/*
Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
The MySQL Connector/J is licensed under the terms of the GPLv2
<http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
this software, see the FLOSS License Exception
<http://www.mysql.com/about/legal/licensing/foss-exception.html>.
This program is free software; you can redistribute it and/or modify it under the terms
of the GNU General Public License as published by the Free Software Foundation; version 2
of the License.
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 General Public License for more details.
You should have received a copy of the GNU General Public License along with this
program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
Floor, Boston, MA 02110-1301 USA
*/
package com.mysql.jdbc;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.Executor;
/**
* A proxy for a dynamic com.mysql.jdbc.Connection implementation that load balances requests across a series of MySQL JDBC connections, where the balancing
* takes place at transaction commit.
*
* Therefore, for this to work (at all), you must use transactions, even if only reading data.
*
* This implementation will invalidate connections that it detects have had communication errors when processing a request. Problematic hosts will be added to a
* global blacklist for loadBalanceBlacklistTimeout ms, after which they will be removed from the blacklist and made eligible once again to be selected for new
* connections.
*
* This implementation is thread-safe, but it's questionable whether sharing a connection instance amongst threads is a good idea, given that transactions are
* scoped to connections in JDBC.
*/
public class LoadBalancingConnectionProxy extends MultiHostConnectionProxy implements PingTarget {
private ConnectionGroup connectionGroup = null;
private long connectionGroupProxyID = 0;
protected Map<String, ConnectionImpl> liveConnections;
private Map<String, Integer> hostsToListIndexMap;
private Map<ConnectionImpl, String> connectionsToHostsMap;
private long activePhysicalConnections = 0;
private long totalPhysicalConnections = 0;
private long[] responseTimes;
private int retriesAllDown;
private BalanceStrategy balancer;
private int autoCommitSwapThreshold = 0;
public static final String BLACKLIST_TIMEOUT_PROPERTY_KEY = "loadBalanceBlacklistTimeout";
private int globalBlacklistTimeout = 0;
private static Map<String, Long> globalBlacklist = new HashMap<String, Long>();
private String hostToRemove = null;
private boolean inTransaction = false;
private long transactionStartTime = 0;
private long transactionCount = 0;
private LoadBalanceExceptionChecker exceptionChecker;
private static Constructor<?> JDBC_4_LB_CONNECTION_CTOR;
static {
if (Util.isJdbc4()) {
try {
JDBC_4_LB_CONNECTION_CTOR = Class.forName("com.mysql.jdbc.JDBC4LoadBalancedMySQLConnection").getConstructor(
new Class[] { LoadBalancingConnectionProxy.class });
} catch (SecurityException e) {
throw new RuntimeException(e);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
}
/**
* Creates a proxy for java.sql.Connection that routes requests between the given list of host:port and uses the given properties when creating connections.
*
* @param hosts
* The list of the hosts to load balance.
* @param props
* Connection properties from where to get initial settings and to be used in new connections.
* @throws SQLException
*/
LoadBalancingConnectionProxy(List<String> hosts, Properties props) throws SQLException {
super();
String group = props.getProperty("loadBalanceConnectionGroup", null);
boolean enableJMX = false;
String enableJMXAsString = props.getProperty("loadBalanceEnableJMX", "false");
try {
enableJMX = Boolean.parseBoolean(enableJMXAsString);
} catch (Exception e) {
throw SQLError.createSQLException(
Messages.getString("LoadBalancingConnectionProxy.badValueForLoadBalanceEnableJMX", new Object[] { enableJMXAsString }),
SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
if (group != null) {
this.connectionGroup = ConnectionGroupManager.getConnectionGroupInstance(group);
if (enableJMX) {
ConnectionGroupManager.registerJmx();
}
this.connectionGroupProxyID = this.connectionGroup.registerConnectionProxy(this, hosts);
hosts = new ArrayList<String>(this.connectionGroup.getInitialHosts());
}
// hosts specifications may have been reset with settings from a previous connection group
int numHosts = initializeHostsSpecs(hosts, props);
this.liveConnections = new HashMap<String, ConnectionImpl>(numHosts);
this.hostsToListIndexMap = new HashMap<String, Integer>(numHosts);
for (int i = 0; i < numHosts; i++) {
this.hostsToListIndexMap.put(this.hostList.get(i), i);
}
this.connectionsToHostsMap = new HashMap<ConnectionImpl, String>(numHosts);
this.responseTimes = new long[numHosts];
String retriesAllDownAsString = this.localProps.getProperty("retriesAllDown", "120");
try {
this.retriesAllDown = Integer.parseInt(retriesAllDownAsString);
} catch (NumberFormatException nfe) {
throw SQLError.createSQLException(
Messages.getString("LoadBalancingConnectionProxy.badValueForRetriesAllDown", new Object[] { retriesAllDownAsString }),
SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String blacklistTimeoutAsString = this.localProps.getProperty(BLACKLIST_TIMEOUT_PROPERTY_KEY, "0");
try {
this.globalBlacklistTimeout = Integer.parseInt(blacklistTimeoutAsString);
} catch (NumberFormatException nfe) {
throw SQLError.createSQLException(
Messages.getString("LoadBalancingConnectionProxy.badValueForLoadBalanceBlacklistTimeout", new Object[] { retriesAllDownAsString }),
SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String strategy = this.localProps.getProperty("loadBalanceStrategy", "random");
if ("random".equals(strategy)) {
this.balancer = (BalanceStrategy) Util.loadExtensions(null, props, "com.mysql.jdbc.RandomBalanceStrategy", "InvalidLoadBalanceStrategy", null).get(
0);
} else if ("bestResponseTime".equals(strategy)) {
this.balancer = (BalanceStrategy) Util.loadExtensions(null, props, "com.mysql.jdbc.BestResponseTimeBalanceStrategy", "InvalidLoadBalanceStrategy",
null).get(0);
} else {
this.balancer = (BalanceStrategy) Util.loadExtensions(null, props, strategy, "InvalidLoadBalanceStrategy", null).get(0);
}
String autoCommitSwapThresholdAsString = props.getProperty("loadBalanceAutoCommitStatementThreshold", "0");
try {
this.autoCommitSwapThreshold = Integer.parseInt(autoCommitSwapThresholdAsString);
} catch (NumberFormatException nfe) {
throw SQLError.createSQLException(Messages.getString("LoadBalancingConnectionProxy.badValueForLoadBalanceAutoCommitStatementThreshold",
new Object[] { autoCommitSwapThresholdAsString }), SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String autoCommitSwapRegex = props.getProperty("loadBalanceAutoCommitStatementRegex", "");
if (!("".equals(autoCommitSwapRegex))) {
try {
"".matches(autoCommitSwapRegex);
} catch (Exception e) {
throw SQLError
.createSQLException(Messages.getString("LoadBalancingConnectionProxy.badValueForLoadBalanceAutoCommitStatementRegex",
new Object[] { autoCommitSwapRegex }), SQLError.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
}
if (this.autoCommitSwapThreshold > 0) {
String statementInterceptors = this.localProps.getProperty("statementInterceptors");
if (statementInterceptors == null) {
this.localProps.setProperty("statementInterceptors", "com.mysql.jdbc.LoadBalancedAutoCommitInterceptor");
} else if (statementInterceptors.length() > 0) {
this.localProps.setProperty("statementInterceptors", statementInterceptors + ",com.mysql.jdbc.LoadBalancedAutoCommitInterceptor");
}
props.setProperty("statementInterceptors", this.localProps.getProperty("statementInterceptors"));
}
this.balancer.init(null, props);
String lbExceptionChecker = this.localProps.getProperty("loadBalanceExceptionChecker", "com.mysql.jdbc.StandardLoadBalanceExceptionChecker");
this.exceptionChecker = (LoadBalanceExceptionChecker) Util.loadExtensions(null, props, lbExceptionChecker, "InvalidLoadBalanceExceptionChecker", null)
.get(0);
pickNewConnection();
}
/**
* Wraps this object with a new load balanced Connection instance.
*
* @return
* The connection object instance that wraps 'this'.
*/
@Override
MySQLConnection getNewWrapperForThisAsConnection() throws SQLException {
if (Util.isJdbc4() || JDBC_4_LB_CONNECTION_CTOR != null) {
return (MySQLConnection) Util.handleNewInstance(JDBC_4_LB_CONNECTION_CTOR, new Object[] { this }, null);
}
return new LoadBalancedMySQLConnection(this);
}
@Deprecated
boolean shouldExceptionTriggerFailover(Throwable t) {
return shouldExceptionTriggerConnectionSwitch(t);
}
/**
* Consults the registered LoadBalanceExceptionChecker if the given exception should trigger a connection fail-over.
*
* @param ex
* The Exception instance to check.
* @return
*/
@Override
boolean shouldExceptionTriggerConnectionSwitch(Throwable t) {
return t instanceof SQLException && this.exceptionChecker.shouldExceptionTriggerFailover((SQLException) t);
}
/**
* Closes specified connection and removes it from required mappings.
*
* @param conn
* @throws SQLException
*/
@Override
synchronized void invalidateConnection(MySQLConnection conn) throws SQLException {
super.invalidateConnection(conn);
// add host to the global blacklist, if enabled
if (this.isGlobalBlacklistEnabled()) {
addToGlobalBlacklist(this.connectionsToHostsMap.get(conn));
}
// remove from liveConnections
this.liveConnections.remove(this.connectionsToHostsMap.get(conn));
Object mappedHost = this.connectionsToHostsMap.remove(conn);
if (mappedHost != null && this.hostsToListIndexMap.containsKey(mappedHost)) {
int hostIndex = this.hostsToListIndexMap.get(mappedHost);
// reset the statistics for the host
synchronized (this.responseTimes) {
this.responseTimes[hostIndex] = 0;
}
}
}
/**
* Picks the "best" connection to use for the next transaction based on the BalanceStrategy in use.
*
* @throws SQLException
*/
@Override
synchronized void pickNewConnection() throws SQLException {
if (this.isClosed && this.closedExplicitly) {
return;
}
if (this.currentConnection == null) { // startup
this.currentConnection = this.balancer.pickConnection(this, Collections.unmodifiableList(this.hostList),
Collections.unmodifiableMap(this.liveConnections), this.responseTimes.clone(), this.retriesAllDown);
return;
}
if (this.currentConnection.isClosed()) {
invalidateCurrentConnection();
}
int pingTimeout = this.currentConnection.getLoadBalancePingTimeout();
boolean pingBeforeReturn = this.currentConnection.getLoadBalanceValidateConnectionOnSwapServer();
for (int hostsTried = 0, hostsToTry = this.hostList.size(); hostsTried <= hostsToTry; hostsTried++) {
ConnectionImpl newConn = null;
try {
newConn = this.balancer.pickConnection(this, Collections.unmodifiableList(this.hostList), Collections.unmodifiableMap(this.liveConnections),
this.responseTimes.clone(), this.retriesAllDown);
if (this.currentConnection != null) {
if (pingBeforeReturn) {
if (pingTimeout == 0) {
newConn.ping();
} else {
newConn.pingInternal(true, pingTimeout);
}
}
syncSessionState(this.currentConnection, newConn);
}
this.currentConnection = newConn;
return;
} catch (SQLException e) {
if (shouldExceptionTriggerConnectionSwitch(e) && newConn != null) {
// connection error, close up shop on current connection
invalidateConnection(newConn);
}
}
}
// no hosts available to swap connection to, close up.
this.isClosed = true;
this.closedReason = "Connection closed after inability to pick valid new connection during load-balance.";
}
/**
* Creates a new physical connection for the given host:port and updates required internal mappings and statistics for that connection.
*
* @param hostPortSpec
* The host:port specification.
* @throws SQLException
*/
@Override
public synchronized ConnectionImpl createConnectionForHost(String hostPortSpec) throws SQLException {
ConnectionImpl conn = super.createConnectionForHost(hostPortSpec);
this.liveConnections.put(hostPortSpec, conn);
this.connectionsToHostsMap.put(conn, hostPortSpec);
this.activePhysicalConnections++;
this.totalPhysicalConnections++;
return conn;
}
/**
* Closes all live connections.
*/
private synchronized void closeAllConnections() {
// close all underlying connections
for (Connection c : this.liveConnections.values()) {
try {
this.activePhysicalConnections--;
c.close();
} catch (SQLException e) {
}
}
if (!this.isClosed) {
this.balancer.destroy();
if (this.connectionGroup != null) {
this.connectionGroup.closeConnectionProxy(this);
}
}
this.liveConnections.clear();
this.connectionsToHostsMap.clear();
}
/**
* Closes all live connections.
*/
@Override
synchronized void doClose() {
closeAllConnections();
}
/**
* Aborts all live connections
*/
@Override
synchronized void doAbortInternal() {
// abort all underlying connections
for (Connection c : this.liveConnections.values()) {
try {
this.activePhysicalConnections--;
c.abortInternal();
} catch (SQLException e) {
}
}
if (!this.isClosed) {
this.balancer.destroy();
if (this.connectionGroup != null) {
this.connectionGroup.closeConnectionProxy(this);
}
}
this.liveConnections.clear();
this.connectionsToHostsMap.clear();
}
/**
* Aborts all live connections, using the provided Executor.
*/
@Override
synchronized void doAbort(Executor executor) {
// close all underlying connections
for (Connection c : this.liveConnections.values()) {
try {
this.activePhysicalConnections--;
c.abort(executor);
} catch (SQLException e) {
}
}
if (!this.isClosed) {
this.balancer.destroy();
if (this.connectionGroup != null) {
this.connectionGroup.closeConnectionProxy(this);
}
}
this.liveConnections.clear();
this.connectionsToHostsMap.clear();
}
/**
* Proxies method invocation on the java.sql.Connection interface, trapping "close", "isClosed" and "commit/rollback" to switch connections for load
* balancing.
* This is the continuation of MultiHostConnectionProxy#invoke(Object, Method, Object[]).
*/
@Override
public synchronized Object invokeMore(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
if (this.isClosed) {
if (this.autoReconnect && !this.closedExplicitly) {
// try to reconnect first!
this.currentConnection = null;
pickNewConnection();
this.isClosed = false;
this.closedReason = null;
} else {
String reason = "No operations allowed after connection closed.";
if (this.closedReason != null) {
reason += (" " + this.closedReason);
}
throw SQLError.createSQLException(reason, SQLError.SQL_STATE_CONNECTION_NOT_OPEN, null /* no access to a interceptor here... */);
}
}
if (!this.inTransaction) {
this.inTransaction = true;
this.transactionStartTime = System.nanoTime();
this.transactionCount++;
}
Object result = null;
try {
result = method.invoke(this.thisAsConnection, args);
if (result != null) {
if (result instanceof com.mysql.jdbc.Statement) {
((com.mysql.jdbc.Statement) result).setPingTarget(this);
}
result = proxyIfIsJdbcInterface(result);
}
} catch (InvocationTargetException e) {
dealWithInvocationException(e);
} finally {
if ("commit".equals(methodName) || "rollback".equals(methodName)) {
this.inTransaction = false;
// Update stats
String host = this.connectionsToHostsMap.get(this.currentConnection);
// avoid NPE if the connection has already been removed from connectionsToHostsMap in invalidateCurrenctConnection()
if (host != null) {
synchronized (this.responseTimes) {
Integer hostIndex = (this.hostsToListIndexMap.get(host));
if (hostIndex != null && hostIndex < this.responseTimes.length) {
this.responseTimes[hostIndex] = System.nanoTime() - this.transactionStartTime;
}
}
}
pickNewConnection();
}
}
return result;
}
/**
* Pings live connections.
*/
public synchronized void doPing() throws SQLException {
SQLException se = null;
boolean foundHost = false;
int pingTimeout = this.currentConnection.getLoadBalancePingTimeout();
synchronized (this) {
for (Iterator<String> i = this.hostList.iterator(); i.hasNext();) {
String host = i.next();
ConnectionImpl conn = this.liveConnections.get(host);
if (conn == null) {
continue;
}
try {
if (pingTimeout == 0) {
conn.ping();
} else {
conn.pingInternal(true, pingTimeout);
}
foundHost = true;
} catch (SQLException e) {
this.activePhysicalConnections--;
// give up if it is the current connection, otherwise NPE faking resultset later.
if (host.equals(this.connectionsToHostsMap.get(this.currentConnection))) {
// clean up underlying connections, since connection pool won't do it
closeAllConnections();
this.isClosed = true;
this.closedReason = "Connection closed because ping of current connection failed.";
throw e;
}
// if the Exception is caused by ping connection lifetime checks, don't add to blacklist
if (e.getMessage().equals(Messages.getString("Connection.exceededConnectionLifetime"))) {
// only set the return Exception if it's null
if (se == null) {
se = e;
}
} else {
// overwrite the return Exception no matter what
se = e;
if (isGlobalBlacklistEnabled()) {
addToGlobalBlacklist(host);
}
}
// take the connection out of the liveConnections Map
this.liveConnections.remove(this.connectionsToHostsMap.get(conn));
}
}
}
// if there were no successful pings
if (!foundHost) {
closeAllConnections();
this.isClosed = true;
this.closedReason = "Connection closed due to inability to ping any active connections.";
// throw the stored Exception, if exists
if (se != null) {
throw se;
}
// or create a new SQLException and throw it, must be no liveConnections
((ConnectionImpl) this.currentConnection).throwConnectionClosedException();
}
}
/**
* Adds a host to the blacklist with the given timeout.
*
* @param host
* The host to be blacklisted.
* @param timeout
* The blacklist timeout for this entry.
*/
public void addToGlobalBlacklist(String host, long timeout) {
if (isGlobalBlacklistEnabled()) {
synchronized (globalBlacklist) {
globalBlacklist.put(host, timeout);
}
}
}
/**
* Adds a host to the blacklist.
*
* @param host
* The host to be blacklisted.
*/
public void addToGlobalBlacklist(String host) {
addToGlobalBlacklist(host, System.currentTimeMillis() + this.globalBlacklistTimeout);
}
/**
* Checks if host blacklist management was enabled.
*
* @return
*/
public boolean isGlobalBlacklistEnabled() {
return (this.globalBlacklistTimeout > 0);
}
/**
* Returns a local hosts blacklist, or a blacklist with a single host to be removed, while cleaning up expired records from the global blacklist.
*
* @return
* A local hosts blacklist.
*/
public synchronized Map<String, Long> getGlobalBlacklist() {
if (!isGlobalBlacklistEnabled()) {
String localHostToRemove = this.hostToRemove;
if (this.hostToRemove != null) {
HashMap<String, Long> fakedBlacklist = new HashMap<String, Long>();
fakedBlacklist.put(localHostToRemove, System.currentTimeMillis() + 5000);
return fakedBlacklist;
}
return new HashMap<String, Long>(1);
}
// Make a local copy of the blacklist
Map<String, Long> blacklistClone = new HashMap<String, Long>(globalBlacklist.size());
// Copy everything from synchronized global blacklist to local copy for manipulation
synchronized (globalBlacklist) {
blacklistClone.putAll(globalBlacklist);
}
Set<String> keys = blacklistClone.keySet();
// We're only interested in blacklisted hosts that are in the hostList
keys.retainAll(this.hostList);
// Don't need to synchronize here as we using a local copy
for (Iterator<String> i = keys.iterator(); i.hasNext();) {
String host = i.next();
// OK if null is returned because another thread already purged Map entry.
Long timeout = globalBlacklist.get(host);
if (timeout != null && timeout < System.currentTimeMillis()) {
// Timeout has expired, remove from blacklist
synchronized (globalBlacklist) {
globalBlacklist.remove(host);
}
i.remove();
}
}
if (keys.size() == this.hostList.size()) {
// return an empty blacklist, let the BalanceStrategy implementations try to connect to everything since it appears that all hosts are
// unavailable - we don't want to wait for loadBalanceBlacklistTimeout to expire.
return new HashMap<String, Long>(1);
}
return blacklistClone;
}
/**
* Removes a host from the host list, allowing it some time to be released gracefully if needed.
*
* @param host
* The host to be removed.
* @throws SQLException
*/
public void removeHostWhenNotInUse(String host) throws SQLException {
int timeBetweenChecks = 1000;
long timeBeforeHardFail = 15000;
synchronized (this) {
addToGlobalBlacklist(host, System.currentTimeMillis() + timeBeforeHardFail + 1000);
long cur = System.currentTimeMillis();
while (System.currentTimeMillis() < cur + timeBeforeHardFail) {
this.hostToRemove = host;
if (!host.equals(this.currentConnection.getHost())) {
removeHost(host);
return;
}
try {
Thread.sleep(timeBetweenChecks);
} catch (InterruptedException e) {
// better to swallow this and retry.
}
}
}
removeHost(host);
}
/**
* Removes a host from the host list.
*
* @param host
* The host to be removed.
* @throws SQLException
*/
public synchronized void removeHost(String host) throws SQLException {
if (this.connectionGroup != null) {
if (this.connectionGroup.getInitialHosts().size() == 1 && this.connectionGroup.getInitialHosts().contains(host)) {
throw SQLError.createSQLException("Cannot remove only configured host.", null);
}
this.hostToRemove = host;
if (host.equals(this.currentConnection.getHost())) {
closeAllConnections();
} else {
this.connectionsToHostsMap.remove(this.liveConnections.remove(host));
Integer idx = this.hostsToListIndexMap.remove(host);
long[] newResponseTimes = new long[this.responseTimes.length - 1];
int newIdx = 0;
for (Iterator<String> i = this.hostList.iterator(); i.hasNext(); newIdx++) {
String copyHost = i.next();
if (idx != null && idx < this.responseTimes.length) {
newResponseTimes[newIdx] = this.responseTimes[idx];
this.hostsToListIndexMap.put(copyHost, newIdx);
}
}
this.responseTimes = newResponseTimes;
}
}
}
/**
* Adds a host to the hosts list.
*
* @param host
* The host to be added.
* @return
*/
public synchronized boolean addHost(String host) {
if (this.hostsToListIndexMap.containsKey(host)) {
return false;
}
long[] newResponseTimes = new long[this.responseTimes.length + 1];
System.arraycopy(this.responseTimes, 0, newResponseTimes, 0, this.responseTimes.length);
this.responseTimes = newResponseTimes;
this.hostList.add(host);
this.hostsToListIndexMap.put(host, this.responseTimes.length - 1);
return true;
}
public synchronized boolean inTransaction() {
return this.inTransaction;
}
public synchronized long getTransactionCount() {
return this.transactionCount;
}
public synchronized long getActivePhysicalConnectionCount() {
return this.activePhysicalConnections;
}
public synchronized long getTotalPhysicalConnectionCount() {
return this.totalPhysicalConnections;
}
public synchronized long getConnectionGroupProxyID() {
return this.connectionGroupProxyID;
}
public synchronized String getCurrentActiveHost() {
MySQLConnection c = this.currentConnection;
if (c != null) {
Object o = this.connectionsToHostsMap.get(c);
if (o != null) {
return o.toString();
}
}
return null;
}
public synchronized long getCurrentTransactionDuration() {
if (this.inTransaction && this.transactionStartTime > 0) {
return System.nanoTime() - this.transactionStartTime;
}
return 0;
}
}