always create a CachedSource, because it's accessed multiple times

sokra · sokra · commit 0d66130daf38 · 2017-12-04T12:23:32.000+01:00
diff --git a/lib/Compilation.js b/lib/Compilation.js
@@ -1544,6 +1544,7 @@ class Compilation extends Tapable {
 
 	createChunkAssets() {
 		const outputOptions = this.outputOptions;
+		const cachedSourceMap = new Map();
 		for(let i = 0; i < this.chunks.length; i++) {
 			const chunk = this.chunks[i];
 			chunk.files = [];
@@ -1568,10 +1569,21 @@ class Compilation extends Tapable {
 						source = this.cache[cacheName].source;
 					} else {
 						source = fileManifest.render();
+						// Ensure that source is a cached source to avoid additional cost because of repeated access
+						if(!(source instanceof CachedSource)) {
+							const cacheEntry = cachedSourceMap.get(source);
+							if(cacheEntry) {
+								source = cacheEntry;
+							} else {
+								const cachedSource = new CachedSource(source);
+								cachedSourceMap.set(source, cachedSource);
+								source = cachedSource;
+							}
+						}
 						if(this.cache) {
 							this.cache[cacheName] = {
 								hash: usedHash,
-								source: source = (source instanceof CachedSource ? source : new CachedSource(source))
+								source
 							};
 						}
 					}
