numbers

Numbers

Application that receives multiple connections and writes down to file deduplicated numbers from the ones received through the connections.

Project structure

• cmd/generator: contains an executable that generates random numbers of 9 digits and prints them to stdout.
• cmd/numbers: contains the main executable of the project.
• config: contains the general configuration of the project. It follows the 12 factor configuration design.
• internal: contains the Domain Driven Design approach to implement the requirements of the task.
• internal/app: contains the application layer, where the use cases for the project have been implemented.
• internal/domain: contains the domain layer.
• internal/infra: contains the infrastructure layer, where the network client manager is implemented.

How to run the project

The following dependencies are required for the project to be executed. make, and go.

Run the binary

Now that the DB is up and running you can start the execution of the project binary:

make run

How to test the project

Besides, the mandatory dependencies to run the project we will need the following extra dependencies to run test and run linting checks in the project. golangci-lint, and moq. They can be installed with the following:

make tools

To run the linting checks it is similar to the previous command:

make lint

Unit test

In order to run the unit test you just need the following command:

make test

Performance test

You can use the generate main contained in the repository to test the throughput of the solution. If you have netcat installed in your system, while the numbers binary is running, explained in the section above, you can execute the following command to send request for 21 seconds.

make send-numbers-for-21-seconds

In my home desktop (Intel i5-4670K and 16GB RAM) I obtained a throughput of 4M.

$ make run
cd cmd/numbers && go run main.go
Received 3281026 unique numbers, 5463 duplicates. Unique total: 3286489
Received 3958772 unique numbers, 21250 duplicates. Unique total: 7266511

Configuration

As mentioned above the project follows the 12 factor configuration design. Therefore, it uses environment variables in order to configure several aspects of the project:

• NUMBERS_CONCURRENT_CLIENTS: sets the number of concurrent clients allowed. It's default value is 5.
• NUMBERS_TIME_BETWEEN_REPORTS: sets the time between reports (in seconds). It's default value is 10.
• NUMBERS_HOST: sets the host name to listen for TCP requests. It's default value is 127.0.0.1.
• NUMBERS_PORT: sets the port to listen for TCP requests. It's default value is 4000.

Exit codes

As it is common in the Unix-like system applications, if the numbers binary stops the execution by entering the terminate command. It will return 0 as its exit code. Please, see the list below with the different exit codes and what do they mean:

• 0: gracefully shutdown performed.
• 1: failure to open numbers.log file.
• 2: configuration failure.
• 3: failure to bind to the port in the interface specified.