awnumar

#!/usr/bin/python2

import requests

def fix_host(host):
    if ((not host.startswith("http://")) and (not host.startswith("https://"))):
        host = "http://" + host
    if (host.endswith("/")):
        host = host[:-1]
    return host

awnumar

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

awnumar

How to recover lost Python source code if it's still resident in-memory

I screwed up using git ("git checkout --" on the wrong file) and managed to delete the code I had just written... but it was still running in a process in a docker container. Here's how I got it back, using https://pypi.python.org/pypi/pyrasite/ and https://pypi.python.org/pypi/uncompyle6

Attach a shell to the docker container

Install GDB (needed by pyrasite)

apt-get update && apt-get install gdb

awnumar

data := "xxx[...]xxx"

var chunk []byte
for i := 0; i < len(data); i += 1024 {
	if i+1024 > len(data) {
		// Remaining data <= 1024.
		chunk = data[len(data)-(len(data)%1024):]
	} else {
		// Split into chunks of 1024 bytes and pad.
		chunk = data[i:i+1024]

awnumar

package ptr2bytes

func GetBytesFromPtr(ptr uintptr, len int, cap int) []byte {
	var sl = struct {
		addr uintptr
		len  int
		cap  int
	}{ptr, len, cap}
	return *(*[]byte)(unsafe.Pointer(&sl))
}

awnumar

package main

import (
	"fmt"
	"encoding/binary"
)

func main() {
	//
	// Largest signed int64 in smallest byte slice.

awnumar

// Encode the length into raw binary.
uint32_t rel_len = length;
unsigned char len_bytes[4];
len_bytes[0] = (rel_len >> 24) & 0xFF;
len_bytes[1] = (rel_len >> 16) & 0xFF;
len_bytes[2] = (rel_len >> 8) & 0xFF;
len_bytes[3] = rel_len & 0xFF;

awnumar

#!/usr/bin/python2

import hashlib
from jinja2.sandbox import SandboxedEnvironment

# We're using only the hashlib functions for demonstratin purposes
# but any algorithm can be implemented and added to the program.

# Define algorithms we support.

awnumar

/*
 * Copyright 2015-2016 Ben Ashford
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software

awnumar

#ifndef PROGRAM
#define PROGRAM enquire.c
#define VERSION "5.1a"
#define PURPOSE Everything you wanted to know about your machine and C compiler
#define BUT	didnt know who to ask
#define FOR	Any OS, any C compiler
#define AUTHOR	Steven Pemberton, CWI, Amsterdam; "Steven.Pemberton@cwi.nl"
#define COPYRIGHT(c) 1993-9 Steven Pemberton, CWI. All rights reserved.
#define NOTE	Improvements gratefully received. Please mention the version.
#define COMPILE	On Unix compile with: "sh enquire.c"; see below for details