frostfs-sdk-java/client/src/main/java/info/frostfs/sdk/pool/InnerPool.java

package info.frostfs.sdk.pool;

import java.util.concurrent.locks.ReentrantLock;

class InnerPool {
    private static final int ATTEMPTS_COUNT = 3;
    private final ReentrantLock lock = new ReentrantLock();
    private final ClientWrapper[] clients;
    private Sampler sampler;

    InnerPool(Sampler sampler, ClientWrapper[] clients) {
        this.sampler = sampler;
        this.clients = clients;
    }

    Sampler getSampler() {
        return sampler;
    }

    void setSampler(Sampler sampler) {
        this.sampler = sampler;
    }

    ClientWrapper[] getClients() {
        return clients;
    }

    ClientWrapper connection() {
        lock.lock();
        try {
            if (clients.length == 1) {
                ClientWrapper client = clients[0];
                if (client.isHealthy()) {
                    return client;
                }
            } else {
                int attempts = ATTEMPTS_COUNT * clients.length;

                for (int i = 0; i < attempts; i++) {
                    int index = sampler.next();

                    if (clients[index].isHealthy()) {
                        return clients[index];
                    }
                }
            }

            return null;
        } finally {
            lock.unlock();
        }
    }
}