Reduce allocated garbage in Database.getAllSchemaObjects()

h2/src/main/org/h2/command/ddl/DropSchema.java

@@ -51,7 +51,7 @@ public class DropSchema extends DefineCommand {
             }
             if (dropAction == ConstraintActionType.RESTRICT && !schema.isEmpty()) {
                 StatementBuilder buff = new StatementBuilder();
-                for (SchemaObject object : schema.getAll()) {
+                for (SchemaObject object : schema.getAll(null)) {
                     buff.appendExceptFirst(", ");
                     buff.append(object.getName());
                 }

h2/src/main/org/h2/engine/Database.java

@@ -1564,7 +1564,7 @@ public class Database implements DataHandler {
         initMetaTables();
         ArrayList<SchemaObject> list = new ArrayList<>();
         for (Schema schema : schemas.values()) {
-            list.addAll(schema.getAll());
+            schema.getAll(list);
         }
         return list;
     }
@@ -1581,7 +1581,7 @@ public class Database implements DataHandler {
         }
         ArrayList<SchemaObject> list = new ArrayList<>();
         for (Schema schema : schemas.values()) {
-            list.addAll(schema.getAll(type));
+            schema.getAll(type, list);
         }
         return list;
     }

h2/src/main/org/h2/schema/Schema.java

@@ -6,6 +6,7 @@
 package org.h2.schema;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -591,30 +592,46 @@ public class Schema extends DbObjectBase {
     /**
      * Get all objects.
      *
-     * @return a (possible empty) list of all objects
+     * @param addTo
+     *                  list to add objects to, or {@code null} to allocate a new
+     *                  list
+     * @return the specified list with added objects, or a new (possibly empty) list
+     *         with all objects
      */
-    public ArrayList<SchemaObject> getAll() {
-        ArrayList<SchemaObject> all = Utils.newSmallArrayList();
-        all.addAll(tablesAndViews.values());
-        all.addAll(synonyms.values());
-        all.addAll(sequences.values());
-        all.addAll(indexes.values());
-        all.addAll(triggers.values());
-        all.addAll(constraints.values());
-        all.addAll(constants.values());
-        all.addAll(functions.values());
-        return all;
+    public ArrayList<SchemaObject> getAll(ArrayList<SchemaObject> addTo) {
+        if (addTo == null) {
+            addTo = Utils.newSmallArrayList();
+        }
+        addTo.addAll(tablesAndViews.values());
+        addTo.addAll(synonyms.values());
+        addTo.addAll(sequences.values());
+        addTo.addAll(indexes.values());
+        addTo.addAll(triggers.values());
+        addTo.addAll(constraints.values());
+        addTo.addAll(constants.values());
+        addTo.addAll(functions.values());
+        return addTo;
     }
 
     /**
      * Get all objects of the given type.
      *
-     * @param type the object type
-     * @return a (possible empty) list of all objects
-     */
-    public ArrayList<SchemaObject> getAll(int type) {
-        Map<String, SchemaObject> map = getMap(type);
-        return new ArrayList<>(map.values());
+     * @param type
+     *                  the object type
+     * @param addTo
+     *                  list to add objects to, or {@code null} to allocate a new
+     *                  list
+     * @return the specified list with added objects, or a new (possibly empty) list
+     *         with objects of the given type
+     */
+    public ArrayList<SchemaObject> getAll(int type, ArrayList<SchemaObject> addTo) {
+        Collection<SchemaObject> values = getMap(type).values();
+        if (addTo != null) {
+            addTo.addAll(values);
+        } else {
+            addTo = new ArrayList<>(values);
+        }
+        return addTo;
     }
 
     /**