/**
* Copyright (C) 2009-2013 FoundationDB, LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.foundationdb.qp.operator;
import com.foundationdb.qp.row.Row;
import com.foundationdb.server.explain.Attributes;
import com.foundationdb.server.explain.CompoundExplainer;
import com.foundationdb.server.explain.ExplainContext;
import com.foundationdb.server.explain.Label;
import com.foundationdb.server.explain.PrimitiveExplainer;
import com.foundationdb.server.explain.std.DUIOperatorExplainer;
import com.foundationdb.util.ArgumentValidation;
import com.foundationdb.util.tap.InOutTap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
<h1>Overview</h1>
Provides row update functionality.
<h1>Arguments</h1>
<ul>
<li><b>PhysicalOperator inputOperator:</b> Provides rows to be updated
<li><b>UpdateFunction updateFunction:</b> specifies which rows are to be updated, and how
</ul>
<h1>Behavior</h1>
For each row from the input operator's cursor, it invokes <i>updateFunction.evaluate</i> to
get the new version of the row. It then performs the update in an
unspecified way (in practice, this is currently done via
<i>StoreAdapater.updateRow</i>, which is implemented by
<i>PersistitAdapater.updateRow</i>, which invokes
<i>PersistitStore.updateRow</i>).
The updated row is then returned to the caller as with other operators.
<h1>Output</h1>
The row as modified by the updateFunction().
<h1>Assumptions</h1>
Selected rows must have a <i>RowType</i> such
that <i>rowType.hasTable() == true</i>.
<h1>Performance</h1>
Updating rows may be slow, especially since indexes are also
updated. There are several random-access reads and writes involved,
which depend on the indexes defined for that row type.
There are potentially ways to optimize this, if we can
push <i>WHERE</i> clauses down; this would mean we could update some
indexes as a batch operation, rather than one at a time. This would
require changes to the API, and is not currently a priority.
<h1>Memory Requirements</h1>
Each <i>UpdateFunction.evaluate</i> method may generate a
new <i>Row</i>.
*/
public class Update_Returning extends Operator {
@Override
public CompoundExplainer getExplainer(ExplainContext context) {
Attributes atts = new Attributes();
if (context.hasExtraInfo(this))
atts.putAll(context.getExtraInfo(this).get());
atts.put(Label.EXTRA_TAG, PrimitiveExplainer.getInstance(updateFunction.toString()));
return new DUIOperatorExplainer(getName(), atts, inputOperator, context);
}
@Override
protected Cursor cursor(QueryContext context, QueryBindingsCursor bindingsCursor) {
return new Execution(context, inputOperator.cursor(context, bindingsCursor));
}
public Update_Returning (Operator inputOperator, UpdateFunction updateFunction) {
ArgumentValidation.notNull("update lambda", updateFunction);
this.inputOperator = inputOperator;
this.updateFunction = updateFunction;
}
@Override
public String toString() {
return String.format("%s(%s -> %s)", getName(), inputOperator, updateFunction);
}
private final Operator inputOperator;
private final UpdateFunction updateFunction;
// Class state
private static final InOutTap TAP_OPEN = OPERATOR_TAP.createSubsidiaryTap("operator: UpdateReturning open");
private static final InOutTap TAP_NEXT = OPERATOR_TAP.createSubsidiaryTap("operator: UpdateReturning next");
private static final Logger LOG = LoggerFactory.getLogger(Update_Returning.class);
// Inner classes
private class Execution extends ChainedCursor
{
// Cursor interface
@Override
public void open()
{
TAP_OPEN.in();
try {
super.open();
} finally {
TAP_OPEN.out();
}
}
@Override
public Row next()
{
if (TAP_NEXT_ENABLED) {
TAP_NEXT.in();
}
try {
if (CURSOR_LIFECYCLE_ENABLED) {
CursorLifecycle.checkIdleOrActive(this);
}
checkQueryCancelation();
Row inputRow;
Row newRow = null;
if ((inputRow = input.next()) != null) {
newRow = updateFunction.evaluate(inputRow, context, bindings);
adapter().updateRow(inputRow, newRow);
}
if (LOG_EXECUTION) {
LOG.debug("Update_Returning: updating {} to {}", inputRow, newRow);
}
return newRow;
} finally {
if (TAP_NEXT_ENABLED) {
TAP_NEXT.out();
}
}
}
// Execution interface
Execution(QueryContext context, Cursor input)
{
super(context, input);
}
// Object state
}
}