Method apply

lib/optimize/FlagIncludedChunksPlugin.js:23–135

* Applies the plugin by registering its hooks on the compiler. * @param {Compiler} compiler the compiler instance * @returns {void}

(compiler)

	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap(PLUGIN_NAME, (compilation) => {
			compilation.hooks.optimizeChunkIds.tap(PLUGIN_NAME, (chunks) => {
				const chunkGraph = compilation.chunkGraph;

				// prepare two bit integers for each module
				// 2^31 is the max number represented as SMI in v8
				// we want the bits distributed this way:
				// the bit 2^31 is pretty rar and only one module should get it
				// so it has a probability of 1 / modulesCount
				// the first bit (2^0) is the easiest and every module could get it
				// if it doesn't get a better bit
				// from bit 2^n to 2^(n+1) there is a probability of p
				// so 1 / modulesCount == p^31
				// <=> p = sqrt31(1 / modulesCount)
				// so we use a modulo of 1 / sqrt31(1 / modulesCount)
				/** @type {WeakMap<Module, number>} */
				const moduleBits = new WeakMap();
				const modulesCount = compilation.modules.size;

				// precalculate the modulo values for each bit
				const modulo = 1 / (1 / modulesCount) ** (1 / 31);
				/** @type {number[]} */
				const modulos = Array.from(
					{ length: 31 },
					/**
					 * Handles the callback logic for this hook.
					 * @param {number} x x
					 * @param {number} i i
					 * @returns {number} result
					 */
					(x, i) => (modulo ** i) | 0
				);

				// iterate all modules to generate bit values
				let i = 0;
				for (const module of compilation.modules) {
					let bit = 30;
					while (i % modulos[bit] !== 0) {
						bit--;
					}
					moduleBits.set(module, 1 << bit);
					i++;
				}

				// iterate all chunks to generate bitmaps
				/** @type {WeakMap<Chunk, number>} */
				const chunkModulesHash = new WeakMap();
				for (const chunk of chunks) {
					let hash = 0;
					for (const module of chunkGraph.getChunkModulesIterable(chunk)) {
						hash |= /** @type {number} */ (moduleBits.get(module));
					}
					chunkModulesHash.set(chunk, hash);
				}

				for (const chunkA of chunks) {
					const chunkAHash =