org.jgroups.protocols.JDBC_PING Maven / Gradle / Ivy
package org.jgroups.protocols;
import org.jgroups.Address;
import org.jgroups.Event;
import org.jgroups.PhysicalAddress;
import org.jgroups.View;
import org.jgroups.annotations.Property;
import org.jgroups.util.Responses;
import org.jgroups.util.UUID;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.*;
import java.util.List;
/**
* Discovery protocol using a JDBC connection to a shared database.
* Connection options can be defined as configuration properties, or the JNDI
* name of a DataSource can be provided (avoid providing both).
*
* Both the schema and the used SQL statements can be customized; make sure
* the order of parameters of such customized SQL statements is maintained and
* that compatible types are used for the columns. The recommended schema uses a
* single table, with two String columns being used primary key (local address,
* cluster name) and a third column to store the serialized form of the objects
* needed by JGroups.
*
* A default table will be created at first connection, errors during this
* operation are not considered critical. Set the initialize_sql
* to an empty value to prevent this initial table creation, or change it to
* create a customized table.
*
* @author Sanne Grinovero
* @since 2.12
*/
public class JDBC_PING extends Discovery {
/* ----------------------------------------- Properties -------------------------------------------------- */
@Property(description = "The JDBC connection URL", writable = false)
protected String connection_url = null;
@Property(description = "The JDBC connection username", writable = false)
protected String connection_username = null;
@Property(description = "The JDBC connection password", writable = false,exposeAsManagedAttribute=false)
protected String connection_password = null;
@Property(description = "The JDBC connection driver name", writable = false)
protected String connection_driver = null;
@Property(description = "If not empty, this SQL statement will be performed at startup."
+ "Customize it to create the needed table on those databases which permit table creation attempt without loosing data, such as "
+ "PostgreSQL and MySQL (using IF NOT EXISTS). To allow for creation attempts, errors performing this statement will be logged"
+ "but not considered fatal. To avoid any DDL operation, set this to an empty string.")
protected String initialize_sql =
"CREATE TABLE JGROUPSPING (" +
"own_addr varchar(200) NOT NULL, " +
"cluster_name varchar(200) NOT NULL, " +
"ping_data varbinary(5000) DEFAULT NULL, " +
"PRIMARY KEY (own_addr, cluster_name) )";
@Property(description = "SQL used to insert a new row. Customizable, but keep the order of parameters and pick compatible types: " +
"1)Own Address, as String 2)Cluster name, as String 3)Serialized PingData as byte[]")
protected String insert_single_sql = "INSERT INTO JGROUPSPING (own_addr, cluster_name, ping_data) values (?, ?, ?)";
@Property(description = "SQL used to delete a row. Customizable, but keep the order of parameters and pick compatible types: " +
"1)Own Address, as String 2)Cluster name, as String")
protected String delete_single_sql = "DELETE FROM JGROUPSPING WHERE own_addr=? AND cluster_name=?";
@Property(description = "SQL used to fetch all node's PingData. Customizable, but keep the order of parameters and pick compatible types: " +
"only one parameter needed, String compatible, representing the Cluster name. Must return a byte[], the Serialized PingData as" +
" it was stored by the insert_single_sql statement")
protected String select_all_pingdata_sql = "SELECT ping_data FROM JGROUPSPING WHERE cluster_name=?";
@Property(description = "To use a DataSource registered in JNDI, specify the JNDI name here. " +
"This is an alternative to all connection_* configuration options: if this property is not empty, then all connection related" +
"properties must be empty.")
protected String datasource_jndi_name;
/* --------------------------------------------- Fields ------------------------------------------------------ */
private DataSource dataSourceFromJNDI = null;
public boolean isDynamic() {return true;}
@Override
public void init() throws Exception {
super.init();
verifyconfigurationParameters();
if (stringIsEmpty(datasource_jndi_name))
loadDriver();
else
dataSourceFromJNDI = getDataSourceFromJNDI(datasource_jndi_name.trim());
attemptSchemaInitialization();
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
remove(cluster_name, local_addr);
}
});
}
@Override
public void stop() {
try {
deleteSelf();
} catch (SQLException e) {
log.error("Error while unregistering of our own Address from JDBC_PING database during shutdown", e);
}
super.stop();
}
public Object down(Event evt) {
switch(evt.getType()) {
case Event.VIEW_CHANGE:
View old_view=view;
boolean previous_coord=is_coord;
Object retval=super.down(evt);
View new_view=(View)evt.getArg();
handleView(new_view, old_view, previous_coord != is_coord);
return retval;
}
return super.down(evt);
}
public void findMembers(final List members, final boolean initial_discovery, Responses responses) {
readAll(members, cluster_name, responses);
writeOwnInformation();
}
// remove all files which are not from the current members
protected void handleView(View new_view, View old_view, boolean coord_changed) {
if(is_coord && old_view != null && new_view != null) {
Address[][] diff=View.diff(old_view, new_view);
Address[] left_mbrs=diff[1];
for(Address left_mbr: left_mbrs)
if(left_mbr != null && !new_view.containsMember(left_mbr))
remove(cluster_name, left_mbr);
}
if(coord_changed)
writeOwnInformation();
}
/** Write my own UUID,logical name and physical address to a file */
protected void writeOwnInformation() {
PhysicalAddress physical_addr=(PhysicalAddress)down(new Event(Event.GET_PHYSICAL_ADDRESS,local_addr));
PingData data=new PingData(local_addr, is_server, UUID.get(local_addr), physical_addr).coord(is_coord);
writeToDB(data, cluster_name); // write my own data to file
}
//It's possible that multiple threads in the same cluster node invoke this concurrently;
//Since delete and insert operations are not atomic
//(and there is no SQL standard way to do this without introducing a transaction)
//we need the synchronization or risk a duplicate insertion on same primary key.
//This synchronization should not be a performance problem as this is just a Discovery protocol.
//Many SQL dialects have some "insert or update" expression, but that would need
//additional configuration and testing on each database. See JGRP-1440
protected synchronized void writeToDB(PingData data, String clustername) {
final String ownAddress = addressAsString(data.getAddress());
final Connection connection = getConnection();
if (connection != null) {
try {
delete(connection, clustername, ownAddress);
insert(connection, data, clustername, ownAddress);
} catch (SQLException e) {
log.error("Error updating JDBC_PING table", e);
} finally {
closeConnection(connection);
}
}
else {
log.error("Failed to store PingData in database");
}
}
protected void remove(String clustername, Address addr) {
final String addressAsString = addressAsString(addr);
try {
delete(clustername, addressAsString);
} catch (SQLException e) {
log.error("Error", e);
}
}
protected void readAll(List members, String clustername, Responses responses) {
final Connection connection = getConnection();
if (connection != null) {
try {
readAll(connection, members, clustername, responses);
} catch (SQLException e) {
log.error("Error reading JDBC_PING table", e);
} finally {
closeConnection(connection);
}
}
}
protected void readAll(Connection connection, List members, String clustername, Responses rsps) throws SQLException {
PreparedStatement ps = connection.prepareStatement(select_all_pingdata_sql);
try {
ps.setString(1, clustername);
ResultSet resultSet = ps.executeQuery();
while (resultSet.next()) {
byte[] bytes = resultSet.getBytes(1);
try {
PingData data=deserialize(bytes);
if(data == null || (members != null && !members.contains(data.getAddress())))
continue;
rsps.addResponse(data, false);
if(local_addr != null && !local_addr.equals(data.getAddress()))
addDiscoveryResponseToCaches(data.getAddress(), data.getLogicalName(), data.getPhysicalAddr());
}
catch(Exception e) {
int row=resultSet.getRow();
log.error("%s: failed deserializing row %d: %s; removing it from the table", local_addr, row, e);
try {
resultSet.deleteRow();
}
catch(Throwable t) {
log.error("%s: failed removing row %d: %s; please delete it manually", local_addr, row, e);
}
}
}
} finally {
ps.close();
}
}
protected void attemptSchemaInitialization() {
if(stringIsEmpty(initialize_sql)) {
log.debug("Table creation step skipped: initialize_sql property is missing");
return;
}
Connection connection=getConnection();
if(connection == null)
return;
try {
connection.prepareStatement(initialize_sql).execute();
log.debug("Table created for JDBC_PING Discovery Protocol");
}
catch(SQLException e) {
log.debug("Could not execute initialize_sql statement; not necessarily an error, we always attempt to create the schema. " +
"To suppress this message, set initialize_sql to an empty value. Cause: %s", e.getMessage());
}
finally {
try {
connection.close();
}
catch(SQLException e) {
log.error("Error closing connection", e);
}
}
}
protected void loadDriver() {
if (stringIsEmpty(connection_driver))
return;
log.debug("Registering JDBC Driver named '%s'", connection_driver);
try {
Class.forName(connection_driver);
} catch (ClassNotFoundException e) {
throw new IllegalArgumentException("JDBC Driver required for JDBC_PING "
+ "protocol could not be loaded: '" + connection_driver + "'");
}
}
protected Connection getConnection() {
if (dataSourceFromJNDI == null) {
Connection connection;
try {
connection = DriverManager.getConnection(connection_url, connection_username, connection_password);
} catch (SQLException e) {
log.error("Could not open connection to database", e);
return null;
}
if (connection == null) {
log.error("Received null connection from the DriverManager!");
}
return connection;
}
else {
try {
return dataSourceFromJNDI.getConnection();
} catch (SQLException e) {
log.error("Could not open connection to database", e);
return null;
}
}
}
protected synchronized void insert(Connection connection, PingData data, String clustername, String address) throws SQLException {
final byte[] serializedPingData = serializeWithoutView(data);
PreparedStatement ps = connection.prepareStatement(insert_single_sql);
try {
ps.setString(1, address);
ps.setString(2, clustername);
ps.setBytes(3, serializedPingData);
ps.executeUpdate();
log.debug("Registered %s for clustername %s into database", address, clustername);
} finally {
ps.close();
}
}
protected synchronized void delete(Connection connection, String clustername, String addressToDelete) throws SQLException {
PreparedStatement ps = connection.prepareStatement(delete_single_sql);
try {
ps.setString(1, addressToDelete);
ps.setString(2, clustername);
ps.executeUpdate();
log.debug("Removed %s for clustername %s from database", addressToDelete, clustername);
} finally {
ps.close();
}
}
protected void delete(String clustername, String addressToDelete) throws SQLException {
final Connection connection = getConnection();
if (connection != null) {
try {
delete(connection, clustername, addressToDelete);
} catch (SQLException e) {
log.error("Error updating JDBC_PING table", e);
} finally {
closeConnection(connection);
}
} else {
log.error("Failed to delete PingData in database");
}
}
protected void deleteSelf() throws SQLException {
final String ownAddress = addressAsString(local_addr);
delete(cluster_name, ownAddress);
}
protected void closeConnection(final Connection connection) {
try {
connection.close();
} catch (SQLException e) {
log.error("Error closing connection to JDBC_PING database", e);
}
}
protected DataSource getDataSourceFromJNDI(String name) {
final DataSource dataSource;
InitialContext ctx = null;
try {
ctx = new InitialContext();
Object wathever = ctx.lookup(name);
if (wathever == null) {
throw new IllegalArgumentException(
"JNDI name " + name + " is not bound");
} else if (!(wathever instanceof DataSource)) {
throw new IllegalArgumentException(
"JNDI name " + name + " was found but is not a DataSource");
} else {
dataSource = (DataSource) wathever;
log.debug("Datasource found via JNDI lookup via name: '%s'", name);
return dataSource;
}
} catch (NamingException e) {
throw new IllegalArgumentException(
"Could not lookup datasource " + name, e);
} finally {
if (ctx != null) {
try {
ctx.close();
} catch (NamingException e) {
log.warn("Failed to close naming context.", e);
}
}
}
}
protected void verifyconfigurationParameters() {
if (stringIsEmpty(this.connection_url) ||
stringIsEmpty(this.connection_driver) ||
stringIsEmpty(this.connection_username) ) {
if (stringIsEmpty(this.datasource_jndi_name)) {
throw new IllegalArgumentException("Either the 4 configuration properties starting with 'connection_' or the datasource_jndi_name must be set");
}
}
if (stringNotEmpty(this.connection_url) ||
stringNotEmpty(this.connection_driver) ||
stringNotEmpty(this.connection_username) ) {
if (stringNotEmpty(this.datasource_jndi_name)) {
throw new IllegalArgumentException("When using the 'datasource_jndi_name' configuration property, all properties starting with 'connection_' must not be set");
}
}
if (stringIsEmpty(this.insert_single_sql)) {
throw new IllegalArgumentException("The insert_single_sql configuration property is mandatory");
}
if (stringIsEmpty(this.delete_single_sql)) {
throw new IllegalArgumentException("The delete_single_sql configuration property is mandatory");
}
if (stringIsEmpty(this.select_all_pingdata_sql)) {
throw new IllegalArgumentException("The select_all_pingdata_sql configuration property is mandatory");
}
}
private static final boolean stringIsEmpty(final String value) {
return value == null || value.trim().isEmpty();
}
private static final boolean stringNotEmpty(final String value) {
return !stringIsEmpty(value);
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy