Multithreading using NSOperation - 2

Transcript

1. Multi - Threading using NSOperation by zeeshan 1 Using Blocks & GCD and Using Asynchronous APIs
2. • Please point out, if anything is wrong. • Please stop me & raise your voice, for: • Going too fast... • Not getting anything... • Any doubts... • Any inclusion from your side. 2
3. Central Processing Unit 3
4. • Why CPU is in the first slide? • How early days of computing works? • What do we understand by cores? • How does these came into existence? • How does it effect our system? 4 CPU
5. nothing is limitless & every problem has a solution Clock Speed A time unit 5
6. Clock Speed • What is Clock Speed? • Any problem with it? • Any solution for that? • How to use these cores? How to take advantage of extra cores? 6
7. Thread ‘Kernel-level’ + ‘Application-level’ Data Structures An application can use multiple cores by creating multiple threads. 7 Parallel Computation Asynchronous Solution
8. Threads • What is Thread? • What are the problems it solves? (Advantages?) • Does anyone can create thread APIs or any standard follows? • What does Objective C do about thread? 8
9. Key Terms • Process • Thread • Task (Any diagram?) • Concurrent / Non-Concurrent • Thread Safe / Thread Un-Safe (Any diagram?) X
10. NSThread POSIX (Mavericks is 100% POSIX conferment) 9 Life Cycle
11. NSThread • In which framework is it written? • What is the lifecycle? • What is it based on? • How can we use it? (Any code?) 10
12. Is Thread a Problem • It is a right solution? • What are the cost of using it? • When does problem arise? and Why? • Who gets the burden of it? • How does Thread is different from Process and Task? (Any visual show?) 11
13. Hazard of Threaded Programming • UIKit access • Database access • Stale result • Cancellation • De-allocation 12
14. Solutions • Operations (Current Session) • GCD (Next Session) • Notification Queue • Asynchronous (Hopefully Next to Next Session) • Timers 13
15. NS Operation to the rescue 14
16. NS Operation • When does it introduced? • What is it actually and how it does? • How to use it? • How many times I can use one operation? • What are the features? 15
17. NS Operation II • Manage all threaded code • Model asynchronous operations • KVO Support (Any APIs) • Dependencies (Any APIs) • Priorities (Any APIs) 16
18. NS Operation III • Thread Confinement • Completion Block (Any APIs?) • Cancellation • Concurrent vs Non-Concurrent • Some Caveats... 17
19. NS Operation Queue • Simpler, Name it • Add, Ready & Execute, Cancel | Finish • Pending Operations (Operations vs OperationCounts) • Multiple Queues • Threads & Queues (How many threads?) 18
20. NS Operations Queue II • Queue Width (Any APIs?) • Pause (Suspended) Queues • Cancellation • KVC Compliant (APIs?) • Add Operation with Blocks 19
21. NS Operations - Use • Blocks • Concrete sub classes • Selector • Block • User defined sub classes 20
22. References: • Multithreading Using NSOperation (http:// izeeshan.wordpress.com/2014/08/17/multi-threading- using-nsoperation/) • Threading Programming Guide • Concurrency Programming Guide • API References (NSOperation and NSOperationQueue) 21
23. Lets Revise 22 • CPU / Clock Speed • Thread Solutions and Problems • Process, Thread, Task, Concurrency, • Safe, Un-Safe, Parallel • Operation, Queue,
24. Demo Use of NS Operation and its queue 23
25. Any Questions? Thank you! http://izeeshan.wordpress.com/ 24
26. 25 @zeeshan_khan