Working version of fully-async log rolling file appender - tests need fixing though
This commit is contained in:
Gareth Jones
@@ -1,6 +1,7 @@
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var layouts = require('../layouts')
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, path = require('path')
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, fs = require('fs');
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, fs = require('fs')
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, streams = require('../streams');
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/**
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* File Appender writing the logs to a text file. Supports rolling of logs by size.
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@@ -18,132 +19,29 @@ function fileAppender (file, layout, logSize, numBackups) {
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//there has to be at least one backup if logSize has been specified
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numBackups = numBackups === 0 ? 1 : numBackups;
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function setupLogRolling () {
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try {
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var stat = fs.statSync(file);
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bytesWritten = stat.size;
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if (bytesWritten >= logSize) {
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rollThatLog();
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}
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} catch (e) {
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//file does not exist
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bytesWritten = 0;
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}
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}
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function rollThatLog () {
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function index(filename) {
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return parseInt(filename.substring((path.basename(file) + '.').length), 10) || 0;
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}
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var nameMatcher = new RegExp('^' + path.basename(file));
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function justTheLogFiles (item) {
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return nameMatcher.test(item);
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}
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function byIndex(a, b) {
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if (index(a) > index(b)) {
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return 1;
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} else if (index(a) < index(b) ) {
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return -1;
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} else {
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return 0;
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}
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}
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function increaseFileIndex (fileToRename) {
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var idx = index(fileToRename);
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if (idx < numBackups) {
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//on windows, you can get a EEXIST error if you rename a file to an existing file
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//so, we'll try to delete the file we're renaming to first
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try {
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fs.unlinkSync(file + '.' + (idx+1));
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} catch (e) {
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//couldn't delete, but that could be because it doesn't exist
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//try renaming anyway
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}
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fs.renameSync(path.join(path.dirname(file), fileToRename), file + '.' + (idx + 1));
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}
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}
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//roll the backups (rename file.n to file.n+1, where n <= numBackups)
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fs.readdirSync(path.dirname(file))
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.filter(justTheLogFiles)
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.sort(byIndex)
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.reverse()
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.forEach(increaseFileIndex);
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//let's make a new file
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var newLogFileFD = fs.openSync(file, 'a', 0644)
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, oldLogFileFD = logFile.fd;
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logFile.fd = newLogFileFD;
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fs.close(oldLogFileFD);
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//reset the counter
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bytesWritten = 0;
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}
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function fileExists (filename) {
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try {
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fs.statSync(filename);
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return true;
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} catch (e) {
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return false;
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}
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}
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function openTheStream() {
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var stream = fs.createWriteStream(file, { flags: 'a', mode: 0644, encoding: 'utf8' });
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stream.on("open", function() {
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canWrite = true;
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flushBuffer();
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});
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function openTheStream(file, fileSize, numFiles) {
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var stream = new streams.BufferedWriteStream(
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new streams.RollingFileStream(
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file,
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fileSize,
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numFiles
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)
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);
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stream.on("error", function (err) {
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console.error("log4js.fileAppender - Writing to file %s, error happened ", file, err);
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});
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stream.on("drain", function() {
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canWrite = true;
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flushBuffer();
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if (logEventBuffer.length > 0) {
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writeToLog(logEventBuffer.shift());
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}
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});
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return stream;
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}
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function flushBuffer() {
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while (logEventBuffer.length > 0 && canWrite) {
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writeToLog(logEventBuffer.shift());
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}
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}
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var logEventBuffer = []
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, canWrite = false
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, logFile = openTheStream();
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if (logSize > 0) {
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setupLogRolling();
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}
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var logFile = openTheStream(file, logSize, numBackups);
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//close the file on process exit.
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process.on('exit', function() {
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flushBuffer();
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logFile.end();
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logFile.destroy();
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});
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function writeToLog(loggingEvent) {
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var logMessage = layout(loggingEvent)+'\n';
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//not entirely accurate, but it'll do.
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bytesWritten += logMessage.length;
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canWrite = logFile.write(logMessage, "utf8");
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if (bytesWritten >= logSize) {
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rollThatLog();
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}
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}
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return function(loggingEvent) {
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logEventBuffer.push(loggingEvent);
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flushBuffer();
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logFile.write(layout(loggingEvent)+'\n', "utf8");
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};
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}
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221
lib/streams.js
Normal file
221
lib/streams.js
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@@ -0,0 +1,221 @@
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var util = require('util')
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, fs = require('fs')
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, path = require('path')
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, events = require('events')
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, async = require('async');
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function BufferedWriteStream(stream) {
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var that = this;
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this.stream = stream;
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this.buffer = [];
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this.canWrite = false;
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this.bytes = 0;
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this.stream.on("open", function() {
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that.canWrite = true;
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that.flushBuffer();
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});
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this.stream.on("error", function (err) {
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that.emit("error", err);
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});
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this.stream.on("drain", function() {
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that.canWrite = true;
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that.flushBuffer();
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});
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}
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util.inherits(BufferedWriteStream, events.EventEmitter);
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Object.defineProperty(
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BufferedWriteStream.prototype,
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"fd",
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{
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get: function() { return this.stream.fd; },
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set: function(newFd) {
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this.stream.fd = newFd;
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this.bytes = 0;
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}
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}
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);
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Object.defineProperty(
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BufferedWriteStream.prototype,
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"bytesWritten",
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{
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get: function() { return this.bytes; }
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}
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);
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BufferedWriteStream.prototype.write = function(data, encoding) {
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this.buffer.push({ data: data, encoding: encoding });
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this.flushBuffer();
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}
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BufferedWriteStream.prototype.end = function(data, encoding) {
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if (data) {
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this.buffer.push({ data: data, encoding: encoding });
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}
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this.flushBufferEvenIfCannotWrite();
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}
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BufferedWriteStream.prototype.writeToStream = function(toWrite) {
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this.bytes += toWrite.data.length;
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this.canWrite = this.stream.write(toWrite.data, toWrite.encoding);
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}
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BufferedWriteStream.prototype.flushBufferEvenIfCannotWrite = function() {
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while (this.buffer.length > 0) {
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this.writeToStream(this.buffer.shift());
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}
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}
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BufferedWriteStream.prototype.flushBuffer = function() {
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while (this.buffer.length > 0 && this.canWrite) {
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this.writeToStream(this.buffer.shift());
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}
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}
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function RollingFileStream (filename, size, backups, options) {
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this.filename = filename;
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this.size = size;
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this.backups = backups || 1;
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this.options = options || { encoding: "utf8", mode: 0644, flags: 'a' };
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this.rolling = false;
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this.writesWhileRolling = [];
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throwErrorIfArgumentsAreNotValid();
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RollingFileStream.super_.call(this, this.filename, this.options);
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this.bytesWritten = currentFileSize(this.filename);
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function currentFileSize(file) {
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var fileSize = 0;
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try {
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fileSize = fs.statSync(file).size;
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} catch (e) {
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//file does not exist
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}
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return fileSize;
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}
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function throwErrorIfArgumentsAreNotValid() {
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if (!filename || !size || size <= 0) {
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throw new Error("You must specify a filename and file size");
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}
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}
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}
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util.inherits(RollingFileStream, fs.FileWriteStream);
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RollingFileStream.prototype.write = function(data, encoding) {
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if (this.rolling) {
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this.writesWhileRolling.push({ data: data, encoding: encoding });
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return false;
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} else {
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var canWrite = RollingFileStream.super_.prototype.write.call(this, data, encoding);
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//this.bytesWritten += data.length;
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console.log("bytesWritten: %d, max: %d", this.bytesWritten, this.size);
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if (this.bytesWritten >= this.size) {
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this.roll();
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}
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return canWrite;
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}
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}
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RollingFileStream.prototype.roll = function () {
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var that = this,
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nameMatcher = new RegExp('^' + path.basename(this.filename));
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function justTheseFiles (item) {
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return nameMatcher.test(item);
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}
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function index(filename) {
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return parseInt(filename.substring((path.basename(that.filename) + '.').length), 10) || 0;
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}
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function byIndex(a, b) {
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if (index(a) > index(b)) {
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return 1;
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} else if (index(a) < index(b) ) {
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return -1;
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} else {
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return 0;
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}
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}
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function increaseFileIndex (fileToRename, cb) {
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var idx = index(fileToRename);
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console.log("Index of %s is %d", fileToRename, idx);
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if (idx < that.backups) {
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//on windows, you can get a EEXIST error if you rename a file to an existing file
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//so, we'll try to delete the file we're renaming to first
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fs.unlink(that.filename + '.' + (idx+1), function (err) {
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//ignore err: if we could not delete, it's most likely that it doesn't exist
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console.log("Renaming %s -> %s", fileToRename, that.filename + '.' + (idx+1));
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fs.rename(path.join(path.dirname(that.filename), fileToRename), that.filename + '.' + (idx + 1), cb);
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});
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} else {
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cb();
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}
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}
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function renameTheFiles(cb) {
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//roll the backups (rename file.n to file.n+1, where n <= numBackups)
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console.log("Renaming the old files");
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fs.readdir(path.dirname(that.filename), function (err, files) {
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async.forEachSeries(
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files.filter(justTheseFiles).sort(byIndex).reverse(),
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increaseFileIndex,
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cb
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);
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});
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}
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function openANewFile(cb) {
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console.log("Opening a new file");
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fs.open(
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that.filename,
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that.options.flags,
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that.options.mode,
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function (err, fd) {
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console.log("opened new file");
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var oldLogFileFD = that.fd;
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that.fd = fd;
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that.writable = true;
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fs.close(oldLogFileFD, function() {
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that.bytesWritten = 0;
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cb();
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});
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}
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);
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}
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function emptyRollingQueue(cb) {
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console.log("emptying the rolling queue");
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var toWrite;
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while ((toWrite = that.writesWhileRolling.shift())) {
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RollingFileStream.super_.prototype.write.call(that, toWrite.data, toWrite.encoding);
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that.bytesWritten += toWrite.data.length;
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}
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that.rolling = false;
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cb();
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}
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console.log("Starting roll");
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console.log("Queueing up data until we've finished rolling");
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this.rolling = true;
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console.log("Flushing underlying stream");
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this.flush();
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async.series([
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renameTheFiles,
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openANewFile,
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emptyRollingQueue
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]);
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}
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exports.RollingFileStream = RollingFileStream;
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exports.BufferedWriteStream = BufferedWriteStream;
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