nicolashery

Elasticsearch: updating the mappings and settings of an existing index

Note: This was written using elasticsearch 0.9.

Elasticsearch will automatically create an index (with basic settings and mappings) for you if you post a first document:

$ curl -X POST 'http://localhost:9200/thegame/weapons/1' -d \
'{
  "_id": 1,

n00neimp0rtant

## within current branch, squashes all commits that are ahead of master down into one
## useful if you merged with upstream in the middle of your commits (rebase could get very ugly if this is the case)
 
## commit any working changes on branch "mybranchname", then...
git checkout master
git checkout -b mybranchname_temp
git merge --squash mybranchname
git commit -am "Message describing all squashed commits"
git branch -m mybranchname mybranchname_unsquashed
git branch -m mybranchname

kasperpeulen

#dart:convert example

How to pretty-print JSON using Dart.

How to display JSON in an easy-to-read (for human readers) format.

Main library: dart:convert
Main element: JsonEncoder.withIndent
Gist: https://gist.github.com/kasperpeulen/d61029fc0bc6cd104602

davecgh

Table of Contents

1. Overview
2. Getting Started

### 1. Overview

When developing bitcoin applications or testing potential changes, it is often extremely useful to have a test network where transactions are actually mined into blocks and difficulty levels are low enough to generate blocks as needed.

In order to facilitate these scenarios, btcd provides a simulation network (--simnet). The following is an overview of the most important properties that distinguish it from the main network:

Gazler

sysctl -w fs.file-max=12000500
sysctl -w fs.nr_open=20000500
ulimit -n 4000000
sysctl -w net.ipv4.tcp_mem='10000000 10000000 10000000'
sysctl -w net.ipv4.tcp_rmem='1024 4096 16384'
sysctl -w net.ipv4.tcp_wmem='1024 4096 16384'
sysctl -w net.core.rmem_max=16384
sysctl -w net.core.wmem_max=16384
wget http://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
sudo dpkg -i erlang-solutions_1.0_all.deb

joepie91

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

• A Russian translation of this article can be found here, contributed by Timur Demin.
• A Turkish translation can be found here, contributed by agyild.
• There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

gunjanpatel

Revert the full commit

Sometimes you may want to undo a whole commit with all changes. Instead of going through all the changes manually, you can simply tell git to revert a commit, which does not even have to be the last one. Reverting a commit means to create a new commit that undoes all changes that were made in the bad commit. Just like above, the bad commit remains there, but it no longer affects the the current master and any future commits on top of it.

git revert {commit_id}

About History Rewriting

Delete the last commit

Deleting the last commit is the easiest case. Let's say we have a remote origin with branch master that currently points to commit dd61ab32. We want to remove the top commit. Translated to git terminology, we want to force the master branch of the origin remote repository to the parent of dd61ab32:

acdlite

// getComponent is a function that returns a promise for a component
// It will not be called until the first mount
function asyncComponent(getComponent) {
  return class AsyncComponent extends React.Component {
    static Component = null;
    state = { Component: AsyncComponent.Component };

    componentWillMount() {
      if (!this.state.Component) {
        getComponent().then(Component => {

andrewelkins

##########################################
# To run: 
# curl -sSL https://gist.githubusercontent.com/andrewelkins/1adc587feb610f586f8f40b50b7efc3a/install-docker-on-linux-mint-18.sh | bash -x
##########################################

# Kernel version http://stackoverflow.com/a/4024263
versionlte() {
    [  "$1" = "`echo -e "$1\n$2" | sort -V | head -n1`" ]
}
versionlt() {

chris-belcher

Design for a CoinSwap Implementation for Massively Improving Bitcoin Privacy and Fungibility

25/5/2020

Abstract

Imagine a future where a user Alice has bitcoins and wants to send them with maximal privacy, so she creates a special kind of transaction. For anyone looking at the blockchain her transaction appears completely normal with her coins seemingly going from address A to address B. But in reality her coins end up in address Z which is entirely unconnected to either A or B.

Now imagine another user, Carol, who isn't too bothered by privacy and sends her bitcoin using a regular wallet which exists today. But because Carol's transaction looks exactly the same as Alice's, anybody analyzing the blockchain must now deal with the possibility that Carol's transaction actually sent her coins to a totally unconnected address. So Carol's privacy is improved even though she didn't change her behaviour, and perhaps had never even heard of this software.