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UCPHarvesting.java
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/* Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.*/
/*
* DESCRIPTION
*
* This code sample illustrates how applications use the connection harvesting
* feature of Oracle Universal Connection Pool (UCP).
*
* Connection Harvesting allows a specified number of borrowed connections
* to be reclaimed when the connection pool reaches a specified number of
* available connections. Least recently used connections are harvested first.
*
* This feature helps to ensure that a certain number of connections are
* always available in the pool to maximize performance.
*
* UCP gives applications control over which borrowed connections can be
* harvested. By default, all connections are harvestable. Applications
* can use the HarvestableConnection interface to explicitly specify
* whether a connection is harvestable.
*
* For harvestable connections, UCP also provides ConnectionHarvestingCallback
* that allows applications to perform customized cleanup tasks when
* connections are harvested by the pool.
*
* It is required that applications have both ucp.jar and Oracle JDBC
* driver jar(s) (such as ojdbc8.jar or ojdbc7.jar) on the classpath,
* and that the database backend supports SQL (this sample uses an
* Oracle Database and the default HR schema).
*
* To run the sample, you must provide non-default and working values
* for ALL 3 of user, password, and URL. This can be done by either updating
* this file directly or supplying the 3 values as command-line options
* and user input. The password is read from console or standard input.
* java UCPHarvesting -l <url> -u <user>
* If you do not update all the defaults, the program proceeds but
* will hit error when connecting.
*/
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import oracle.ucp.ConnectionHarvestingCallback;
import oracle.ucp.admin.UniversalConnectionPoolManagerImpl;
import oracle.ucp.jdbc.HarvestableConnection;
import oracle.ucp.jdbc.PoolDataSource;
import oracle.ucp.jdbc.PoolDataSourceFactory;
public class UCPHarvesting {
final static String DEFAULT_URL = "jdbc:oracle:thin:@//myhost:myport/myservice";
final static String DEFAULT_USER = "myuser";
final static String DEFAULT_PASSWORD = "mypassword";
final static String CONN_FACTORY_CLASS = "oracle.jdbc.pool.OracleDataSource";
// You must provide non-default values for ALL 3 to execute the program
static String url = DEFAULT_URL;
static String user = DEFAULT_USER;
static String password = DEFAULT_PASSWORD;
public static void main(String args[]) throws Exception {
UCPHarvesting sample = new UCPHarvesting();
getRealUserPasswordUrl(args);
sample.run();
}
void run() throws Exception {
runDefaultAllConnectionsHarvestable();
runWithNonHarvestableConnections();
}
void runDefaultAllConnectionsHarvestable() throws Exception {
show("\n*** Run with default: all connections are harvestable ***");
try {
int INITIAL_POOL_SIZE = 10;
final String POOL_NAME = "UCPHarvesting_pool1";
Connection conns[] = new Connection[INITIAL_POOL_SIZE];
PoolDataSource pds = createPoolDataSource(POOL_NAME);
/*
* ConnectionHarvestTriggerCount specifies the available connections
* threshold that triggers connection harvesting. For example, if the
* connection harvest trigger count is set to 5, connection harvesting
* is triggered when the number of available connections in the pool
* drops to 5.
*
* A value of Integer.MAX_VALUE disables connection harvesting.
* By default, connection harvesting is disabled.
*/
pds.setConnectionHarvestTriggerCount(5);
/*
* ConnectionHarvestMaxumCount specifies the maximum number of
* borrowed connections that can be returned to the pool, once
* connection harvesting is triggered. The default is 1.
*/
pds.setConnectionHarvestMaxCount(2);
show("Connection pool " + POOL_NAME + " configured");
show("Initial pool size: " + pds.getInitialPoolSize());
show("\nBorrowing 4 connections, conns[0] and conns[1] are LRU");
TestHarvestingCallback[] cbks = new TestHarvestingCallback[5];
for (int i = 0; i < 4; i++) {
conns[i] = pds.getConnection();
// Register harvesting callbacks to cleanup reclaimed connections.
cbks[i] = new TestHarvestingCallback(conns[i]);
((HarvestableConnection) conns[i]).registerConnectionHarvestingCallback(cbks[i]);
makeJDBCCalls(conns[i]);
}
showPoolStatistics("\nAfter borrowing 4 connections", pds);
// Borrowing the 5th connection to trigger harvesting
show("\nBorrowing 5th connection to trigger harvesting ...");
conns[4] = pds.getConnection();
cbks[4] = new TestHarvestingCallback(conns[4]);
((HarvestableConnection) conns[4]).registerConnectionHarvestingCallback(cbks[4]);
// Harvesting should happen
Thread.sleep(15000);
// After harvesting, there will be 7 available connections and
// 3 borrowed connections in the pool.
showPoolStatistics("\nAfter harvesting", pds);
// conns[0] and [1]'s physical connections should be "harvested"
// by the pool and these two logical connections should be closed
show("\nChecking on the 5 borrowed connections ...");
show(" conns[0] should be closed -- " + conns[0].isClosed());
show(" conns[1] should be closed -- " + conns[1].isClosed());
show(" conns[2] should be open -- " + !conns[2].isClosed());
show(" conns[3] should be open -- " + !conns[3].isClosed());
show(" conns[4] should be open -- " + !conns[4].isClosed());
// Returning all connections to pool.
for (int i = 2; i < 5; i++)
conns[i].close();
destroyConnectionPool(POOL_NAME);
} catch (Throwable e) {
showError("runDefaultAllConnectionsHarvestable", e);
}
show("\n*** Run with default completes ***");
}
void runWithNonHarvestableConnections() throws Exception {
show("\n*** Run with non-harvestable connections ***");
try {
int INITIAL_POOL_SIZE = 10;
final String POOL_NAME = "UCPHarvesting_pool2";
Connection conns[] = new Connection[INITIAL_POOL_SIZE];
PoolDataSource pds = createPoolDataSource(POOL_NAME);
/*
* ConnectionHarvestTriggerCount specifies the available connections
* threshold that triggers connection harvesting. For example, if the
* connection harvest trigger count is set to 5, connection harvesting
* is triggered when the number of available connections in the pool
* drops to 5.
*
* A value of Integer.MAX_VALUE disables connection harvesting.
* By default, connection harvesting is disabled.
*/
pds.setConnectionHarvestTriggerCount(5);
/*
* ConnectionHarvestMaxumCount specifies the maximum number of
* borrowed connections that can be returned to the pool, once
* connection harvesting is triggered. The default is 1.
*/
pds.setConnectionHarvestMaxCount(2);
show("Connection pool " + POOL_NAME + " configured");
show("Initial pool size: " + pds.getInitialPoolSize());
show("\nBorrowing 4 connections, conns[0] and conns[1] are LRU");
TestHarvestingCallback[] cbks = new TestHarvestingCallback[5];
for (int i = 0; i < 4; i++) {
conns[i] = pds.getConnection();
// Register harvesting callbacks to cleanup reclaimed connections.
cbks[i] = new TestHarvestingCallback(conns[i]);
((HarvestableConnection) conns[i]).registerConnectionHarvestingCallback(cbks[i]);
makeJDBCCalls(conns[i]);
}
show("\nMarking conns[0] and conns[1] as non-harvestable");
// Assuming application is doing critical work on conns[0] and [1]
// and doesn't want those 2 connections to be "harvested".
// Mark conns[0] and [1] as non-harvestable connections.
((HarvestableConnection) conns[0]).setConnectionHarvestable(false);
((HarvestableConnection) conns[1]).setConnectionHarvestable(false);
showPoolStatistics("\nAfter borrowing 4 connections", pds);
// Borrowing the 5th connection to trigger harvesting
show("\nBorrowing 5th connection to trigger harvesting ...");
conns[4] = pds.getConnection();
cbks[4] = new TestHarvestingCallback(conns[4]);
((HarvestableConnection) conns[4]).registerConnectionHarvestingCallback(cbks[4]);
// Harvesting should happen
Thread.sleep(15000);
// After harvesting, there will be 7 available connections and
// 3 borrowed connections in the pool.
showPoolStatistics("\nAfter harvesting", pds);
// conns[2] and [3]'s physical connections should be "harvested"
// by the pool and these two logical connections should be closed.
// conns[0] and [1]'s physical connections will not be "harvested".
show("\nChecking on the 5 borrowed connections ...");
show(" conns[0] should be open -- " + !conns[0].isClosed());
show(" conns[1] should be open -- " + !conns[1].isClosed());
show(" conns[2] should be closed -- " + conns[2].isClosed());
show(" conns[3] should be closed -- " + conns[3].isClosed());
show(" conns[4] should be open -- " + !conns[4].isClosed());
// Returning all connections to pool.
conns[0].close();
conns[1].close();
conns[4].close();
destroyConnectionPool(POOL_NAME);
} catch (Throwable e) {
showError("runWithNonHarvestableConnections", e);
}
show("\n*** Run with non-harvestable connections completes ***");
}
// See sample UCPBasic.java for basic steps to set up a connection pool.
PoolDataSource createPoolDataSource(String poolName) throws Exception {
PoolDataSource pds = PoolDataSourceFactory.getPoolDataSource();
pds.setConnectionFactoryClassName(CONN_FACTORY_CLASS);
pds.setURL(url);
pds.setUser(user);
pds.setPassword(password);
pds.setConnectionPoolName(poolName);
pds.setInitialPoolSize(10);
pds.setMaxPoolSize(10);
pds.setTimeoutCheckInterval(5);
return pds;
}
void destroyConnectionPool(String poolName) {
try {
UniversalConnectionPoolManagerImpl.getUniversalConnectionPoolManager()
.destroyConnectionPool(poolName);
show("\nConnection pool " + poolName + " destroyed");
} catch (Throwable e) {
showError("destroyConnectinoPool", e);
}
}
void showPoolStatistics(String prompt, PoolDataSource pds)
throws SQLException {
show(prompt + " -");
show(" Available connections: " + pds.getAvailableConnectionsCount());
show(" Borrowed connections: " + pds.getBorrowedConnectionsCount());
}
// Simple query
void makeJDBCCalls(Connection conn) {
try (Statement statement = conn.createStatement()) {
statement.execute("SELECT 1 FROM DUAL");
} catch (SQLException exc) {
showError("makeJDBCCalls", exc);
}
}
static void show(String msg) {
System.out.println(msg);
}
static void showError(String msg, Throwable exc) {
System.out.println(msg + " hit error: " + exc.getMessage());
}
static void getRealUserPasswordUrl(String args[]) throws Exception {
// URL can be modified in file, or taken from command-line
url = getOptionValue(args, "-l", DEFAULT_URL);
// DB user can be modified in file, or taken from command-line
user = getOptionValue(args, "-u", DEFAULT_USER);
// DB user's password can be modified in file, or explicitly entered
readPassword(" Password for " + user + ": ");
}
// Get specified option value from command-line.
static String getOptionValue(
String args[], String optionName, String defaultVal) {
String argValue = "";
try {
int i = 0;
String arg = "";
boolean found = false;
while (i < args.length) {
arg = args[i++];
if (arg.equals(optionName)) {
if (i < args.length)
argValue = args[i++];
if (argValue.startsWith("-") || argValue.equals("")) {
argValue = defaultVal;
}
found = true;
}
}
if (!found) {
argValue = defaultVal;
}
} catch (Exception e) {
showError("getOptionValue", e);
}
return argValue;
}
static void readPassword(String prompt) throws Exception {
if (System.console() != null) {
char[] pchars = System.console().readPassword("\n[%s]", prompt);
if (pchars != null) {
password = new String(pchars);
java.util.Arrays.fill(pchars, ' ');
}
} else {
BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
show(prompt);
password = r.readLine();
}
}
/*
* Sample connection harvesting callback implementation.
*/
class TestHarvestingCallback implements ConnectionHarvestingCallback {
private Object objForCleanup = null;
public TestHarvestingCallback(Object objForCleanup) {
this.objForCleanup = objForCleanup;
}
public boolean cleanup() {
try {
doCleanup(objForCleanup);
} catch (Exception exc) {
return false;
}
return true;
}
private void doCleanup(Object obj) throws Exception {
((Connection) obj).close();
}
}
}