Number of times REST API was called

Question

If I have a HTTP REST API : example /getCount

Sample Code

@RestController
public class CountController {
    long count = 0;
    @Getmapping("/getCount")
    public long getCount(){
        count++; // Here is the problem, how to keep the latest count if the API was hit by multiple Application/clients
        return count;
    }
}

Problem Description: Every time any app/system call the above mentioned API, count will be increased by 1 and the caller entity can get the exact number of hit.

Condition: Its a open API.Need guidance how to achieve it. This is the only problem statement I am having

Answer 1

you can use static type if you want counter behavior as follows

• Counter is common for all clients calling APIs.
• Counter will restart to 0 as soon as server will restart.

@RestController
public class CountController {
    static long count = 0;
    @Getmapping("/getCount")
    public long getCount(){
        count++; // Here is the problem, how to keep the latest count if the API was hit by multiple Application/clients
        return count;
    }
}

If You want different counter for all client or want to hold counter value even if server is shutdown or restart then you need to use DB to store counter.

Answer 2

Java provides a nice capability through AtomicInteger. This is a thread-safe object and you can rely on to increment whenever your counter method is called.

First:

You need to define your Resource class as Singleton and initiate the AtomicInteger.

private AtomicInteger count = new AtomicInteger();

Second:

You need to add the following code inside your rest method to increment the current counter by one. This will be automatically taken care by the following method,

count.incrementAndGet();

Finally:

When you need to get the current counter you can have a REST method to get the details like below,

@GetMapping("count")
public int getCount() {
    return this.count.get();
}

I hope this would clarify your question.