/
chunkAssignment.ts
354 lines (332 loc) · 10.5 KB
/
chunkAssignment.ts
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import ExternalModule from '../ExternalModule';
import Module from '../Module';
import { getOrCreate } from './getOrCreate';
import { concatLazy } from './iterators';
import { timeEnd, timeStart } from './timers';
type DependentModuleMap = Map<Module, Set<Module>>;
type ReadonlyDependentModuleMap = ReadonlyMap<Module, ReadonlySet<Module>>;
type ChunkDefinitions = { alias: string | null; modules: Module[] }[];
export function getChunkAssignments(
entries: readonly Module[],
manualChunkAliasByEntry: ReadonlyMap<Module, string>,
minChunkSize: number
): ChunkDefinitions {
const chunkDefinitions: ChunkDefinitions = [];
const modulesInManualChunks = new Set(manualChunkAliasByEntry.keys());
const manualChunkModulesByAlias: Record<string, Module[]> = Object.create(null);
for (const [entry, alias] of manualChunkAliasByEntry) {
addStaticDependenciesToManualChunk(
entry,
(manualChunkModulesByAlias[alias] ||= []),
modulesInManualChunks
);
}
for (const [alias, modules] of Object.entries(manualChunkModulesByAlias)) {
chunkDefinitions.push({ alias, modules });
}
const { allEntries, dependentEntriesByModule, dynamicallyDependentEntriesByDynamicEntry } =
analyzeModuleGraph(entries);
const staticEntries = new Set(entries);
const assignedEntriesByModule: DependentModuleMap = new Map();
for (const entry of allEntries) {
if (!modulesInManualChunks.has(entry)) {
assignEntryToStaticDependencies(
entry,
dependentEntriesByModule,
assignedEntriesByModule,
modulesInManualChunks,
staticEntries,
dynamicallyDependentEntriesByDynamicEntry
);
}
}
chunkDefinitions.push(...createChunks(allEntries, assignedEntriesByModule, minChunkSize));
return chunkDefinitions;
}
function addStaticDependenciesToManualChunk(
entry: Module,
manualChunkModules: Module[],
modulesInManualChunks: Set<Module>
): void {
const modulesToHandle = new Set([entry]);
for (const module of modulesToHandle) {
modulesInManualChunks.add(module);
manualChunkModules.push(module);
for (const dependency of module.dependencies) {
if (!(dependency instanceof ExternalModule || modulesInManualChunks.has(dependency))) {
modulesToHandle.add(dependency);
}
}
}
}
function analyzeModuleGraph(entries: Iterable<Module>): {
allEntries: Iterable<Module>;
dependentEntriesByModule: DependentModuleMap;
dynamicallyDependentEntriesByDynamicEntry: DependentModuleMap;
} {
const dynamicEntries = new Set<Module>();
const dependentEntriesByModule: DependentModuleMap = new Map();
const allEntries = new Set(entries);
for (const currentEntry of allEntries) {
const modulesToHandle = new Set([currentEntry]);
for (const module of modulesToHandle) {
getOrCreate(dependentEntriesByModule, module, () => new Set()).add(currentEntry);
for (const dependency of module.getDependenciesToBeIncluded()) {
if (!(dependency instanceof ExternalModule)) {
modulesToHandle.add(dependency);
}
}
for (const { resolution } of module.dynamicImports) {
if (
resolution instanceof Module &&
resolution.includedDynamicImporters.length > 0 &&
!allEntries.has(resolution)
) {
dynamicEntries.add(resolution);
allEntries.add(resolution);
}
}
for (const dependency of module.implicitlyLoadedBefore) {
if (!allEntries.has(dependency)) {
dynamicEntries.add(dependency);
allEntries.add(dependency);
}
}
}
}
return {
allEntries,
dependentEntriesByModule,
dynamicallyDependentEntriesByDynamicEntry: getDynamicallyDependentEntriesByDynamicEntry(
dependentEntriesByModule,
dynamicEntries
)
};
}
function getDynamicallyDependentEntriesByDynamicEntry(
dependentEntriesByModule: ReadonlyDependentModuleMap,
dynamicEntries: ReadonlySet<Module>
): DependentModuleMap {
const dynamicallyDependentEntriesByDynamicEntry: DependentModuleMap = new Map();
for (const dynamicEntry of dynamicEntries) {
const dynamicDependentEntries = getOrCreate(
dynamicallyDependentEntriesByDynamicEntry,
dynamicEntry,
() => new Set()
);
for (const importer of [
...dynamicEntry.includedDynamicImporters,
...dynamicEntry.implicitlyLoadedAfter
]) {
for (const entry of dependentEntriesByModule.get(importer)!) {
dynamicDependentEntries.add(entry);
}
}
}
return dynamicallyDependentEntriesByDynamicEntry;
}
function assignEntryToStaticDependencies(
entry: Module,
dependentEntriesByModule: ReadonlyDependentModuleMap,
assignedEntriesByModule: DependentModuleMap,
modulesInManualChunks: ReadonlySet<Module>,
staticEntries: ReadonlySet<Module>,
dynamicallyDependentEntriesByDynamicEntry: ReadonlyDependentModuleMap
) {
const dynamicDependentEntries = dynamicallyDependentEntriesByDynamicEntry.get(entry);
const modulesToHandle = new Set([entry]);
for (const module of modulesToHandle) {
const assignedEntries = getOrCreate(assignedEntriesByModule, module, () => new Set());
if (
dynamicDependentEntries &&
areEntriesContainedOrDynamicallyDependent(
dynamicDependentEntries,
dependentEntriesByModule.get(module)!,
staticEntries,
dynamicallyDependentEntriesByDynamicEntry
)
) {
continue;
} else {
assignedEntries.add(entry);
}
for (const dependency of module.getDependenciesToBeIncluded()) {
if (!(dependency instanceof ExternalModule || modulesInManualChunks.has(dependency))) {
modulesToHandle.add(dependency);
}
}
}
}
const MAX_ENTRIES_TO_CHECK_FOR_SHARED_DEPENDENCIES = 3;
function areEntriesContainedOrDynamicallyDependent(
entries: ReadonlySet<Module>,
containedIn: ReadonlySet<Module>,
staticEntries: ReadonlySet<Module>,
dynamicallyDependentEntriesByDynamicEntry: ReadonlyDependentModuleMap
): boolean {
if (entries.size > MAX_ENTRIES_TO_CHECK_FOR_SHARED_DEPENDENCIES) {
return false;
}
const entriesToCheck = new Set(entries);
for (const entry of entriesToCheck) {
if (!containedIn.has(entry)) {
if (staticEntries.has(entry)) {
return false;
}
const dynamicallyDependentEntries = dynamicallyDependentEntriesByDynamicEntry.get(entry)!;
if (dynamicallyDependentEntries.size > MAX_ENTRIES_TO_CHECK_FOR_SHARED_DEPENDENCIES) {
return false;
}
for (const dependentEntry of dynamicallyDependentEntries) {
entriesToCheck.add(dependentEntry);
}
}
}
return true;
}
interface ChunkDescription {
alias: null;
modules: Module[];
signature: string;
size: number | null;
}
interface MergeableChunkDescription extends ChunkDescription {
size: number;
}
function createChunks(
allEntries: Iterable<Module>,
assignedEntriesByModule: DependentModuleMap,
minChunkSize: number
): ChunkDefinitions {
const chunkModulesBySignature = getChunkModulesBySignature(assignedEntriesByModule, allEntries);
return minChunkSize === 0
? Object.values(chunkModulesBySignature).map(modules => ({
alias: null,
modules
}))
: getOptimizedChunks(chunkModulesBySignature, minChunkSize);
}
function getOptimizedChunks(
chunkModulesBySignature: { [chunkSignature: string]: Module[] },
minChunkSize: number
) {
timeStart('optimize chunks', 3);
const { chunksToBeMerged, unmergeableChunks } = getMergeableChunks(
chunkModulesBySignature,
minChunkSize
);
for (const sourceChunk of chunksToBeMerged) {
chunksToBeMerged.delete(sourceChunk);
let closestChunk: ChunkDescription | null = null;
let closestChunkDistance = Infinity;
const { signature, size, modules } = sourceChunk;
for (const targetChunk of concatLazy(chunksToBeMerged, unmergeableChunks)) {
const distance = getSignatureDistance(
signature,
targetChunk.signature,
!chunksToBeMerged.has(targetChunk)
);
if (distance === 1) {
closestChunk = targetChunk;
break;
} else if (distance < closestChunkDistance) {
closestChunk = targetChunk;
closestChunkDistance = distance;
}
}
if (closestChunk) {
closestChunk.modules.push(...modules);
if (chunksToBeMerged.has(closestChunk)) {
closestChunk.signature = mergeSignatures(signature, closestChunk.signature);
if ((closestChunk.size += size) > minChunkSize) {
chunksToBeMerged.delete(closestChunk);
unmergeableChunks.push(closestChunk);
}
}
} else {
unmergeableChunks.push(sourceChunk);
}
}
timeEnd('optimize chunks', 3);
return unmergeableChunks;
}
const CHAR_DEPENDENT = 'X';
const CHAR_INDEPENDENT = '_';
const CHAR_CODE_DEPENDENT = CHAR_DEPENDENT.charCodeAt(0);
function getChunkModulesBySignature(
assignedEntriesByModule: ReadonlyDependentModuleMap,
allEntries: Iterable<Module>
) {
const chunkModules: { [chunkSignature: string]: Module[] } = Object.create(null);
for (const [module, assignedEntries] of assignedEntriesByModule) {
let chunkSignature = '';
for (const entry of allEntries) {
chunkSignature += assignedEntries.has(entry) ? CHAR_DEPENDENT : CHAR_INDEPENDENT;
}
const chunk = chunkModules[chunkSignature];
if (chunk) {
chunk.push(module);
} else {
chunkModules[chunkSignature] = [module];
}
}
return chunkModules;
}
function getMergeableChunks(
chunkModulesBySignature: { [chunkSignature: string]: Module[] },
minChunkSize: number
) {
const chunksToBeMerged = new Set() as Set<MergeableChunkDescription> & {
has(chunk: unknown): chunk is MergeableChunkDescription;
};
const unmergeableChunks: ChunkDescription[] = [];
const alias = null;
for (const [signature, modules] of Object.entries(chunkModulesBySignature)) {
let size = 0;
checkModules: {
for (const module of modules) {
if (module.hasEffects()) {
break checkModules;
}
size += module.magicString.toString().length;
if (size > minChunkSize) {
break checkModules;
}
}
chunksToBeMerged.add({ alias, modules, signature, size });
continue;
}
unmergeableChunks.push({ alias, modules, signature, size: null });
}
return { chunksToBeMerged, unmergeableChunks };
}
function getSignatureDistance(
sourceSignature: string,
targetSignature: string,
enforceSubset: boolean
): number {
let distance = 0;
const { length } = sourceSignature;
for (let index = 0; index < length; index++) {
const sourceValue = sourceSignature.charCodeAt(index);
if (sourceValue !== targetSignature.charCodeAt(index)) {
if (enforceSubset && sourceValue === CHAR_CODE_DEPENDENT) {
return Infinity;
}
distance++;
}
}
return distance;
}
function mergeSignatures(sourceSignature: string, targetSignature: string): string {
let signature = '';
const { length } = sourceSignature;
for (let index = 0; index < length; index++) {
signature +=
sourceSignature.charCodeAt(index) === CHAR_CODE_DEPENDENT ||
targetSignature.charCodeAt(index) === CHAR_CODE_DEPENDENT
? CHAR_DEPENDENT
: CHAR_INDEPENDENT;
}
return signature;
}