org.apache.spark.sql.sources.v2.reader.streaming.Offset Maven / Gradle / Ivy
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* 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.spark.sql.sources.v2.reader.streaming;
import org.apache.spark.annotation.InterfaceStability;
/**
* An abstract representation of progress through a {@link MicroBatchReader} or
* {@link ContinuousReader}.
* During execution, offsets provided by the data source implementation will be logged and used as
* restart checkpoints. Each source should provide an offset implementation which the source can use
* to reconstruct a position in the stream up to which data has been seen/processed.
*
* Note: This class currently extends {@link org.apache.spark.sql.execution.streaming.Offset} to
* maintain compatibility with DataSource V1 APIs. This extension will be removed once we
* get rid of V1 completely.
*/
@InterfaceStability.Evolving
public abstract class Offset extends org.apache.spark.sql.execution.streaming.Offset {
/**
* A JSON-serialized representation of an Offset that is
* used for saving offsets to the offset log.
* Note: We assume that equivalent/equal offsets serialize to
* identical JSON strings.
*
* @return JSON string encoding
*/
public abstract String json();
/**
* Equality based on JSON string representation. We leverage the
* JSON representation for normalization between the Offset's
* in deserialized and serialized representations.
*/
@Override
public boolean equals(Object obj) {
if (obj instanceof org.apache.spark.sql.execution.streaming.Offset) {
return this.json()
.equals(((org.apache.spark.sql.execution.streaming.Offset) obj).json());
} else {
return false;
}
}
@Override
public int hashCode() {
return this.json().hashCode();
}
@Override
public String toString() {
return this.json();
}
}