danbst

timeSpent = 0;
timeStarts = 0

browser.tabs.onActivated.addListener((activeInfo) => {
    browser.tabs.sendMessage(
        activeInfo.tabId,
        {timeSpent: timeSpent}
    ).then(response => {
        timeStarts = (new Date).getTime();
    }).catch(error => {

danbst

let
  sub = { config, lib, parentConfig, ...}: {
      options.foo = lib.mkOption {
          type = lib.types.bool;
          default = parentConfig.bar;
      };
  };

in { config, lib, ...}: {
    options.bar = lib.mkOption { type = lib.types.bool; default = true; };

danbst

...

 inherit (import ../servers/sql/postgresql-default.nix pkgs super)
    postgresql
    postgresqlPackages
    postgresql_9_4
    postgresql_9_5
    postgresql_9_6
    postgresql_10
    postgresql_11

danbst

nixos executable

Basic features:

• installable as package, even on non-nixos
• is named nixos
• is written in C++ and binds to Nix C++ library (or maybe Haskell? Nodejs? What you think?)
• autocomplete, ncurses, Nix 2.0
• commit to Git by default on each rebuild

Subcommands

danbst

#!/usr/bin/env bash
statefile=~/.config/nixpkgs/declarative

action="$1"
package="$2"

mkdir -p $(dirname "$statefile")
touch "$statefile"
function update {
  envExpr=~/.config/nixpkgs/declarative-env.nix

danbst

VACUUM FREEZE

Our database has fast rate of transactions. I did think, that such rate is impossible, until I've seen it with my eyes. I've been instinctively insisting on fixing code to reduce number of transactions (sometimes successful), but never checked what are consequences for database.

One of consequences is fast rate of autovacuum VACUUM FREEZE.

VACUUM is essential for Postgresql to mark non-visible rows (those which were normal rows, but became invisible because of update or delete) as visible to PG. Note, that they become visible only to PG, previously PG didn't know they are free for use, and thus had allocated extra buffers in the end of a table for any new rows (inserts or updates). PG not knowing which rows are free for use is another problem, which causes table bloat, which deserves another post.

VACUUM FREEZE is special kind of VACUUM. From resource usage perspective, it differs from VACUUM by that it has to scan full table (normal VACUUM processes only buffers known to contain at

danbst

# First add this module to your /etc/nixos/configuration.nix
# ...
#   imports = [ /path/to/iphone.nix ];
#   iphone.enable = true;
#   iphone.user = "yourusername";
# ...
# Then rebuild system. Attach iPhone via cable, open terminal and run command `iphone`
# It will fail, but there will occure a dialog on your iPhone to "trust this computer"
# Press OK there and run `iphone` again. If it succeeds it will open a freshly mounted folder

danbst

Цей список складений з технологій (утиліт Linux), які я використаю для однієї життєвої ситуації - пошуку аренди квартири по риночній ціні.

Знайомим з поняттям "скрейпінг" мабуть уже зрозуміло, про що буде пост. Тим не менше, запрошую під кат.

Постановка задачі

OLX є, здається, найактивнішою площадкою для пошуку аренди квартири у Києві. Але просто зайти на OLX, задати фільтри (район, кількість кімнат) недостатньо. Справа в тім, що є 3 типи аренд:

• аренди від ріелторів - ціни на ці квартири майже завжди завищені, тому-що від ціни квартири залежить дохід ріелтора. Через завищену вартість (неринкову) афіші висять відносно довго
• аренди від хазяїв - ціни на квартири нижчі, щоб швидше знаходити арендаторів

danbst

with import <nixpkgs> { };
runCommand "some-test" {
    buildInputs = [ postgresql ];
    preCheck = ''
        set -e
        export PGDATA=$TMP/db
        export PGHOST=$TMP/socketdir
        mkdir $PGDATA $PGHOST
        pg_ctl initdb
        echo "unix_socket_directories = '$PGHOST'" >> $PGDATA/postgresql.conf

danbst

#! /usr/bin/env bash

# More info at: https://github.com/elitak/nixos-infect
set -o pipefail
set -e

makeConf() {
  # Skip everything if main config already present
  [[ -e /etc/nixos/configuration.nix ]] && return 0
  # NB <<"EOF" quotes / $ ` in heredocs, <<EOF does not