DefaultFenceWait.java

/*
 * Copyright © 2016 Cask Data, Inc.
 *
 * 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 co.cask.tephra.visibility;

import co.cask.tephra.TransactionContext;
import co.cask.tephra.TransactionFailureException;
import com.google.common.base.Stopwatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Default implementation of {@link FenceWait}.
 */
public class DefaultFenceWait implements FenceWait {
  private static final Logger LOG = LoggerFactory.getLogger(DefaultFenceWait.class);

  private final TransactionContext txContext;

  DefaultFenceWait(TransactionContext txContext) {
    this.txContext = txContext;
  }

  @Override
  public void await(long timeout, TimeUnit timeUnit)
    throws TransactionFailureException, InterruptedException, TimeoutException {
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.start();
    long sleepTimeMicros = timeUnit.toMicros(timeout) / 10;
    // Have sleep time to be within 1 microsecond and 500 milliseconds
    sleepTimeMicros = Math.max(Math.min(sleepTimeMicros, 500 * 1000), 1);
    while (stopwatch.elapsedTime(timeUnit) < timeout) {
      txContext.start();
      try {
        txContext.finish();
        return;
      } catch (TransactionFailureException e) {
        LOG.error("Got exception waiting for fence. Sleeping for {} microseconds", sleepTimeMicros, e);
        txContext.abort();
        TimeUnit.MICROSECONDS.sleep(sleepTimeMicros);
      }
    }
    throw new TimeoutException("Timeout waiting for fence");
  }
}