57 lines
1.9 KiB
Python
57 lines
1.9 KiB
Python
import time
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class Ratelimiter:
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def __init__(self, allowance_per_period, period, operation_cost=1, mode='sleep'):
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'''
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allowance_per_period:
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The number of operations we can perform per `period` seconds.
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period:
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The number of seconds over which we can perform `allowance_per_period` operations.
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operation_cost:
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The default amount to remove from our balance after each operation.
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Pass a `cost` parameter to `self.limit` to use a nondefault value.
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mode:
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'sleep': If we do not have the balance for an operation, sleep until we do.
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Return True every time.
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'reject': If we do not have the balance for an operation, return False.
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'''
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if mode not in ('sleep', 'reject'):
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raise ValueError('Invalid mode %s' % repr(mode))
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self.allowance_per_period = allowance_per_period
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self.period = period
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self.operation_cost = operation_cost
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self.mode = mode
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self.last_operation = time.time()
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self.balance = 0
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self.gain_rate = allowance_per_period / period
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def limit(self, cost=None):
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if cost is None:
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cost = self.operation_cost
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timediff = time.time() - self.last_operation
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self.balance += timediff * self.gain_rate
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self.balance = min(self.balance, self.allowance_per_period)
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successful = False
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deficit = cost - self.balance
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if deficit > 0 and self.mode == 'sleep':
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time_needed = (deficit / self.gain_rate)
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#print(self.balance, deficit, 'Need to sleep %f' % time_needed)
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time.sleep(time_needed)
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self.balance = cost
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#print(self.balance)
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if self.balance >= cost:
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#print('pass')
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self.balance -= cost
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successful = True
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self.last_operation = time.time()
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return successful
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