Skip to content

Instantly share code, notes, and snippets.

View snej's full-sized avatar

Jens Alfke snej

View GitHub Profile
snej / missing_includes.rb
Created October 2, 2023 16:19
Script to find missing std #includes in C++ headers
#! /usr/bin/env ruby
# missing_includes.rb
# By Jens Alfke <>
# Version 2.0 -- 2 Oct 2023
# Copyright 2021-Present Couchbase, Inc.
# This script scans C++ header files looking for usage of common standard library classes, like
# `std::vector`, without including their corresponding headers, like `<vector>`. It similarly looks
# for standard C functions like `strlen` that are used without including their header (`<cstring>`.)
snej /
Last active May 8, 2021 18:27
Tails! A tiny Forth core written as a hack for May Forth 2021, using some of Wasm3's secret optimization sauce.
// Tails has grown a bit and moved out into its own repository:
// Please visit it there!
// If you want to see the tiny original version from May Forth 2021, it's still here;
// click the "Revisions" button above, or go to:
snej / threadSafeFuture.nim
Last active November 12, 2020 14:38
Thread-safe Futures for Nim
# threadSafeFuture.nim
# Jens Alfke, 30 June 2020
import asyncdispatch, deques, locks, sugar, threadpool
## Utilities for mixing async/await with threads.
## ``threadSafe()`` takes a Future and returns a new Future that can be completed on any thread.
## The original Future's callback will still be invoked on its original thread, and ``await``
## works normally.
snej / QRCodeScanner.m
Created September 21, 2015 16:45
Snippet showing how to capture QR codes from the device camera on iOS or Mac OS X
- (BOOL) startCapture: (NSError**)outError {
if (!_session) {
_session = [[AVCaptureSession alloc] init];
AVCaptureDevice* video = [AVCaptureDevice defaultDeviceWithMediaType: AVMediaTypeVideo];
if (!video)
return [self failWithMessage: @"No video camera available" error: outError];
AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice: video
error: outError];
if (!input)
return [self failWithMessage: @"Couldn't acquire input device" error: outError];
snej / QRCode.m
Created September 21, 2015 16:48
Shows how to generate a QRCode on iOS or Mac OS X
#import <UIKit/UIKit.h>
typedef UIImage QRImage;
#import <AppKit/AppKit.h>
typedef NSImage QRImage;
+ (QRImage*) QRCodeImageWithData: (NSData*)data size: (CGFloat)size {
snej / Async.hh
Created August 28, 2018 22:26
C++ implementation of C# / JavaScript style async calls
// Async.hh
// Copyright © 2018 Couchbase. All rights reserved.
#pragma once
#include "RefCounted.hh"
#include <functional>
snej /
Created July 8, 2016 04:46
Stuff to prove my identity on

Keybase proof

I hereby claim:

  • I am snej on github.
  • I am snej ( on keybase.
  • I have a public key ASA32IteNIxEuZRwRwerBGrd-RL2UMiz4nxBpK5Kqu6TjQo

To claim this, I am signing this object:

snej / bitcodesize.rb
Created March 1, 2016 21:52
Simple tool that scans an iOS library and checks the size of the bitcode segment for each included object file. It logs a warning for files with no bitcode or whose bitcode is less than 1Kbyte; or with the -v flag it logs the sizes of all bitcode segments.
#! /usr/bin/env ruby
# By Jens Alfke. Do What Thou Wilt shall be the whole of the license.
def listBitcode(path, arch, verbose =false)
result = []
filename = nil
section = nil
output = `otool -l -arch #{arch} "#{path}"`
snej / gist:6216072
Created August 12, 2013 22:48
Output of 'changes' view of sync gateway, in form "key[tab]value[tab]docid". Note the discontinuity, where keys 1181-2174 appear at the start (before 401) and then later there is a gap from 994-2175.
/db: “channels” View
Key Value ID
["*",1181] ["78k9je3j3k6","1-7b6054260a204912852c3021cab9168c"] 78k9je3j3k6
["*",1182] ["kcd0neg7kac","1-ebd3a623c406b28b80d1ebf651ffacec"] kcd0neg7kac
["*",1183] ["eb33dbinaii","1-4b4a5598313a2f79321f60364b43a990"] eb33dbinaii
["*",1184] ["f41cig0kk86","1-d44e48481e63331720822afa9fbf3e1f"] f41cig0kk86
["*",1185] ["6k5anc2kaii","1-1cec51d3336824eaefc45b3b5fc492f8"] 6k5anc2kaii
["*",1186] ["j026jml39","1-92f7448c5727533df4e070d06f67386d"] j026jml39
["*",1187] ["bnn1ae3b6","1-6dd3cd60eefd7a44184db3368bdcaa7a"] bnn1ae3b6
snej / new_cas.go
Created July 12, 2013 20:43
New implementation of memcached.CAS that doesn't reserve the client connection for the duration of the transaction.
type CASState struct {
initialized bool // false on the first call to CASNext, then true
Value []byte // Current value of key; update in place to new value
Cas uint64 // Current CAS value of key
Exists bool // Does a value exist for the key? (If not, Value will be nil)
Err error // Error, if any, after CASNext returns false
resp *gomemcached.MCResponse
// Non-callback, loop-based version of CAS method. Usage is like this: