package com.taobao.tddl.sequence.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import javax.sql.DataSource;
import com.taobao.tddl.common.utils.logger.Logger;
import com.taobao.tddl.common.utils.logger.LoggerFactory;
import com.taobao.tddl.sequence.SequenceDao;
import com.taobao.tddl.sequence.SequenceRange;
import com.taobao.tddl.sequence.exception.SequenceException;
/**
* 序列DAO默认实现，JDBC方式
*
* @author nianbing
*/
public class DefaultSequenceDao implements SequenceDao {
private static final Logger logger = LoggerFactory.getLogger(DefaultSequenceDao.class);
private static final int MIN_STEP = 1;
private static final int MAX_STEP = 100000;
private static final int DEFAULT_STEP = 1000;
private static final int DEFAULT_RETRY_TIMES = 150;
private static final String DEFAULT_TABLE_NAME = "sequence";
private static final String DEFAULT_NAME_COLUMN_NAME = "name";
private static final String DEFAULT_VALUE_COLUMN_NAME = "value";
private static final String DEFAULT_GMT_MODIFIED_COLUMN_NAME = "gmt_modified";
private static final long DELTA = 100000000L;
private DataSource dataSource;
/**
* 重试次数
*/
private int retryTimes = DEFAULT_RETRY_TIMES;
/**
* 步长
*/
private int step = DEFAULT_STEP;
/**
* 序列所在的表名
*/
private String tableName = DEFAULT_TABLE_NAME;
/**
* 存储序列名称的列名
*/
private String nameColumnName = DEFAULT_NAME_COLUMN_NAME;
/**
* 存储序列值的列名
*/
private String valueColumnName = DEFAULT_VALUE_COLUMN_NAME;
/**
* 存储序列最后更新时间的列名
*/
private String gmtModifiedColumnName = DEFAULT_GMT_MODIFIED_COLUMN_NAME;
private volatile String selectSql;
private volatile String updateSql;
public SequenceRange nextRange(String name) throws SequenceException {
if (name == null) {
throw new IllegalArgumentException("序列名称不能为空");
}
long oldValue;
long newValue;
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
for (int i = 0; i < retryTimes + 1; ++i) {
try {
conn = dataSource.getConnection();
stmt = conn.prepareStatement(getSelectSql());
stmt.setString(1, name);
rs = stmt.executeQuery();
rs.next();
oldValue = rs.getLong(1);
if (oldValue < 0) {
StringBuilder message = new StringBuilder();
message.append("Sequence value cannot be less than zero, value = ").append(oldValue);
message.append(", please check table ").append(getTableName());
throw new SequenceException(message.toString());
}
if (oldValue > Long.MAX_VALUE - DELTA) {
StringBuilder message = new StringBuilder();
message.append("Sequence value overflow, value = ").append(oldValue);
message.append(", please check table ").append(getTableName());
throw new SequenceException(message.toString());
}
newValue = oldValue + getStep();
} catch (SQLException e) {
throw new SequenceException(e);
} finally {
closeResultSet(rs);
rs = null;
closeStatement(stmt);
stmt = null;
closeConnection(conn);
conn = null;
}
try {
conn = dataSource.getConnection();
stmt = conn.prepareStatement(getUpdateSql());
stmt.setLong(1, newValue);
stmt.setTimestamp(2, new Timestamp(System.currentTimeMillis()));
stmt.setString(3, name);
stmt.setLong(4, oldValue);
int affectedRows = stmt.executeUpdate();
if (affectedRows == 0) {
// retry
continue;
}
return new SequenceRange(oldValue + 1, newValue);
} catch (SQLException e) {
throw new SequenceException(e);
} finally {
closeStatement(stmt);
stmt = null;
closeConnection(conn);
conn = null;
}
}
throw new SequenceException("Retried too many times, retryTimes = " + retryTimes);
}
private String getSelectSql() {
if (selectSql == null) {
synchronized (this) {
if (selectSql == null) {
StringBuilder buffer = new StringBuilder();
buffer.append("select ").append(getValueColumnName());
buffer.append(" from ").append(getTableName());
buffer.append(" where ").append(getNameColumnName()).append(" = ?");
selectSql = buffer.toString();
}
}
}
return selectSql;
}
private String getUpdateSql() {
if (updateSql == null) {
synchronized (this) {
if (updateSql == null) {
StringBuilder buffer = new StringBuilder();
buffer.append("update ").append(getTableName());
buffer.append(" set ").append(getValueColumnName()).append(" = ?, ");
buffer.append(getGmtModifiedColumnName()).append(" = ? where ");
buffer.append(getNameColumnName()).append(" = ? and ");
buffer.append(getValueColumnName()).append(" = ?");
updateSql = buffer.toString();
}
}
}
return updateSql;
}
private static void closeResultSet(ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
logger.debug("Could not close JDBC ResultSet", e);
} catch (Throwable e) {
logger.debug("Unexpected exception on closing JDBC ResultSet", e);
}
}
}
private static void closeStatement(Statement stmt) {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
logger.debug("Could not close JDBC Statement", e);
} catch (Throwable e) {
logger.debug("Unexpected exception on closing JDBC Statement", e);
}
}
}
private static void closeConnection(Connection conn) {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
logger.debug("Could not close JDBC Connection", e);
} catch (Throwable e) {
logger.debug("Unexpected exception on closing JDBC Connection", e);
}
}
}
public DataSource getDataSource() {
return dataSource;
}
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public int getRetryTimes() {
return retryTimes;
}
public void setRetryTimes(int retryTimes) {
if (retryTimes < 0) {
throw new IllegalArgumentException("Property retryTimes cannot be less than zero, retryTimes = "
+ retryTimes);
}
this.retryTimes = retryTimes;
}
public int getStep() {
return step;
}
public void setStep(int step) {
if (step < MIN_STEP || step > MAX_STEP) {
StringBuilder message = new StringBuilder();
message.append("Property step out of range [").append(MIN_STEP);
message.append(",").append(MAX_STEP).append("], step = ").append(step);
throw new IllegalArgumentException(message.toString());
}
this.step = step;
}
public String getTableName() {
return tableName;
}
public void setTableName(String tableName) {
this.tableName = tableName;
}
public String getNameColumnName() {
return nameColumnName;
}
public void setNameColumnName(String nameColumnName) {
this.nameColumnName = nameColumnName;
}
public String getValueColumnName() {
return valueColumnName;
}
public void setValueColumnName(String valueColumnName) {
this.valueColumnName = valueColumnName;
}
public String getGmtModifiedColumnName() {
return gmtModifiedColumnName;
}
public void setGmtModifiedColumnName(String gmtModifiedColumnName) {
this.gmtModifiedColumnName = gmtModifiedColumnName;
}
}