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Reverter.py: clock change protection, and debugging for #1243

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This commit is contained in:
Peter Eckersley 2016-04-08 15:30:27 -07:00
parent b347e9fba1
commit 3ca825592e
1 changed files with 27 additions and 10 deletions
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37
letsencrypt/reverter.py
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@ -4,6 +4,7 @@ import logging
import os
import shutil
import time
import traceback
import zope.component
@ -333,16 +334,14 @@ class Reverter(object):
# Make sure some files are provided... as this is an error
# Made this mistake in my initial implementation of apache.dvsni.py
if not files:
raise errors.ReverterError(
"Forgot to provide files to registration call")
raise errors.ReverterError("Forgot to provide files to registration call")
cp_dir = self._get_cp_dir(temporary)
# Append all new files (that aren't already registered)
new_fd = None
try:
new_fd, ex_files = self._read_and_append(
os.path.join(cp_dir, "NEW_FILES"))
new_fd, ex_files = self._read_and_append(os.path.join(cp_dir, "NEW_FILES"))
for path in files:
if path not in ex_files:
@ -503,26 +502,44 @@ class Reverter(object):
shutil.move(changes_since_tmp_path, changes_since_path)
except (IOError, OSError):
logger.error("Unable to finalize checkpoint - adding title")
logger.debug("Exception was:\%s", traceback.format_exc())
raise errors.ReverterError("Unable to add title")
self._timestamp_progress_dir()
def _checkpoint_timestamp(self)
"Determine the timestamp of the checkpoint, enforcing monotonicity."
timestamp = str(time.time())
others = os.listdir(self.config.backup_dir)
others.append(new_dir)
others.sort()
if others[-1] != timestamp:
timetravel = str(float(others[-1]) + 1)
logger.warn("Current timestamp %s does not correspond to newest reverter "
"checkpoint; your clock probably jumped. Time travelling to %s",
new_dir, timetravel)
timestamp = timetravel
elif len(others) > 1 and others[-2] == timestamp:
# It is possible if the checkpoints are made extremely quickly
# that will result in a name collision.
logger.debug("Race condition with timestamp %s, incrementing by 0.01", timestamp)
timetravel = str(float(others[-1]) + 0.01)
timestamp = timetravel
return timestamp
def _timestamp_progress_dir(self):
"""Timestamp the checkpoint."""
# It is possible save checkpoints faster than 1 per second resulting in
# collisions in the naming convention.
cur_time = time.time()
for _ in xrange(10):
final_dir = os.path.join(self.config.backup_dir, str(cur_time))
timestamp = self._checkpoint_timestamp()
final_dir = os.path.join(self.config.backup_dir, timestamp)
try:
os.rename(self.config.in_progress_dir, final_dir)
return
except OSError:
# It is possible if the checkpoints are made extremely quickly
# that will result in a name collision.
# If so, increment and try again
cur_time += .01
logger.warning("Extreme, unexpected race condition, retrying (%s)", timestamp)
# After 10 attempts... something is probably wrong here...
logger.error(