Better exclude_address function in ipaddress.py

Bắt đầu trong ipaddress.py tại address_exclude và đọc các đường đi hiện có của subnets() và summarize_address_range(). So sánh cách tiếp cận dựa trên phạm vi số nguyên được đề xuất với hành vi hiện tại, đồng thời giữ nguyên các kết quả mạng đã được minh họa và giải quyết vấn đề hiệu năng đã được báo cáo.

Feature or enhancement

Increase the speed of exclude_address by treating IPs as integer ranges making exclude_address O(1).

Pitch

Currently exclude_address will take a subnet and split it by calling subnets()

import ipaddress
>>> ip = ipaddress.IPv4Network('10.0.0.0/8')
>>> [i for i in ip.subnets()]
[IPv4Network('10.0.0.0/9'), IPv4Network('10.128.0.0/9')]

each time it is split, it checks which one contains the subnet being excluded and splits again.
This ends up being a lot of work.

Instead I propose we can use the fact that IPs are represented as integers behind the scene

For a given subnet, it can be thought of as an integer range between its network and broadcast address

>>> ip.network_address._ip
167772160
>>> ip.broadcast_address._ip
184549375

Given these can be treated as an integer range, excluding is just removing the range integers you wish to exclude

>>> [i for i in ipaddress.summarize_address_range(
    ipaddress.IPv4Address(
        ip.network_address._ip),
        ipaddress.IPv4Address(exclude_ip.network_address._ip-1
))]
[IPv4Network('10.0.0.0/22')]

>>> [i for i in ipaddress.summarize_address_range(
    ipaddress.IPv4Address(
        exclude_ip.broadcast_address._ip)+1,
        ipaddress.IPv4Address(ip.broadcast_address._ip
))]
[IPv4Network('10.0.5.0/24'), IPv4Network('10.0.6.0/23'), IPv4Network('10.0.8.0/21'), IPv4Network('10.0.16.0/20'), IPv4Network('10.0.32.0/19'), IPv4Network('10.0.64.0/18'), IPv4Network('10.0.128.0/17'), IPv4Network('10.1.0.0/16'), IPv4Network('10.2.0.0/15'), IPv4Network('10.4.0.0/14'), IPv4Network('10.8.0.0/13'), IPv4Network('10.16.0.0/12'), IPv4Network('10.32.0.0/11'), IPv4Network('10.64.0.0/10'), IPv4Network('10.128.0.0/9')]

>>> sorted([i for i in ip.address_exclude(
    ipaddress.IPv4Network('10.0.4.0/24'
))])
[IPv4Network('10.0.0.0/22'), IPv4Network('10.0.5.0/24'), IPv4Network('10.0.6.0/23'), IPv4Network('10.0.8.0/21'), IPv4Network('10.0.16.0/20'), IPv4Network('10.0.32.0/19'), IPv4Network('10.0.64.0/18'), IPv4Network('10.0.128.0/17'), IPv4Network('10.1.0.0/16'), IPv4Network('10.2.0.0/15'), IPv4Network('10.4.0.0/14'), IPv4Network('10.8.0.0/13'), IPv4Network('10.16.0.0/12'), IPv4Network('10.32.0.0/11'), IPv4Network('10.64.0.0/10'), IPv4Network('10.128.0.0/9')]

Previous discussion

https://discuss.python.org/t/ipaddress-py-exclude-address-speed-up/19445