id-generator | id-generator部署即使用的ID生成器 , 支持HTTP、Dubbo、Spring Cloud方式 | Generator Utils library

As it's stated in the documentation:

You need to ensure that names defined under spring.jpa.properties.* exactly match those expected by your JPA provider. Spring Boot will not attempt any kind of relaxed binding for these entries.

For example, if you want to configure Hibernate’s batch size you must use spring.jpa.properties.hibernate.jdbc.batch_size. If you use other forms, such as batchSize or batch-size, Hibernate will not apply the setting.

So, for your case you should use:

Receiving the same service and characteristic UUID for multiple BLE devices is perfectly normal and only means that all the devices offer exactly the same service.

For example: If you have two devices which measure the heart rate of a person, e.g. a smartwatch, both devices might offer the heart rate service with the same UUID.

If you want to differentiate between the device you can use the identifier which you received in step 3 of your provided log.

In this case, you should instruct your application how to create tables.

You have 2 options:

1. Tell JPA to do that, adding spring.jpa.hibernate.ddl-auto=create or spring.jpa.hibernate.ddl-auto=update
2. Use a more robust tool like flyway, liquibase, etc

All the other configs you showed looks fine.

• @GeneratedValue annotation is used to generate primary key value automatically. There are 4 generation types: AUTO, IDENTITY, SEQUENCE, TABLE.

• AUTO: The persistence provider will determine values based on the type of the primary key attribute. Numeric values are generated based on a sequence generator and UUID values use the UUIDGenerator.

• IDENTITY: It relies on the value generated by an identity column in the database, meaning they are auto-incremented. Note that IDENTITY generation disables batch updates.

You are using IDENTITY strategy without an identity column in your schema. Change the schema.sql as follows:

You need to configure the map on the server side, which means you need to have some of the Spring classes on member's classpath. But keep in mind that you need this configuration only when HazelcastIndexedSessionRepository#findByIndexNameAndIndexValue is used.

Also in client mode, do not forget to deploy necessary classes and enable user code deployment for members. Otherwise session updates will fail:

If you want to generate the id and at the same time using *sql files, you need define the auto_increment property to your id field in creation table.

Because when you using generation strategy - Identity, hibernate believes that your columns is auto increments on a table side.

You don't have to use Dockerfile but you need to define and pass to Docker container username, password and database name. You could do that also in the run command:

docker run --rm --name postgresContainer -d -p 54320:5432 -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=yourDatabase postgres

default username is postgres so you don't need to specify that. Last postgres word in command is the name of the image

I also called yourDatabase differently because I think there is a default database in postgres called postgres.

After running the above command you can execute the following to check that your database is running:

docker exec -it postgresContainer bash

su postgres

psql

\list

This will show you all of the databases available. Now type:

\c yourDatabase

and you are connected to your database in postgres Docker. Feel free to run create tables/selects or whatever.

to exit just type \q and exit like 2 times. Container will keep running.

Don't forget to update you spring properties to match

Failed to determine a suitable driver class

You need to add mariadb driver dependency to your gradle or maven file.

https://mvnrepository.com/artifact/org.mariadb.jdbc/mariadb-java-client/2.6.2

Make sure that dependency scope is suitable for test

If you already have and its still not working try to clean and rebuild your project.

Your Questions:

Do the application.yml files get layered (*-test.yml settings on top of application.yml)?

If you add @ActiveProfiles("test") to you TestClass Spring will try to find an application-test.yml and overrrides application.yml properties with the given properties

Why does Spring try to build a connection to my database when I am not setting a datasource on my application-test.yml AND mocking the repository on the test?

Thats the magic of spring boot - it has default configurations for everything. You just need to set the Datasource properties and it will create the bean by itself.

Is it normal that Spring trys to establish a connection at this part? 3.1) If not: How to i prevent it from doing so?

You are starting the whole spring context with @SpringBootTest Annotation. So it will startup all Repositories and try to establish connection to your database. If you don't want spring to startup the database layer you can just use @WebMvcTest

eg:

I doubt that you'll find any

direct evidence

in the code. There are only 3 possibilities:

1. A comment in the code from the author explaining that AtomicLong is used for thread safety reasons. But it's still indirect evidence, because author can be wrong in his assumptions (he is't).
2. A test that checks if the count correctly updated in some multi-thread scenario. But it's again indirect evidence, because it states that the count correctly updated, not that it would be incorrectly updated in other cases.
3. And the only direct evidence will be the test with error. For that you'll need to test a version of code without AtomicLong... Well, you can do that.

But if you do understand that

the threads in the thread pool may be created in a multi-threading way thus to ensure the id of the threads not get duplicated we need the id-generator to be a atomic variable

what else do you need? The mental experiment (unlike the test from the third bullet) is quite simple:

1. newThread is called from Thread1
2. It gets to the point when it needs to update the count
3. The value of the count is read, and placed in a register.
4. The value of the count is incremented in the register but not yet written to the memory where the count is stored.
5. At this moment the context is switched. newThread from Thread1 is paused. newThread is called again but from Thread2
6. It gets to the point when we need to update the count
7. Oops! The Thread2 can't read the updated value of the count from the register. It can read it from the memory, but there is still an old value.