jyoung/system/loggerd/deleter.py

#!/usr/bin/env python3
import os
import shutil
import threading
from typing import List

from system.swaglog import cloudlog
from system.loggerd.config import ROOT, get_available_bytes, get_available_percent
from system.loggerd.uploader import listdir_by_creation
from system.loggerd.xattr_cache import getxattr

MIN_BYTES = 5 * 1024 * 1024 * 1024
MIN_PERCENT = 10

DELETE_LAST = ['boot', 'crash']

PRESERVE_ATTR_NAME = 'user.preserve'
PRESERVE_ATTR_VALUE = b'1'
PRESERVE_COUNT = 5


def has_preserve_xattr(d: str) -> bool:
  return getxattr(os.path.join(ROOT, d), PRESERVE_ATTR_NAME) == PRESERVE_ATTR_VALUE


def get_preserved_segments(dirs_by_creation: List[str]) -> List[str]:
  preserved = []
  for n, d in enumerate(filter(has_preserve_xattr, reversed(dirs_by_creation))):
    if n == PRESERVE_COUNT:
      break
    date_str, _, seg_str = d.rpartition("--")

    # ignore non-segment directories
    if not date_str:
      continue
    try:
      seg_num = int(seg_str)
    except ValueError:
      continue

    # preserve segment and its prior
    preserved.append(d)
    preserved.append(f"{date_str}--{seg_num - 1}")

  return preserved


def deleter_thread(exit_event):
  while not exit_event.is_set():
    out_of_bytes = get_available_bytes(default=MIN_BYTES + 1) < MIN_BYTES
    out_of_percent = get_available_percent(default=MIN_PERCENT + 1) < MIN_PERCENT

    if out_of_percent or out_of_bytes:
      dirs = listdir_by_creation(ROOT)

      # skip deleting most recent N preserved segments (and their prior segment)
      preserved_dirs = get_preserved_segments(dirs)

      # remove the earliest directory we can
      for delete_dir in sorted(dirs, key=lambda d: (d in DELETE_LAST, d in preserved_dirs)):
        delete_path = os.path.join(ROOT, delete_dir)

        if any(name.endswith(".lock") for name in os.listdir(delete_path)):
          continue

        try:
          cloudlog.info(f"deleting {delete_path}")
          if os.path.isfile(delete_path):
            os.remove(delete_path)
          else:
            shutil.rmtree(delete_path)
          break
        except OSError:
          cloudlog.exception(f"issue deleting {delete_path}")
      exit_event.wait(.1)
    else:
      exit_event.wait(30)


def main():
  deleter_thread(threading.Event())


if __name__ == "__main__":
  main()