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// Demo of how mmap() affects VIRT, RES, SHR memory usage in Linux.
//
// A useful resource for more background:
// https://techtalk.intersec.com/2013/07/memory-part-2-understanding-process-memory/

// Required for:
// * `O_TMPFILE`
// * `fallocate()`
#define _GNU_SOURCE

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module SocketUtils
  ( isPortOpen
  , simpleSockAddr
  ) where

import           Data.Word (Word8)
import           Foreign.C.Error (Errno(..), eCONNREFUSED)
import           GHC.IO.Exception (IOException(..))
import           Network.Socket (PortNumber, socket, connect, close', Family(AF_INET), SocketType(Stream), SockAddr(SockAddrInet), tupleToHostAddress)
import           UnliftIO.Exception (try, bracket, throwIO)

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"The [TH] Recompilation Problem"

Usually, when you use ghci's :reload or ghc --make (with -O0 to disable unfoldings which are used for cross-module inlining), after changing implementation code of functions, GHC will incrementally recompile only the modules you changed, making for a fast development experience when iterating on implementation details.

(When you change API like functions types, export lists, etc.,

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#! /usr/bin/env bash

# Script to install NixOS from the Hetzner Cloud NixOS bootable ISO image.
# Wipes the disk!
# Tested with Hetzner's `NixOS 20.03 (amd64/minimal)` ISO image.
#
# Run like:
#
#     curl https://nh2.me/nixos-install-hetzner-cloud.sh | sudo bash
#

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#!/usr/bin/env bash

# Installs NixOS on a Hetzner server, wiping the server.
#
# This is for a specific server configuration; adjust where needed.
#
# Prerequisites:
#   * Update the script to adjust SSH pubkeys, hostname, NixOS version etc.
#
# Usage:

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# ./ghc-performance-categorizer.py ghci-v-output-1.txt --sort-by time

TASK                            time ms   mem MB
------------------------------------------------
systool:cpp                           4        2
systool:merge-objects                11        3
Simplify                             38       68
ByteCodeGen                          70      164
initializing                         72      119
systool:as                          175       68

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#! /usr/bin/env python3

# Moves contents of one directory tree into another, safely.

import argparse
import filecmp
import shlex
import sys

from dataclasses import dataclass

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# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, pkgs, ... }:
let
  floatingIPv4 = "95.216.183.106";
  floatingIPv6 = "2a01:4f9:c01f:65::1";
in
{

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-- Written for GHC 8.0

import           Data.Foldable (foldr')


-- The other day I had the feeling that if I can write
--
--   minumumABy :: (Applicative f)
--              => (b -> b -> Ordering) -> [a] -> (a -> f b) -> f (Maybe b)
--

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I believe the following is the best way to work with Nagle's algorithm / TCP_NODELAY / TCP_CORK.

It is described in this RedHat manual and the verdict is:

• Set TCP_NODELAY = 1, always.
• If you can batch data for sending by creating a buffer manually, or using writev(), prefer that.
• If you cannot (e.g. "when using different libraries that provides abstractions for layers" from the above manual):
  • Set TCP_CORK = 1, then write the data, then set TCP_CORK = 0.
• This builds a packet in kernel space and then flushes it out.