log4js-node/lib/appenders/file.js
2011-07-26 18:40:41 +10:00

123 lines
3.7 KiB
JavaScript

var layouts = require('../layouts')
, fs = require('fs');
/**
* File Appender writing the logs to a text file. Supports rolling of logs by size.
*
* @param file file log messages will be written to
* @param layout a function that takes a logevent and returns a string (defaults to basicLayout).
* @param logSize - the maximum size (in bytes) for a log file, if not provided then logs won't be rotated.
* @param numBackups - the number of log files to keep after logSize has been reached (default 5)
* @param filePollInterval - the time in seconds between file size checks (default 30s)
*/
function fileAppender (file, layout, logSize, numBackups, filePollInterval) {
layout = layout || layouts.basicLayout;
numBackups = numBackups === undefined ? 5 : numBackups;
//there has to be at least one backup if logSize has been specified
numBackups = numBackups === 0 ? 1 : numBackups;
filePollInterval = filePollInterval * 1000 || 30000;
function setupLogRolling () {
fs.watchFile(
file,
{
persistent: false,
interval: filePollInterval
},
function (curr, prev) {
if (curr.size >= logSize) {
rollThatLog();
}
}
);
}
function rollThatLog () {
//roll the backups (rename file.n-1 to file.n, where n <= numBackups)
for (var i=numBackups; i > 0; i--) {
if (i > 1) {
if (fileExists(file + '.' + (i-1))) {
fs.renameSync(file+'.'+(i-1), file+'.'+i);
}
} else {
fs.renameSync(file, file+'.1');
}
}
//let's make a new file
var newLogFileFD = fs.openSync(file, 'a', 0644)
, oldLogFileFD = logFile.fd;
logFile.fd = newLogFileFD;
fs.close(oldLogFileFD);
}
function fileExists (filename) {
try {
fs.statSync(filename);
return true;
} catch (e) {
return false;
}
}
function openTheStream() {
var stream = fs.createWriteStream(file, { flags: 'a', mode: 0644, encoding: 'utf8' });
stream.on("open", function() {
canWrite = true;
while (logEventBuffer.length > 0 && canWrite) {
canWrite = writeToLog(logEventBuffer.shift());
}
});
stream.on("error", function (err) {
console.error("log4js.fileAppender - Error happened ", err);
});
stream.on("drain", function() {
canWrite = true;
while (logEventBuffer.length > 0 && canWrite) {
canWrite = writeToLog(logEventBuffer.shift());
}
});
return stream;
}
var logEventBuffer = []
, canWrite = false
, logFile = openTheStream();
if (logSize > 0) {
setupLogRolling();
}
//close the file on process exit.
process.on('exit', function() {
logFile.end();
logFile.destroy();
});
function writeToLog(loggingEvent) {
return logFile.write(layout(loggingEvent)+'\n', "utf8");
}
return function(loggingEvent) {
//because the log stream is opened asynchronously, we don't want to write
//until it is ready.
if (canWrite) {
canWrite = writeToLog(loggingEvent);
} else {
logEventBuffer.push(loggingEvent);
}
};
}
function configure(config) {
var layout;
if (config.layout) {
layout = layouts.layout(config.layout.type, config.layout);
}
return fileAppender(config.filename, layout, config.maxLogSize, config.backups, config.pollInterval);
}
exports.name = "file";
exports.appender = fileAppender;
exports.configure = configure;