connect/lib/connect/middleware/logger.js

High performance middleware framework

/*!
 * Ext JS Connect
 * Copyright(c) 2010 Sencha Inc.
 * MIT Licensed
 */

/**
 * Log buffer.
 * 
 * @type Array
 */

var buf = [];

/**
 * Default log buffer duration.
 *
 * @type Number
 */

var defaultBufferDuration = 1000;

/**
 * Log requests with the given `options`.
 *
 * Options:
 *
 *   - `format`  Format string, see below for tokens
 *   - `stream`  Output stream, defaults to _stdout_
 *   - `buffer`  Buffer duration, defaults to 1000ms when _true_
 *
 * Tokens:
 *
 *   - `:req[header]` ex: `:req[Accept]`
 *   - `:res[header]` ex: `:res[Content-Length]`
 *   - `:http-version`
 *   - `:response-time`
 *   - `:remote-addr`
 *   - `:date`
 *   - `:method`
 *   - `:url`
 *   - `:referrer`
 *   - `:user-agent`
 *   - `:status`
 *
 * @return {Function}
 * @api public
 */

module.exports = function logger(options) {
    if ('string' == typeof options) {
      options = { format: options };
    } else {
      options = options || {};
    }

    var fmt = process.connectEnv.logFormat || options.format,
        stream = options.stream || process.stdout,
        buffer = options.buffer;

    // Buffering support
    if (buffer) {
        var realStream = stream;
        setInterval(function(){
            if (buf.length) {
                realStream.write(buf.join(''), 'ascii');
                buf.length = 0;
            }
        }, typeof buffer === 'number' ? buffer : defaultBufferDuration); 
        stream = {
            write: function(str){
                buf.push(str);
            }
        };
    }

    return function logger(req, res, next) {
        var start = +new Date,
            statusCode,
            resHeaders,
            writeHead = res.writeHead,
            end = res.end,
            url = req.url;

        // Proxy for statusCode.
        res.writeHead = function(code, headers){
            res.writeHead = writeHead;
            res.writeHead(code, headers);
            res.statusCode = statusCode = code;
            res._headers = resHeaders = headers || {};
        };

        // Proxy end to output a line to the provided logger.
        if (fmt) {
            res.end = function(chunk, encoding) {
                res.end = end;
                res.end(chunk, encoding);
                res.responseTime = +new Date - start;
                stream.write(format(fmt, req, res) + '\n', 'ascii');
            };
        } else {
            res.end = function(chunk, encoding) {
                res.end = end;
                res.end(chunk, encoding);

                stream.write((req.socket && req.socket.remoteAddress)
                 + ' - - [' + (new Date).toUTCString() + ']'
                 + ' "' + req.method + ' ' + url
                 + ' HTTP/' + req.httpVersionMajor + '.' + req.httpVersionMinor + '" '
                 + statusCode + ' ' + (resHeaders['Content-Length'] || '-')
                 + ' "' + (req.headers['referer'] || req.headers['referrer'] || '')
                 + '" "' + (req.headers['user-agent'] || '') + '"\n', 'ascii');
            };
        }

        // Fall through to the next layer.
        next();
    };

};

/**
 * Return formatted log line.
 *
 * @param  {String} str
 * @param  {IncomingMessage} req
 * @param  {ServerResponse} res
 * @return {String}
 * @api private
 */
function format(str, req, res) {
    return str
        .replace(':url', req.url)
        .replace(':method', req.method)
        .replace(':status', res.statusCode)
        .replace(':response-time', res.responseTime)
        .replace(':date', new Date().toUTCString())
        .replace(':referrer', req.headers['referer'] || req.headers['referrer'] || '')
        .replace(':http-version', req.httpVersionMajor + '.' + req.httpVersionMinor)
        .replace(':remote-addr', req.socket && req.socket.remoteAddress)
        .replace(':user-agent', req.headers['user-agent'] || '')
        .replace(/:req\[([^\]]+)\]/g, function(_, header){ return req.headers[header]; })
        .replace(/:res\[([^\]]+)\]/g, function(_, header){ return res._headers[header]; });
}