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JDBC Type 4 driver for MySQL
/*
* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License, version 2.0, as published by the
* Free Software Foundation.
*
* This program is also distributed with certain software (including but not
* limited to OpenSSL) that is licensed under separate terms, as designated in a
* particular file or component or in included license documentation. The
* authors of MySQL hereby grant you an additional permission to link the
* program and your derivative works with the separately licensed software that
* they have included with MySQL.
*
* Without limiting anything contained in the foregoing, this file, which is
* part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
* version 1.0, a copy of which can be found at
* http://oss.oracle.com/licenses/universal-foss-exception.
*
* 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, version 2.0,
* 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.cj.jdbc.ha;
import static com.mysql.cj.util.StringUtils.isNullOrEmpty;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.Executor;
import com.mysql.cj.Messages;
import com.mysql.cj.PingTarget;
import com.mysql.cj.conf.ConnectionUrl;
import com.mysql.cj.conf.HostInfo;
import com.mysql.cj.conf.HostsListView;
import com.mysql.cj.conf.PropertyKey;
import com.mysql.cj.conf.url.LoadBalanceConnectionUrl;
import com.mysql.cj.conf.url.ReplicationConnectionUrl;
import com.mysql.cj.exceptions.MysqlErrorNumbers;
import com.mysql.cj.jdbc.JdbcConnection;
import com.mysql.cj.jdbc.JdbcStatement;
import com.mysql.cj.jdbc.exceptions.SQLError;
/**
* Connection that opens two connections, one two a replication master, and another to one or more slaves, and decides to use master when the connection is not
* read-only, and use slave(s) when the connection is read-only.
*/
public class ReplicationConnectionProxy extends MultiHostConnectionProxy implements PingTarget {
private ReplicationConnection thisAsReplicationConnection;
protected boolean enableJMX = false;
protected boolean allowMasterDownConnections = false;
protected boolean allowSlaveDownConnections = false;
protected boolean readFromMasterWhenNoSlaves = false;
protected boolean readFromMasterWhenNoSlavesOriginal = false;
protected boolean readOnly = false;
ReplicationConnectionGroup connectionGroup;
private long connectionGroupID = -1;
private List masterHosts;
protected LoadBalancedConnection masterConnection;
private List slaveHosts;
protected LoadBalancedConnection slavesConnection;
/**
* Static factory to create {@link ReplicationConnection} instances.
*
* @param connectionUrl
* The connection URL containing the hosts in a replication setup.
* @return A {@link ReplicationConnection} proxy.
* @throws SQLException
* if an error occurs
*/
public static ReplicationConnection createProxyInstance(ConnectionUrl connectionUrl) throws SQLException {
ReplicationConnectionProxy connProxy = new ReplicationConnectionProxy(connectionUrl);
return (ReplicationConnection) java.lang.reflect.Proxy.newProxyInstance(ReplicationConnection.class.getClassLoader(),
new Class[] { ReplicationConnection.class, JdbcConnection.class }, connProxy);
}
/**
* Creates a proxy for java.sql.Connection that routes requests to a load-balanced connection of master servers or a load-balanced connection of slave
* servers. Each sub-connection is created with its own set of independent properties.
*
* @param connectionUrl
* The connection URL containing the hosts in a replication setup.
* @throws SQLException
* if an error occurs
*/
private ReplicationConnectionProxy(ConnectionUrl connectionUrl) throws SQLException {
super();
Properties props = connectionUrl.getConnectionArgumentsAsProperties();
this.thisAsReplicationConnection = (ReplicationConnection) this.thisAsConnection;
this.connectionUrl = connectionUrl;
String enableJMXAsString = props.getProperty(PropertyKey.ha_enableJMX.getKeyName(), "false");
try {
this.enableJMX = Boolean.parseBoolean(enableJMXAsString);
} catch (Exception e) {
throw SQLError.createSQLException(Messages.getString("MultihostConnection.badValueForHaEnableJMX", new Object[] { enableJMXAsString }),
MysqlErrorNumbers.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String allowMasterDownConnectionsAsString = props.getProperty(PropertyKey.allowMasterDownConnections.getKeyName(), "false");
try {
this.allowMasterDownConnections = Boolean.parseBoolean(allowMasterDownConnectionsAsString);
} catch (Exception e) {
throw SQLError.createSQLException(
Messages.getString("ReplicationConnectionProxy.badValueForAllowMasterDownConnections", new Object[] { enableJMXAsString }),
MysqlErrorNumbers.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String allowSlaveDownConnectionsAsString = props.getProperty(PropertyKey.allowSlaveDownConnections.getKeyName(), "false");
try {
this.allowSlaveDownConnections = Boolean.parseBoolean(allowSlaveDownConnectionsAsString);
} catch (Exception e) {
throw SQLError.createSQLException(
Messages.getString("ReplicationConnectionProxy.badValueForAllowSlaveDownConnections", new Object[] { allowSlaveDownConnectionsAsString }),
MysqlErrorNumbers.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String readFromMasterWhenNoSlavesAsString = props.getProperty(PropertyKey.readFromMasterWhenNoSlaves.getKeyName());
try {
this.readFromMasterWhenNoSlavesOriginal = Boolean.parseBoolean(readFromMasterWhenNoSlavesAsString);
} catch (Exception e) {
throw SQLError.createSQLException(
Messages.getString("ReplicationConnectionProxy.badValueForReadFromMasterWhenNoSlaves", new Object[] { readFromMasterWhenNoSlavesAsString }),
MysqlErrorNumbers.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
String group = props.getProperty(PropertyKey.replicationConnectionGroup.getKeyName(), null);
if (!isNullOrEmpty(group) && ReplicationConnectionUrl.class.isAssignableFrom(connectionUrl.getClass())) {
this.connectionGroup = ReplicationConnectionGroupManager.getConnectionGroupInstance(group);
if (this.enableJMX) {
ReplicationConnectionGroupManager.registerJmx();
}
this.connectionGroupID = this.connectionGroup.registerReplicationConnection(this.thisAsReplicationConnection,
((ReplicationConnectionUrl) connectionUrl).getMastersListAsHostPortPairs(),
((ReplicationConnectionUrl) connectionUrl).getSlavesListAsHostPortPairs());
this.masterHosts = ((ReplicationConnectionUrl) connectionUrl).getMasterHostsListFromHostPortPairs(this.connectionGroup.getMasterHosts());
this.slaveHosts = ((ReplicationConnectionUrl) connectionUrl).getSlaveHostsListFromHostPortPairs(this.connectionGroup.getSlaveHosts());
} else {
this.masterHosts = new ArrayList<>(connectionUrl.getHostsList(HostsListView.MASTERS));
this.slaveHosts = new ArrayList<>(connectionUrl.getHostsList(HostsListView.SLAVES));
}
resetReadFromMasterWhenNoSlaves();
// Initialize slaves connection first so that it is ready to be used in case the masters connection fails and 'allowMasterDownConnections=true'.
try {
initializeSlavesConnection();
} catch (SQLException e) {
if (!this.allowSlaveDownConnections) {
if (this.connectionGroup != null) {
this.connectionGroup.handleCloseConnection(this.thisAsReplicationConnection);
}
throw e;
} // Else swallow this exception.
}
SQLException exCaught = null;
try {
this.currentConnection = initializeMasterConnection();
} catch (SQLException e) {
exCaught = e;
}
if (this.currentConnection == null) {
if (this.allowMasterDownConnections && this.slavesConnection != null) {
// Set read-only and fail over to the slaves connection.
this.readOnly = true;
this.currentConnection = this.slavesConnection;
} else {
if (this.connectionGroup != null) {
this.connectionGroup.handleCloseConnection(this.thisAsReplicationConnection);
}
if (exCaught != null) {
throw exCaught;
}
throw SQLError.createSQLException(Messages.getString("ReplicationConnectionProxy.initializationWithEmptyHostsLists"),
MysqlErrorNumbers.SQL_STATE_ILLEGAL_ARGUMENT, null);
}
}
}
/**
* Wraps this object with a new replication Connection instance.
*
* @return
* The connection object instance that wraps 'this'.
*/
@Override
JdbcConnection getNewWrapperForThisAsConnection() throws SQLException {
return new ReplicationMySQLConnection(this);
}
/**
* Propagates the connection proxy down through all live connections.
*
* @param proxyConn
* The top level connection in the multi-host connections chain.
*/
@Override
protected void propagateProxyDown(JdbcConnection proxyConn) {
if (this.masterConnection != null) {
this.masterConnection.setProxy(proxyConn);
}
if (this.slavesConnection != null) {
this.slavesConnection.setProxy(proxyConn);
}
}
/**
* Has no use in replication connections. Always return false.
*
* @param t
* The Exception instance to check.
*/
@Override
boolean shouldExceptionTriggerConnectionSwitch(Throwable t) {
return false;
}
/**
* Checks if current connection is the masters l/b connection.
*/
@Override
public boolean isMasterConnection() {
return this.currentConnection != null && this.currentConnection == this.masterConnection;
}
/**
* Checks if current connection is the slaves l/b connection.
*
* @return true if current connection is the slaves l/b connection
*/
public boolean isSlavesConnection() {
return this.currentConnection != null && this.currentConnection == this.slavesConnection;
}
@Override
void pickNewConnection() throws SQLException {
// no-op
}
@Override
void syncSessionState(JdbcConnection source, JdbcConnection target, boolean readonly) throws SQLException {
try {
super.syncSessionState(source, target, readonly);
} catch (SQLException e1) {
try {
// Try again. It may happen that the connection had recovered in the meantime but the right syncing wasn't done yet.
super.syncSessionState(source, target, readonly);
} catch (SQLException e2) {
}
// Swallow both exceptions. Replication connections must continue to "work" after swapping between masters and slaves.
}
}
@Override
void doClose() throws SQLException {
if (this.masterConnection != null) {
this.masterConnection.close();
}
if (this.slavesConnection != null) {
this.slavesConnection.close();
}
if (this.connectionGroup != null) {
this.connectionGroup.handleCloseConnection(this.thisAsReplicationConnection);
}
}
@Override
void doAbortInternal() throws SQLException {
this.masterConnection.abortInternal();
this.slavesConnection.abortInternal();
if (this.connectionGroup != null) {
this.connectionGroup.handleCloseConnection(this.thisAsReplicationConnection);
}
}
@Override
void doAbort(Executor executor) throws SQLException {
this.masterConnection.abort(executor);
this.slavesConnection.abort(executor);
if (this.connectionGroup != null) {
this.connectionGroup.handleCloseConnection(this.thisAsReplicationConnection);
}
}
/**
* Proxies method invocation on the java.sql.Connection interface.
* This is the continuation of MultiHostConnectionProxy#invoke(Object, Method, Object[]).
*/
@Override
Object invokeMore(Object proxy, Method method, Object[] args) throws Throwable {
checkConnectionCapabilityForMethod(method);
boolean invokeAgain = false;
while (true) {
try {
Object result = method.invoke(this.thisAsConnection, args);
if (result != null && result instanceof JdbcStatement) {
((JdbcStatement) result).setPingTarget(this);
}
return result;
} catch (InvocationTargetException e) {
if (invokeAgain) {
invokeAgain = false;
} else if (e.getCause() != null && e.getCause() instanceof SQLException
&& ((SQLException) e.getCause()).getSQLState() == MysqlErrorNumbers.SQL_STATE_INVALID_TRANSACTION_STATE
&& ((SQLException) e.getCause()).getErrorCode() == MysqlErrorNumbers.ERROR_CODE_NULL_LOAD_BALANCED_CONNECTION) {
try {
// Try to re-establish the connection with the last known read-only state.
setReadOnly(this.readOnly);
invokeAgain = true;
} catch (SQLException sqlEx) {
// Still not good. Swallow this exception.
}
}
if (!invokeAgain) {
throw e;
}
}
}
}
/**
* Checks if this connection is in a state capable to invoke the provided method. If the connection is in an inconsistent state, i.e. it has no hosts for
* both sub-connections, then throw an invalid transaction state exception. Nevertheless, the methods defined in the ReplicationConnection interface will be
* allowed as they are the only way to leave from an empty hosts lists situation.
*
* @param method
* method
* @throws Throwable
* if an error occurs
*/
private void checkConnectionCapabilityForMethod(Method method) throws Throwable {
if (this.masterHosts.isEmpty() && this.slaveHosts.isEmpty() && !ReplicationConnection.class.isAssignableFrom(method.getDeclaringClass())) {
throw SQLError.createSQLException(Messages.getString("ReplicationConnectionProxy.noHostsInconsistentState"),
MysqlErrorNumbers.SQL_STATE_INVALID_TRANSACTION_STATE, MysqlErrorNumbers.ERROR_CODE_REPLICATION_CONNECTION_WITH_NO_HOSTS, true, null);
}
}
/**
* Pings both l/b connections. Switch to another connection in case of failure.
*/
@Override
public void doPing() throws SQLException {
boolean isMasterConn = isMasterConnection();
SQLException mastersPingException = null;
SQLException slavesPingException = null;
if (this.masterConnection != null) {
try {
this.masterConnection.ping();
} catch (SQLException e) {
mastersPingException = e;
}
} else {
initializeMasterConnection();
}
if (this.slavesConnection != null) {
try {
this.slavesConnection.ping();
} catch (SQLException e) {
slavesPingException = e;
}
} else {
try {
initializeSlavesConnection();
if (switchToSlavesConnectionIfNecessary()) {
isMasterConn = false;
}
} catch (SQLException e) {
if (this.masterConnection == null || !this.readFromMasterWhenNoSlaves) {
throw e;
} // Else swallow this exception.
}
}
if (isMasterConn && mastersPingException != null) {
// Switch to slaves connection.
if (this.slavesConnection != null && slavesPingException == null) {
this.masterConnection = null;
this.currentConnection = this.slavesConnection;
this.readOnly = true;
}
throw mastersPingException;
} else if (!isMasterConn && (slavesPingException != null || this.slavesConnection == null)) {
// Switch to masters connection, setting read-only state, if 'readFromMasterWhenNoSlaves=true'.
if (this.masterConnection != null && this.readFromMasterWhenNoSlaves && mastersPingException == null) {
this.slavesConnection = null;
this.currentConnection = this.masterConnection;
this.readOnly = true;
this.currentConnection.setReadOnly(true);
}
if (slavesPingException != null) {
throw slavesPingException;
}
}
}
private JdbcConnection initializeMasterConnection() throws SQLException {
this.masterConnection = null;
if (this.masterHosts.size() == 0) {
return null;
}
LoadBalancedConnection newMasterConn = LoadBalancedConnectionProxy
.createProxyInstance(new LoadBalanceConnectionUrl(this.masterHosts, this.connectionUrl.getOriginalProperties()));
newMasterConn.setProxy(getProxy());
this.masterConnection = newMasterConn;
return this.masterConnection;
}
private JdbcConnection initializeSlavesConnection() throws SQLException {
this.slavesConnection = null;
if (this.slaveHosts.size() == 0) {
return null;
}
LoadBalancedConnection newSlavesConn = LoadBalancedConnectionProxy
.createProxyInstance(new LoadBalanceConnectionUrl(this.slaveHosts, this.connectionUrl.getOriginalProperties()));
newSlavesConn.setProxy(getProxy());
newSlavesConn.setReadOnly(true);
this.slavesConnection = newSlavesConn;
return this.slavesConnection;
}
private synchronized boolean switchToMasterConnection() throws SQLException {
if (this.masterConnection == null || this.masterConnection.isClosed()) {
try {
if (initializeMasterConnection() == null) {
return false;
}
} catch (SQLException e) {
this.currentConnection = null;
throw e;
}
}
if (!isMasterConnection() && this.masterConnection != null) {
syncSessionState(this.currentConnection, this.masterConnection, false);
this.currentConnection = this.masterConnection;
}
return true;
}
private synchronized boolean switchToSlavesConnection() throws SQLException {
if (this.slavesConnection == null || this.slavesConnection.isClosed()) {
try {
if (initializeSlavesConnection() == null) {
return false;
}
} catch (SQLException e) {
this.currentConnection = null;
throw e;
}
}
if (!isSlavesConnection() && this.slavesConnection != null) {
syncSessionState(this.currentConnection, this.slavesConnection, true);
this.currentConnection = this.slavesConnection;
}
return true;
}
private boolean switchToSlavesConnectionIfNecessary() throws SQLException {
// Switch to slaves connection:
// - If the current connection is null. Or,
// - If we're currently on the master and in read-only mode - we didn't have any slaves to use until now. Or,
// - If we're currently on a closed master connection and there are no masters to connect to. Or,
// - If we're currently not on a master connection that is closed - means that we were on a closed slaves connection before it was re-initialized.
if (this.currentConnection == null || isMasterConnection() && (this.readOnly || this.masterHosts.isEmpty() && this.currentConnection.isClosed())
|| !isMasterConnection() && this.currentConnection.isClosed()) {
return switchToSlavesConnection();
}
return false;
}
public synchronized JdbcConnection getCurrentConnection() {
return this.currentConnection == null ? LoadBalancedConnectionProxy.getNullLoadBalancedConnectionInstance() : this.currentConnection;
}
public long getConnectionGroupId() {
return this.connectionGroupID;
}
public synchronized JdbcConnection getMasterConnection() {
return this.masterConnection;
}
public synchronized void promoteSlaveToMaster(String hostPortPair) throws SQLException {
HostInfo host = getSlaveHost(hostPortPair);
if (host == null) {
return;
}
this.masterHosts.add(host);
removeSlave(hostPortPair);
if (this.masterConnection != null) {
this.masterConnection.addHost(hostPortPair);
}
// Switch back to the masters connection if this connection was running in fail-safe mode.
if (!this.readOnly && !isMasterConnection()) {
switchToMasterConnection();
}
}
public synchronized void removeMasterHost(String hostPortPair) throws SQLException {
this.removeMasterHost(hostPortPair, true);
}
public synchronized void removeMasterHost(String hostPortPair, boolean waitUntilNotInUse) throws SQLException {
this.removeMasterHost(hostPortPair, waitUntilNotInUse, false);
}
public synchronized void removeMasterHost(String hostPortPair, boolean waitUntilNotInUse, boolean isNowSlave) throws SQLException {
HostInfo host = getMasterHost(hostPortPair);
if (host == null) {
return;
}
if (isNowSlave) {
this.slaveHosts.add(host);
resetReadFromMasterWhenNoSlaves();
}
this.masterHosts.remove(host);
// The master connection may have been implicitly closed by a previous op., don't let it stop us.
if (this.masterConnection == null || this.masterConnection.isClosed()) {
this.masterConnection = null;
return;
}
if (waitUntilNotInUse) {
this.masterConnection.removeHostWhenNotInUse(hostPortPair);
} else {
this.masterConnection.removeHost(hostPortPair);
}
// Close the connection if that was the last master.
if (this.masterHosts.isEmpty()) {
this.masterConnection.close();
this.masterConnection = null;
// Default behavior, no need to check this.readFromMasterWhenNoSlaves.
switchToSlavesConnectionIfNecessary();
}
}
public boolean isHostMaster(String hostPortPair) {
if (hostPortPair == null) {
return false;
}
return this.masterHosts.stream().anyMatch(hi -> hostPortPair.equalsIgnoreCase(hi.getHostPortPair()));
}
public synchronized JdbcConnection getSlavesConnection() {
return this.slavesConnection;
}
public synchronized void addSlaveHost(String hostPortPair) throws SQLException {
if (this.isHostSlave(hostPortPair)) {
return;
}
this.slaveHosts.add(getConnectionUrl().getSlaveHostOrSpawnIsolated(hostPortPair));
resetReadFromMasterWhenNoSlaves();
if (this.slavesConnection == null) {
initializeSlavesConnection();
switchToSlavesConnectionIfNecessary();
} else {
this.slavesConnection.addHost(hostPortPair);
}
}
public synchronized void removeSlave(String hostPortPair) throws SQLException {
removeSlave(hostPortPair, true);
}
public synchronized void removeSlave(String hostPortPair, boolean closeGently) throws SQLException {
HostInfo host = getSlaveHost(hostPortPair);
if (host == null) {
return;
}
this.slaveHosts.remove(host);
resetReadFromMasterWhenNoSlaves();
if (this.slavesConnection == null || this.slavesConnection.isClosed()) {
this.slavesConnection = null;
return;
}
if (closeGently) {
this.slavesConnection.removeHostWhenNotInUse(hostPortPair);
} else {
this.slavesConnection.removeHost(hostPortPair);
}
// Close the connection if that was the last slave.
if (this.slaveHosts.isEmpty()) {
this.slavesConnection.close();
this.slavesConnection = null;
// Default behavior, no need to check this.readFromMasterWhenNoSlaves.
switchToMasterConnection();
if (isMasterConnection()) {
this.currentConnection.setReadOnly(this.readOnly); // Maintain.
}
}
}
public boolean isHostSlave(String hostPortPair) {
if (hostPortPair == null) {
return false;
}
return this.slaveHosts.stream().anyMatch(hi -> hostPortPair.equalsIgnoreCase(hi.getHostPortPair()));
}
public synchronized void setReadOnly(boolean readOnly) throws SQLException {
if (readOnly) {
if (!isSlavesConnection() || this.currentConnection.isClosed()) {
boolean switched = true;
SQLException exceptionCaught = null;
try {
switched = switchToSlavesConnection();
} catch (SQLException e) {
switched = false;
exceptionCaught = e;
}
if (!switched && this.readFromMasterWhenNoSlaves && switchToMasterConnection()) {
exceptionCaught = null; // The connection is OK. Cancel the exception, if any.
}
if (exceptionCaught != null) {
throw exceptionCaught;
}
}
} else {
if (!isMasterConnection() || this.currentConnection.isClosed()) {
boolean switched = true;
SQLException exceptionCaught = null;
try {
switched = switchToMasterConnection();
} catch (SQLException e) {
switched = false;
exceptionCaught = e;
}
if (!switched && switchToSlavesConnectionIfNecessary()) {
exceptionCaught = null; // The connection is OK. Cancel the exception, if any.
}
if (exceptionCaught != null) {
throw exceptionCaught;
}
}
}
this.readOnly = readOnly;
/*
* Reset masters connection read-only state if 'readFromMasterWhenNoSlaves=true'. If there are no slaves then the masters connection will be used with
* read-only state in its place. Even if not, it must be reset from a possible previous read-only state.
*/
if (this.readFromMasterWhenNoSlaves && isMasterConnection()) {
this.currentConnection.setReadOnly(this.readOnly);
}
}
public boolean isReadOnly() throws SQLException {
return !isMasterConnection() || this.readOnly;
}
private void resetReadFromMasterWhenNoSlaves() {
this.readFromMasterWhenNoSlaves = this.slaveHosts.isEmpty() || this.readFromMasterWhenNoSlavesOriginal;
}
private HostInfo getMasterHost(String hostPortPair) {
return this.masterHosts.stream().filter(hi -> hostPortPair.equalsIgnoreCase(hi.getHostPortPair())).findFirst().orElse(null);
}
private HostInfo getSlaveHost(String hostPortPair) {
return this.slaveHosts.stream().filter(hi -> hostPortPair.equalsIgnoreCase(hi.getHostPortPair())).findFirst().orElse(null);
}
private ReplicationConnectionUrl getConnectionUrl() {
return (ReplicationConnectionUrl) this.connectionUrl;
}
}