matthewdowney

(import java.util.concurrent.CountDownLatch)

(defmacro dothreads
  "Like (dotimes [i n] ...) except the body is executed concurrently, and the result is
  a map from `i` to the result (or an exception if one is thrown).

  Spins up `n-threads` threads and execute `body` in each with the thread number bound to
  the given `tid-binding`, but use a CountDownLatch to make sure they all start at as close
  to the same exact time as possible."
  [[tid-binding n-threads] & body]

matthewdowney

(ns blessed-cljs.core
  "Compiles for :node-js. Attempts to connect to a TCP socket at the port
  given as a command line argument, and receives pure data specifications
  for a blessed-contrib dashboard which it updates in real time.

  Expects JSON data following the format:
    {:type (a string in gauge, table, sparkline, bar, donut, gauge, lcd, log, markdown, map)
     :meta (a map to pass to grid.set along the the contrib.object)
     :data (data to display)}

matthewdowney

(defn parsed-file-delay
  "A delay that returns `(parse-fn (slurp file-path))` on each dereference,
  recalculating the return value only when `(.lastModified (io/file file-path))`
  changes.
  
  Useful if you don't need any sort of push notification when the file changes."
  [file-path parse-fn]
  (let [last-contents (atom {:modified -1 :contents nil})
        ^File f (io/file file-path)]
    (reify IDeref

matthewdowney

Keybase proof

I hereby claim:

• I am matthewdowney on github.
• I am matthewdowney (https://keybase.io/matthewdowney) on keybase.
• I have a public key ASA5-6Rf3lYjOJowTXj54xl2nhKdjc1jvET1YsVd4Q0YcQo

To claim this, I am signing this object:

matthewdowney

(defn stats
  "Calculate :mean :min :max :stdev and :n given a data point, and possibly a prior `stats` result.
  I.e. to calculate statistics from scratch:
  ```
  (def statistics (reduce stats nil data-set))
  ```
  Or to maintain statistics for a constantly updating data series that you don't want to keep in memory:
  ```
  (def statistics (atom (stats 0))
  (defn add-data-point! [dp]

matthewdowney

(defn xf-sort
  "A sorting transducer. Mostly a syntactic improvement to allow composition of
  sorting with the standard transducers, but also provides a slight performance
  increase over transducing, sorting, and then continuing to transduce."
  ([]
   (xf-sort compare))
  ([cmp]
   (fn [rf]
     (let [temp-list (java.util.ArrayList.)]
       (fn

matthewdowney

Issues with the Blockchain Info API

The blockchain.info API for XPUBs only works with Legacy Bitcoin XPUBs, whereas their web interface confusingly works with Segwit as well.

I provide a couple solutions at the end, and we end up with three useful functions:

• legacy_wallet_balance
• segwit_wallet_balance
• segwit_wallet_balance_hack

matthewdowney

# Pipe some data to stdin. Each line should contain a number.
import csv
from collections import defaultdict
from math import log10
import matplotlib
import matplotlib.pyplot as plt
import functools

import fileinput

matthewdowney

import hmac
from functools import wraps


def safe_equal(a, b):
    """
    Perform an equality check between strings that guards against a timing attack by checking every index in the each
    string. Note that length is compared first, so the length may be leaked through a timing attack, which does not
    compromise the security of an HMAC.

matthewdowney

"""
Implementation of "Pay to Witness Public Key Hash nested in BIP16 Pay to Script Hash" (P2WPKH-P2SH) address generation.
Described in BIP 141 (SegWit) https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#P2WPKH_nested_in_BIP16_P2SH

I.e.: Public key -> SegWit address
"""

import hashlib
from hashlib import sha256