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Leif Warner LeifW

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@juur
juur / SystemdNotify.java
Last active May 22, 2023 02:09
system sd_notify wrapper for Java
// Based on this answer https://stackoverflow.com/a/36945256/784804
/*
* Copyright (c) 2018 Ian Kirk
*
* 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 the Software, and to permit persons to whom the Software is
@konn
konn / Data.Aeson.Generic.DerivingVia.hs
Last active December 7, 2020 21:06
Type-driven safe derivation of ToJSON and FromJSON, using DerivingVia in GHC 8.6 and some type-level hacks
{-# LANGUAGE ConstraintKinds, DataKinds, DeriveGeneric, DerivingVia #-}
{-# LANGUAGE ExplicitNamespaces, FlexibleContexts, FlexibleInstances #-}
{-# LANGUAGE GADTs, GeneralizedNewtypeDeriving, MultiParamTypeClasses #-}
{-# LANGUAGE PolyKinds, ScopedTypeVariables, StandaloneDeriving #-}
{-# LANGUAGE TypeApplications, TypeFamilies, TypeInType, TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
{-# OPTIONS_GHC -Wall #-}
module Data.Aeson.Generic.DerivingVia
( StrFun(..), Setting(..), SumEncoding'(..), DefaultOptions, WithOptions(..)
, -- Utility type synonyms to save ticks (') before promoted data constructors
@neko-kai
neko-kai / MonadRandom.scala
Created June 13, 2018 15:56
difference between mtl-style and tagless final style
import cats._
import cats.implicits._
trait MonadRandom[F[_]] {
def getRandom: F[Int]
}
final case class DummyRandom[A](a: A)
final case class RealRandom[A](a: A)
@zparnold
zparnold / one_liner.sh
Last active June 25, 2024 07:12
A simply script to delete all failed pods from Kubernetes
kubectl get pods --all-namespaces | grep Evicted | awk '{print $2 " --namespace=" $1}' | xargs kubectl delete pod
@nkpart
nkpart / Don't use new-build.md
Last active January 20, 2019 04:35 
∴ cat cabal.project
packages: tools/work-common/
          tools/work-project/

I did the expected thing, and tried to build everything:

∴ cabal new-build
@notxcain
notxcain / App.scala
Last active March 17, 2021 19:39
Akka Http Prometheus Endpoint
import io.prometheus.client.CollectorRegistry
import io.prometheus.client.dropwizard.DropwizardExports
import io.prometheus.client.hotspot.DefaultExports
import nl.grons.metrics.scala.DefaultInstrumented
import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import akka.http.scaladsl.Http
object App extends App with DefaultInstrumented {
@svanoort
svanoort / gcsettings.sh
Last active December 20, 2023 02:27
Blessed GC settings for big servers
# Base settings and GC logging
-server -XX:+AlwaysPreTouch # First should be default, but we make it explicit, second pre-zeroes memory mapped pages on JVM startup -- improves runtime performance
# -Xloggc:gc-%t.log # CUSTOMIZE LOCATION HERE - $path/gc-%t.log -- the %t in the gc log file path is so we get a new file with each JVM restart
-XX:NumberOfGCLogFiles=5 -XX:+UseGCLogFileRotation -XX:GCLogFileSize=20m # Limits the number of files, logs to folder
-XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintGCCause
-XX:+PrintTenuringDistribution -XX:+PrintReferenceGC -XX:+PrintAdaptiveSizePolicy # gather info on object age & reference GC time for further tuning if needed.
# G1 specific settings -- probably should be default for multi-core systems with >2 GB of heap (below that, default is probably fine)
-XX:+UseG1GC
-XX:+UseStringDeduplication
@grabcode
grabcode / cookie-recipe.html
Created June 17, 2016 02:27
@JoshRosen
JoshRosen / scala-lambda-serialization-with-lifted-local-defs.md
Last active June 12, 2021 16:35
Serialization of Scala closures that contain local defs

Serialization of Scala closures that contain local defs

Several Apache Spark APIs rely on the ability to serialize Scala closures. Closures may reference non-Serializable objects, preventing them from being serialized. In some cases (SI-1419 and others), however, these references are unnecessary and can be nulled out, allowing otherwise-unserializable closures to be serialized (in Spark, this nulling is performed by the ClosureCleaner).

Scala 2.12's use of Java 8 lambdas for implementing closures appears to have broken our ability to serialize closures which contain local defs. If we cannot resolve this problem, Spark will be unable to support Scala 2.12 and will be stuck on 2.10 and 2.11 forever.

As an example which illustrates this problem, the following closure has a nested localDef and is defined inside of a non-serializable class:

``

@markus1189
markus1189 / lightswitch.scala
Last active January 31, 2016 08:30
Safe LightSwitch using phantom types and typelevel calculation
sealed abstract class Power
final abstract class On extends Power
final abstract class Off extends Power
class LightSwitch[State <: Power] private {
def on(implicit ev: State =:= Off) = LightSwitch.on
def off(implicit ev: State =:= On) = LightSwitch.off
def toggleP[S<:Power](implicit t: ToggleP[State,S]): LightSwitch[S] = new LightSwitch[S]
def toggleM[S<:Power](implicit t: ToggleM.Aux[State,S]): LightSwitch[S] =
new LightSwitch[S]