iomonad

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

iomonad

iomonad

#include <stdio.h>
#include <stdint.h>
// Philips Sonicare NFC Head Password calculation by @atc1441 Video manual: https://www.youtube.com/watch?v=EPytrn8i8sc
uint16_t CRC16(uint16_t crc, uint8_t *buffer, int len) // Default CRC16 Algo
{
  while(len--)
  {
    crc ^= *buffer++ << 8;
    int bits = 0;
    do

iomonad

#!/bin/sh -exu
dev=$1
cd $(mktemp -d)

function umountboot {
    umount boot || true
    umount root || true
}

# RPi1/Zero (armv6h):

iomonad

# source:http://reocities.com/SiliconValley/heights/7052/opcode.txt
From: [email protected] (Mark Hopkins)
Newsgroups: alt.lang.asm
Subject: A Summary of the 80486 Opcodes and Instructions

(1) The 80x86 is an Octal Machine
   This is a follow-up and revision of an article posted in alt.lang.asm on
7-5-92 concerning the 80x86 instruction encoding.
 
   The only proper way to understand 80x86 coding is to realize that ALL 80x86

iomonad

(ns swordfish.sortable
  (:require [reagent.core :as r]
            ["react" :as react]
            ["@dnd-kit/core" :refer [DndContext
                                     closestCenter
                                     KeyboardSensor
                                     PointerSensor
                                     TouchSensor
                                     DragOverlay
                                     useSensor

iomonad

Google dork cheatsheet

Search filters

Filter	Description	Example
allintext	Searches for occurrences of all the keywords given.	allintext:"keyword"
intext	Searches for the occurrences of keywords all at once or one at a time.	intext:"keyword"
inurl	Searches for a URL matching one of the keywords.	inurl:"keyword"
allinurl	Searches for a URL matching all the keywords in the query.	allinurl:"keyword"
intitle	Searches for occurrences of keywords in title all or one.	intitle:"keyword"

iomonad

(ns interceptors.auth
  (:require [cheshire.core :as json]
            [clojure.spec.alpha :as s]
            [clojure.walk :refer [postwalk]]
            [clojure.core.async :as a])
  (:import (java.net URL)
           (com.auth0.jwk GuavaCachedJwkProvider UrlJwkProvider)
           (com.auth0.jwt.interfaces RSAKeyProvider ECDSAKeyProvider)
           (com.auth0.jwt.algorithms Algorithm)
           (com.auth0.jwt JWT)

iomonad

(ns authexample.web
  (:gen-class)
  (:require [buddy.auth :refer [authenticated? throw-unauthorized]]
            [buddy.auth.backends.session :refer [session-backend]]
            [buddy.auth.middleware :refer [wrap-authentication wrap-authorization]]
            [clojure.java.io :as io]
            [compojure.response :refer [render]]
            [reitit.ring :as ring]
            [ring.adapter.jetty :as jetty]
            [ring.middleware.params :refer [wrap-params]]

iomonad

# Comma separated list of channels
/set colorize_nicks.look.blacklist_channels ""

# Comma separated list of nicks
/set colorize_nicks.look.blacklist_nicks "so,root"

# Whether to colorize input
/set colorize_nicks.look.colorize_input off

# If off, then use lazy matching instead