Working version of fully-async log rolling file appender - tests need fixing though
This commit is contained in:
Gareth Jones
221
lib/streams.js
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221
lib/streams.js
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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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