Log error if hashing takes more than 3 seconds

brick/lib.py

@@ -98,11 +98,18 @@ def compute_hash_from_paths(paths: List[str]) -> str:
  if not paths:
  raise ValueError("Expected input paths")
 
+ t_start = time.time()
  sha1_command = get_sha1_command()
  cmd = f"find {' '.join(paths)} -type f -print0 | sort -z | xargs -0 {sha1_command} | {sha1_command}"
  sha1_sum: str = run_shell_command(cmd=cmd, cwd=ROOT_PATH).split(" ")[0].strip()
  assert len(sha1_sum) == 40, "expected sha1sum of length 40"
 
+ # Wasting more than a few seconds hashing usually means that the input dependencies
+ # should be tweaked.
+ hashing_time = time.time() - t_start
+ if hashing_time > 3:
+ logger.info(f'😴 Observed slow hashing ({hashing_time:.1f}s) for command "{cmd}"')
+
  return sha1_sum