ADD file via upload

ConnectionPoolManager.java

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+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * Object pool manager: Responsible for DatabaseConnection creation, reuse, and recycling
+ * @author chuyang
+ * @version 1.0
+ */
+public class ConnectionPoolManager {
+
+	/**
+	 * Connection pool storage
+	 */
+	private final List<DatabaseConnection> connectionPool;
+	/**
+	 * Database URL
+	 */
+	private final String databaseUrl;
+	/**
+	 * Initial pool size
+	 */
+	private final int initialSize;
+	/**
+	 * Maximum pool size
+	 */
+	private final int maxSize;
+	/**
+	 * For thread safety
+	 */
+	private final Lock poolLock = new ReentrantLock();
+	public DatabaseConnection m_DatabaseConnection;
+
+	public ConnectionPoolManager(){
+		this.connectionPool = new ArrayList<>();
+		this.databaseUrl = "";
+		this.initialSize = 0;
+		this.maxSize = 0;
+	}
+
+	@Override
+	public void finalize() throws Throwable {
+		// Close all connections
+		poolLock.lock();
+		try {
+			for (DatabaseConnection conn : connectionPool) {
+				System.out.println("Closing connection " + conn.getConnectionId());
+			}
+			connectionPool.clear();
+		} finally {
+			poolLock.unlock();
+		}
+	}
+	/**
+	 * Constructor: Initialize object pool
+	 * 
+	 * @param initialSize Initial number of connections
+	 * @param maxSize Maximum number of connections
+	 * @param databaseUrl Database URL
+	 */
+	public ConnectionPoolManager(int initialSize, int maxSize, String databaseUrl){
+		if (initialSize < 0 || maxSize < initialSize) {
+			throw new IllegalArgumentException("Invalid pool size parameters");
+		}
+		this.connectionPool = new ArrayList<>(maxSize);
+		this.databaseUrl = databaseUrl;
+		this.initialSize = initialSize;
+		this.maxSize = maxSize;
+		
+		// Initialize connection pool
+		initializePool();
+	}
+
+	/**
+	 * Initialize the connection pool, create initial connections
+	 */
+	private void initializePool() {
+		System.out.println("Initializing connection pool with " + initialSize + " connections");
+		for (int i = 0; i < initialSize; i++) {
+			String connId = "conn-" + i;
+			DatabaseConnection conn = new DatabaseConnection(connId, databaseUrl);
+			connectionPool.add(conn);
+		}
+		System.out.println("Connection pool initialized with " + connectionPool.size() + " connections");
+	}
+
+	/**
+	 * Borrow a connection from the pool
+	 * @return Available connection, or null (pool is full)
+	 */
+	public DatabaseConnection borrowConnection(){
+		poolLock.lock();
+		try {
+			// 1. Look for idle connection
+			for (DatabaseConnection conn : connectionPool) {
+				if (!conn.isInUse()) {
+					conn.setInUse(true);
+					System.out.println("Borrowed existing connection: " + conn.getConnectionId());
+					return conn;
+				}
+			}
+			
+			// 2. If no idle connections and max size not reached, create new connection
+			if (connectionPool.size() < maxSize) {
+				String connId = "conn-" + connectionPool.size();
+				DatabaseConnection newConn = new DatabaseConnection(connId, databaseUrl);
+				newConn.setInUse(true);
+				connectionPool.add(newConn);
+				System.out.println("Created and borrowed new connection: " + newConn.getConnectionId());
+				return newConn;
+			}
+			
+			// 3. Pool is full, return null
+			System.out.println("Connection pool is full, no available connections");
+			return null;
+		} finally {
+			poolLock.unlock();
+		}
+	}
+
+	/**
+	 * Return connection to the pool
+	 * 
+	 * @param conn Connection to return
+	 */
+	public void returnConnection(DatabaseConnection conn){
+		if (conn == null) {
+			return;
+		}
+		
+		poolLock.lock();
+		try {
+			// Check if connection belongs to this pool
+			if (connectionPool.contains(conn)) {
+				// Reset connection state
+				conn.reset();
+				conn.setInUse(false);
+				System.out.println("Connection returned to pool: " + conn.getConnectionId());
+			} else {
+				System.out.println("Warning: Attempting to return a connection not managed by this pool");
+			}
+		} finally {
+			poolLock.unlock();
+		}
+	}
+
+	/**
+	 * Shrink pool: Destroy idle connections
+	 */
+	public void shrinkPool(){
+		poolLock.lock();
+		try {
+			// Only keep initial size of connections
+			List<DatabaseConnection> connectionsToRemove = new ArrayList<>();
+			int activeConnections = 0;
+			
+			for (DatabaseConnection conn : connectionPool) {
+				if (conn.isInUse()) {
+					activeConnections++;
+				} else if (connectionPool.size() - connectionsToRemove.size() > initialSize) {
+					connectionsToRemove.add(conn);
+					System.out.println("Removing idle connection: " + conn.getConnectionId());
+				}
+			}
+			
+			connectionPool.removeAll(connectionsToRemove);
+			System.out.println("Pool shrunk. Active connections: " + activeConnections + ", Idle connections: " + connectionPool.size() + ", Removed: " + connectionsToRemove.size());
+		} finally {
+			poolLock.unlock();
+		}
+	}
+	
+	/**
+	 * Get pool status information
+	 */
+	public String getPoolStatus() {
+		poolLock.lock();
+		try {
+			int activeConnections = 0;
+			for (DatabaseConnection conn : connectionPool) {
+				if (conn.isInUse()) {
+					activeConnections++;
+				}
+			}
+			return "Pool status: " + connectionPool.size() + " total connections, " + 
+				   activeConnections + " active, " + 
+				   (connectionPool.size() - activeConnections) + " idle, " +
+				   "Max capacity: " + maxSize;
+		} finally {
+			poolLock.unlock();
+		}
+	}
+}