Mohammad Abdurraafay (Raafay) iamraafay

Preventing Data Races in the Swift Concurrency Model

One of the goals of the concurrency effort is to prevent data races. This document describes the approach taken to preventing data races overall, by categorizing the sources of data races and describing how they are addressed with other proposals in the Swift Concurrency effort.

Data races

A data race occurs when two threads access the same memory concurrently and at least one of the accesses can change the value. Within the safe subset of Swift (e.g., ignoring the use of UnsafeMutablePointer and related types), the memory in question is always a stored property. There are several different categories of stored properties that need to be considered for data races:

Global and static stored properties:

GROKKING NOTES

I liked the way Grokking the coding interview organized problems into learnable patterns. However, the course is expensive and the majority of the time the problems are copy-pasted from leetcode. As the explanations on leetcode are usually just as good, the course really boils down to being a glorified curated list of leetcode problems.

So below I made a list of leetcode problems that are as close to grokking problems as possible.

Pattern: Sliding Window

To remove a submodule you need to:

Delete the relevant section from the .gitmodules file.
Stage the .gitmodules changes git add .gitmodules
Delete the relevant section from .git/config.
Run git rm --cached path_to_submodule (no trailing slash).
Run rm -rf .git/modules/path_to_submodule (no trailing slash).
Commit git commit -m "Removed submodule "
Delete the now untracked submodule files rm -rf path_to_submodule

Creating a Happy Git Environment on OS X

Step 1: Install Git

brew install git bash-completion

Configure things:

git config --global user.name "Your Name"

git config --global user.email "[email protected]"

	// Lines
	float hash( float n ) {
	return fract(sin(n)*753.5453123);
	}

	// Slight modification of iq's noise function.
	float noise(vector_float2 x )
	{
	vector_float2 p = floor(x);
	vector_float2 f = fract(x);

	- (UIImage *)dynamicImage
	{
	UITraitCollection const baseTraitCollection = / an existing trait collection */;
	UITraitCollection *const lightTraitCollection = [UITraitCollection traitCollectionWithTraitsFromCollections:@[baseTraitCollection, [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleLight]]];
	UITraitCollection *const purelyDarkTraitCollection = [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleDark];
	UITraitCollection *const darkTraitCollection = [UITraitCollection traitCollectionWithTraitsFromCollections:@[baseTraitCollection, purelyDarkTraitCollection]];

	__block UIImage *lightImage;
	[lightTraitCollection performAsCurrentTraitCollection:^{
	lightImage = /* draw image */;

	// with the help of: https://gist.github.com/phpmaple/9458264

	extension UIButton {
	func centerImageAndButton(_ gap: CGFloat, imageOnTop: Bool) {

	guard let imageView = self.imageView,
	let titleLabel = self.titleLabel else { return }

	let sign: CGFloat = imageOnTop ? 1 : -1;
	let imageSize = imageView.frame.size;

	///
	/// https://stackoverflow.com/a/29741007
	///
	let s = Struct() // Struct
	withUnsafePointer(to: s) {
	print(String(format: "%p", $0)
	}

	///
	/// http://stackoverflow.com/a/36539213/226791

	curl -X POST \
	-H "X-Parse-Application-Id: LL9oIdzIkmwl5xyowQQu0fTmXyUWfet9RuAzwHfj" \
	-H "X-Parse-REST-API-Key: R3S8PYQKuzeV4c8MUeO5ved46C50MEp56boDHW1O" \
	-H "Content-Type: application/json" \
	-d @data.json \
	https://parseapi.back4app.com/functions/import

	-(void)setCompletionBlockWithSuccess:(void (^)(AFHTTPRequestOperation *, id))success
	failure:(void (^)(AFHTTPRequestOperation , NSError ))failure {

	void (^newSuccessBlock)(AFHTTPRequestOperation*, id) =
	^(AFHTTPRequestOperation *operation, id responseObject){

	NSError * customError = nil;
	//Do some custom error processessing
	if(customError){
	if(nil != failure)