Merge pull request webpack#5298 from asolove/cache-relative-paths

[Perf] Memoize relative paths to speed up builds
italoadler · Jul 18, 2017 · a014332 · a014332
2 parents 0e69f1b + 0a540b4
commit a014332
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Showing 2 changed files with 26 additions and 4 deletions.
diff --git a/lib/optimize/AggressiveSplittingPlugin.js b/lib/optimize/AggressiveSplittingPlugin.js
@@ -56,7 +56,7 @@ class AggressiveSplittingPlugin {
 
 						const nameToModuleMap = new Map();
 						chunk.forEachModule(m => {
-							const name = identifierUtils.makePathsRelative(compiler.context, m.identifier());
+							const name = identifierUtils.makePathsRelative(compiler.context, m.identifier(), compilation.cache);
 							nameToModuleMap.set(name, m);
 						});
 
@@ -127,7 +127,7 @@ class AggressiveSplittingPlugin {
 							newChunk.origins = chunk.origins.map(copyWithReason);
 							chunk.origins = chunk.origins.map(copyWithReason);
 							compilation._aggressiveSplittingSplits = (compilation._aggressiveSplittingSplits || []).concat({
-								modules: newChunk.mapModules(m => identifierUtils.makePathsRelative(compiler.context, m.identifier()))
+								modules: newChunk.mapModules(m => identifierUtils.makePathsRelative(compiler.context, m.identifier(), compilation.cache))
 							});
 							return true;
 						} else {
@@ -144,7 +144,7 @@ class AggressiveSplittingPlugin {
 					if(chunk.hasEntryModule()) return;
 					const size = chunk.size(this.options);
 					const incorrectSize = size < minSize;
-					const modules = chunk.mapModules(m => identifierUtils.makePathsRelative(compiler.context, m.identifier()));
+					const modules = chunk.mapModules(m => identifierUtils.makePathsRelative(compiler.context, m.identifier(), compilation.cache));
 					if(typeof chunk._fromAggressiveSplittingIndex === "undefined") {
 						if(incorrectSize) return;
 						chunk.recorded = true;

diff --git a/lib/util/identifier.js b/lib/util/identifier.js
@@ -7,10 +7,32 @@ const looksLikeAbsolutePath = (maybeAbsolutePath) => {
 
 const normalizePathSeparator = (p) => p.replace(/\\/g, "/");
 
-exports.makePathsRelative = (context, identifier) => {
+const _makePathsRelative = (context, identifier) => {
 	return identifier
 		.split(/([|! ])/)
 		.map(str => looksLikeAbsolutePath(str) ?
 			normalizePathSeparator(path.relative(context, str)) : str)
 		.join("");
 };
+
+exports.makePathsRelative = (context, identifier, cache) => {
+	if(!cache) return _makePathsRelative(context, identifier);
+
+	const relativePaths = cache.relativePaths || (cache.relativePaths = new Map());
+
+	let cachedResult;
+	let contextCache = relativePaths.get(context);
+	if(typeof contextCache === "undefined") {
+		relativePaths.set(context, contextCache = new Map());
+	} else {
+		cachedResult = contextCache.get(identifier);
+	}
+
+	if(typeof cachedResult !== "undefined") {
+		return cachedResult;
+	} else {
+		const relativePath = _makePathsRelative(context, identifier);
+		contextCache.set(identifier, relativePath);
+		return relativePath;
+	}
+};