Synchronized | Exposes Objective-C 's @ synchronized directive to Swift | iOS library

I'm trying to understand best practices for Golang concurrency. I read O'Reilly's book on Go's concurrency and then came back to the Golang Codewalks, specifically this example:

https://golang.org/doc/codewalk/sharemem/

This is the code I was hoping to review with you in order to learn a little bit more about Go. My first impression is that this code is breaking some best practices. This is of course my (very) unexperienced opinion and I wanted to discuss and gain some insight on the process. This isn't about who's right or wrong, please be nice, I just want to share my views and get some feedback on them. Maybe this discussion will help other people see why I'm wrong and teach them something.

I'm fully aware that the purpose of this code is to teach beginners, not to be perfect code.

Issue 1 - No Goroutine cleanup logic

code

I have a Room database in my application with one table containing received and sent messages. Inside of the table, the messages are just differentiated by the phone number, being null for the backend-server (since a server has no phone number) and the phone number of the user for the sent messages. (Entered on app installation, just as Whatsapp.) To sync the table with the backend, I introduced a new column, containing the backend id of the messages on the server. Since the server seperates sent and received messages (due to different information contained in the tables backend), the id of a sent message and the id of a received message can be equal, only distinguishable by the corresponding phone number. (Either null or own) So I created a unique constraint over both columns: backend_id & phone number.

I have some question. In my application I use Sqlite Database, named "Templates", and I want to create several tables, like peopleTemplates, animalsTemplates, which consist of columns id, description, image_link. Also there will be special table favourites, I will add there all templates user likes. I am going to use RoomDatabase. Here is my TemplatesClass:

I am working on a tasks app, and I want to use Room to save my data. So I've created the 3 required classes. However, in my DAO class, my @Query statement isn't working, as it says:

Cannot resolve certain symbols

I have no idea why this is happening. Please help.

Code for subtaskdetails (the first class):

Here is what I did:

• I have a "my_branch" and there is a "master" branch.
• I kept committing my work to "my_branch" for, say one month.
• To align with code in "master", for every 2 or 3 days, I merge master into "my_branch".
• I change code under "my_dir/" only, while nobody else touched this directory
• Other people change code under "somebody1/", "somebody2/" etc., but I had never touched.

Here is my problem:

• For some reason which I don't know, files under directories other than "my_dir/" (which I didn't touch them) are not as same as what in "master".
• One possible cause might be, when merging "master" into "my_branch", some files under directories other than "my_dir/" changed, and there were conflicts. Maybe I chose "resolve conflict" rather than "use theirs", and made me touched those files unintentionally.
• Even if I keep merge "master" into "my_branch", those unintentionally changed files never get synchronized unless they are changed by somebody else in master.
• If I merge "my_branch" into "master", files under directories other than "my_dir/" and inconsist with "master" will be changed because of "my_branch", and that's not what I want.

Here is what I want to do:

How can I make files other than "my_dir/" in "my_branch" to be same with "master", while keep files under "my_dir/" to be same with "my_branch"? One possible way is that I checkout "master", copy all files under directories like "somebody1/", "somebody2/" etc., to some place else, then checkout "my_branch", then copy those files back to my working directory and then commit.

But How can I do it with Git command? Does Git provide such util?

I'm trying to draw something use OpenGL ES 1.0, the rendering to screen works good. Then I want to use ImageReader to get the image data from surface, but its callback ImageReader.OnImageAvailableListener is not called at all while rendering, what's wrong about my code?

I wrote a class (userRepository) including a method named init(). init method initializes ConcurrentHashMap, when I invoke this method in multiple threads (for example in three threads and in each thread for n times), I expect that the size of the map equals nx3. but it is not! on the other hand, when I use ReentrantLock or synchronized keyword on the signature of the method it works perfectly fine. I mean the size of the map is equal to nx3. please check the following example:

I am trying to use wait() and notify() on a class to notify the waiting thread but the scenario is whoever go first into the synchronized block will wait for other to print some values and notify the waiting thread. but the waiting thread is keep waiting. what am doing wrong.