exec/java-exec/src/main/java/org/apache/drill/exec/testing/PauseInjection.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.drill.exec.testing;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

import java.util.concurrent.TimeUnit;

import org.apache.drill.common.concurrent.ExtendedLatch;

/**
 * Injection for a single pause. Pause indefinitely until signalled. This class is used internally for tracking
 * injected pauses. Note that pauses can be fired only once; nFire field is ignored. These pauses are specified via
 * {@link org.apache.drill.exec.ExecConstants#DRILLBIT_CONTROL_INJECTIONS} session option.
 *
 * After the pauses are set, the user sends another signal to unpause all the pauses. This triggers the Foreman to
 * 1) unpause all pauses in QueryContext, and
 * 2) send an unpause signal to all fragments, each of which unpauses all pauses in FragmentContext.
 */
@JsonAutoDetect(fieldVisibility = Visibility.ANY)
public class PauseInjection extends Injection {

  private final ExtendedLatch latch = new ExtendedLatch(1);

  @JsonCreator // ensures instances are created only through JSON
  private PauseInjection(@JsonProperty("address") final String address,
                         @JsonProperty("port") final int port,
                         @JsonProperty("siteClass") final String siteClass,
                         @JsonProperty("desc") final String desc,
                         @JsonProperty("nSkip") final int nSkip,
                         @JsonProperty("msPause") final long msPause) throws InjectionConfigurationException {
    //nFire is 1 since we will inject pauses only once
    super(address, port, siteClass, desc, nSkip, 1, msPause);
  }

  /**
   * Pause indefinitely, unless a duration exists
   */
  public void pause() {
    if (!injectNow()) {
      return;
    }
    if (this.getMsPause() > 0L) {
      try {
        latch.await(getMsPause(), TimeUnit.MILLISECONDS);
      } catch (InterruptedException e) {
        //Unpausing self as this is timed
        unpause();
      }
    } else {
      latch.awaitUninterruptibly();
    }
  }

  public void interruptiblePause() throws InterruptedException {
    if (!injectNow()) {
      return;
    }
    latch.await();
  }

  public void unpause() {
    latch.countDown();
  }
}