AlexITC

# See https://hector.dev/2020/11/18/centralized-scala-steward-with-github-actions
name: Scala Steward

on:
  schedule:
    # Schedule to run every Sunday @ 12PM UTC. Replace this with
    # whatever seems appropriate to you.
    - cron: "0 0 * * 0"
  # Provide support for manually triggering the workflow via GitHub.
  workflow_dispatch:

AlexITC

Nginx upstream HTTP keepalive config example

As per Nginx documentation, the key directives of proxy_http_version and proxy_set_header need to be set as per below:

upstream backend {
	server 127.0.0.1:8080;
	keepalive 8;
}

server {

AlexITC

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

1. CPU-bound
2. Blocking IO
3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

AlexITC

build-web:
  working_directory: ~/repo
  docker:
    - image: circleci/node:8-browsers
  steps:
    - checkout
    - restore_cache:
        key: my-project-{{ .Branch }}-{{ checksum "enterprise-web/package-lock.json" }}
    - run: cd web && npm install
    - save_cache:

AlexITC

import play.api.libs.json._
import scala.reflect.runtime.universe._

case class Sample(id: String, value: Int = 0)

def checkedReads[T](underlyingReads: Reads[T])(implicit typeTag: TypeTag[T]): Reads[T] = new Reads[T] {

  def classFields[T: TypeTag]: Set[String] = typeOf[T].members.collect {
    case m: MethodSymbol if m.isCaseAccessor => m.name.decodedName.toString
  }.toSet

AlexITC

# script that updates the commit log from external repos
#
# steps:
# - create a file called commits.log containing the git log to be applied,
#   a simple way is replacing the commit hash with the last known commit hash
#   and run this command on the external repo:
#   git log | sed '/7467bdc51ad57371ef20bffc2f79cc4a792eb97f/Q' > commits.log
#
# - move the commits.log file to the root of the XSN repo.
# - run: ruby apply-commits.rb

AlexITC

import java.security.KeyPairGenerator;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.KeyFactory;
import java.security.spec.EncodedKeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.NoSuchAlgorithmException;

AlexITC

# run the following commands, one after another one
# these commands assumed you have a working masternode

# 1. download latest version
wget https://github.com/X9Developers/XSN/releases/download/v1.0.13/xsn-1.0.13-linux64.tar.gz -O xsn.tar.gz

# 2. unzip the files
tar -zxvf xsn.tar.gz

# 3. stop previous xsnd if running, if this fails, it means no xsnd was running

AlexITC

// from https://github.com/AlexITC/crypto-coin-alerts/blob/master/alerts-server/app/com/alexitc/coinalerts/data/anorm/AnormPostgresDAL.scala#L24
def withConnection[A](block: Connection => ApplicationResult[A]): ApplicationResult[A] = {
  try {
    database.withConnection(block)
  } catch {
    case e: PSQLException if isIntegrityConstraintViolationError(e) =>
      Bad(createIntegrityConstraintViolationError(e)).accumulating
  }
}

AlexITC

import org.postgresql.util.PSQLException

object PostgresErrorMapper {
  // see https://www.postgresql.org/docs/9.6/static/errcodes-appendix.html
  def isForeignKeyViolationError(e: PSQLException): Boolean = "23503" == e.getSQLState

  def createForeignKeyViolationError(e: PSQLException): PostgresIntegrityViolationError = {
    // assumes not null
    val detail = e.getServerErrorMessage.getDetail