luminousmen

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

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# Hash implementations from
# http://www.partow.net/programming/hashfunctions/index.html
# Author: @luminousmen

class BloomFilter:
    def __init__(self, size: int):
        self.size = size
        self.bitmap = size * [0]

    def FNV(self, key: str):

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function retry {
  local retries=3
  local count=0
  until "$@"; do
    exit=$?
    wait=$((10 ** $count))
    count=$(($count + 1))
    if [ $count -lt $retries ]; then
      echo "Retry $count/$retries exited $exit, retrying in $wait seconds..."
      sleep $wait

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echo "this is the body" | mail -s "this is the subject" "to@address"

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import random
letters = [
    "Person 1",
    "Person 2",
    "Person 3",
    "Person 4",
]
print(f"Next: `{random.choice(letters)}`")

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import os

import pyspark.sql.functions as F
from pyspark.sql import SparkSession


if __name__ == "__main__":
    spark = SparkSession.builder.master("local").getOrCreate()

    spark.conf.set(

luminousmen

.PHONY: clean-pyc clean-build docs clean
define BROWSER_PYSCRIPT
import os, webbrowser, sys
try:
	from urllib import pathname2url
except:
	from urllib.request import pathname2url

webbrowser.open("file://" + pathname2url(os.path.abspath(sys.argv[1])))
endef

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from weakref import WeakValueDictionary

class Singleton(type):
    _instances = WeakValueDictionary()

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            instance = super(Singleton, cls).__call__(*args, **kwargs)
            cls._instances[cls] = instance
        return cls._instances[cls]