jsl

#!/bin/bash

# First change your Rails dependency in the Gemfile to 3.2.12.
# Make sure afterwards that the commit includes the update to the Rails version
# and that it contains the JSON gem version 1.7.7.

git co -b patch_CVE-2013-0269_CVE-2013-0276
bundle update rails
bundle update json
git add -A

jsl

In the resque web interface, if you see a process that is hanging for a long 
time, you can figure out what it's waiting on by looking at the PID. Say 
we see pid 4894 taking a long time. In the console do:

$ sudo strace -p 4894
Process 4894 attached - interrupt to quit
wait4(15045, 

The strace just hangs there, and we think that perhaps the process isn't 
doing anything. If you look at the man page for wait4, you see that the 

jsl

vmstat is a helpful tool for figuring out performance problems on servers.

user@server-prod-db01:~$ vmstat 5
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 1  0  10860  51884  41656 3712392    0    0  1297   107    0    0 10  3 84  3
 0  0  10860  50388  41668 3713204    0    0    41   446 1409 1173  6  2 91  1


The "b" column shows blocked processes waiting for IO. In this case it's 0, which is a good thing. 

jsl

;; Clojure library clj-yaml deserializes into arbitrary Java classes

user=> (require '[clj-yaml.core :as yaml])
nil
user=> (yaml/parse-string "!!java.io.File")
#<File >

jsl

(defn sha-512
  "Return the SHA-512 of the given string"
  [data]
  (let [md (. java.security.MessageDigest getInstance "SHA-512")]
    (. md update (.getBytes data))
    (let [bytes (. md digest)]
      (reduce #(str %1 (format "%02x" %2)) "" bytes))))

(defn hash-repeatedly
  "Hash the given string n number of times"

jsl

(defn all-functions
  ([root-n] (all-functions root-n []))
  ([cur fns]
     (if (= java.util.ArrayList (class cur))
       (if (empty? cur)
         fns
         (map #(all-functions % fns) cur))
       (if (= org.jruby.ast.DefnNode (class cur))
         (all-functions (.childNodes cur) (conj fns cur))
         (all-functions (.childNodes cur) fns)))))

jsl

1.9.3-p125 :036 > p = DotHash::Properties.new({})
 => #<DotHash::Properties:0x007f8cf408a308 @hash={}> 
1.9.3-p125 :037 > p = DotHash::Properties.new({:foo => :bar})
 => #<DotHash::Properties:0x007f8cf4067740 @hash={:foo=>:bar}> 
1.9.3-p125 :038 > p.respond_to?(:foo)
 => false 
1.9.3-p125 :039 > p.foo
 => :bar 

jsl

# These MIME types, which we don't use, are vulnerable per CVE-2013-0156
ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::XML)
ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::YAML)

jsl

require 'minitest/autorun'

# Demonstrates the way that refinements are applied in Ruby 2.0.0preview1.

module RegularStringCounts
  refine String do
    def num_caps
      self.scan(/[A-Z]/).count
    end
  end

jsl

class Node
  attr_accessor :next
end

a = Node.new
b = Node.new
c = Node.new

a.next = b
b.next = c