com.github.javaclub.cdl.client.group.AbstractDBSelector Maven / Gradle / Ivy

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package com.github.javaclub.cdl.client.group;

import java.sql.SQLException;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.sql.DataSource;

import com.github.javaclub.cdl.client.common.DataSourceHolder;
import com.github.javaclub.cdl.client.common.ExceptionSorter;
import com.github.javaclub.cdl.client.common.MySQLExceptionSorter;

public abstract class AbstractDBSelector implements DBSelector {
	private static final int default_retryBadDbInterval = 2000; // milliseconds
	protected static int retryBadDbInterval = default_retryBadDbInterval;
	protected ExceptionSorter exceptionSorter = new MySQLExceptionSorter();

	protected  T tryOnDataSourceHolder(DataSourceHolder dsHolder, Map failedDataSources,
			DataSourceTryer tryer, int times, Object... args) throws SQLException {
		List exceptions = new LinkedList();
		if (failedDataSources != null) {
			exceptions.addAll(failedDataSources.values());
		}
		if (failedDataSources != null && failedDataSources.containsKey(dsHolder.dsw)) {
			return tryer.onSQLException(exceptions, exceptionSorter, args);
		}

		try {
			if (dsHolder.isNotAvailable) {
				boolean toTry = System.currentTimeMillis() - dsHolder.lastRetryTime > default_retryBadDbInterval;
				if (toTry && dsHolder.lock.tryLock()) {
					try {
						T t = tryer.tryOnDataSource(dsHolder.dsw, args);
						dsHolder.isNotAvailable = false;
						return t;
					} finally {
						dsHolder.lastRetryTime = System.currentTimeMillis();
						dsHolder.lock.unlock();
					}
				} else {
					exceptions.add(new SQLException("dsKey:" + dsHolder.dsw.getDataSourceKey() + " not Available,toTry:" + toTry));
					return tryer.onSQLException(exceptions, exceptionSorter, args);
				}
			} else {
				return tryer.tryOnDataSource(dsHolder.dsw, args);
			}
		} catch (SQLException e) {
			if (exceptionSorter.isExceptionFatal(e)) {
				dsHolder.isNotAvailable = true;
			}
			exceptions.add(e);
			return tryer.onSQLException(exceptions, exceptionSorter, args);
		}
	}

	public  T tryExecute(Map failedDataSources, DataSourceTryer tryer, int times, Object... args)
			throws SQLException {
		Integer dataSourceIndex = null;
		if (args != null && args.length > 0) {
			dataSourceIndex = (Integer) args[args.length - 1];
		}
		if (dataSourceIndex != null && dataSourceIndex != NOT_EXIST_USER_SPECIFIED_INDEX) {
			DataSourceHolder dsHolder = findDataSourceWrapperByIndex(dataSourceIndex);
			if (dsHolder == null) {
				throw new IllegalArgumentException("找不到索引编号为 '" + dataSourceIndex + "'的数据源");
			}
			return tryOnDataSourceHolder(dsHolder, failedDataSources, tryer, times, args);
		} else {
			return tryExecuteInternal(failedDataSources, tryer, times, args);
		}
	}

	public  T tryExecute(DataSourceTryer tryer, int times, Object... args) throws SQLException {
		return this.tryExecute(null, tryer, times, args);
	}

	protected abstract DataSourceHolder findDataSourceWrapperByIndex(int dataSourceIndex);

	protected  T tryExecuteInternal(DataSourceTryer tryer, int times, Object... args) throws SQLException {
		return this.tryExecuteInternal(new LinkedHashMap(0), tryer, times, args);
	}

	protected abstract  T tryExecuteInternal(Map failedDataSources, DataSourceTryer tryer, int times,
			Object... args) throws SQLException;
	
}