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package oracle.toplink.essentials.threetier;
import java.util.*;
import oracle.toplink.essentials.internal.databaseaccess.*;
import oracle.toplink.essentials.sessions.Login;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.localization.*;
/**
* <p>
* <b>Purpose</b>: Used to specify how connection should be pooled in a server session.
* @see ServerSession
*/
public class ConnectionPool {
protected boolean isConnected;
protected int maxNumberOfConnections;
protected int minNumberOfConnections;
protected Vector connectionsAvailable;
protected Vector connectionsUsed;
protected Login login;
protected String name;
protected ServerSession owner;
/**
* PUBLIC:
* A connection pool is used to specify how connection should be pooled in a server session.
*/
public ConnectionPool() {
this.maxNumberOfConnections = 50;
this.minNumberOfConnections = 3;
resetConnections();
}
/**
* PUBLIC:
* A connection pool is used to specify how connection should be pooled in a server session.
*/
public ConnectionPool(String name, Login login, int minNumberOfConnections, int maxNumberOfConnections, ServerSession owner) {
this.login = login;
this.owner = owner;
this.name = name;
this.maxNumberOfConnections = maxNumberOfConnections;
this.minNumberOfConnections = minNumberOfConnections;
resetConnections();
}
/**
* INTERNAL:
* Wait until a connection is avaiable and allocate the connection for the client.
*/
public synchronized Accessor acquireConnection() throws ConcurrencyException {
while (!hasConnectionAvailable()) {
if (getTotalNumberOfConnections() < getMaxNumberOfConnections()) {
Accessor connection = buildConnection();
getConnectionsUsed().addElement(connection);
return connection;
}
try {
wait();// Notify is called when connections are released.
} catch (InterruptedException exception) {
throw ConcurrencyException.waitFailureOnClientSession(exception);
}
}
Accessor connection = (Accessor)getConnectionsAvailable().firstElement();
getConnectionsAvailable().removeElement(connection);
getConnectionsUsed().addElement(connection);
getOwner().updateProfile(getName(), new Integer(getConnectionsUsed().size()));
return connection;
}
/**
* INTERNAL:
* Create a new connection, accessors are used as connections.
*/
protected Accessor buildConnection() {
Login localLogin = (Login)getLogin().clone();
Accessor connection = localLogin.buildAccessor();
connection.connect(localLogin, getOwner());
return connection;
}
/**
* INTERNAL:
* returns the connections currently available for use in the pool
*/
public Vector getConnectionsAvailable() {
return connectionsAvailable;
}
/**
* Return a list of the connections that are being used.
* @return java.util.Vector
**/
protected Vector getConnectionsUsed() {
return connectionsUsed;
}
/**
* PUBLIC:
* Return the login used to create connections.
*/
public Login getLogin() {
return login;
}
/**
* PUBLIC:
* Return the maximum number of connections allowed.
* When the max is reached clients must wait for a connection to become available.
*/
public int getMaxNumberOfConnections() {
return maxNumberOfConnections;
}
/**
* PUBLIC:
* Return the minimum number of connections.
* These connection will be create on startup.
*/
public int getMinNumberOfConnections() {
return minNumberOfConnections;
}
/**
* PUBLIC:
* Return the name of this pool.
* Pools are identified by name to allow multiple connection pools.
*/
public String getName() {
return name;
}
/**
* Return the ServerSession that is the owner of this connection pool.
* @return oracle.toplink.essentials.threetier.ServerSession
*/
protected ServerSession getOwner() {
return owner;
}
/**
* INTERNAL:
* Return the total number of connections currently in use.
*/
public int getTotalNumberOfConnections() {
return getConnectionsUsed().size() + getConnectionsAvailable().size();
}
/**
* INTERNAL:
* Wait until a connection is avaiable and allocate the connection for the client.
*/
public boolean hasConnectionAvailable() {
return !getConnectionsAvailable().isEmpty();
}
/**
* INTERNAL:
* Return if this pool has been connected to the database.
*/
public boolean isConnected() {
return isConnected;
}
/**
* INTERNAL:
* Checks for a conflict between pool's type and pool's login
*/
public boolean isThereConflictBetweenLoginAndType() {
return getLogin().shouldUseExternalConnectionPooling();
}
/**
* INTERNAL:
* Add the connection as single that a new connection is available.
*/
public synchronized void releaseConnection(Accessor connection) throws DatabaseException {
getConnectionsUsed().removeElement(connection);
if (getTotalNumberOfConnections() < getMinNumberOfConnections()) {
getConnectionsAvailable().addElement(connection);
} else {
connection.disconnect(getOwner());
}
notify();
}
/**
* INTERNAL:
* Reset the connections on shutDown and when the pool is started.
*/
public void resetConnections() {
this.connectionsUsed = new Vector();
this.connectionsAvailable = new Vector();
}
/**
* INTERNAL:
* Set this list of connections available
* @param java.util.Vector
*/
protected void setConnectionsAvailable(Vector connectionsAvailable) {
this.connectionsAvailable = connectionsAvailable;
}
/**
* INTERNAL:
* Set the list of connections being used.
* @param java.util.Vector
*/
protected void setConnectionsUsed(Vector connectionsUsed) {
this.connectionsUsed = connectionsUsed;
}
/**
* INTERNAL:
* Set if this pool has been connected to the database.
*/
public void setIsConnected(boolean isConnected) {
this.isConnected = isConnected;
}
/**
* PUBLIC:
* Set the login used to create connections.
*/
public void setLogin(Login login) {
this.login = login;
}
/**
* PUBLIC:
* Set the maximum number of connections allowed.
* When the max is reached clients must wait for a connection to become available.
*/
public void setMaxNumberOfConnections(int maxNumberOfConnections) {
this.maxNumberOfConnections = maxNumberOfConnections;
}
/**
* PUBLIC:
* Set the minimum number of connections.
* These connection will be create on startup.
*/
public void setMinNumberOfConnections(int minNumberOfConnections) {
this.minNumberOfConnections = minNumberOfConnections;
}
/**
* PUBLIC:
* Set the name of this pool.
* Pools are identified by name to allow multiple connection pools.
*/
public void setName(String name) {
this.name = name;
}
/**
* Set the ServerSession that owns this connection pool
* @param oracle.toplink.essentials.threetier.ServerSession
*/
protected void setOwner(ServerSession owner) {
this.owner = owner;
}
/**
* INTERNAL:
* Disconnect all connections.
*/
public synchronized void shutDown() {
setIsConnected(false);
for (Enumeration avaiableEnum = getConnectionsAvailable().elements();
avaiableEnum.hasMoreElements();) {
try {
((Accessor)avaiableEnum.nextElement()).disconnect(getOwner());
} catch (DatabaseException exception) {
// Ignore.
}
}
for (Enumeration usedEnum = getConnectionsUsed().elements(); usedEnum.hasMoreElements();) {
try {
((Accessor)usedEnum.nextElement()).disconnect(getOwner());
} catch (DatabaseException exception) {
// Ignore.
}
}
resetConnections();
}
/**
* INTERNAL:
* Allocate the minimum connections.
*/
public synchronized void startUp() {
for (int index = getMinNumberOfConnections(); index > 0; index--) {
getConnectionsAvailable().addElement(buildConnection());
}
setIsConnected(true);
}
/**
* INTERNAL:
* return a string representation of this connection pool
*/
public String toString() {
Object[] args = { new Integer(getMinNumberOfConnections()), new Integer(getMaxNumberOfConnections()) };
return Helper.getShortClassName(getClass()) + ToStringLocalization.buildMessage("min_max", args);
}
}