iframe-proxy | Sunbelt Computer Software

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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2019 Brett Slatkin, Pearson Education Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Reproduce book environment
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# Write all output to a temporary directory
import atexit
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# Make sure Windows processes exit cleanly
OLD_CWD = os.getcwd()
atexit.register(lambda: os.chdir(OLD_CWD))
os.chdir(TEST_DIR.name)
def close_open_files():
    everything = gc.get_objects()
    for obj in everything:
        if isinstance(obj, io.IOBase):
            obj.close()
atexit.register(close_open_files)
# Example 1
from datetime import datetime, timedelta
class Bucket:
    def __init__(self, period):
        self.period_delta = timedelta(seconds=period)
        self.reset_time = datetime.now()
        self.quota = 0
    def __repr__(self):
        return f'Bucket(quota={self.quota})'
bucket = Bucket(60)
print(bucket)
# Example 2
def fill(bucket, amount):
    now = datetime.now()
    if (now - bucket.reset_time) > bucket.period_delta:
        bucket.quota = 0
        bucket.reset_time = now
    bucket.quota += amount
# Example 3
def deduct(bucket, amount):
    now = datetime.now()
    if (now - bucket.reset_time) > bucket.period_delta:
        return False  # Bucket hasn't been filled this period
    if bucket.quota - amount < 0:
        return False  # Bucket was filled, but not enough
    bucket.quota -= amount
    return True       # Bucket had enough, quota consumed
# Example 4
bucket = Bucket(60)
fill(bucket, 100)
print(bucket)
# Example 5
if deduct(bucket, 99):
    print('Had 99 quota')
    print('Not enough for 99 quota')
print(bucket)
# Example 6
if deduct(bucket, 3):
    print('Had 3 quota')
    print('Not enough for 3 quota')
print(bucket)
# Example 7
class NewBucket:
    def __init__(self, period):
        self.period_delta = timedelta(seconds=period)
        self.reset_time = datetime.now()
        self.max_quota = 0
        self.quota_consumed = 0
    def __repr__(self):
        return (f'NewBucket(max_quota={self.max_quota}, '
                f'quota_consumed={self.quota_consumed})')
# Example 8
    @property
    def quota(self):
        return self.max_quota - self.quota_consumed
# Example 9
    @quota.setter
    def quota(self, amount):
        delta = self.max_quota - amount
        if amount == 0:
            # Quota being reset for a new period
            self.quota_consumed = 0
            self.max_quota = 0
        elif delta < 0:
            # Quota being filled for the new period
            assert self.quota_consumed == 0
            self.max_quota = amount
        else:
            # Quota being consumed during the period
            assert self.max_quota >= self.quota_consumed
            self.quota_consumed += delta
# Example 10
bucket = NewBucket(60)
print('Initial', bucket)
fill(bucket, 100)
print('Filled', bucket)
if deduct(bucket, 99):
    print('Had 99 quota')
    print('Not enough for 99 quota')
print('Now', bucket)
if deduct(bucket, 3):
    print('Had 3 quota')
    print('Not enough for 3 quota')
print('Still', bucket)
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