com.google.cloud.spanner.hibernate.schema.TableDependencyTracker Maven / Gradle / Ivy
/*
* Copyright 2019-2020 Google LLC
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
package com.google.cloud.spanner.hibernate.schema;
import com.google.cloud.spanner.hibernate.Interleaved;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import org.hibernate.boot.Metadata;
import org.hibernate.internal.HEMLogging;
import org.hibernate.mapping.Table;
import org.hibernate.tool.schema.Action;
import org.jboss.logging.Logger;
/**
* Tracks the order in which tables should be processed (created/dropped) by Hibernate.
*
* In Spanner, interleaved tables must be created or dropped in the correct order. For example,
* one must create a parent table before its interleaved table. And one must drop the interleaved
* table first before its parent table.
*/
public class TableDependencyTracker {
private static final Logger log = HEMLogging.logger(TableDependencyTracker.class);
// For each map entry (key, value), the key is a table which is being blocked by the
// table stored as the value.
private Map tableDependencies;
private HashSet processedTables;
/**
* Initializes the table dependency tracker.
*
* @param metadata the Hibernate metadata
* @param schemaAction the kind of schema operation being done: {CREATE or DROP}.
*/
public void initializeDependencies(Metadata metadata, Action schemaAction) {
HashMap dependencies = new HashMap<>();
for (Table childTable : metadata.collectTableMappings()) {
Class entity = SchemaUtils.getEntityClass(childTable, metadata);
Interleaved interleaved = entity != null ? entity.getAnnotation(Interleaved.class) : null;
if (interleaved != null) {
if (!SchemaUtils.validateInterleaved(entity)) {
log.warnf(
"Composite key for Interleaved table '%s' should be a superset of the parent's key.",
entity.getName());
}
// Add table dependency
if (schemaAction == Action.CREATE || schemaAction == Action.UPDATE) {
// If creating tables, the parent blocks the child.
dependencies.put(childTable, SchemaUtils.getTable(interleaved.parentEntity(), metadata));
} else {
// If dropping tables, the child blocks the parent.
dependencies.put(SchemaUtils.getTable(interleaved.parentEntity(), metadata), childTable);
}
}
}
this.tableDependencies = dependencies;
this.processedTables = new HashSet<>();
}
/**
* Returns the list of tables that one must process before processing the provided {@code table}.
*
* @param table The table that you wish to process
* @return the ordered {@link ArrayDeque} of tables to process before processing {@code table}
*/
public Collection getDependentTables(Table table) {
ArrayDeque tableStack = new ArrayDeque<>();
while (table != null && !processedTables.contains(table)) {
tableStack.push(table);
processedTables.add(table);
table = tableDependencies.get(table);
}
return tableStack;
}
}
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