import java.io.IOException;
import java.io.InputStream;
+import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
+import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map.Entry;
import java.util.Properties;
import java.util.StringJoiner;
import java.util.regex.Matcher;
public class DatabaseConnection {
- public static final int CURRENT_SCHEMA_VERSION = 5;
+ public static final int MAX_CACHED_INSTANCES = 3;
+
+ private static class StatementDescriptor {
+
+ String query;
+
+ boolean scrollable;
+
+ int instance;
+
+ PreparedStatement target;
+
+ public StatementDescriptor(String query, boolean scrollable) {
+ this.query = query;
+ this.scrollable = scrollable;
+ this.instance = 0;
+ }
+
+ public synchronized void instanciate(Connection c) throws SQLException {
+ if (scrollable) {
+ target = c.prepareStatement(query, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+ } else {
+ target = c.prepareStatement(query, query.startsWith("SELECT ") ? Statement.NO_GENERATED_KEYS : Statement.RETURN_GENERATED_KEYS);
+ }
+
+ }
+
+ public synchronized PreparedStatement getTarget() {
+ return target;
+ }
+
+ public synchronized void increase() {
+ if (target != null) {
+ throw new IllegalStateException();
+ }
+ instance++;
+ }
+
+ @Override
+ public int hashCode() {
+ final int prime = 31;
+ int result = 1;
+ result = prime * result + instance;
+ result = prime * result + ((query == null) ? 0 : query.hashCode());
+ result = prime * result + (scrollable ? 1231 : 1237);
+ return result;
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (obj == null) {
+ return false;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ StatementDescriptor other = (StatementDescriptor) obj;
+ if (instance != other.instance) {
+ return false;
+ }
+ if (query == null) {
+ if (other.query != null) {
+ return false;
+ }
+ } else if ( !query.equals(other.query)) {
+ return false;
+ }
+ if (scrollable != other.scrollable) {
+ return false;
+ }
+ return true;
+ }
+
+ }
+
+ public static final int CURRENT_SCHEMA_VERSION = 9;
public static final int CONNECTION_TIMEOUT = 24 * 60 * 60;
private Connection c;
- private HashMap<String, GigiPreparedStatement> statements = new HashMap<String, GigiPreparedStatement>();
+ private HashMap<StatementDescriptor, PreparedStatement> statements = new HashMap<StatementDescriptor, PreparedStatement>();
+
+ HashSet<PreparedStatement> underUse = new HashSet<>();
private static Properties credentials;
}
}
- public GigiPreparedStatement prepare(String query) {
- ensureOpen();
- query = preprocessQuery(query);
- GigiPreparedStatement statement = statements.get(query);
- if (statement == null) {
- try {
- statement = new GigiPreparedStatement(c.prepareStatement(query, query.startsWith("SELECT ") ? Statement.NO_GENERATED_KEYS : Statement.RETURN_GENERATED_KEYS));
- } catch (SQLException e) {
- throw new Error(e);
- }
- statements.put(query, statement);
- }
- return statement;
+ protected synchronized PreparedStatement prepareInternal(String query) throws SQLException {
+ return prepareInternal(query, false);
}
- public GigiPreparedStatement prepareScrollable(String query) {
+ protected synchronized PreparedStatement prepareInternal(String query, boolean scrollable) throws SQLException {
+
ensureOpen();
query = preprocessQuery(query);
- GigiPreparedStatement statement = statements.get(query);
- if (statement == null) {
- try {
- statement = new GigiPreparedStatement(c.prepareStatement(query, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY));
- } catch (SQLException e) {
- throw new Error(e);
+ StatementDescriptor searchHead = new StatementDescriptor(query, scrollable);
+ PreparedStatement statement = null;
+ while (statement == null) {
+ statement = statements.get(searchHead);
+ if (statement == null) {
+ searchHead.instanciate(c);
+ statement = searchHead.getTarget();
+ if (searchHead.instance >= MAX_CACHED_INSTANCES) {
+ return statement;
+ }
+ underUse.add(statement);
+ statements.put(searchHead, statement);
+ } else if (underUse.contains(statement)) {
+ searchHead.increase();
+ statement = null;
+ } else {
+ underUse.add(statement);
}
- statements.put(query, statement);
}
return statement;
}
+ protected synchronized PreparedStatement prepareInternalScrollable(String query) throws SQLException {
+ return prepareInternal(query, true);
+ }
+
private long lastAction = System.currentTimeMillis();
private void ensureOpen() {
lastAction = System.currentTimeMillis();
}
- private static ThreadLocal<DatabaseConnection> instances = new ThreadLocal<DatabaseConnection>() {
+ private static volatile DatabaseConnection instance;
- @Override
- protected DatabaseConnection initialValue() {
- return new DatabaseConnection();
+ public static synchronized DatabaseConnection getInstance() {
+ if (instance == null) {
+ instance = new DatabaseConnection();
}
- };
-
- public static DatabaseConnection getInstance() {
- return instances.get();
+ return instance;
}
public static boolean isInited() {
throw new Error("Re-initiaizing is forbidden.");
}
credentials = conf;
- GigiResultSet rs = getInstance().prepare("SELECT version FROM \"schemeVersion\" ORDER BY version DESC LIMIT 1;").executeQuery();
int version = 0;
- if (rs.next()) {
- version = rs.getInt(1);
+ try (GigiPreparedStatement gigiPreparedStatement = new GigiPreparedStatement("SELECT version FROM \"schemeVersion\" ORDER BY version DESC LIMIT 1;")) {
+ GigiResultSet rs = gigiPreparedStatement.executeQuery();
+ if (rs.next()) {
+ version = rs.getInt(1);
+ }
}
if (version == CURRENT_SCHEMA_VERSION) {
return; // Good to go
}
return ident;
}
+
+ protected synchronized void returnStatement(PreparedStatement target) throws SQLException {
+ if ( !underUse.remove(target)) {
+ target.close();
+ }
+ }
+
+ public synchronized int getNumberOfLockedStatements() {
+ return underUse.size();
+ }
+
+ public synchronized void lockedStatements(PrintWriter writer) {
+ writer.println(underUse.size());
+ for (PreparedStatement ps : underUse) {
+ for (Entry<StatementDescriptor, PreparedStatement> e : statements.entrySet()) {
+ if (e.getValue() == ps) {
+ writer.println("<br/>");
+ writer.println(e.getKey().instance + ":");
+
+ writer.println(e.getKey().query);
+ }
+ }
+ }
+ }
}