Concurrency.java

package vigilancia.service;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;

/*
 * Classe para operações de concorrência;
 * Evitar que o usuário realize muitiplas requisições subsequentemente; 
 *
 * https://www.baeldung.com/spring-webclient-limit-requests-per-second
 */
public class Concurrency {

    private static final long limitSeconds = 2;
    private static final long millis = 2000;//2;
    private static final int MAX_CONCURRENT = 5;
    private static final int MAX_CONCURRENT_SEQ = 5;
    private static final AtomicInteger CONCURRENT_REQUESTS = new AtomicInteger();
    private static final AtomicInteger CONCURRENT_REQUESTS_SEQ = new AtomicInteger();
    private static LocalDateTime tempoAnt = LocalDateTime.now();

    public static int protect() {
        try {
            if (CONCURRENT_REQUESTS.incrementAndGet() > MAX_CONCURRENT) {
                throw new UnsupportedOperationException("max concurrent requests reached");
            }
            LocalDateTime atual = LocalDateTime.now();
            long seconds = ChronoUnit.SECONDS.between(tempoAnt, atual);
            if(CONCURRENT_REQUESTS.get() > 0 && seconds <= limitSeconds){
                CONCURRENT_REQUESTS_SEQ.incrementAndGet();
                /**\/ [fase de BLOCK]; */
                // System.out.println(">>>>>>>>> [BLOCK] >>>>>>>>>");
                // System.out.println( seconds );
                // System.out.println( CONCURRENT_REQUESTS.get() );
                // System.out.println( CONCURRENT_REQUESTS_SEQ.get() );
                if(CONCURRENT_REQUESTS_SEQ.get() >= MAX_CONCURRENT_SEQ){
                    /**\/ [BLOCK usuário]; */
                    // System.out.println(">>>>>>>>> [BLOCK XX] >>>>>>>>>");
                }
            }
            tempoAnt = atual;
            TimeUnit.SECONDS.sleep(millis);
            return 1;
        }catch(InterruptedException e){;
            return 0;
        } finally {
            CONCURRENT_REQUESTS.decrementAndGet();
            System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
            System.out.println(">>>>>>>>> MAX >>>>>>>>");
            System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
        }
    }

}