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Neo4j kernel is a lightweight, embedded Java database designed to
store data structured as graphs rather than tables. For more
information, see http://neo4j.org.
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see predicate =
typeId == TokenRead.ANY_RELATIONSHIP_TYPE ? alwaysTrue() : CursorPredicates.hasType(typeId);
var filteredCursor = new FilteringRelationshipScanCursorWrapper(rels, predicate);
count = countRelationshipsWithEndLabels(filteredCursor, sourceNode, targetNode, startLabelId, endLabelId);
}
return count;
}
private IndexDescriptor findUsableRelationshipTypeTokenIndex(Read read) throws IndexNotFoundKernelException {
var descriptor = SchemaDescriptors.forAnyEntityTokens(EntityType.RELATIONSHIP);
var index = read.index(descriptor, IndexType.LOOKUP);
if (index != IndexDescriptor.NO_INDEX && read.indexGetState(index) == InternalIndexState.ONLINE) {
return index;
}
return IndexDescriptor.NO_INDEX;
}
private static long countRelationshipsWithEndLabels(
RelationshipIndexCursor relationship,
DefaultNodeCursor sourceNode,
DefaultNodeCursor targetNode,
int startLabelId,
int endLabelId) {
long internalCount = 0;
while (relationship.next()) {
if (relationship.readFromStore()
&& matchesLabels(relationship, sourceNode, targetNode, startLabelId, endLabelId)) {
internalCount++;
}
}
return internalCount;
}
private static long countRelationshipsWithEndLabels(
RelationshipScanCursor relationship,
DefaultNodeCursor sourceNode,
DefaultNodeCursor targetNode,
int startLabelId,
int endLabelId) {
long internalCount = 0;
while (relationship.next()) {
if (matchesLabels(relationship, sourceNode, targetNode, startLabelId, endLabelId)) {
internalCount++;
}
}
return internalCount;
}
private static boolean matchesLabels(
RelationshipDataAccessor relationship,
DefaultNodeCursor sourceNode,
DefaultNodeCursor targetNode,
int startLabelId,
int endLabelId) {
relationship.source(sourceNode);
relationship.target(targetNode);
return sourceNode.next()
&& (startLabelId == TokenRead.ANY_LABEL || sourceNode.hasLabel(startLabelId))
&& targetNode.next()
&& (endLabelId == TokenRead.ANY_LABEL || targetNode.hasLabel(endLabelId));
}
private long countsForRelationshipInTxState(
int startLabelId,
int typeId,
int endLabelId,
TxStateHolder txStateHolder,
StorageReader storageReader,
StoreCursors storageCursors,
CursorContext cursorContext) {
long count = 0;
if (txStateHolder.hasTxStateWithChanges()) {
CountsDelta counts = new CountsDelta();
try {
TransactionState txState = txStateHolder.txState();
try (var countingVisitor = new TransactionCountingStateVisitor(
EMPTY, storageReader, txState, counts, cursorContext, storageCursors)) {
txState.accept(countingVisitor);
}
if (counts.hasChanges()) {
count += counts.relationshipCount(startLabelId, typeId, endLabelId);
}
} catch (KernelException e) {
throw new IllegalArgumentException("Unexpected error: " + e.getMessage());
}
}
return count;
}
private static class MostCommonLabelGivenRelTypeVisitor implements CountsVisitor {
private final int relationshipType;
private long labelCount = -1;
public ArrayList highest = new ArrayList<>();
public MostCommonLabelGivenRelTypeVisitor(int relationshipType) {
this.relationshipType = relationshipType;
}
@Override
public void visitNodeCount(int labelId, long count) {}
@Override
public void visitRelationshipCount(int startLabelId, int typeId, int endLabelId, long count) {
if (typeId == relationshipType
&& (startLabelId > TokenConstants.ANY_LABEL ^ endLabelId > TokenConstants.ANY_LABEL)) {
int labelId = startLabelId > TokenConstants.ANY_LABEL ? startLabelId : endLabelId;
if (count > labelCount) {
labelCount = count;
highest = new ArrayList<>(List.of(labelId));
} else if (count == labelCount) {
highest.add(labelId);
}
}
}
}
public List mostCommonLabelGivenRelationshipType(
int type, StorageReader storageReader, CursorContext cursorContext) {
var visitor = new MostCommonLabelGivenRelTypeVisitor(type);
storageReader.visitAllCounts(visitor, cursorContext);
return visitor.highest;
}
}