Mercurial > p > roundup > code
annotate roundup/anypy/random_.py @ 6610:db3f0ba75b4a
Change checkpoint_data and restore_connection_on_error to subtransaction
checkpoint_data and restore_connection_on_error used to commit() and
rollback() the db connection. This causes additional I/O and load.
Changed them to use 'SAVEPOINT name' and 'ROLLBACK TO name' to get a
faster method for handling errors within a tranaction.
One thing to note is that postgresql (unlike SQL std) doesn't
overwrite an older savepoint with he same name. It keeps all
savepoints but only rolls back to the newest one with a given name.
This could be a resource issue. I left a commented out release
statement in case somebody runs into an issue due to too many
savepoints. I expect it to slow down the import but....
| author | John Rouillard <rouilj@ieee.org> |
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| date | Sat, 29 Jan 2022 11:29:36 -0500 |
| parents | adf54478cdaf |
| children | 07ce4e4110f5 |
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1 try: |
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2 from secrets import choice, randbelow, token_bytes |
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3 |
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4 def seed(v=None): |
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5 pass |
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6 |
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7 is_weak = False |
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8 except ImportError: |
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9 import os as _os |
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10 import random as _random |
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11 |
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12 # prefer to use SystemRandom if it is available |
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13 if hasattr(_random, 'SystemRandom'): |
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14 def seed(v=None): |
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15 pass |
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16 |
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17 _r = _random.SystemRandom() |
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18 is_weak = False |
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19 else: |
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20 # don't completely throw away the existing state, but add some |
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21 # more random state to the existing state |
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22 def seed(v=None): |
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23 import os, time |
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24 _r.seed((_r.getstate(), |
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25 v, |
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26 hasattr(os, 'getpid') and os.getpid(), |
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27 time.time())) |
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28 |
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29 # create our own instance so we don't mess with the global |
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30 # random number generator |
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31 _r = _random.Random() |
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32 seed() |
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33 is_weak = True |
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34 |
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35 choice = _r.choice |
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36 |
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37 def randbelow(i): |
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38 return _r.randint(0, i - 1) |
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39 |
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40 if hasattr(_os, 'urandom'): |
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41 def token_bytes(l): |
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42 return _os.urandom(l) |
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43 else: |
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44 def token_bytes(l): |
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45 _bchr = chr if str == bytes else lambda x: bytes((x,)) |
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46 return b''.join([_bchr(_r.getrandbits(8)) for i in range(l)]) |
