core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/QueryRetryingCopycatClient.java

/*
 * Copyright 2016-present Open Networking Laboratory
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.onosproject.store.primitives.impl;

import static org.slf4j.LoggerFactory.getLogger;

import java.net.ConnectException;
import java.nio.channels.ClosedChannelException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Predicate;

import org.slf4j.Logger;

import com.google.common.base.Throwables;

import io.atomix.catalyst.transport.TransportException;
import io.atomix.copycat.Query;
import io.atomix.copycat.client.CopycatClient;
import io.atomix.copycat.error.QueryException;
import io.atomix.copycat.error.UnknownSessionException;
import io.atomix.copycat.session.ClosedSessionException;

/**
 * {@code CopycatClient} that can retry when certain recoverable errors are encoutered.
 */
public class QueryRetryingCopycatClient extends DelegatingCopycatClient {

    private final int maxRetries;
    private final long delayBetweenRetriesMillis;
    private final ScheduledExecutorService executor;
    private final Logger log = getLogger(getClass());

    private final Predicate<Throwable> retryableCheck = e -> e instanceof ConnectException
            || e instanceof TimeoutException
            || e instanceof TransportException
            || e instanceof ClosedChannelException
            || e instanceof QueryException
            || e instanceof UnknownSessionException
            || e instanceof ClosedSessionException;

    QueryRetryingCopycatClient(CopycatClient client, int maxRetries, long delayBetweenRetriesMillis) {
        super(client);
        this.maxRetries = maxRetries;
        this.delayBetweenRetriesMillis = delayBetweenRetriesMillis;
        this.executor = Executors.newSingleThreadScheduledExecutor();
    }

    @Override
    public CompletableFuture<Void> close() {
        executor.shutdown();
        return super.close();
    }

    @Override
    public <T> CompletableFuture<T> submit(Query<T> query) {
        CompletableFuture<T> future = new CompletableFuture<>();
        executor.submit(() -> submit(query, 1, future));
        return future;
    }

    private <T> void submit(Query<T> query, int attemptIndex, CompletableFuture<T> future) {
        client.submit(query).whenComplete((r, e) -> {
            if (e != null) {
                if (attemptIndex < maxRetries + 1 && retryableCheck.test(Throwables.getRootCause(e))) {
                    log.debug("Retry attempt ({} of {}). Failure due to {}",
                            attemptIndex, maxRetries, Throwables.getRootCause(e).getClass());
                    executor.schedule(() ->
                        submit(query, attemptIndex + 1, future), delayBetweenRetriesMillis, TimeUnit.MILLISECONDS);
                } else {
                    future.completeExceptionally(e);
                }
            } else {
                future.complete(r);
            }
        });
    }
}