mirror of
https://github.com/python/cpython.git
synced 2025-07-30 06:34:15 +00:00
506f7b559a
now works reliably. It has been updated to use automatic BerkeleyDB deadlock detection and the bsddb.dbutils.DeadlockWrap wrapper to retry database calls that would previously deadlock. [SF python bug #775414]
77 lines
2.7 KiB
Python
77 lines
2.7 KiB
Python
#------------------------------------------------------------------------
|
|
#
|
|
# Copyright (C) 2000 Autonomous Zone Industries
|
|
#
|
|
# License: This is free software. You may use this software for any
|
|
# purpose including modification/redistribution, so long as
|
|
# this header remains intact and that you do not claim any
|
|
# rights of ownership or authorship of this software. This
|
|
# software has been tested, but no warranty is expressed or
|
|
# implied.
|
|
#
|
|
# Author: Gregory P. Smith <greg@electricrain.com>
|
|
#
|
|
# Note: I don't know how useful this is in reality since when a
|
|
# DBLockDeadlockError happens the current transaction is supposed to be
|
|
# aborted. If it doesn't then when the operation is attempted again
|
|
# the deadlock is still happening...
|
|
# --Robin
|
|
#
|
|
#------------------------------------------------------------------------
|
|
|
|
|
|
#
|
|
# import the time.sleep function in a namespace safe way to allow
|
|
# "from bsddb.dbutils import *"
|
|
#
|
|
from time import sleep as _sleep
|
|
|
|
import db
|
|
|
|
# always sleep at least N seconds between retrys
|
|
_deadlock_MinSleepTime = 1.0/128
|
|
# never sleep more than N seconds between retrys
|
|
_deadlock_MaxSleepTime = 3.14159
|
|
|
|
# Assign a file object to this for a "sleeping" message to be written to it
|
|
# each retry
|
|
_deadlock_VerboseFile = None
|
|
|
|
|
|
def DeadlockWrap(function, *_args, **_kwargs):
|
|
"""DeadlockWrap(function, *_args, **_kwargs) - automatically retries
|
|
function in case of a database deadlock.
|
|
|
|
This is a function intended to be used to wrap database calls such
|
|
that they perform retrys with exponentially backing off sleeps in
|
|
between when a DBLockDeadlockError exception is raised.
|
|
|
|
A 'max_retries' parameter may optionally be passed to prevent it
|
|
from retrying forever (in which case the exception will be reraised).
|
|
|
|
d = DB(...)
|
|
d.open(...)
|
|
DeadlockWrap(d.put, "foo", data="bar") # set key "foo" to "bar"
|
|
"""
|
|
sleeptime = _deadlock_MinSleepTime
|
|
max_retries = _kwargs.get('max_retries', -1)
|
|
if _kwargs.has_key('max_retries'):
|
|
del _kwargs['max_retries']
|
|
while True:
|
|
try:
|
|
return function(*_args, **_kwargs)
|
|
except db.DBLockDeadlockError:
|
|
if _deadlock_VerboseFile:
|
|
_deadlock_VerboseFile.write(
|
|
'dbutils.DeadlockWrap: sleeping %1.3f\n' % sleeptime)
|
|
_sleep(sleeptime)
|
|
# exponential backoff in the sleep time
|
|
sleeptime *= 2
|
|
if sleeptime > _deadlock_MaxSleepTime:
|
|
sleeptime = _deadlock_MaxSleepTime
|
|
max_retries -= 1
|
|
if max_retries == -1:
|
|
raise
|
|
|
|
|
|
#------------------------------------------------------------------------
|