Singleton Design Pattern | Implementation with details & code ✌🏻

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Really really wanted my first RU-vid 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

Опубликовано:

21 июл 2024

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Комментарии : 138

@arjungupta250 2 года назад

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 года назад

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

@vaibhavjain8672 3 месяца назад

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.

@aryanyadav3926 11 месяцев назад

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 месяцев назад

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...😍

@pratikwadekar4981 2 года назад

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 года назад

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

@kedarsadhu2816 Год назад

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 Год назад

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

@shashankcool 2 года назад

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 Год назад

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

@virendramane7818 6 месяцев назад

Thank you Keerti! Really appreciate your work.

@user-xr6qq9gf4o Год назад

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

@ritikapande21 2 года назад

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

@KeertiPurswani 2 года назад

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

@sivakumardugana3272 10 месяцев назад

Very clear explanation with examples. Thanks Kreeti

@2008suryan 2 года назад

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

@rahulsagarvoduru5158 2 года назад

You are a great teacher !! Thank You !!

@SugamMaheshwari 2 месяца назад

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

@AnkitSingh-lb9fj 2 года назад

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

@nehakale9427 9 месяцев назад

Excellent explaination Keerti!

@SourabhDesaiBrief Год назад

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

@KeertiPurswani Год назад

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

@RohitRaj-qv5nq 2 года назад

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

@KeertiPurswani Год назад

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

@mayankprabhakar5336 Год назад

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.

@kushagrabhardwaj4436 2 года назад

Thank you so much for this series :)

@insofcury 2 месяца назад

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.

@nileshpatil4111 11 дней назад

Nicely explained. Understood it completely

@47hriday 2 года назад

Its best explanation about singleton.Thank You.

@tarunkumar7656 Месяц назад

AWESOME, Great work!

@vipulpurbey4323 Год назад

goldmine of a video

@kartheekgoud9009 2 года назад

Thanks Keerthi.. Really great explanation 👏.

@bheemsenkulkarni2471 Год назад

Thanks Keerthi, this was a very good explanation about singleton

@RaisShaikh-bs7dh Год назад

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 Год назад

Will do for sure!

@user-ek5jw3cl7k 10 месяцев назад

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

@krishnasummer5603 Год назад

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

@AnkitaSingh-vv5rc Месяц назад

Thankyou so much, Keerti Mam

@durgeshrai04 Год назад

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

@KeertiPurswani Год назад

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

@jenishadsouza907 2 года назад

Really great explanation!!!

@arkosnatoneogy2366 6 месяцев назад

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

@PkSam07 Год назад

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?

@meme_engineering4521 2 года назад

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

@shyamchauhan520 2 года назад

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

@AdityaNakhare 2 года назад

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.

@Ww-ul8oe 2 года назад

Thank you Keerti. Appreciate implementing in c++

@KeertiPurswani Год назад

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

@j.r.krishna1122 Год назад

You made my day

@kingshahzadaamir Год назад

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.

@srilakshmiuvpakala3267 Год назад

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.

@amithtripst9851 Месяц назад

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

@VY-zt3ph 2 года назад

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

@KeertiPurswani Год назад

Woah! How awesome is that! ❤️😇

@VY-zt3ph Год назад

@@KeertiPurswani Thank you Di

@shankarBinnar-xl8en Год назад

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

@roushanraj8530 2 года назад

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 RU-vid for LLD and system design 💯💯

@nkjat123 Год назад

Hi Guys.. awesome videos

@mayurbadwaik6401 Год назад

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

@rosansenapati-pl5hr Год назад

wonderful explanation thank you so much for teaching us

@KeertiPurswani Год назад

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

@rosansenapati-pl5hr Год назад

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

@amarnathsama Год назад

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

@integrateeverythingpower 2 года назад

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

@KeertiPurswani Год назад

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

@fakecake7608 2 года назад

Great complete Video :)

@PRANAVMAPPOLI 10 месяцев назад

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

@akshayyadav6854 7 месяцев назад

Have the same question...

@osamayounus4867 Год назад

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

@KeertiPurswani Год назад

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

@mayankrai7938 2 года назад

Finally back ☺️

@KeertiPurswani 2 года назад

With many many videos this time❤️😇

@rohit_kapdi Год назад

Superb explanation. ❤

@KeertiPurswani Год назад

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

@mobin1457 Год назад

Perfect work

@vivekshivhare8820 11 месяцев назад

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..

@athena2986 2 года назад

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

@theSDE2 2 года назад

keerti please do a parallel code for java as well.

@JimitRupani 2 года назад

It was really helpful.

@aloklakhotia7251 2 года назад

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

@KeertiPurswani 2 года назад

Thanks Suraj. For explaining so well! ❤️😇

@geeksentertainmentmedia4827 2 года назад

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

@venkatkrishna3774 2 года назад

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

@nikhillaad941 Год назад

awsome explaination

@sheshitkarthikeya1528 2 года назад

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

@KeertiPurswani Год назад

Hehe thank you so much! ❤️❤️

@anonymoushacker9094 2 года назад

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

@sasageyo9571 2 года назад

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

@hari8222 28 дней назад

nice explanation

@rohitsankarpal7866 11 месяцев назад

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

@whynesspower 9 месяцев назад

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

@user-wg4is1ur4k Год назад

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

@mohanganesh1055 2 года назад

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

@Archak77 Год назад

Excellent video ...simple explaination 👍

@KeertiPurswani Год назад

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

@vishalsethi4024 2 года назад

Great Teacher YOU are

@KeertiPurswani 2 года назад

Thank you! Means a lot❤️😇

@niksgupta36 2 года назад

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 года назад

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 года назад

@@geeksentertainmentmedia4827 Makes sense now. Thanks.

@bsratuoh Год назад

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

@KeertiPurswani Год назад

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

@teluguanimetoon2811 2 месяца назад

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

@matheens6689 Год назад

You can use semaphore ? Why mutex

@ss-md4qn 2 года назад

Superb

@powprashant 2 года назад

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

@aryankumar87771 Год назад

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

@svarajdhanulkar1791 8 месяцев назад

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

@paraskaushik2639 Год назад

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 ?

@whynesspower 9 месяцев назад

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

@siddeo85 Год назад

nice video but could you make videos using java?

@svarajdhanulkar1791 8 месяцев назад

Thanks mam

@sohelsheikh1934 2 года назад

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; }

@hrudayd4217 2 года назад

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

@KeertiPurswani 2 года назад

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.

@kushagra4401 2 года назад

di do you work in cpp in your company too?

@Kaushikraj9845 2 года назад

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; } }

@mrCetus 2 года назад

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

@KeertiPurswani Год назад

There’s a playlist on the channel - Design Patterns ru-vid.com/group/PLliXPok7ZonlZJuAN0hvUnf5ovFepjxU0 😇😇

@user-en9fs1ev7r 8 месяцев назад

How about RU-vid adding search option in comments section.

@varshakancham5944 2 года назад

Why are locks expensive

@skandan6266 2 года назад

Please make the code view bigger. It becomes difficult to read while watching on a phone

@potassium_cyanide_boy8515 Год назад

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 😒😒

@PROTECHRAHUL 2 года назад

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

@KeertiPurswani 2 года назад

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 года назад

@@KeertiPurswani Thanks dii. 🤗

@RishabhRD Год назад

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