102 lines
3.5 KiB
JavaScript
102 lines
3.5 KiB
JavaScript
var debug = require('debug')('ylt:gzipCompressor');
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var Q = require('q');
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var zlib = require('zlib');
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var GzipCompressor = function() {
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function compressFile(entry) {
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debug('Entering compressFile');
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return gzipUncompressedFile(entry)
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.then(gzipOptimizedFile);
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}
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// Gzip a file if it was not already gziped
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function gzipUncompressedFile(entry) {
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var deferred = Q.defer();
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if (entryTypeCanBeGzipped(entry) && entry.weightCheck && !entry.weightCheck.isCompressed && entry.weightCheck.bodyBuffer) {
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debug('Compression missing, trying to gzip file %s', entry.url);
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var uncompressedSize = entry.weightCheck.uncompressedSize;
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zlib.gzip(entry.weightCheck.bodyBuffer, function(err, buffer) {
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if (err) {
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debug('Could not compress uncompressed file with gzip');
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debug(err);
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deferred.reject(err);
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} else {
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var compressedSize = buffer.length;
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if (gainIsEnough(uncompressedSize, compressedSize)) {
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debug('File correctly gziped, was %d and is now %d bytes', uncompressedSize, compressedSize);
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entry.weightCheck.afterCompression = compressedSize;
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} else {
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debug('Gzip gain is not enough, was %d and is now %d bytes', uncompressedSize, compressedSize);
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}
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deferred.resolve(entry);
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}
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});
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} else {
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debug('Compression not needed');
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deferred.resolve(entry);
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}
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return deferred.promise;
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}
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// Gzip a file after minification or optimization if this step was successful
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function gzipOptimizedFile(entry) {
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var deferred = Q.defer();
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if (entryTypeCanBeGzipped(entry) && entry.weightCheck && entry.weightCheck.isOptimized === false) {
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debug('Trying to gzip file after minification: %s', entry.url);
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var uncompressedSize = entry.weightCheck.optimized;
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zlib.gzip(new Buffer(entry.weightCheck.bodyAfterOptimization, 'utf8'), function(err, buffer) {
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if (err) {
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debug('Could not compress minified file with gzip');
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debug(err);
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deferred.reject(err);
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} else {
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var compressedSize = buffer.length;
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debug('Correctly gziped the minified file, was %d and is now %d bytes', uncompressedSize, compressedSize);
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entry.weightCheck.afterOptimizationAndCompression = compressedSize;
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deferred.resolve(entry);
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}
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});
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} else {
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debug('Compressing optimized file not needed');
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deferred.resolve(entry);
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}
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return deferred.promise;
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}
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// The gain is estimated of enough value if it's over 1KB or over 20%,
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// but it's ignored if is below 100 bytes
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function gainIsEnough(oldWeight, newWeight) {
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var gain = oldWeight - newWeight;
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var ratio = gain / oldWeight;
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return (gain > 2048 || (ratio > 0.2 && gain > 100));
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}
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function entryTypeCanBeGzipped(entry) {
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return entry.isJS || entry.isCSS || entry.isHTML || entry.isJSON || entry.isSVG || entry.isTTF || entry.isXML || entry.isFavicon;
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}
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return {
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compressFile: compressFile,
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entryTypeCanBeGzipped: entryTypeCanBeGzipped
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};
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};
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module.exports = new GzipCompressor(); |