Optimizing Local AST Indexing for 500k+ Monorepos

In-Memory Tree Representation

Traditional language servers serialize AST nodes into JSON-RPC packets across IPC boundaries. In monorepos spanning hundreds of thousands of lines of TypeScript and Rust, this introduces noticeable cursor latency.

CodeXa Studio stores the symbol index in a flat continuous memory buffer using pointer arrays. Node coordinates, references, and type signatures remain in memory without round-trip serialization.

// CodeXa Flat Buffer AST Allocation
interface ASTBufferHeader {
  magic: 0x435841; // 'CXA'
  symbolCount: number;
  byteLength: number;
}

export function lookupSymbolFast(buffer: ArrayBuffer, hash: number): number {
  const view = new DataView(buffer);
  let low = 0, high = view.getUint32(4, true) - 1;
  while (low <= high) {
    const mid = (low + high) >>> 1;
    const midHash = view.getUint32(16 + mid * 16, true);
    if (midHash === hash) return view.getUint32(20 + mid * 16, true);
    if (midHash < hash) low = mid + 1; else high = mid - 1;
  }
  return -1;
}

Incremental File Watching

When a file changes on disk, only the affected sub-tree is reparsed. Invariant hashing ensures downstream symbol references are retained without re-indexing the entire workspace directory.

The watcher operates through native operating system APIs: ReadDirectoryChangesW on Windows, FSEvents on macOS, and inotify on Linux.

Empirical Latency Benchmarks

Under stress testing on a 500,000-line TypeScript repository, average rename propagation completed in under 24 milliseconds, maintaining full 120 FPS editor render frames.