io.delta.standalone.actions.Protocol Maven / Gradle / Ivy
/*
* Copyright (2020-present) The Delta Lake Project Authors.
*
* 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 io.delta.standalone.actions;
import java.util.Objects;
/**
* Used to block older clients from reading or writing the log when backwards
* incompatible changes are made to the protocol. Readers and writers are
* responsible for checking that they meet the minimum versions before performing
* any other operations.
*
* Since this action allows us to explicitly block older clients in the case of a
* breaking change to the protocol, clients should be tolerant of messages and
* fields that they do not understand.
*
* @see Delta Transaction Log Protocol: Protocol Evolution
*/
public final class Protocol implements Action {
private final int minReaderVersion;
private final int minWriterVersion;
public Protocol(int minReaderVersion, int minWriterVersion) {
this.minReaderVersion = minReaderVersion;
this.minWriterVersion = minWriterVersion;
}
/**
* @return the minimum version of the Delta read protocol that a client must implement in order
* to correctly read this table
*/
public int getMinReaderVersion() {
return minReaderVersion;
}
/**
* @return the minimum version of the Delta write protocol that a client must implement in order
* to correctly write this table
*/
public int getMinWriterVersion() {
return minWriterVersion;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Protocol protocol = (Protocol) o;
return minReaderVersion == protocol.minReaderVersion &&
minWriterVersion == protocol.minWriterVersion;
}
@Override
public int hashCode() {
return Objects.hash(minReaderVersion, minWriterVersion);
}
}