content: /*
   * 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.asterix.runtime.evaluators.functions;
  
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.runtime.runningaggregates.base.AbstractRunningAggregateFunctionDynamicDescriptor;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IRunningAggregateEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IRunningAggregateEvaluatorFactory;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.IntegerPointable;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  /**
   * Create global unique id within a query.
   */
  public class CreateQueryUIDDescriptor extends AbstractRunningAggregateFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
  
      public static final IFunctionDescriptorFactory FACTORY = CreateQueryUIDDescriptor::new;
  
      @Override
      public IRunningAggregateEvaluatorFactory createRunningAggregateEvaluatorFactory(IScalarEvaluatorFactory[] args) {
          return new IRunningAggregateEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
              private static final int BINARY_LENGTH = 14;
              private static final int PAYLOAD_START = 2;
  
              @Override
              public IRunningAggregateEvaluator createRunningAggregateEvaluator(IEvaluatorContext ctx) {
                  // Format: |TypeTag | PayloadLength | Payload |
                  // TypeTag: 1 byte
                  // PayloadLength: 1 byte
                  // Payload: 12 bytes:  |partition-id (4 bytes) | local-id (8 bytes) |
                  final byte[] uidBytes = new byte[BINARY_LENGTH];
                  // Writes the type tag.
                  uidBytes[0] = ATypeTag.SERIALIZED_BINARY_TYPE_TAG;
                  // Writes the payload size.
                  uidBytes[1] = BINARY_LENGTH - PAYLOAD_START;
                  // Writes the 4 byte partition id.
                  IntegerPointable.setInteger(uidBytes, PAYLOAD_START,
                          ctx.getTaskContext().getTaskAttemptId().getTaskId().getPartition());
  
                  return new IRunningAggregateEvaluator() {
                      @Override
                      public void init() {
                      }
  
                      @Override
                      public void step(IFrameTupleReference tuple, IPointable result) {
                          // Increments the Unique ID value.
                          for (int i = BINARY_LENGTH - 1; i >= PAYLOAD_START; i--) {
                              if (++uidBytes[i] != 0) {
                                  break;
                              }
                          }
                          result.set(uidBytes, 0, BINARY_LENGTH);
                      }
                  };
              }
          };
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.CREATE_QUERY_UID;
      }
  }
  