index of talks about performance in Swift guide added

[shilpeegupta14]

High Performance in Swift guide added

Motivation

Contributing to the repository.

Description:

Overview of the readme file:

Class vs Struct tradeoff and Copy-on-Write

i)difference btw memory allocations
ii)copy-on-write
iii)benchmarking structs with classes
iv)implementing structs backed by classes
v) implementing structs backed by classes with copy on write
vi) Drawbacks of CoW

Concurrency and Locking

i) Race Condition with Semaphores
ii) Priority inversion with Semaphores
iii) Thread explosion
iv) Runtime contract and rewriting code with async/await semantics for better performance of the code.
iv) Synchronization offering:

1. Mutual Exclusion
   This covers:
   i) Actors with data races when we are accessing the mutable states within the actors
   ii) Actors with data races when we are accessing the mutable states outside the actors and fixing it with sendable
   protocols
2. Reentrancy and Prioritization
   This covers actors with Priority Inversion
3. Main Actor
   Batching up code to improve time complexity and performance

v) Potential bug around await semantics
vi) Other primitives and Lock Contention Pattern

References:

https://www.youtube.com/watch?v=iLDldae64xE
https://www.youtube.com/watch?v=WCUj581Dpec
https://developer.apple.com/videos/play/wwdc2021/10254/
https://developer.apple.com/videos/play/wwdc2021/10133/

Result:

Resolves: #64 guide for writing high performance systems in swift

[tomerd]

task again for the PR @shilpeegupta14

circling back to the feedback on #78: iiuc correctly this content mostly summarizes talks available publicly, which is what is pointed out in the "references" section above. if this is true, perhaps we can -restructure the suggested content around talks rather then as a "performance guide"? i.e

1. have an index page with a list of talks, having each entry link to the the talk recording and the summary (item 2)
2. have page summarizing the key take away from the talk, one page per talk

[shilpeegupta14]

@tomerd
The update pr #80 contains some additions that are not part of any WWDC talk and were not added previously in #78.
Such topics are:
drawbacks of COW
Race Condition and Priority Inversion with Semaphores
Accessing mutable state outside the actor

Also, some topics like main Actor, mutual exclusion, reentrancy and prioritisation are talked about in both the WWDC talks. https://developer.apple.com/videos/play/wwdc2021/10254/
https://developer.apple.com/videos/play/wwdc2021/10133/

Summarising them talk wise will scatter information in many parts and might cause repetition.