业务中经常需要对redis执行一组连续的 gitbit ，即 gitbits 。以下通过 getrange 方法来优化 getbits 的速度。redis 的 bit 并非按照自然顺序排序，所以需要计算。

bit.go

package redis

import (
	r "github.com/garyburd/redigo/redis"
)

type Pool struct {
	r.Pool
}

var nums = [8]uint8{1, 2, 4, 8, 16, 32, 64, 128}

// BitRange 计算下标表
// str: 计算的字符串
// start: 开始的座标
// offset: 偏移值
// size: 查询个数
func BitRange(str []byte, start int, offset int, size int) []int {
	bits := []int{}
	k := 0
	for i, b := range str {
		// 按位，依次判断0-7下标每位是否为真
		for j, num := range nums {
			if b&num != num {
				continue
			}
			// redis 存储offset 是从左向右存
			// 下标位置 = 7 - 当前位
			k = int(i*8 + 7 - j)
			if offset <= k && k < offset+size {
				bits = append(bits, start*8+k)
			}
			
		}
	}
	return bits
}

// GetBitRange 按位查询 返回bit位为1的下标
// client: redis的client
// key: redis 存储的key
// cur: 开始位置
// size: 查询个数
func (p *Pool) BitRange(key string, cur int, size int) ([]int, error) {
	start := cur / 8
	// end必须按8取整
	end := (cur+size+7)/8
	str, err := r.Bytes(p.ExecuteCMD("GETRANGE", key, start, end))
	if err != nil {
		return nil, err
	}
	bits := BitRange(str, start, cur%8, size)
	return bits, nil
}

bit_range.py

# -*- coding: utf-8 -*-
"""
业务中经常需要对redis执行一组连续的gitbit
以下通过getrange 方法来优化getbits的速度

empty key, times 10
git_bits 1: 0.508
get_bits_pipe 1: 0.604
git_bits 10: 0.543
get_bits_pipe 10: 1.159
git_bits 100: 0.587
get_bits_pipe 100: 3.477
git_bits 1000: 0.744
get_bits_pipe 1000: 34.866
git_bits 5000: 0.629
get_bits_pipe 5000: 120.348

all true, times 10
git_bits 1: 0.405
get_bits_pipe 1: 0.478
git_bits 10: 0.420
get_bits_pipe 10: 1.390
git_bits 100: 0.995
get_bits_pipe 100: 3.562
git_bits 1000: 1.615
get_bits_pipe 1000: 28.776
git_bits 5000: 4.770
get_bits_pipe 5000: 120.539

由此可见getrange 确实有效的提升了查询性能

"""
import time
import redis

redis_bit_map = {
    "\x00": [],
    "\x01": [7],
    "\x02": [6],
    "\x03": [6, 7],
    "\x04": [5],
    "\x05": [5, 7],
    "\x06": [5, 6],
    "\x07": [5, 6, 7],
    "\x08": [4],
    "\t": [4, 7],
    "\n": [4, 6],
    "\x0b": [4, 6, 7],
    "\x0c": [4, 5],
    "\r": [4, 5, 7],
    "\x0e": [4, 5, 6],
    "\x0f": [4, 5, 6, 7],
    "\x10": [3],
    "\x11": [3, 7],
    "\x12": [3, 6],
    "\x13": [3, 6, 7],
    "\x14": [3, 5],
    "\x15": [3, 5, 7],
    "\x16": [3, 5, 6],
    "\x17": [3, 5, 6, 7],
    "\x18": [3, 4],
    "\x19": [3, 4, 7],
    "\x1a": [3, 4, 6],
    "\x1b": [3, 4, 6, 7],
    "\x1c": [3, 4, 5],
    "\x1d": [3, 4, 5, 7],
    "\x1e": [3, 4, 5, 6],
    "\x1f": [3, 4, 5, 6, 7],
    " ": [2],
    "!": [2, 7],
    """: [2, 6],
    "#": [2, 6, 7],
    "$": [2, 5],
    "%": [2, 5, 7],
    "&": [2, 5, 6],
    """: [2, 5, 6, 7],
    "(": [2, 4],
    ")": [2, 4, 7],
    "*": [2, 4, 6],
    "+": [2, 4, 6, 7],
    ",": [2, 4, 5],
    "-": [2, 4, 5, 7],
    ".": [2, 4, 5, 6],
    "/": [2, 4, 5, 6, 7],
    "0": [2, 3],
    "1": [2, 3, 7],
    "2": [2, 3, 6],
    "3": [2, 3, 6, 7],
    "4": [2, 3, 5],
    "5": [2, 3, 5, 7],
    "6": [2, 3, 5, 6],
    "7": [2, 3, 5, 6, 7],
    "8": [2, 3, 4],
    "9": [2, 3, 4, 7],
    ":": [2, 3, 4, 6],
    ";": [2, 3, 4, 6, 7],
    "<": [2, 3, 4, 5],
    "=": [2, 3, 4, 5, 7],
    ">": [2, 3, 4, 5, 6],
    "?": [2, 3, 4, 5, 6, 7],
    "@": [1],
    "A": [1, 7],
    "B": [1, 6],
    "C": [1, 6, 7],
    "D": [1, 5],
    "E": [1, 5, 7],
    "F": [1, 5, 6],
    "G": [1, 5, 6, 7],
    "H": [1, 4],
    "I": [1, 4, 7],
    "J": [1, 4, 6],
    "K": [1, 4, 6, 7],
    "L": [1, 4, 5],
    "M": [1, 4, 5, 7],
    "N": [1, 4, 5, 6],
    "O": [1, 4, 5, 6, 7],
    "P": [1, 3],
    "Q": [1, 3, 7],
    "R": [1, 3, 6],
    "S": [1, 3, 6, 7],
    "T": [1, 3, 5],
    "U": [1, 3, 5, 7],
    "V": [1, 3, 5, 6],
    "W": [1, 3, 5, 6, 7],
    "X": [1, 3, 4],
    "Y": [1, 3, 4, 7],
    "Z": [1, 3, 4, 6],
    "[": [1, 3, 4, 6, 7],
    "\\": [1, 3, 4, 5],
    "]": [1, 3, 4, 5, 7],
    "^": [1, 3, 4, 5, 6],
    "_": [1, 3, 4, 5, 6, 7],
    "`": [1, 2],
    "a": [1, 2, 7],
    "b": [1, 2, 6],
    "c": [1, 2, 6, 7],
    "d": [1, 2, 5],
    "e": [1, 2, 5, 7],
    "f": [1, 2, 5, 6],
    "g": [1, 2, 5, 6, 7],
    "h": [1, 2, 4],
    "i": [1, 2, 4, 7],
    "j": [1, 2, 4, 6],
    "k": [1, 2, 4, 6, 7],
    "l": [1, 2, 4, 5],
    "m": [1, 2, 4, 5, 7],
    "n": [1, 2, 4, 5, 6],
    "o": [1, 2, 4, 5, 6, 7],
    "p": [1, 2, 3],
    "q": [1, 2, 3, 7],
    "r": [1, 2, 3, 6],
    "s": [1, 2, 3, 6, 7],
    "t": [1, 2, 3, 5],
    "u": [1, 2, 3, 5, 7],
    "v": [1, 2, 3, 5, 6],
    "w": [1, 2, 3, 5, 6, 7],
    "x": [1, 2, 3, 4],
    "y": [1, 2, 3, 4, 7],
    "z": [1, 2, 3, 4, 6],
    "{": [1, 2, 3, 4, 6, 7],
    "|": [1, 2, 3, 4, 5],
    "}": [1, 2, 3, 4, 5, 7],
    "~": [1, 2, 3, 4, 5, 6],
    "\x7f": [1, 2, 3, 4, 5, 6, 7],
    "\x80": [0],
    "\x81": [0, 7],
    "\x82": [0, 6],
    "\x83": [0, 6, 7],
    "\x84": [0, 5],
    "\x85": [0, 5, 7],
    "\x86": [0, 5, 6],
    "\x87": [0, 5, 6, 7],
    "\x88": [0, 4],
    "\x89": [0, 4, 7],
    "\x8a": [0, 4, 6],
    "\x8b": [0, 4, 6, 7],
    "\x8c": [0, 4, 5],
    "\x8d": [0, 4, 5, 7],
    "\x8e": [0, 4, 5, 6],
    "\x8f": [0, 4, 5, 6, 7],
    "\x90": [0, 3],
    "\x91": [0, 3, 7],
    "\x92": [0, 3, 6],
    "\x93": [0, 3, 6, 7],
    "\x94": [0, 3, 5],
    "\x95": [0, 3, 5, 7],
    "\x96": [0, 3, 5, 6],
    "\x97": [0, 3, 5, 6, 7],
    "\x98": [0, 3, 4],
    "\x99": [0, 3, 4, 7],
    "\x9a": [0, 3, 4, 6],
    "\x9b": [0, 3, 4, 6, 7],
    "\x9c": [0, 3, 4, 5],
    "\x9d": [0, 3, 4, 5, 7],
    "\x9e": [0, 3, 4, 5, 6],
    "\x9f": [0, 3, 4, 5, 6, 7],
    "\xa0": [0, 2],
    "\xa1": [0, 2, 7],
    "\xa2": [0, 2, 6],
    "\xa3": [0, 2, 6, 7],
    "\xa4": [0, 2, 5],
    "\xa5": [0, 2, 5, 7],
    "\xa6": [0, 2, 5, 6],
    "\xa7": [0, 2, 5, 6, 7],
    "\xa8": [0, 2, 4],
    "\xa9": [0, 2, 4, 7],
    "\xaa": [0, 2, 4, 6],
    "\xab": [0, 2, 4, 6, 7],
    "\xac": [0, 2, 4, 5],
    "\xad": [0, 2, 4, 5, 7],
    "\xae": [0, 2, 4, 5, 6],
    "\xaf": [0, 2, 4, 5, 6, 7],
    "\xb0": [0, 2, 3],
    "\xb1": [0, 2, 3, 7],
    "\xb2": [0, 2, 3, 6],
    "\xb3": [0, 2, 3, 6, 7],
    "\xb4": [0, 2, 3, 5],
    "\xb5": [0, 2, 3, 5, 7],
    "\xb6": [0, 2, 3, 5, 6],
    "\xb7": [0, 2, 3, 5, 6, 7],
    "\xb8": [0, 2, 3, 4],
    "\xb9": [0, 2, 3, 4, 7],
    "\xba": [0, 2, 3, 4, 6],
    "\xbb": [0, 2, 3, 4, 6, 7],
    "\xbc": [0, 2, 3, 4, 5],
    "\xbd": [0, 2, 3, 4, 5, 7],
    "\xbe": [0, 2, 3, 4, 5, 6],
    "\xbf": [0, 2, 3, 4, 5, 6, 7],
    "\xc0": [0, 1],
    "\xc1": [0, 1, 7],
    "\xc2": [0, 1, 6],
    "\xc3": [0, 1, 6, 7],
    "\xc4": [0, 1, 5],
    "\xc5": [0, 1, 5, 7],
    "\xc6": [0, 1, 5, 6],
    "\xc7": [0, 1, 5, 6, 7],
    "\xc8": [0, 1, 4],
    "\xc9": [0, 1, 4, 7],
    "\xca": [0, 1, 4, 6],
    "\xcb": [0, 1, 4, 6, 7],
    "\xcc": [0, 1, 4, 5],
    "\xcd": [0, 1, 4, 5, 7],
    "\xce": [0, 1, 4, 5, 6],
    "\xcf": [0, 1, 4, 5, 6, 7],
    "\xd0": [0, 1, 3],
    "\xd1": [0, 1, 3, 7],
    "\xd2": [0, 1, 3, 6],
    "\xd3": [0, 1, 3, 6, 7],
    "\xd4": [0, 1, 3, 5],
    "\xd5": [0, 1, 3, 5, 7],
    "\xd6": [0, 1, 3, 5, 6],
    "\xd7": [0, 1, 3, 5, 6, 7],
    "\xd8": [0, 1, 3, 4],
    "\xd9": [0, 1, 3, 4, 7],
    "\xda": [0, 1, 3, 4, 6],
    "\xdb": [0, 1, 3, 4, 6, 7],
    "\xdc": [0, 1, 3, 4, 5],
    "\xdd": [0, 1, 3, 4, 5, 7],
    "\xde": [0, 1, 3, 4, 5, 6],
    "\xdf": [0, 1, 3, 4, 5, 6, 7],
    "\xe0": [0, 1, 2],
    "\xe1": [0, 1, 2, 7],
    "\xe2": [0, 1, 2, 6],
    "\xe3": [0, 1, 2, 6, 7],
    "\xe4": [0, 1, 2, 5],
    "\xe5": [0, 1, 2, 5, 7],
    "\xe6": [0, 1, 2, 5, 6],
    "\xe7": [0, 1, 2, 5, 6, 7],
    "\xe8": [0, 1, 2, 4],
    "\xe9": [0, 1, 2, 4, 7],
    "\xea": [0, 1, 2, 4, 6],
    "\xeb": [0, 1, 2, 4, 6, 7],
    "\xec": [0, 1, 2, 4, 5],
    "\xed": [0, 1, 2, 4, 5, 7],
    "\xee": [0, 1, 2, 4, 5, 6],
    "\xef": [0, 1, 2, 4, 5, 6, 7],
    "\xf0": [0, 1, 2, 3],
    "\xf1": [0, 1, 2, 3, 7],
    "\xf2": [0, 1, 2, 3, 6],
    "\xf3": [0, 1, 2, 3, 6, 7],
    "\xf4": [0, 1, 2, 3, 5],
    "\xf5": [0, 1, 2, 3, 5, 7],
    "\xf6": [0, 1, 2, 3, 5, 6],
    "\xf7": [0, 1, 2, 3, 5, 6, 7],
    "\xf8": [0, 1, 2, 3, 4],
    "\xf9": [0, 1, 2, 3, 4, 7],
    "\xfa": [0, 1, 2, 3, 4, 6],
    "\xfb": [0, 1, 2, 3, 4, 6, 7],
    "\xfc": [0, 1, 2, 3, 4, 5],
    "\xfd": [0, 1, 2, 3, 4, 5, 7],
    "\xfe": [0, 1, 2, 3, 4, 5, 6],
    "\xff": [0, 1, 2, 3, 4, 5, 6, 7],
}


def find_bit(bits):
    """ 位计算为真的下标
    >>> find_bit(b"\x80")
    [0]
    >>> find_bit("@")
    [1]
    >>> find_bit(b"\xff\xff")
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
    >>> find_bit(b"\x11")
    [3, 7]
    >>> find_bit(b"\x01\x01")
    [7, 15]
    >>> find_bit(b"\x11\x11")
    [3, 7, 11, 15]
    """
    return [no * 8 + j for no, i in enumerate(bits) for j in redis_bit_map[i]]


def git_bits(redis_client, key, cur, num=10):
    """ 按位查询 返回bit位为1的下标
    :param cur: 开始位置
    :param num: 查询个数
    :return: []
    """
    start, offset = divmod(cur, 8)
    # end 必须按8取整
    end = (cur + num + 7) / 8
    return [start * 8 + _id for _id in find_bit(redis_client.getrange(key, start, end))
            if offset <= _id <= offset + num]


def get_bits_pipe(pipe, key, cur, num=10):
    """ 使用pipeline gitbit"""
    for i in xrange(num + 1):
        pipe.getbit(key, cur + i)
    return [cur + i for i, v in enumerate(pipe.execute()) if v]


def bench(func, *a, **kw):
    """压力测试"""
    s = time.time()
    times = kw.pop("times", 1)
    res = None
    for _ in range(times):
        res = func(*a, **kw)
    e = time.time()
    print("%s %d: %.3f" % (func.func_name, kw["num"], (e - s) * 1000 / times))


if __name__ == "__main__":
    key = "bench_bits"
    r = redis.Redis()

    Times = 10
    print("empty key, times %d" % Times)
    r.delete(key)
    pipe = r.pipeline(transaction=False)
    for MAX in (1, 10, 100, 1000, 5000):
        bench(git_bits, r, key, 0, num=MAX, times=Times)
        bench(get_bits_pipe, pipe, key, 0, num=MAX, times=Times)

    for i in range(MAX):
        r.setbit(key, i, 1)
    print("all true, times %d" % Times)
    for MAX in (1, 10, 100, 1000, 5000):
        bench(git_bits, r, key, 0, num=MAX, times=Times)
        bench(get_bits_pipe, pipe, key, 0, num=MAX, times=Times)

bits_test.go

package redis

import (
	r "github.com/garyburd/redigo/redis"
	"fmt"
)

var (
	key = "bits"
	p = &Pool{r.Pool{
		Dial: func() (r.Conn, error) {
			return r.Dial("tcp", "127.0.0.1:6379")
		}, }}
)
func ExamplePool_GetBitRange() {
	p.ExecuteCMD("DEL", key)
	p.ExecuteCMD("SETBIT", key, 1, 1)
	bits, _ := p.GetBitRange(key, 0, 8)
	fmt.Println(bits)
	// Output: [1]
}

func TestPool_GetBitRange(t *testing.T) {
	// 测试边界 11 [12 13] 14
	p.ExecuteCMD("SETBIT", key, 11, 1)
	p.ExecuteCMD("SETBIT", key, 12, 1)
	p.ExecuteCMD("SETBIT", key, 14, 1)
	bits, _ := p.GetBitRange(key, 12, 2)
	if intInSlice(11, bits) && intInSlice(14, bits) && !intInSlice(12, bits) {
		t.Error("error in test TestGetBitRange")
	}
}

// intInSlice 数字是否在数组中
func intInSlice(a int, list []int) bool {
	for _, i := range list {
		if i == a {
			return true
		}
	}
	return false
}

redis 使用pipeline 获取 GETBIT（get_bits_pipe）和使用 GETRANGE （git_bits）性能差异。

git_bits 1: 0.405
get_bits_pipe 1: 0.478
git_bits 10: 0.420
get_bits_pipe 10: 1.390
git_bits 100: 0.995
get_bits_pipe 100: 3.562
git_bits 1000: 1.615
get_bits_pipe 1000: 28.776
git_bits 5000: 4.770
get_bits_pipe 5000: 120.539

你好，你的这个代码对我有非常大的帮助，请问我是否可以把它用到我自己的项目中？

你好, 谢谢您的无私分享, 有个细节想请教, redis_bit_map = {
"\x00": [],
"\x01": [7],
...
能理解 \x01 其实是1000 0000 , \x01 看起来也像是 ASCII 码, 但是是否说明 redis bitmap 底层 sds 是以 ascii 码进行编码的?