/*
* Copyright 1999-2012 Alibaba Group.
*
* Licensed 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 com.alibaba.cobar.server.session;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.log4j.Logger;
import com.alibaba.cobar.config.ErrorCode;
import com.alibaba.cobar.exception.UnknownPacketException;
import com.alibaba.cobar.mysql.bio.Channel;
import com.alibaba.cobar.mysql.bio.MySQLChannel;
import com.alibaba.cobar.mysql.bio.executor.DefaultCommitExecutor;
import com.alibaba.cobar.mysql.bio.executor.MultiNodeExecutor;
import com.alibaba.cobar.mysql.bio.executor.NodeExecutor;
import com.alibaba.cobar.mysql.bio.executor.RollbackExecutor;
import com.alibaba.cobar.mysql.bio.executor.SingleNodeExecutor;
import com.alibaba.cobar.net.FrontendConnection;
import com.alibaba.cobar.net.mysql.BinaryPacket;
import com.alibaba.cobar.net.mysql.ErrorPacket;
import com.alibaba.cobar.net.mysql.OkPacket;
import com.alibaba.cobar.route.RouteResultset;
import com.alibaba.cobar.route.RouteResultsetNode;
import com.alibaba.cobar.server.ServerConnection;
import com.alibaba.cobar.server.parser.ServerParse;
/**
* 由前后端参与的一次执行会话过程
*
* @author xianmao.hexm
*/
public class BlockingSession implements Session {
private static final Logger LOGGER = Logger.getLogger(BlockingSession.class);
private final ServerConnection source;
private final ConcurrentHashMap<RouteResultsetNode, Channel> target;
private final SingleNodeExecutor singleNodeExecutor;
private final MultiNodeExecutor multiNodeExecutor;
private final DefaultCommitExecutor commitExecutor;
private final RollbackExecutor rollbackExecutor;
public BlockingSession(ServerConnection source) {
this.source = source;
this.target = new ConcurrentHashMap<RouteResultsetNode, Channel>();
this.singleNodeExecutor = new SingleNodeExecutor();
this.multiNodeExecutor = new MultiNodeExecutor();
this.commitExecutor = new DefaultCommitExecutor();
this.rollbackExecutor = new RollbackExecutor();
}
@Override
public ServerConnection getSource() {
return source;
}
@Override
public int getTargetCount() {
return target.size();
}
public ConcurrentHashMap<RouteResultsetNode, Channel> getTarget() {
return target;
}
@Override
public void execute(RouteResultset rrs, int type) {
if (LOGGER.isDebugEnabled()) {
StringBuilder s = new StringBuilder();
LOGGER.debug(s.append(source).append(rrs).toString());
}
// 检查路由结果是否为空
RouteResultsetNode[] nodes = rrs.getNodes();
if (nodes == null || nodes.length == 0) {
source.writeErrMessage(ErrorCode.ER_NO_DB_ERROR, "No dataNode selected");
return;
}
// 选择执行方式
if (nodes.length == 1) {
singleNodeExecutor.execute(nodes[0], this, rrs.getFlag());
} else {
// 多数据节点，非事务模式下，执行的是可修改数据的SQL，则后端为事务模式。
boolean autocommit = source.isAutocommit();
if (autocommit && isModifySQL(type)) {
autocommit = false;
}
multiNodeExecutor.execute(nodes, autocommit, this, rrs.getFlag());
}
}
@Override
public void commit() {
final int initCount = target.size();
if (initCount <= 0) {
ByteBuffer buffer = source.allocate();
buffer = source.writeToBuffer(OkPacket.OK, buffer);
source.write(buffer);
return;
}
commitExecutor.commit(null, this, initCount);
}
@Override
public void rollback() {
rollbackExecutor.rollback(this);
}
@Override
public void cancel(FrontendConnection sponsor) {
// TODO terminate session
source.writeErrMessage(ErrorCode.ER_QUERY_INTERRUPTED, "Query execution was interrupted");
if (sponsor != null) {
OkPacket packet = new OkPacket();
packet.packetId = 1;
packet.affectedRows = 0;
packet.serverStatus = 2;
packet.write(sponsor);
}
}
@Override
public void terminate() {
// 终止所有正在执行的任务
kill();
// 等待所有任务结束，包括还未执行的，执行中的，执行完的。
try {
singleNodeExecutor.terminate();
multiNodeExecutor.terminate();
commitExecutor.terminate();
rollbackExecutor.terminate();
} catch (InterruptedException e) {
for (RouteResultsetNode rrn : target.keySet()) {
Channel c = target.remove(rrn);
if (c != null) {
c.close();
}
}
LOGGER.warn("termination interrupted: " + source, e);
}
// 清理绑定的资源
clear(false);
}
/**
* 释放session关联的资源
*/
public void release() {
for (RouteResultsetNode rrn : target.keySet()) {
Channel c = target.remove(rrn);
if (c != null) {
if (c.isRunning()) {
c.close();
try {
throw new IllegalStateException("running connection is found: " + c);
} catch (Exception e) {
LOGGER.error(e.getMessage(), e);
}
} else if (!c.isClosed()) {
if (source.isClosed()) {
c.close();
} else {
c.release();
}
}
}
}
}
public void clear() {
clear(true);
}
/**
* MUST be called at the end of {@link NodeExecutor}
*
* @param pessimisticRelease true if this method might be invoked
* concurrently with {@link #kill()}
*/
private void clear(boolean pessimisticRelease) {
for (RouteResultsetNode rrn : target.keySet()) {
Channel c = target.remove(rrn);
// 通道不存在或者已被关闭
if (c == null || c.isClosed()) {
continue;
}
// 如果通道正在运行中，则关闭当前通道。
if (c.isRunning() || (pessimisticRelease && source.isClosed())) {
c.close();
continue;
}
// 非事务中的通道，直接释放资源。
if (c.isAutocommit()) {
c.release();
continue;
}
// 事务中的通道，需要先回滚后再释放资源。
MySQLChannel mc = (MySQLChannel) c;
try {
BinaryPacket bin = mc.rollback();
switch (bin.data[0]) {
case OkPacket.FIELD_COUNT:
mc.release();
break;
case ErrorPacket.FIELD_COUNT:
mc.close();
break;
default:
throw new UnknownPacketException(bin.toString());
}
} catch (IOException e) {
StringBuilder s = new StringBuilder();
LOGGER.warn(s.append(mc).append("rollback").toString(), e);
mc.close();
} catch (RuntimeException e) {
StringBuilder s = new StringBuilder();
LOGGER.warn(s.append(mc).append("rollback").toString(), e);
mc.close();
}
}
}
/**
* 终止执行中的通道
*/
private void kill() {
for (RouteResultsetNode rrn : target.keySet()) {
Channel c = target.get(rrn);
if (c != null && c.isRunning()) {
c.kill();
}
}
}
/**
* 检查是否会引起数据变更的语句
*/
private static boolean isModifySQL(int type) {
switch (type) {
case ServerParse.INSERT:
case ServerParse.DELETE:
case ServerParse.UPDATE:
case ServerParse.REPLACE:
return true;
default:
return false;
}
}
}