Multiple Producers Consumers

Each of the producers and consumers share a counter with an initial value. The producers increment the value by one, and the consumers decrement the value by one. Each of the threads continues to run in parallel until the counter reaches to boundary, i.e., the value is equal to the lower limit or upper limit.

Controller

The app exposed the following endpoints:

• POST /api/v1/producers to create a producer thread.
• POST /api/v1/consumers to create a consumer thread.
• PATCH /api/v1/value/{value} to update the counter value.

Database

Each of the requests for creating a producer and consumer is persisted in the requests table in the following format:

• worker_type is either producer or consumer.
• worker_id is the unique id of the thread.
• created_at is the timestamp of the request.

Also, each time the counter value reaches to either lower limit or upper limit, the event is stored in the analytics table in the following format:

• worker_type is either producer or consumer.
• worker_id is the unique id of the thread.
• value is the counter value.
• created_at is the timestamp of the request.

We use the Flyway migrations. The migration files are created in the resources/db/migration directory.

Running the Application

Go to docker/development and run docker-compose up. It will start the database and counter_app services. It should build the following two images:

$ docker image ls
REPOSITORY                TAG       IMAGE ID       CREATED          SIZE
development_counter_app   latest    b71f2e32e1af   39 seconds ago   455MB
mysql                     8.0.25    c0cdc95609f1   39 seconds ago   556MB

Also, the following two containers should be started:

$ docker container ls
CONTAINER ID   IMAGE                     COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
e8d0af0bbc4d   development_counter_app   "java -cp app:app/li…"   53 seconds ago   Up 50 seconds   0.0.0.0:8080->8080/tcp, :::8080->8080/tcp              development_counter_app_1
d567d77da0fd   mysql:8.0.25              "docker-entrypoint.s…"   22 minutes ago   Up 53 seconds   0.0.0.0:3306->3306/tcp, :::3306->3306/tcp, 33060/tcp   development_database_1

Run the following command to check the app health:

$ curl localhost:8080/actuator/health
{"status":"UP"}

Sample Run

Suppose we make the following requests:

curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/producers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers
curl -XPOST localhost:8080/api/v1/consumers

The requests table data is:

mysql> select * from requests;
+----+-------------+--------------------------------------+---------------------+
| id | worker_type | worker_id                            | created_at          |
+----+-------------+--------------------------------------+---------------------+
|  1 | producer    | ccdf9be2-06e7-4258-aa07-aa08384aaf61 | 2021-05-30 17:52:35 |
|  2 | producer    | d95d0299-152f-4c69-8fa4-1be4b0855daf | 2021-05-30 17:52:36 |
|  3 | consumer    | b34e2478-1db4-47c3-81aa-47d797337932 | 2021-05-30 17:52:40 |
|  4 | consumer    | d9611a54-148e-40a5-9800-aafdc2f3f5ab | 2021-05-30 17:52:41 |
|  5 | consumer    | bba20181-e690-4b0b-9310-587a70de5dac | 2021-05-30 17:52:42 |
|  6 | producer    | 908e871a-56a5-40c6-a6b7-187bf81c293f | 2021-05-30 17:52:44 |
|  7 | producer    | b694dc73-ce0c-4e7a-b8f1-2eebb91a0d8e | 2021-05-30 17:52:45 |
|  8 | producer    | 1f6ab780-d08b-42d5-a415-6500601719cd | 2021-05-30 17:52:45 |
|  9 | producer    | beec64ac-1111-4243-857b-570071c0c570 | 2021-05-30 17:52:46 |
| 10 | consumer    | 71f7bcef-c3c2-45ca-80a5-9e99dd7ac624 | 2021-05-30 17:52:48 |
| 11 | consumer    | c1c14c1c-a194-4c68-8cc7-5665230b19ff | 2021-05-30 17:52:48 |
| 12 | consumer    | 77bb9caf-af43-4f00-82ae-f5da360981e2 | 2021-05-30 17:52:49 |
| 13 | consumer    | 19bb2101-36e7-4e8f-8612-5b1f026cc1cb | 2021-05-30 17:53:30 |
| 14 | consumer    | bdaae35a-83f9-49e8-ad6b-30f5f5f6b097 | 2021-05-30 17:53:30 |
| 15 | consumer    | e04f15ba-4f6c-4b50-8e32-e0e95b0bf1e4 | 2021-05-30 17:53:31 |
+----+-------------+--------------------------------------+---------------------+
15 rows in set (0.00 sec)

The analytics table data is:

mysql> select * from analytics;
+----+-------------+--------------------------------------+-------+---------------------+
| id | worker_type | worker_id                            | value | created_at          |
+----+-------------+--------------------------------------+-------+---------------------+
|  1 | consumer    | b34e2478-1db4-47c3-81aa-47d797337932 |     0 | 2021-05-30 17:54:08 |
+----+-------------+--------------------------------------+-------+---------------------+
1 row in set (0.01 sec)