mirror of https://github.com/python/cpython
70 lines
2.5 KiB
Python
70 lines
2.5 KiB
Python
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#------------------------------------------------------------------------
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#
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# In my performance tests, using this (as in dbtest.py test4) is
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# slightly slower than simply compiling _db.c with MYDB_THREAD
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# undefined to prevent multithreading support in the C module.
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# Using NoDeadlockDb also prevent deadlocks from mutliple processes
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# accessing the same database.
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#
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# Copyright (C) 2000 Autonomous Zone Industries
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#
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# License: This is free software. You may use this software for any
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# purpose including modification/redistribution, so long as
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# this header remains intact and that you do not claim any
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# rights of ownership or authorship of this software. This
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# software has been tested, but no warranty is expressed or
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# implied.
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#
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# Author: Gregory P. Smith <greg@electricrain.com>
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#
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# Note: I don't know how useful this is in reality since when a
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# DBDeadlockError happens the current transaction is supposed to be
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# aborted. If it doesn't then when the operation is attempted again
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# the deadlock is still happening...
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# --Robin
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#
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#------------------------------------------------------------------------
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#
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# import the time.sleep function in a namespace safe way to allow
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# "from bsddb3.db import *"
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#
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from time import sleep
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_sleep = sleep
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del sleep
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import _db
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_deadlock_MinSleepTime = 1.0/64 # always sleep at least N seconds between retrys
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_deadlock_MaxSleepTime = 1.0 # never sleep more than N seconds between retrys
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def DeadlockWrap(function, *_args, **_kwargs):
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"""DeadlockWrap(function, *_args, **_kwargs) - automatically retries
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function in case of a database deadlock.
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This is a DeadlockWrapper method which DB calls can be made using to
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preform infinite retrys with sleeps in between when a DBLockDeadlockError
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exception is raised in a database call:
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d = DB(...)
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d.open(...)
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DeadlockWrap(d.put, "foo", data="bar") # set key "foo" to "bar"
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"""
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sleeptime = _deadlock_MinSleepTime
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while (1) :
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try:
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return apply(function, _args, _kwargs)
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except _db.DBLockDeadlockError:
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print 'DeadlockWrap sleeping ', sleeptime
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_sleep(sleeptime)
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# exponential backoff in the sleep time
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sleeptime = sleeptime * 2
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if sleeptime > _deadlock_MaxSleepTime :
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sleeptime = _deadlock_MaxSleepTime
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#------------------------------------------------------------------------
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