compute-filesystem-cache.ts

/*
This is used by src/compute/compute/lib/filesystem-cache.
*/

import { join } from "path";
import { open, rm, stat } from "fs/promises";
import { exists } from "@cocalc/backend/misc/async-utils-node";
import type { ComputeFilesystemOptions } from "@cocalc/comm/websocket/types";

export default async function computeFilesystemCache(
  opts: ComputeFilesystemOptions,
) {
  const { func } = opts;
  switch (func) {
    case "filesToDelete":
      return await filesToDelete(opts.allComputeFiles);
    case "deleteWhiteouts":
      return await deleteWhiteouts(opts.whiteouts);
    default:
      throw Error(`unknown command ${func}`);
  }
}

// Given a path to a file that contains a list (one per line)
// of the files and on the compute server that are sync'd,
// return the ones that should be deleted from the compute server,
// because they were deleted locally.
async function filesToDelete(allComputeFiles: string) {
  if (typeof allComputeFiles != "string") {
    throw Error(
      "filesToDelete takes the path to list of all files in the compute server as input",
    );
  }
  if (!process.env.HOME) {
    throw Error("HOME must be defined");
  }
  const file = await open(join(process.env.HOME, allComputeFiles));
  const toDelete: string[] = [];
  for await (const path of file.readLines()) {
    const abspath = join(process.env.HOME, path);
    if (!(await exists(abspath))) {
      toDelete.push(path);
    }
  }
  await file.close();
  return toDelete;
}

async function deleteWhiteouts(whiteouts: { [path: string]: number }) {
  if (!process.env.HOME) {
    throw Error("HOME must be defined");
  }
  for (const path in whiteouts) {
    try {
      const abspath = join(process.env.HOME, path);
      // if file already gone, this throws, which is fine
      const { ctimeMs } = await stat(abspath);
      if (ctimeMs >= whiteouts[path]) {
        // file changed in the project *after* the delete, so don't delete.
        continue;
      }
      await rm(join(process.env.HOME, path), { recursive: true });
    } catch (_) {}
  }
}