webpack/lib/optimize/AggressiveSplittingPlugin.js

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const identifierUtils = require("../util/identifier");
const intersect = require("../util/SetHelpers").intersect;
const validateOptions = require("schema-utils");
const schema = require("../../schemas/plugins/optimize/AggressiveSplittingPlugin.json");

const moveModuleBetween = (oldChunk, newChunk) => {
	return module => {
		oldChunk.moveModule(module, newChunk);
	};
};

const isNotAEntryModule = entryModule => {
	return module => {
		return entryModule !== module;
	};
};

class AggressiveSplittingPlugin {
	constructor(options) {
		validateOptions(schema, options || {}, "Aggressive Splitting Plugin");

		this.options = options || {};
		if(typeof this.options.minSize !== "number") this.options.minSize = 30 * 1024;
		if(typeof this.options.maxSize !== "number") this.options.maxSize = 50 * 1024;
		if(typeof this.options.chunkOverhead !== "number") this.options.chunkOverhead = 0;
		if(typeof this.options.entryChunkMultiplicator !== "number") this.options.entryChunkMultiplicator = 1;

	}
	apply(compiler) {
		compiler.hooks.thisCompilation.tap("AggressiveSplittingPlugin", (compilation) => {
			let needAdditionalSeal = false;
			let newSplits;
			let fromAggressiveSplittingSet;
			let chunkSplitDataMap;
			compilation.hooks.optimize.tap("AggressiveSplittingPlugin", () => {
				newSplits = [];
				fromAggressiveSplittingSet = new Set();
				chunkSplitDataMap = new Map();
			});
			compilation.hooks.optimizeChunksAdvanced.tap("AggressiveSplittingPlugin", (chunks) => {
				// Precompute stuff
				const nameToModuleMap = new Map();
				const moduleToNameMap = new Map();
				for(const m of compilation.modules) {
					const name = identifierUtils.makePathsRelative(compiler.context, m.identifier(), compilation.cache);
					nameToModuleMap.set(name, m);
					moduleToNameMap.set(m, name);
				}

				// Check used chunk ids
				const usedIds = new Set();
				for(const chunk of chunks) {
					usedIds.add(chunk.id);
				}

				const recordedSplits = compilation.records && compilation.records.aggressiveSplits || [];
				const usedSplits = newSplits ? recordedSplits.concat(newSplits) : recordedSplits;

				const minSize = this.options.minSize;
				const maxSize = this.options.maxSize;

				const applySplit = (splitData) => {
					// Cannot split if id is already taken
					if(splitData.id !== undefined && usedIds.has(splitData.id)) return false;

					// Get module objects from names
					const selectedModules = splitData.modules.map(name => nameToModuleMap.get(name));

					// Does the modules exist at all?
					if(!selectedModules.every(Boolean)) return false;

					// Check if size matches (faster than waiting for hash)
					const size = selectedModules.reduce((sum, m) => sum + m.size(), 0);
					if(size !== splitData.size) return false;

					// get chunks with all modules
					const selectedChunks = intersect(selectedModules.map(m => new Set(m.chunksIterable)));

					// No relevant chunks found
					if(selectedChunks.size === 0) return false;

					// The found chunk is already the split or similar
					if(selectedChunks.size === 1 && Array.from(selectedChunks)[0].getNumberOfModules() === selectedModules.length) {
						const chunk = Array.from(selectedChunks)[0];
						if(fromAggressiveSplittingSet.has(chunk)) return false;
						fromAggressiveSplittingSet.add(chunk);
						chunkSplitDataMap.set(chunk, splitData);
						return true;
					}

					// split the chunk into two parts
					const newChunk = compilation.addChunk();
					newChunk.chunkReason = "aggressive splitted";
					for(const chunk of selectedChunks) {
						selectedModules.forEach(moveModuleBetween(chunk, newChunk));
						chunk.split(newChunk);
						chunk.name = null;
					}
					fromAggressiveSplittingSet.add(newChunk);
					chunkSplitDataMap.set(newChunk, splitData);

					if(splitData.id !== null && splitData.id !== undefined) {
						newChunk.id = splitData.id;
					}
					return true;
				};

				// try to restore to recorded splitting
				let changed = false;
				for(let j = 0; j < usedSplits.length; j++) {
					const splitData = usedSplits[j];
					if(applySplit(splitData))
						changed = true;
				}

				// for any chunk which isn't splitted yet, split it and create a new entry
				// start with the biggest chunk
				const sortedChunks = chunks.slice().sort((a, b) => {
					const diff1 = b.modulesSize() - a.modulesSize();
					if(diff1) return diff1;
					const diff2 = a.getNumberOfModules() - b.getNumberOfModules();
					if(diff2) return diff2;
					const modulesA = Array.from(a.modulesIterable);
					const modulesB = Array.from(b.modulesIterable);
					modulesA.sort();
					modulesB.sort();
					const aI = modulesA[Symbol.iterator]();
					const bI = modulesB[Symbol.iterator]();
					while(true) { // eslint-disable-line
						const aItem = aI.next();
						const bItem = bI.next();
						if(aItem.done) return 0;
						const aModuleIdentifier = aItem.value.identifier();
						const bModuleIdentifier = bItem.value.identifier();
						if(aModuleIdentifier > bModuleIdentifier) return -1;
						if(aModuleIdentifier < bModuleIdentifier) return 1;
					}
				});
				for(const chunk of sortedChunks) {
					if(fromAggressiveSplittingSet.has(chunk)) continue;
					const size = chunk.modulesSize();
					if(size > maxSize && chunk.getNumberOfModules() > 1) {
						const modules = chunk.getModules()
							.filter(isNotAEntryModule(chunk.entryModule))
							.sort((a, b) => {
								a = a.identifier();
								b = b.identifier();
								if(a > b) return 1;
								if(a < b) return -1;
								return 0;
							});
						const selectedModules = [];
						let selectedModulesSize = 0;
						for(let k = 0; k < modules.length; k++) {
							const module = modules[k];
							const newSize = selectedModulesSize + module.size();
							if(newSize > maxSize && selectedModulesSize >= minSize) break;
							selectedModulesSize = newSize;
							selectedModules.push(module);
						}
						if(selectedModules.length === 0) continue;
						const splitData = {
							modules: selectedModules.map(m => moduleToNameMap.get(m)).sort(),
							size: selectedModulesSize
						};

						if(applySplit(splitData)) {
							newSplits = (newSplits || []).concat(splitData);
							changed = true;
						}
					}
				}
				if(changed)
					return true;
			});
			compilation.hooks.recordHash.tap("AggressiveSplittingPlugin", (records) => {
				// 4. save made splittings to records
				const allSplits = new Set();
				const invalidSplits = new Set();

				// Check if some splittings are invalid
				// We remove invalid splittings and try again
				for(const chunk of compilation.chunks) {
					const splitData = chunkSplitDataMap.get(chunk);
					if(splitData !== undefined) {
						if(splitData.hash && chunk.hash !== splitData.hash) {
							// Split was successful, but hash doesn't equal
							// We can throw away the split since it's useless now
							invalidSplits.add(splitData);
						}
					}
				}

				if(invalidSplits.size > 0) {

					records.aggressiveSplits = records.aggressiveSplits.filter(splitData => !invalidSplits.has(splitData));
					needAdditionalSeal = true;

				} else {

					// set hash and id values on all (new) splittings
					for(const chunk of compilation.chunks) {
						const splitData = chunkSplitDataMap.get(chunk);
						if(splitData !== undefined) {
							splitData.hash = chunk.hash;
							splitData.id = chunk.id;
							allSplits.add(splitData);
							// set flag for stats
							chunk.recorded = true;
						}
					}

					// Also add all unused historial splits (after the used ones)
					// They can still be used in some future compilation
					const recordedSplits = compilation.records && compilation.records.aggressiveSplits;
					if(recordedSplits) {
						for(const splitData of recordedSplits) {
							if(!invalidSplits.has(splitData))
								allSplits.add(splitData);
						}
					}

					// record all splits
					records.aggressiveSplits = Array.from(allSplits);

					needAdditionalSeal = false;
				}
			});
			compilation.hooks.needAdditionalSeal.tap("AggressiveSplittingPlugin", () => {
				if(needAdditionalSeal) {
					needAdditionalSeal = false;
					return true;
				}
			});
		});
	}
}
module.exports = AggressiveSplittingPlugin;