simplify and cleanup

Move the list of things to be cleaned up down to Prepared.
Store the list as a list of TableView rather than Runnable, we don't
need that much flexibility.

h2/src/main/org/h2/command/Command.java

@@ -7,8 +7,6 @@ package org.h2.command;
 
 import java.sql.SQLException;
 import java.util.ArrayList;
-import java.util.List;
-
 import org.h2.api.ErrorCode;
 import org.h2.engine.Constants;
 import org.h2.engine.Database;
@@ -47,8 +45,6 @@ public abstract class Command implements CommandInterface {
 
     private boolean canReuse;
 
-    private List<Runnable> cleanupCallbacks;
-
     Command(Parser parser, String sql) {
         this.session = parser.getSession();
         this.sql = sql;
@@ -172,7 +168,6 @@ public abstract class Command implements CommandInterface {
                 trace.info("slow query: {0} ms", timeMillis);
             }
         }
-        session.commandCleanup(this);
     }
 
     /**
@@ -375,14 +370,6 @@ public abstract class Command implements CommandInterface {
         }
     }
 
-    public void setCleanupCallbacks(List<Runnable> cleanupCallbacks) {
-        this.cleanupCallbacks = cleanupCallbacks;
-    }
-
-    public List<Runnable> getCleanupCallbacks() {
-        return cleanupCallbacks;
-    }
-
     public void setCanReuse(boolean canReuse) {
         this.canReuse = canReuse;
     }

h2/src/main/org/h2/command/CommandContainer.java

@@ -12,6 +12,7 @@ import org.h2.command.dml.Query;
 import org.h2.expression.Parameter;
 import org.h2.expression.ParameterInterface;
 import org.h2.result.ResultInterface;
+import org.h2.table.TableView;
 import org.h2.value.Value;
 import org.h2.value.ValueNull;
 
@@ -116,6 +117,27 @@ public class CommandContainer extends Command {
         return result;
     }
 
+    @Override
+    public void stop() {
+        super.stop();
+        // Clean up after the command was run in the session.
+        // Must restart query (and dependency construction) to reuse.
+        if (prepared.getCteCleanups() != null) {
+            for (TableView view : prepared.getCteCleanups()) {
+                // check if view was previously deleted as their name is set to
+                // null
+                if (view.getName() != null) {
+                    session.removeLocalTempTable(view);
+                }
+            }
+        }
+    }
+
+    @Override
+    public boolean canReuse() {
+        return super.canReuse() && prepared.getCteCleanups() == null;
+    }
+
     @Override
     public boolean isReadOnly() {
         if (!readOnlyKnown) {

h2/src/main/org/h2/command/Parser.java

@@ -4914,25 +4914,6 @@ public class Parser {
         return command;
     }
 
-    private class WithCleanup implements Runnable {
-
-        TableView view;
-        Session session;
-
-        public WithCleanup(TableView view, Session session){
-            this.view = view;
-            this.session = session;
-        }
-
-        @Override
-        public void run() {
-            // check if view was previously deleted as their name is set to null
-            if(view.getName()!=null) {
-                session.removeLocalTempTable(view);
-            }
-        }
-    }
-
     private Prepared parseWith() {
         List<TableView> viewsCreated = new ArrayList<TableView>();
         readIf("RECURSIVE");
@@ -4978,18 +4959,10 @@ public class Parser {
                     WITH_STATEMENT_SUPPORTS_LIMITED_STATEMENTS);
         }
 
-                List<Runnable> cleanupCallbacks = new ArrayList<Runnable>();
-
-        // clean up temp views starting with last to first (in case of dependencies)
+        // clean up temp views starting with last to first (in case of
+        // dependencies)
         Collections.reverse(viewsCreated);
-
-        for (final TableView view : viewsCreated){
-            if(view==null){
-                continue;
-            }
-            cleanupCallbacks.add(new WithCleanup(view,session));
-        }
-        p.setCleanupCallbacks(cleanupCallbacks);
+        p.setCteCleanups(viewsCreated);
         return p;
     }
 

h2/src/main/org/h2/command/Prepared.java

@@ -7,7 +7,6 @@ package org.h2.command;
 
 import java.util.ArrayList;
 import java.util.List;
-
 import org.h2.api.DatabaseEventListener;
 import org.h2.api.ErrorCode;
 import org.h2.engine.Database;
@@ -17,6 +16,7 @@ import org.h2.expression.Parameter;
 import org.h2.message.DbException;
 import org.h2.message.Trace;
 import org.h2.result.ResultInterface;
+import org.h2.table.TableView;
 import org.h2.util.StatementBuilder;
 import org.h2.value.Value;
 
@@ -57,7 +57,11 @@ public abstract class Prepared {
     private int objectId;
     private int currentRowNumber;
     private int rowScanCount;
-    private List<Runnable> cleanupCallbacks;
+    /**
+     * Common table expressions (CTE) in queries require us to create temporary views,
+     * which need to be cleaned up once a command is done executing.
+     */
+    private List<TableView> cteCleanups;
 
     /**
      * Create a new object.
@@ -176,9 +180,6 @@ public abstract class Prepared {
      */
     public void setCommand(Command command) {
         this.command = command;
-        if(command!=null && cleanupCallbacks!=null){
-            command.setCleanupCallbacks(cleanupCallbacks);
-        }
     }
 
     /**
@@ -440,13 +441,17 @@ public abstract class Prepared {
         return false;
     }
 
-    public List<Runnable> getCleanupCallbacks() {
-        return cleanupCallbacks;
+    /**
+     * Get the temporary views created for CTE's.
+     */
+    public List<TableView> getCteCleanups() {
+        return cteCleanups;
     }
 
-    public void setCleanupCallbacks(List<Runnable> cleanupCallbacks) {
-        this.cleanupCallbacks = cleanupCallbacks;
+    /**
+     * Set the temporary views created for CTE's.
+     */
+    public void setCteCleanups(List<TableView> cteCleanups) {
+        this.cteCleanups = cteCleanups;
     }
-
-
 }

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

@@ -1707,22 +1707,6 @@ public class Session extends SessionWithState {
         tablesToAnalyze.add(table);
     }
 
-    /**
-     * Clean up after the command was run in the session
-     *
-     * @param command the command to cleanup for
-     */
-    public void commandCleanup(Command command) {
-        if (command.getCleanupCallbacks()!=null){
-            for(Runnable eachCleanup : command.getCleanupCallbacks()){
-                eachCleanup.run();
-                // clean up done - must restart query (and dependency construction) to reuse
-                command.setCanReuse(false);
-            }
-            command.getCleanupCallbacks().clear();
-        }
-    }
-
     /**
      * Represents a savepoint (a position in a transaction to where one can roll
      * back to).