级别使用不同颜色输出</li> <li>支持stdout输出的同时写入文件日志</li> <li>文件日志使用缓存以降低io次数</li> </ul> 使用示例 <pre escaped=“true” lang=“javascript”>var log = require(’./log’), logWithoutFile = log.create(); logWithFile = log.create(log.WARNING, ‘my.log’), logWithoutFile.info(‘info msg’); logWithoutFile.debug(‘debug msg’); logWithoutFile.warning(‘warning msg’); logWithoutFile.error(‘error msg’); logWithoutFile.trace(‘trace msg’); logWithFile.info(‘info msg’); logWithFile.debug(‘debug msg’); logWithFile.warning(‘warning msg’); logWithFile.error(‘error msg’); logWithFile.trace(‘trace msg’);</pre> 输出效果 <img title=“cnode-log-demo.jpg” src=“http://static.data.taobaocdn.com/up/nodeclub/2011/03/cnode-log-demo.jpg” border=“0” alt=“cnode-log-demo” width=“579” height=“159” /> 源码如下 <pre escaped=“true” lang=“javascript”>var fs = require(‘fs’); var cwd = process.cwd() + ‘/’, INFO = 0; DEBUG = 1; WARNING = 2; ERROR = 3; TRACE = 4; INIT = 6; type = [‘INFO’, ‘DEBUG’, ‘WARNING’, ‘ERROR’, ‘TRACE’, ‘’, ‘LOG_INIT’]; colors = [38, 34, 35, 31, 32, 36, 33]; bufferSize = 20000; writeSize = 16384; exports.INFO = INFO; exports.DEBUG = DEBUG; exports.WARNING = WARNING; exports.ERROR = ERROR; exports.TRACE = TRACE; function getPos() { try { throw new Error(); } catch(e) { var pos = e.stack.split(’\n’)[4].split(’(’)[1].split(’)’)[0].split(’:’); return pos[0].replace(cwd, ‘’) + ‘:’ + pos[1]; } } function pad2(num) { return num > 9 ? num : ‘0’ + num; } function getTime() { var t = new Date(); return [t.getFullYear(), ‘-’, pad2(t.getMonth() + 1) , ‘-’, pad2(t.getDate()), ’ ‘, pad2(t.getHours()), ‘:’, pad2(t.getMinutes()), ‘:’, pad2(t.getSeconds())].join(’’); } function formatLog(log, color) { var tag = head = foot = ‘’; if (color) { head = ‘\x1B[’; foot = ‘\x1B[0m’; tag = colors[5]+‘m’; color = colors[log.type]+‘m’; } return [log.time, ’ [’, head, color, type[log.type], foot, ‘] [’, head, tag, log.pos, foot, ‘] ‘, log.msg].join(’’); } exports.create = function(level, file) { if (!level) { level = INFO; } if (file) { var buffer = new Buffer(bufferSize); var pos = 0; var fd = fs.openSync(file, ‘a’); process.on(‘exit’, function(){ fs.writeSync(fd, buffer, 0, pos, null); }) } function log(type, msg) { if (type < level){ return; } var log = {type:type, msg:msg, time:getTime(), pos:getPos()}; console.log(formatLog(log, true)); if (file) { if (pos >= writeSize) { fs.writeSync(fd, buffer, 0, pos, null); pos = 0; } pos += buffer.write(formatLog(log) + “\r\n”, pos); } } console.log(formatLog({type:INIT, pos:file, time:getTime(), msg: 'log init with level ’ + type[level]}, true)); return { info : function(msg) {log(INFO, msg);}, debug : function(msg) {log(DEBUG, msg);}, warning : function(msg) {log(WARNING, msg);}, error : function(msg) {log(ERROR, msg);}, trace : function(msg) {log(TRACE, msg);}, }; }</pre>

sinazl 1楼

好的，下面是关于“Node.js 一个简单的日志模块”的详细内容：

Node.js 一个简单的日志模块

功能概述

该模块提供了一个简单的日志功能，包含以下特性：

显示时间戳
显示调用 log 函数的文件名和行号
不同的日志级别使用不同的颜色输出
支持标准输出（stdout）的同时写入文件日志
文件日志使用缓存以降低IO次数

使用示例

var log = require('./log');
var logWithoutFile = log.create();
var logWithFile = log.create(log.WARNING, 'my.log');

logWithoutFile.info('info msg');
logWithoutFile.debug('debug msg');
logWithoutFile.warning('warning msg');
logWithoutFile.error('error msg');
logWithoutFile.trace('trace msg');

logWithFile.info('info msg');
logWithFile.debug('debug msg');
logWithFile.warning('warning msg');
logWithFile.error('error msg');
logWithFile.trace('trace msg');

输出效果

cnode-log-demo

源码

var fs = require('fs');

var cwd = process.cwd() + '/';
var INFO = 0;
var DEBUG = 1;
var WARNING = 2;
var ERROR = 3;
var TRACE = 4;
var INIT = 6;

var type = ['INFO', 'DEBUG', 'WARNING', 'ERROR', 'TRACE', '', 'LOG_INIT'];
var colors = [38, 34, 35, 31, 32, 36, 33];
var bufferSize = 20000;
var writeSize = 16384;

exports.INFO = INFO;
exports.DEBUG = DEBUG;
exports.WARNING = WARNING;
exports.ERROR = ERROR;
exports.TRACE = TRACE;

function getPos() {
    try {
        throw new Error();
    } catch(e) {
        var pos = e.stack.split('\n')[4].split('(')[1].split(')')[0].split(':');
        return pos[0].replace(cwd, '') + ':' + pos[1];
    }
}

function pad2(num) {
    return num > 9 ? num : '0' + num;
}

function getTime() {
    var t = new Date();
    return [
        t.getFullYear(),
        '-', pad2(t.getMonth() + 1),
        '-', pad2(t.getDate()),
        ' ',
        pad2(t.getHours()),
        ':', pad2(t.getMinutes()),
        ':', pad2(t.getSeconds())
    ].join('');
}

function formatLog(log, color) {
    var tag = head = foot = '';
    if (color) {
        head = '\x1B[';
        foot = '\x1B[0m';
        tag = colors[5] + 'm';
        color = colors[log.type] + 'm';
    }

    return [
        log.time,
        ' [', head, color, type[log.type], foot, '] [', head, tag, log.pos, foot, '] ',
        log.msg
    ].join('');
}

exports.create = function(level, file) {
    if (!level) {
        level = INFO;
    }
    if (file) {
        var buffer = new Buffer(bufferSize);
        var pos = 0;
        var fd = fs.openSync(file, 'a');
        process.on('exit', function(){
            fs.writeSync(fd, buffer, 0, pos, null);
        });
    }

    function log(type, msg) {
        if (type < level) {
            return;
        }
        var log = {type: type, msg: msg, time: getTime(), pos: getPos()};
        console.log(formatLog(log, true));

        if (file) {
            if (pos >= writeSize) {
                fs.writeSync(fd, buffer, 0, pos, null);
                pos = 0;
            }
            pos += buffer.write(formatLog(log) + "\r\n", pos);
        }
    }

    console.log(formatLog({type: INIT, pos: file, time: getTime(), msg: 'log init with level ' + type[level]}, true));
    return {
        info: function(msg) { log(INFO, msg); },
        debug: function(msg) { log(DEBUG, msg); },
        warning: function(msg) { log(WARNING, msg); },
        error: function(msg) { log(ERROR, msg); },
        trace: function(msg) { log(TRACE, msg); },
    };
}

解释

定义常量：定义了不同日志级别的常量。
获取位置信息：通过抛出错误来获取调用者的文件名和行号。
格式化时间：将当前时间格式化为字符串。
格式化日志：根据日志级别添加颜色，并将日志信息格式化为字符串。
创建日志对象：创建一个日志对象，可以指定日志级别和日志文件。如果指定了日志文件，则会使用缓冲区来减少IO操作。

希望这些内容能帮助你理解和使用这个简单的日志模块。

htzhanglong 2楼

实用小模块。buffer是细节，细节体现专业！

h691938207 3楼

buffer的值设置得不专业，清爷迷糊了

yuanlaile 4楼

偷了个懒而已…

zlyuanteng 5楼

长过3k的单条log毕竟是少数, 这样少做一次bytelength…可以提高点性能

nodeper 6楼作者

那倒是。如果这个log非常重要，比如计费系统的log，就不能这么搞了

itying888 7楼

顶个~~不错的东东。。

ionicwang 8楼

一般来说，INFO和WARNING的日志级别不应该输出DEBUG级别的log all < debug < info < waring < error < trace

vueper 9楼

适当的去做一些偷懒来提高性能，对于某些情况还是必要的（比如：log长度不可能超过3K）。

wuwangju 10楼

求server及client完整代码。

wuwangju 11楼

var pos = e.stack.split(’\n’)[4].split(’(’)[1].split(’)’)[0].split(’:’); 有些情况下是没有()会导致一个错误 某种情况我猜测是在不同的文件夹下的原因. 这是我的修改 var pos = e.stack.split(/\n/)[4].split(‘at’)[1].replace(’)’, ‘’).replace(’(’, ‘’).replace(’ ', ‘’); pos = cwd + pos.split(":")[1]; return pos.replace("\/", ‘’);

bupafengyu 12楼

你好，初学nodeJS 我试了下…… 不知道为什么 info : function(msg) {log(INFO, msg);}, 这个位置报语法错误% 求详解

nodeper 13楼作者

如果是计费log，具体需要考虑那些东西呢。能给个思路吗？TX

nodeper 14楼作者

为了实现一个简单的日志模块，我们可以根据上述描述编写一个Node.js模块。这个模块将提供时间戳、调用文件名和行号、不同日志级别的颜色输出、同时输出到标准输出和文件，并且通过缓存减少IO操作。

以下是根据上述描述编写的日志模块的简化版本：

// log.js
const fs = require('fs');
const util = require('util');

const INFO = 0;
const DEBUG = 1;
const WARNING = 2;
const ERROR = 3;
const TRACE = 4;

const type = ['INFO', 'DEBUG', 'WARNING', 'ERROR', 'TRACE'];
const colors = ['', '\x1b[34m', '\x1b[35m', '\x1b[31m', '\x1b[32m'];

function getPos() {
    try {
        throw new Error();
    } catch (e) {
        const stack = e.stack.split('\n')[4];
        const matches = stack.match(/\((.+):(\d+)\)$/);
        return matches ? `${matches[1]}:${matches[2]}` : '';
    }
}

function getTime() {
    const date = new Date();
    return `${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()} ${date.getHours()}:${date.getMinutes()}:${date.getSeconds()}`;
}

function formatLog(log, color) {
    const tag = colors[log.type];
    return `${tag}[${log.time}] [${log.pos}] ${log.msg}\x1b[0m`;
}

exports.create = function (level = INFO, file) {
    let buffer = '';
    let bufferSize = 1024 * 1024; // 1MB

    if (file) {
        const fd = fs.openSync(file, 'a');
        process.on('exit', () => {
            if (buffer) {
                fs.writeSync(fd, buffer);
                buffer = '';
            }
        });
    }

    function log(type, msg) {
        if (type < level) return;
        const logEntry = {
            type,
            msg,
            time: getTime(),
            pos: getPos()
        };
        console.log(formatLog(logEntry, colors[type]));
        if (file) {
            buffer += formatLog(logEntry) + '\n';
            if (buffer.length > bufferSize) {
                fs.writeSync(fd, buffer);
                buffer = '';
            }
        }
    }

    return {
        info: msg => log(INFO, msg),
        debug: msg => log(DEBUG, msg),
        warning: msg => log(WARNING, msg),
        error: msg => log(ERROR, msg),
        trace: msg => log(TRACE, msg),
    };
};

使用示例：

const log = require('./log');
const logWithoutFile = log.create();
const logWithFile = log.create(log.WARNING, 'app.log');

logWithoutFile.info('info message');
logWithoutFile.debug('debug message');
logWithoutFile.warning('warning message');
logWithoutFile.error('error message');
logWithoutFile.trace('trace message');

logWithFile.info('info message');
logWithFile.debug('debug message');
logWithFile.warning('warning message');
logWithFile.error('error message');
logWithFile.trace('trace message');

这个模块提供了时间戳、调用文件名和行号以及不同日志级别的颜色输出。它还支持将日志同时输出到标准输出和文件，并使用缓冲区来减少IO操作。