https://github.com/lbrndnr/swift-stm
An optimistic STM written in Swift
https://github.com/lbrndnr/swift-stm
concurrency stm swift thread-safety
Last synced: about 1 month ago
JSON representation
An optimistic STM written in Swift
- Host: GitHub
- URL: https://github.com/lbrndnr/swift-stm
- Owner: lbrndnr
- License: mit
- Created: 2017-07-02T17:28:12.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2019-01-06T20:54:34.000Z (over 6 years ago)
- Last Synced: 2025-04-22T05:42:33.532Z (about 2 months ago)
- Topics: concurrency, stm, swift, thread-safety
- Language: Swift
- Size: 80.1 KB
- Stars: 7
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# swift-stm
[](https://twitter.com/lbrndnr)
[](https://github.com/lbrndnr/ImagePickerSheetController/blob/master/LICENSE)
## About
swift-stm is an optimistic and lock free [software transactional memory](https://en.wikipedia.org/wiki/Software_transactional_memory) written in Swift. It's very rudimental and really only a draft as of now. I wouldn't be using it in production code if I were you. Feel free to try it out though :)
## What does it do exactly?
An STM allows you to write thread safe code by making blocks of code seem to be executed atomically. This means that the transaction is either executed in a given point in time or not at all. In reality, however, it just executes the transaction and notices potential collisions.
The idea behind this is that in real life, collisions are rare and locks a bit of an overhead. This means that (technically) STMs are a lot easier to use (no deadlocks, better performance yada yada) than traditional locks.
Note that this is just a draft, I can't guarantee mutex nor performance!
## So how do I use it?
So instead of using Dispatch...
```swift
func transfer(from: Account, to: Account, amount: Int) -> Bool {
var res = false
queue.async {
let i = from.balance
guard i >= amount else {
return
}
from.balance = i - amount
to.balance = to.balance + amount
res = true
}
return res
}
```
... you'd write something like this
```swift
func transfer(from: Account, to: Account, amount: Int) -> Bool {
var res = false
atomic {
let i = try from.balance.get()
guard i >= amount else {
return
}
try from.balance.set(i - amount)
try to.balance.set(to.balance.get() + amount)
res = true
}
return res
}
```
I must admit that the syntax is a bit clumsy as of now...
## License
swift-stm is licensed under the [MIT License](http://opensource.org/licenses/mit-license.php).