Singleton Design Pattern | Implementation with details & code ✌🏻

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Singleton Design Pattern | Implementation with details & code ✌🏻

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Күн бұрын

Really really wanted my first KZfaq video this year to be a Tutorial! It’s a symbol that this year is going to be filled with a LOT of tutorials - starting with finishing 𝐃𝐞𝐬𝐢𝐠𝐧 𝐏𝐚𝐭𝐭𝐞𝐫𝐧 𝐒𝐞𝐫𝐢𝐞𝐬.
Today’s video is on 𝐒𝐢𝐧𝐠𝐥𝐞𝐭𝐨𝐧 𝐃𝐞𝐬𝐢𝐠𝐧 𝐏𝐚𝐭𝐭𝐞𝐫𝐧. I know most people think they know this design pattern as it’s a basic and common one, but there are details to it that we end up missing. Making the code thread safe and efficient is important when it comes to implementing the code.
So, obviously. I have covered everything with code in detail. Link is in comments. Please keep sharing your feedback.
If you guys really want educators to be motivated and create a lot of tutorials, please do support us - just a like, share or subscribe can mean a lot to us. Trust me - a LOT of effort goes behind these videos!
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The video contains following parts-
0:00-1:45 - Intro of Singleton Design Pattern
1:45-2:08 - Educative Promotion
2:08-4:45 - Simple Logger Class Code
4:45-6:33 - Count instances of Logger
6:33-7:25 - Restrict Logger Instantiation
7:25-11:52 - Simple Singleton Implementation
11:52-15:32 - Code fails in MultiThreading Case
15:32-17:20 - Thread Safe Singleton
17:20-19:03 - Double-checked Locking
19:03-20:15 - Points to keep in mind!
#designpatterns #singleton #systemdesign #softwareengineering

Пікірлер: 139

@arjungupta250 2 жыл бұрын

Thanks a ton Keerti! Such an awesome video including the multithreading handling part which was unexpected, and while learning I enjoyed it throughly. Paused the video in between to like it because this video and this design pattern series deserves it. Looking forward for next videos in the series :D

@KeertiPurswani 2 жыл бұрын

Thank you so much. Sorry for releasing the rest of the series late but finishing it soon ❤️😇

@vaibhavjain8672 3 ай бұрын

Thanks a lot, Keerti. I am fresher and was super scared when I first check what it is online, but you made it super simple that even a fresher who barely knows these concepts in detail can understand it. Super happy learning this in such a simple way.

@pratikwadekar4981 2 жыл бұрын

Hey Keerti, This was really great explanation. Most videos would stop showing the implementation about singleton design pattern. But the fact that you showed how to make them thread safe was a cherry on top. One request though, could you increase the font size or zoom in into your code editor in upcoming videos as it becomes difficult when viewing on phone.

@KeertiPurswani 2 жыл бұрын

Thanks Pratik. Will definitely increase more from next time😇 Feedback like yours helps me improve in every video❤️😇

@aryanyadav3926 Жыл бұрын

Once we have checked that loggerInstance==nullptr, why is there a need to check it again, can't we just apply the lock and create a new loggerInstance as we know that it is null?

@swatiacharya9073 8 ай бұрын

I use to always skip the design pattern concepts..but with your videos...its so easy to understand...i look forward to other videos... great work thanks for sharing the knowledge wirh us...😍

@RohitRaj-qv5nq 2 жыл бұрын

Wonderful explanation Keerti, It is hard to find Oops tutorial in C++ and you have handled it easily. Thanks a lot again.

@KeertiPurswani Жыл бұрын

Thank you so much! Means a lot! Please do share with your friends! ❤️

@SugamMaheshwari 3 ай бұрын

Lovely explanation of double checking before locking for thread-safe single ton logging🔥

@kedarsadhu2816 Жыл бұрын

Thanks a lot Keerti. This is the most complete video I have seen so far. I like the way you explain "WHY" we need to do it. Really appreciate your work.

@KeertiPurswani Жыл бұрын

Thank you so much! Means a lot! Hoping you like rest of the videos as well! ❤️😇

@guruprasad_sannenahalli 20 күн бұрын

Thanks Keerti. Very useful.

@PRANAVMAPPOLI 11 ай бұрын

Hey, thanks for the awesome explanation. Why we need the 2 if check, cant we remove the inner if check?

@akshayyadav6854 7 ай бұрын

Have the same question...

@nileshpatil4111 Ай бұрын

Nicely explained. Understood it completely

@insofcury 3 ай бұрын

Keerti awesome work on the video. I do have a suggestion though. It would be great to if you have have those multiple files in the split window so that it is easily to reference and connect while watching the video itself. This is one way to do it, but the idea is to have visibility or maybe use lesser files. I totally understand that this way it is much more modular but I think for watching everything on a single screen helps better.

@47hriday 2 жыл бұрын

Its best explanation about singleton.Thank You.

@user-ek5jw3cl7k 11 ай бұрын

Thank you ma'am. I have a question. If you null pointer check for loggerInstance on Ln. 21 then do you really think null check required on Ln.24 as well

@aloklakhotia7251 2 жыл бұрын

Great video. Thanks for this. :D One doubt: Isn't the inner if condition redundant as the lock is already captured?

@KeertiPurswani 2 жыл бұрын

Thanks Suraj. For explaining so well! ❤️😇

@geeksentertainmentmedia4827 2 жыл бұрын

And "upper if" to just stop "locking" once you have created the instance.

@shashankcool 2 жыл бұрын

Thanks Keerti for such crisp & nice video capturing all the necessary points related to singleton design pattern. Really appreciate for posting such videos which helps the entire developer community.

@KeertiPurswani Жыл бұрын

Thank you so much, means a lot! Hoping you will like the new videos as well! 😇

@RaisShaikh-bs7dh Жыл бұрын

Thanks Keerti, Such a great video including each smaller things in it. One request if you can give one session on only mutex and semaphore will help us a lot. Thank you so much again for this wonderful session.

@KeertiPurswani Жыл бұрын

Will do for sure!

@SourabhDesaiBrief Жыл бұрын

Clearly Visible, Thank You :) It complied on first time, on staging code - Truly magical!

@KeertiPurswani Жыл бұрын

Thank you! A lot of effort goes behind every single video! ❤️

@venkatkrishna3774 2 жыл бұрын

Please increase the font size when you write code or zoom in a bit. Difficult to read from distance. Thanks

@mayankrai7938 2 жыл бұрын

Finally back ☺️

@KeertiPurswani 2 жыл бұрын

With many many videos this time❤️😇

@sivakumardugana3272 11 ай бұрын

Very clear explanation with examples. Thanks Kreeti

@whynesspower 10 ай бұрын

To restrict access to the operator=, you can declare it as private in the class definition, as you've already done. However, you should also provide an empty definition for it to make it inaccessible and avoid compilation errors. Here's how you can do it: cpp code private: Logger& operator=(const Logger&) = delete; Adding = delete explicitly specifies that the copy assignment operator is deleted and cannot be used. This way, any attempt to use the copy assignment operator will result in a compilation error

@mayankprabhakar5336 Жыл бұрын

Thanks for such a simple explanation!! I have one Q. Should I also delete "move constructor" & "move assignment operator" in singleton class? If YES or No, explanation would be very helpful.

@AdityaNakhare 2 жыл бұрын

In a main method, you can create a singleton class instance before creating a thread. There won't be any contention issue, locking is also not needed.

@user-xr6qq9gf4o Жыл бұрын

Thanks Keerti! Very good way of explanation. God bless you.

@theSDE2 2 жыл бұрын

keerti please do a parallel code for java as well.

@bheemsenkulkarni2471 Жыл бұрын

Thanks Keerthi, this was a very good explanation about singleton

@Ww-ul8oe 2 жыл бұрын

Thank you Keerti. Appreciate implementing in c++

@KeertiPurswani Жыл бұрын

Thank you! Please do subscribe and share the video with your friends❤️😇

@durgeshrai04 Жыл бұрын

Thanks a lot Kreerti! for the wonderful explantion of singleton design pattern.

@KeertiPurswani Жыл бұрын

Thank you! Hope you like other videos on the channel as well! 😇

@mohanganesh1055 2 жыл бұрын

Mam, please complete the design pattern playlist as fast as possible.

@VY-zt3ph 2 жыл бұрын

Fantastic video. I came here after hearing your interview experience. I learned MULTITHREADING just to understand this video.

@KeertiPurswani Жыл бұрын

Woah! How awesome is that! ❤️😇

@VY-zt3ph Жыл бұрын

@@KeertiPurswani Thank you Di

@tarunkumar7656 2 ай бұрын

AWESOME, Great work!

@vipulpurbey4323 Жыл бұрын

goldmine of a video

@virendramane7818 7 ай бұрын

Thank you Keerti! Really appreciate your work.

@AnkitaSingh-vv5rc Ай бұрын

Thankyou so much, Keerti Mam

@roushanraj8530 2 жыл бұрын

Thank you very much Di, got this from end to end like thread safe and all.... One doubt why we use .hpp and .cpp files both..... we can't do in .cpp file only, its little bit confusing to me, i haven't code like this in cpp And please add more videos.... this Playlist is going to be best on KZfaq for LLD and system design 💯💯

@nehakale9427 10 ай бұрын

Excellent explaination Keerti!

@osamayounus4867 2 жыл бұрын

Thanks for these videos. One thing which would help with visibility is if you can show all open code files side by side

@KeertiPurswani Жыл бұрын

But you won’t be able to see the code clearly on screen. I am going to upload all to github pretty soon!

@ritikapande21 2 жыл бұрын

Hey Keerti, Really a good video and detailed explanation. Hats off and please continue to contribute.

@KeertiPurswani 2 жыл бұрын

Thank you so much Ritika, means a lot! More videos coming up soon ❤️😇

@sohelsheikh1934 2 жыл бұрын

For Java People, to handle multithreading do below changes in Logger class - public static Logger getLogger() { if(logger == null) { logger = getInstance(); } return logger; } synchronized public static Logger getInstance(){ if(logger == null) return new Logger(); else return logger; }

@krishnasummer5603 Жыл бұрын

Hi sis, your explanation is very clean & good, if u can add more design patterns .It'll be a great help. Thanks.

@rahulsagarvoduru5158 2 жыл бұрын

You are a great teacher !! Thank You !!

@j.r.krishna1122 Жыл бұрын

You made my day

@PkSam07 Жыл бұрын

Awesome explanation! but I think you missed to explain why we should go for singleton pattern? I think you mentioned in order to avoid multiple logs in different places? I didn't get that?

@rosansenapati-pl5hr Жыл бұрын

wonderful explanation thank you so much for teaching us

@KeertiPurswani Жыл бұрын

Thank you! Please do share the video with your friends!

@rosansenapati-pl5hr Жыл бұрын

@@KeertiPurswani ofcourse I will this is great stuffs and people need to know about your amazing videos

@nkjat123 Жыл бұрын

Hi Guys.. awesome videos

@Kaushikraj9845 2 жыл бұрын

Assuming if we write the code in java ..Can we create object during initialization like below public class Singleton { private static Singleton singleton=new Singleton();; private Singleton() { super(); } public static Singleton getSingleton() { return singleton; } }

@arkosnatoneogy2366 7 ай бұрын

after you implement the double checked lock is the inner if condition needed any more? isnt it bound to be TRUE?

@mayurbadwaik6401 Жыл бұрын

wonderfull explantion keerti, one doubt -> as explained to use mutex, can we follow this approach -> run 1st thread and after that remaining threads -> anyways we are just blocking 2 threads to make instances for the first time and after the instance is created it would not matter how many threads access it

@kartheekgoud9009 2 жыл бұрын

Thanks Keerthi.. Really great explanation 👏.

@rohit_kapdi Жыл бұрын

Superb explanation. ❤

@KeertiPurswani Жыл бұрын

Thank you! Hope you like other videos as well! 😇

@amithtripst9851 2 ай бұрын

Could you please let us know what is the IDE you are using for practice?

@srilakshmiuvpakala3267 Жыл бұрын

Hi Keerthi, thanks a million for the wonderful videos. I have one question in implementation of singleton design pattern. "Why do we need to make assignment operator in private. Assignment operator gets called when we try to assign existing object to another already existing object. In other words this gets called only when we have two instances already created which we already prevented from happening by making default and copy constructors private.

@AnkitSingh-lb9fj 2 жыл бұрын

great stuff as always, waiting for next video on design pattern

@2008suryan 2 жыл бұрын

Very good clear explanation. Expecting more videos on other design patterns.

@hari8222 Ай бұрын

nice explanation

@aryankumar87771 2 жыл бұрын

wait wait what was that at the last? making constructor private and operator overloading private... as a non C++ coder that hit me like a train

@anonymoushacker9094 2 жыл бұрын

Isn't it better to use static class for logger rather than singleton pattern. Some of the useful example can be parking lot

@amarnathsama Жыл бұрын

Can someone explain why we need to have objects of the class at all? why can't getLogger function be static also?

@sasageyo9571 2 жыл бұрын

Are freshers (university grads ) expected to face these questions ? Great video btw !!!

@Archak77 Жыл бұрын

Excellent video ...simple explaination 👍

@KeertiPurswani Жыл бұрын

Thank you so much! Please do share with your friends?

@shankarBinnar-xl8en Жыл бұрын

Thanks Keerti for this video..learn singlton design pattern in detailed . can I get your codes on any website ??

@kingshahzadaamir 2 жыл бұрын

Hey Keerti, I tried this on gcc linux terminal. without mutex also it gave single instance all the time. spent 15 minutes to figure out what wrong I wrote. but then tried it on online gdb compiler; there it varied then.

@sheshitkarthikeya1528 2 жыл бұрын

Your effort to keep things simple is amazing...Also don't worry no one will steal your logger constructor.😂

@KeertiPurswani Жыл бұрын

Hehe thank you so much! ❤️❤️

@vivekshivhare8820 Жыл бұрын

Can we delete the second time nullptr checking as we are already checking it for mtx locking, or that can also cause some problem? just curious, please do reply..

@jenishadsouza907 2 жыл бұрын

Really great explanation!!!

@svarajdhanulkar1791 9 ай бұрын

Yar jo wo problem tha like k if Multithreading is in picture then singleton fails or tabhi muje realise hua uska bhi jugad hota hai par ye interview me pucha tha or sch me tabhi realise hua k hmm such a diff pov

@user-wg4is1ur4k Жыл бұрын

Thanks Keerti, can you please record the session on "Smart Pointer"

@kushagrabhardwaj4436 2 жыл бұрын

Thank you so much for this series :)

@bsratuoh Жыл бұрын

It is really a great session and helpful. Thanks for this. If possible pls increase the font size while explaining codes.

@KeertiPurswani Жыл бұрын

Thanks for the feedback! Hoping it’s better in the present videos! ❤️😇

@powprashant 2 жыл бұрын

Hello Keerti, Thanks for the video, but this is still not complete. Particularly the ownership of the instance, how the instance will be released/destroyed. You can use smart pointer (since C++11) But the best would be using Meyer's Singleton that works with C++98 and C++O3 as well

@niksgupta36 2 жыл бұрын

In Double-checked Locking, instead of adding another nullpointer check, could we have just added mtx.lock() and unlock() inside the initial nullpointercheck? Should work right. Let me know.

@geeksentertainmentmedia4827 2 жыл бұрын

You mean putting lock inside if? It would have same problem . Two threads would have entered inside the "if " condition , and then lock would have happened. So one thread would create instance , unlock , then another would have created instance.

@niksgupta36 2 жыл бұрын

@@geeksentertainmentmedia4827 Makes sense now. Thanks.

@paraskaushik2639 Жыл бұрын

Why have you made 3 files ? logger.hpp , logger.cpp and user.cpp . why cant we directly used logger.hpp in user.cpp ? is there some pattern , folder structuring you have followed ?

@vishalsethi4024 2 жыл бұрын

Great Teacher YOU are

@KeertiPurswani 2 жыл бұрын

Thank you! Means a lot❤️😇

@rohitsankarpal7866 Жыл бұрын

Can someone help me with VS Code as the thread is not supporting !! Any idea how to resolve that ?

@teluguanimetoon2811 2 ай бұрын

When we delete the instance and created new instance 2nd time in main we are unable to delete the instance which we created 2nd time getting double free error

@shyamchauhan520 2 жыл бұрын

Nice explanation :) One doubt: when are we going to delete the resource(loggerInstance) which we have created dynamically using new keyword.

@nikhillaad941 2 жыл бұрын

awsome explaination

@siddeo85 Жыл бұрын

nice video but could you make videos using java?

@mobin1457 Жыл бұрын

Perfect work

@integrateeverythingpower 2 жыл бұрын

Hi didi ,your videos are just awesome keep making videos like this and motivating us

@KeertiPurswani Жыл бұрын

Thank you! Please keep sharing videos and motivating me! ❤️

@mrCetus 2 жыл бұрын

One Request: Please give the direct link to the playlist of design patterns you are covering to check other patterns easily.

@KeertiPurswani Жыл бұрын

There’s a playlist on the channel - Design Patterns kzfaq.info/sun/PLliXPok7ZonlZJuAN0hvUnf5ovFepjxU0 😇😇

@fakecake7608 2 жыл бұрын

Great complete Video :)

@whynesspower 10 ай бұрын

20:05 can you give me the code for that? Will it be something like delete Logger operator=(const Logger &)? Correct me if I am wrong

@athena2986 2 жыл бұрын

Thank you for explaining in detail.can you please create GitHub links for the codes specially the design pattern ones

@meme_engineering4521 2 жыл бұрын

excellent!!, can someone please tell me if this playlist is enough for sde1 interviews?

@hrudayd4217 2 жыл бұрын

Normally front end developer uses js, learning dsa using js is it useful or not ?

@KeertiPurswani 2 жыл бұрын

Dsa is useful for sure (language doesn’t matter that much - as long as you can solve questions) But I do know some front end developers who are doing really well and don’t know dsa much.

@potassium_cyanide_boy8515 Жыл бұрын

What if exception is thrown Inside a mutex lock ? It will never ever unlock the mutex and no other thread will be able to enter the critical section or they will keep waiting to mutex to get unlocked that will never happened. So we should use unique_lock or lock_guard i guess 😒😒

@RishabhRD 2 жыл бұрын

If you are writing singleton in C++... Meyers singleton is the standard way of doing this. I guess covering meyers singleton was super important not done.... BTW singletons are anti pattern avoid it

@JimitRupani 2 жыл бұрын

It was really helpful.

@matheens6689 Жыл бұрын

You can use semaphore ? Why mutex

@user-en9fs1ev7r 9 ай бұрын

How about KZfaq adding search option in comments section.

@svarajdhanulkar1791 9 ай бұрын

Thanks mam

@ss-md4qn 2 жыл бұрын

Superb

@RiyaSingh-nj1fx 2 жыл бұрын

I have 3 things to say.... 1. How is your armpit...seems like due to pole dance you had some issue. 2. Nice explaination 3. How is work at intuit one of my friend joined there and tell me he work day and night and even weekends too.

@PROTECHRAHUL 2 жыл бұрын

Hey diii i didn't get what are you teaching can you please tell? So i can learn it.

@KeertiPurswani 2 жыл бұрын

Hi Rahul, start watching the design pattern playlist. The first video is introduction of what design patterns are. It should help. Let me know if you have any doubts😇

@PROTECHRAHUL 2 жыл бұрын

@@KeertiPurswani Thanks dii. 🤗