Function createPackWithRenamedFilesWithOptions

src/packFileSerializer.ts:3410–3531

(
  originalPack: Pack,
  tempPath: string,
  renameMap: Map<string, PackedFile>,
)

  }
};
const createPackWithRenamedFilesWithOptions = async (
  originalPack: Pack,
  tempPath: string,
  renameMap: Map<string, PackedFile>,
): Promise<void> => {
  let outFile: BinaryFile | undefined;
  let sourceFileId = -1;
  try {
    // Create the final list of packed files
    const finalPackedFiles: PackedFile[] = [];
    // Add all files, using renamed versions where applicable
    for (const originalFile of originalPack.packedFiles) {
      const renamedFile = renameMap.get(originalFile.name);
      if (renamedFile) {
        finalPackedFiles.push(renamedFile);
      } else {
        finalPackedFiles.push(originalFile);
      }
    }
    // Write the new pack file
    outFile = new BinaryFile(tempPath, "w", true);
    sourceFileId = fs.openSync(originalPack.path, "r");
    await outFile.open();
    // Write header
    await writePackHeader(
      outFile,
      originalPack.packHeader,
      finalPackedFiles,
      originalPack.dependencyPacks || [],
    );
    // Pre-build file lookup map for O(1) instead of O(N) lookups
    const originalFileMap = new Map<string, PackedFile>();
    for (const pf of originalPack.packedFiles) {
      originalFileMap.set(pf.name, pf);
    }
    // Build reverse lookup for renamed files
    const renamedToOriginalMap = new Map<string, string>();
    for (const [originalName, renamedFile] of renameMap.entries()) {
      renamedToOriginalMap.set(renamedFile.name, originalName);
    }
    // Sort files by original pack position for sequential disk reads (much faster I/O)
    finalPackedFiles.sort((a, b) => {
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      const origA = originalFileMap.get(a.name) || originalFileMap.get(renamedToOriginalMap.get(a.name)!);
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      const origB = originalFileMap.get(b.name) || originalFileMap.get(renamedToOriginalMap.get(b.name)!);
      return (origA?.start_pos || 0) - (origB?.start_pos || 0);
    });
    // Create buffer pool for efficient memory reuse
    const bufferPool = new BufferPool();
    // Optimized batching for files mostly <1MB
    const SMALL_FILE_BATCH_SIZE = 2 * 1024 * 1024; // 2MB batches for small files
    const LARGE_FILE_THRESHOLD = 1024 * 1024; // 1MB threshold
    let currentBatchSize = 0;
    let batchBuffers: { buffer: Buffer; actualSize: number; poolBuffer: Buffer }[] = [];
    const flushBatch = async () => {
      if (batchBuffers.length > 0) {
        // Create array of buffer slices for concatenation