CAY-2170 MergeToken sorting is highly unstable

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/DataMapMerger.java

@@ -22,7 +22,6 @@
 import org.apache.cayenne.dbsync.merge.factory.MergerTokenFactory;
 import org.apache.cayenne.dbsync.merge.token.EmptyValueForNullProvider;
 import org.apache.cayenne.dbsync.merge.token.MergerToken;
-import org.apache.cayenne.dbsync.merge.token.TokenComparator;
 import org.apache.cayenne.dbsync.merge.token.ValueForNullProvider;
 import org.apache.cayenne.dbsync.reverse.filters.FiltersConfig;
 import org.apache.cayenne.dbsync.reverse.filters.PatternFilter;
@@ -76,7 +75,7 @@ private List<MergerToken> createTokens() {
         for(AbstractMerger<?, ?> merger : mergerList) {
             tokens.addAll(merger.createMergeTokens());
         }
-        Collections.sort(tokens, new TokenComparator());
+        Collections.sort(tokens);
         return tokens;
     }
 

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/AbstractMergerToken.java

@@ -0,0 +1,59 @@
+/*****************************************************************
+ *   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.cayenne.dbsync.merge.token;
+
+/**
+ * @since 4.0
+ */
+public abstract class AbstractMergerToken implements MergerToken {
+
+    private final String tokenName;
+
+    private final int sortingWeight;
+
+    protected AbstractMergerToken(String tokenName, int sortingWeight) {
+        this.tokenName = tokenName;
+        this.sortingWeight = sortingWeight;
+    }
+
+    @Override
+    public final String getTokenName() {
+        return tokenName;
+    }
+
+    @Override
+    public int getSortingWeight() {
+        return sortingWeight;
+    }
+
+    @Override
+    public int compareTo(MergerToken o) {
+        return getSortingWeight() - o.getSortingWeight();
+    }
+
+    @Override
+    public String toString() {
+        return getTokenName() + ' ' + getTokenValue() + ' ' + getDirection();
+    }
+
+    public boolean isEmpty() {
+        return false;
+    }
+}

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/DummyReverseToken.java

@@ -65,4 +65,14 @@ public String getTokenName() {
     public String getTokenValue() {
         return reverse.getTokenValue();
     }
+
+    @Override
+    public int getSortingWeight() {
+        return 0;
+    }
+
+    @Override
+    public int compareTo(MergerToken o) {
+        return -o.getSortingWeight();
+    }
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/MergerToken.java

@@ -26,12 +26,14 @@
 /**
  * Represents a minimal atomic synchronization operation between database and Cayenne model.
  */
-public interface MergerToken {
+public interface MergerToken extends Comparable<MergerToken> {
 
     String getTokenName();
 
     String getTokenValue();
 
+    int getSortingWeight();
+
     /**
      * The direction of this token. One of {@link MergeDirection#TO_DB} or
      * {@link MergeDirection#TO_MODEL}

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/AbstractToDbToken.java

@@ -22,6 +22,7 @@
 import org.apache.cayenne.dba.DbAdapter;
 import org.apache.cayenne.dbsync.merge.context.MergeDirection;
 import org.apache.cayenne.dbsync.merge.context.MergerContext;
+import org.apache.cayenne.dbsync.merge.token.AbstractMergerToken;
 import org.apache.cayenne.dbsync.merge.token.MergerToken;
 import org.apache.cayenne.log.JdbcEventLogger;
 import org.apache.cayenne.map.DbAttribute;
@@ -37,22 +38,10 @@
  * Common abstract superclass for all {@link MergerToken}s going from the model
  * to the database.
  */
-public abstract class AbstractToDbToken implements MergerToken, Comparable<MergerToken> {
+public abstract class AbstractToDbToken extends AbstractMergerToken {
 
-	private final String tokenName;
-
-	protected AbstractToDbToken(String tokenName) {
-		this.tokenName = tokenName;
-	}
-
-	@Override
-	public final String getTokenName() {
-		return tokenName;
-	}
-
-	@Override
-	public final MergeDirection getDirection() {
-		return MergeDirection.TO_DB;
+	protected AbstractToDbToken(String tokenName, int sortingWeight) {
+		super(tokenName, sortingWeight);
 	}
 
 	@Override
@@ -62,7 +51,7 @@ public void execute(MergerContext mergerContext) {
 		}
 	}
 
-	protected void executeSql(MergerContext mergerContext, String sql) {
+	void executeSql(MergerContext mergerContext, String sql) {
 		JdbcEventLogger logger = mergerContext.getDataNode().getJdbcEventLogger();
 		logger.log(sql);
 
@@ -77,23 +66,19 @@ protected void executeSql(MergerContext mergerContext, String sql) {
 		}
 	}
 
-	@Override
-	public String toString() {
-		return getTokenName() + ' ' + getTokenValue() + ' ' + getDirection();
-	}
+	public abstract List<String> createSql(DbAdapter adapter);
 
-	public boolean isEmpty() {
-		return false;
+	@Override
+	public final MergeDirection getDirection() {
+		return MergeDirection.TO_DB;
 	}
 
-	public abstract List<String> createSql(DbAdapter adapter);
-
 	abstract static class Entity extends AbstractToDbToken {
 
-		private DbEntity entity;
+		private final DbEntity entity;
 
-		public Entity(String tokenName, DbEntity entity) {
-			super(tokenName);
+		protected Entity(String tokenName, int sortingWeight, DbEntity entity) {
+			super(tokenName, sortingWeight);
 			this.entity = entity;
 		}
 
@@ -104,20 +89,14 @@ public DbEntity getEntity() {
 		public String getTokenValue() {
 			return getEntity().getName();
 		}
-
-		public int compareTo(MergerToken o) {
-			// default order as tokens are created
-			return 0;
-		}
-
 	}
 
 	abstract static class EntityAndColumn extends Entity {
 
-		private DbAttribute column;
+		private final DbAttribute column;
 
-		public EntityAndColumn(String tokenName, DbEntity entity, DbAttribute column) {
-			super(tokenName, entity);
+		protected EntityAndColumn(String tokenName, int sortingWeight, DbEntity entity, DbAttribute column) {
+			super(tokenName, sortingWeight, entity);
 			this.column = column;
 		}
 
@@ -129,6 +108,5 @@ public DbAttribute getColumn() {
 		public String getTokenValue() {
 			return getEntity().getName() + "." + getColumn().getName();
 		}
-
 	}
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/AddColumnToDb.java

@@ -33,7 +33,7 @@
 public class AddColumnToDb extends AbstractToDbToken.EntityAndColumn {
 
     public AddColumnToDb(DbEntity entity, DbAttribute column) {
-        super("Add Column", entity, column);
+        super("Add Column", 50, entity, column);
     }
 
     /**
@@ -64,13 +64,4 @@ public List<String> createSql(DbAdapter adapter) {
     public MergerToken createReverse(MergerTokenFactory factory) {
         return factory.createDropColumnToModel(getEntity(), getColumn());
     }
-
-    @Override
-    public int compareTo(MergerToken o) {
-        // add all AddRelationshipToDb to the end.
-        if (o instanceof AddRelationshipToDb) {
-            return -1;
-        }
-        return super.compareTo(o);
-    }
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/AddRelationshipToDb.java

@@ -34,7 +34,7 @@ public class AddRelationshipToDb extends AbstractToDbToken.Entity {
     private DbRelationship relationship;
 
     public AddRelationshipToDb(DbEntity entity, DbRelationship relationship) {
-        super("Add foreign key", entity);
+        super("Add foreign key", 110, entity);
         this.relationship = relationship;
     }
 
@@ -72,13 +72,4 @@ public boolean isEmpty() {
         return relationship.isSourceIndependentFromTargetChange();
     }
 
-    @Override
-    public int compareTo(MergerToken o) {
-        // add all AddRelationshipToDb to the end.
-        if (o instanceof AddRelationshipToDb) {
-            return super.compareTo(o);
-        }
-        return 1;
-    }
-
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/CreateTableToDb.java

@@ -35,7 +35,7 @@
 public class CreateTableToDb extends AbstractToDbToken.Entity {
 
     public CreateTableToDb(DbEntity entity) {
-        super("Create Table", entity);
+        super("Create Table", 40, entity);
     }
 
     @Override

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/DropColumnToDb.java

@@ -32,7 +32,7 @@
 public class DropColumnToDb extends AbstractToDbToken.EntityAndColumn {
 
     public DropColumnToDb(DbEntity entity, DbAttribute column) {
-        super("Drop Column", entity, column);
+        super("Drop Column", 20, entity, column);
     }
 
     @Override
@@ -50,14 +50,4 @@ public List<String> createSql(DbAdapter adapter) {
     public MergerToken createReverse(MergerTokenFactory factory) {
         return factory.createAddColumnToModel(getEntity(), getColumn());
     }
-
-    @Override
-    public int compareTo(MergerToken o) {
-        // add all AddRelationshipToDb to the end.
-        if (o instanceof DropRelationshipToDb) {
-            return 1;
-        }
-        return super.compareTo(o);
-    }
-
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/DropRelationshipToDb.java

@@ -35,7 +35,7 @@ public class DropRelationshipToDb extends AbstractToDbToken.Entity {
     private DbRelationship relationship;
 
     public DropRelationshipToDb(DbEntity entity, DbRelationship relationship) {
-        super("Drop foreign key", entity);
+        super("Drop foreign key", 10, entity);
         this.relationship = relationship;
     }
 
@@ -73,13 +73,4 @@ public String getTokenValue() {
         }
         return relationship.getSourceEntity().getName() + "->" + relationship.getTargetEntityName();
     }
-
-    @Override
-    public int compareTo(MergerToken o) {
-        // add all AddRelationshipToDb to the end.
-        if (o instanceof DropRelationshipToDb) {
-            return super.compareTo(o);
-        }
-        return -1;
-    }
 }

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/DropTableToDb.java

@@ -30,7 +30,7 @@
 public class DropTableToDb extends AbstractToDbToken.Entity {
 
     public DropTableToDb(DbEntity entity) {
-        super("Drop Table", entity);
+        super("Drop Table", 30, entity);
     }
 
     @Override

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/merge/token/db/SetAllowNullToDb.java

@@ -36,7 +36,7 @@
 public class SetAllowNullToDb extends AbstractToDbToken.EntityAndColumn {
 
     public SetAllowNullToDb(DbEntity entity, DbAttribute column) {
-        super("Set Allow Null", entity, column);
+        super("Set Allow Null", 70, entity, column);
     }
 
     @Override