com.netflix.hollow.tools.history.HollowHistoricalState Maven / Gradle / Ivy
/*
* Copyright 2016-2019 Netflix, 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 com.netflix.hollow.tools.history;
import com.netflix.hollow.core.read.dataaccess.HollowDataAccess;
import com.netflix.hollow.tools.history.keyindex.HollowHistoricalStateKeyOrdinalMapping;
import com.netflix.hollow.tools.history.keyindex.HollowHistoryKeyIndex;
import java.util.Map;
/**
* A data state from the past, represented as just the changes which happened on the subsequent transition.
* Contains links to all subsequent deltas which happened in the interim between this state
* and the now current state.
*/
public class HollowHistoricalState {
private final long version;
private final HollowHistoricalStateKeyOrdinalMapping keyOrdinalMapping;
private final HollowHistoricalStateDataAccess dataAccess;
private final Map headerEntries;
private HollowHistoricalState nextState;
public HollowHistoricalState(long version, HollowHistoricalStateKeyOrdinalMapping keyOrdinalMapping, HollowHistoricalStateDataAccess dataAccess, Map headerEntries) {
this.version = version;
this.dataAccess = dataAccess;
this.keyOrdinalMapping = keyOrdinalMapping;
this.headerEntries = headerEntries;
}
/**
* @return The version of this state
*/
public long getVersion() {
return version;
}
/**
* @return A {@link HollowDataAccess} which can be used to retrieve the data from this state. For example,
* you can use this with a generated Hollow API or the generic hollow object API.
*/
public HollowHistoricalStateDataAccess getDataAccess() {
return dataAccess;
}
/**
* To find a specific historical record which changed
* in this state:
*
* - Use the {@link HollowHistoryKeyIndex} from the {@link HollowHistory} to look up a key ordinal by an indexed primary key.
* - Use the retrieved key ordinal with the {@link HollowHistoricalStateKeyOrdinalMapping} in this state to find the record's ordinal in this state.
*
*
* If a change isn't found for the key ordinal in this state, you can try walking the chain of states up to
* the present using successive calls to {@link #getNextState()}
*
* @return the historical state key ordinal mapping
*/
public HollowHistoricalStateKeyOrdinalMapping getKeyOrdinalMapping() {
return keyOrdinalMapping;
}
/**
* @return The subsequent historical state which occurred after this one
*/
public HollowHistoricalState getNextState() {
return nextState;
}
/**
* @return The blob header entries from this state.
*/
public Map getHeaderEntries() {
return headerEntries;
}
void setNextState(HollowHistoricalState nextState) {
this.nextState = nextState;
}
public long getApproximateHeapFootprintInBytes() {
long total = 0L;
for (HollowHistoricalTypeDataAccess typeDataAccess : dataAccess.getTypeDataAccessMap().values()) {
total += typeDataAccess.removedRecords.getApproximateHeapFootprintInBytes();
}
return total;
}
}