com.alibaba.druid.pool.ha.balance.WeightBalancer Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of druid Show documentation
Show all versions of druid Show documentation
An JDBC datasource implementation.
package com.alibaba.druid.pool.ha.balance;
import java.sql.SQLException;
import com.alibaba.druid.pool.ha.DataSourceChangedEvent;
import com.alibaba.druid.pool.ha.DataSourceHolder;
import com.alibaba.druid.pool.ha.MultiConnectionHolder;
import com.alibaba.druid.pool.ha.MultiDataSource;
import com.alibaba.druid.pool.ha.MultiDataSourceConnection;
import com.alibaba.druid.util.ThreadLocalRandom;
public class WeightBalancer extends AbstractBalancer {
private int totalWeight = 0;
public void afterDataSourceChanged(DataSourceChangedEvent event) {
computeTotalWeight();
}
public int produceRandomNumber() {
if (totalWeight == 0) {
return 0;
}
return ThreadLocalRandom.current().nextInt(totalWeight);
}
public void computeTotalWeight() {
int totalWeight = 0;
for (DataSourceHolder holder : getMultiDataSource().getDataSources().values()) {
if (!holder.isEnable()) {
holder.setWeightRegionBegin(-1);
holder.setWeightRegionEnd(-1);
continue;
}
holder.setWeightRegionBegin(totalWeight);
totalWeight += holder.getWeight();
holder.setWeightRegionEnd(totalWeight);
}
this.totalWeight = totalWeight;
getMultiDataSource().notFailSignal();
}
@Override
public MultiConnectionHolder getConnection(MultiDataSourceConnection conn, String sql) throws SQLException {
MultiDataSource multiDataSource = conn.getMultiDataSource();
DataSourceHolder dataSource = null;
int randomNumber = produceRandomNumber();
DataSourceHolder first = null;
for (DataSourceHolder item : multiDataSource.getDataSources().values()) {
if (!item.isEnable()) {
continue;
}
if (first == null) {
first = item;
}
if (randomNumber >= item.getWeightRegionBegin() && randomNumber < item.getWeightRegionEnd()) {
if (!item.isEnable()) {
continue;
}
if (item.getDataSource().isBusy()) {
multiDataSource.incrementBusySkipCount();
break;
}
dataSource = item;
}
}
if (dataSource == null) {
dataSource = first;
}
if (dataSource == null) {
throw new SQLException("cannot get connection. enabledDataSourceCount "
+ multiDataSource.getEnabledDataSourceCount());
}
return dataSource.getConnection();
}
}