Unit tests for transaction isolation. #272

briar-tests/src/org/briarproject/db/TransactionIsolationTest.java

+package org.briarproject.db;
+
+import org.briarproject.BriarTestCase;
+import org.briarproject.TestUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public class TransactionIsolationTest extends BriarTestCase {
+
+	private static final String DROP_TABLE = "DROP TABLE foo IF EXISTS";
+	private static final String CREATE_TABLE = "CREATE TABLE foo"
+			+ " (key INT NOT NULL,"
+			+ " counter INT NOT NULL)";
+	private static final String INSERT_ROW =
+			"INSERT INTO foo (key, counter) VALUES (1, 123)";
+	private static final String GET_COUNTER =
+			"SELECT counter FROM foo WHERE key = 1";
+	private static final String SET_COUNTER =
+			"UPDATE foo SET counter = ? WHERE key = 1";
+
+	private final File testDir = TestUtils.getTestDirectory();
+	private final File db = new File(testDir, "db");
+	private final String withMvcc = "jdbc:h2:" + db.getAbsolutePath()
+			+ ";MV_STORE=TRUE;MVCC=TRUE";
+	private final String withoutMvcc = "jdbc:h2:" + db.getAbsolutePath()
+			+ ";MV_STORE=FALSE;MVCC=FALSE;LOCK_MODE=1";
+
+	@Before
+	public void setUp() throws Exception {
+		assertTrue(testDir.mkdirs());
+		Class.forName("org.h2.Driver");
+	}
+
+	@After
+	public void tearDown() throws Exception {
+		TestUtils.deleteTestDirectory(testDir);
+	}
+
+	@Test
+	public void testDoesNotReadUncommittedWritesWithMvcc() throws Exception {
+		Connection connection = openConnection(true);
+		try {
+			createTableAndInsertRow(connection);
+		} finally {
+			connection.close();
+		}
+		// Start the first transaction
+		Connection txn1 = openConnection(true);
+		try {
+			txn1.setAutoCommit(false);
+			// The first transaction should read the initial value
+			assertEquals(123, getCounter(txn1));
+			// The first transaction updates the value but doesn't commit it
+			assertEquals(1, setCounter(txn1, 234));
+			// Start the second transaction
+			Connection txn2 = openConnection(true);
+			try {
+				txn2.setAutoCommit(false);
+				// The second transaction should still read the initial value
+				assertEquals(123, getCounter(txn2));
+				// Commit the second transaction
+				txn2.commit();
+			} finally {
+				txn2.close();
+			}
+			// Commit the first transaction
+			txn1.commit();
+		} finally {
+			txn1.close();
+		}
+	}
+
+	@Test
+	public void testLastWriterWinsWithMvcc() throws Exception {
+		Connection connection = openConnection(true);
+		try {
+			createTableAndInsertRow(connection);
+		} finally {
+			connection.close();
+		}
+		// Start the first transaction
+		Connection txn1 = openConnection(true);
+		try {
+			txn1.setAutoCommit(false);
+			// The first transaction should read the initial value
+			assertEquals(123, getCounter(txn1));
+			// The first transaction updates the value but doesn't commit it
+			assertEquals(1, setCounter(txn1, 234));
+			// Start the second transaction
+			Connection txn2 = openConnection(true);
+			try {
+				txn2.setAutoCommit(false);
+				// The second transaction should still read the initial value
+				assertEquals(123, getCounter(txn2));
+				// Commit the first transaction
+				txn1.commit();
+				// The second transaction updates the value
+				assertEquals(1, setCounter(txn2, 345));
+				// Commit the second transaction
+				txn2.commit();
+			} finally {
+				txn2.close();
+			}
+		} finally {
+			txn1.close();
+		}
+		// The second transaction was the last writer, so it should win
+		connection = openConnection(true);
+		try {
+			assertEquals(345, getCounter(connection));
+		} finally {
+			connection.close();
+		}
+	}
+
+	@Test
+	public void testLockTimeoutOnRowWithMvcc() throws Exception {
+		Connection connection = openConnection(true);
+		try {
+			createTableAndInsertRow(connection);
+		} finally {
+			connection.close();
+		}
+		// Start the first transaction
+		Connection txn1 = openConnection(true);
+		try {
+			txn1.setAutoCommit(false);
+			// The first transaction should read the initial value
+			assertEquals(123, getCounter(txn1));
+			// Start the second transaction
+			Connection txn2 = openConnection(true);
+			try {
+				txn2.setAutoCommit(false);
+				// The second transaction should read the initial value
+				assertEquals(123, getCounter(txn2));
+				// The first transaction updates the value but doesn't commit it
+				assertEquals(1, setCounter(txn1, 234));
+				// The second transaction tries to update the value
+				try {
+					setCounter(txn2, 345);
+					fail();
+				} catch (SQLException expected) {
+					// Expected: the row is locked by the first transaction
+				}
+				// Abort the transactions
+				txn1.rollback();
+				txn2.rollback();
+			} finally {
+				txn2.close();
+			}
+		} finally {
+			txn1.close();
+		}
+	}
+
+	@Test
+	public void testReadLockTimeoutOnTableWithoutMvcc() throws Exception {
+		Connection connection = openConnection(false);
+		try {
+			createTableAndInsertRow(connection);
+		} finally {
+			connection.close();
+		}
+		// Start the first transaction
+		Connection txn1 = openConnection(false);
+		try {
+			txn1.setAutoCommit(false);
+			// The first transaction should read the initial value
+			assertEquals(123, getCounter(txn1));
+			// Start the second transaction
+			Connection txn2 = openConnection(false);
+			try {
+				txn2.setAutoCommit(false);
+				// The second transaction should read the initial value
+				assertEquals(123, getCounter(txn2));
+				// The first transaction tries to update the value
+				try {
+					setCounter(txn1, 345);
+					fail();
+				} catch (SQLException expected) {
+					// Expected: the table is locked by the second transaction
+				}
+				// Abort the transactions
+				txn1.rollback();
+				txn2.rollback();
+			} finally {
+				txn2.close();
+			}
+		} finally {
+			txn1.close();
+		}
+	}
+
+	@Test
+	public void testWriteLockTimeoutOnTableWithoutMvcc() throws Exception {
+		Connection connection = openConnection(false);
+		try {
+			createTableAndInsertRow(connection);
+		} finally {
+			connection.close();
+		}
+		// Start the first transaction
+		Connection txn1 = openConnection(false);
+		try {
+			txn1.setAutoCommit(false);
+			// The first transaction should read the initial value
+			assertEquals(123, getCounter(txn1));
+			// The first transaction updates the value but doesn't commit yet
+			assertEquals(1, setCounter(txn1, 345));
+			// Start the second transaction
+			Connection txn2 = openConnection(false);
+			try {
+				txn2.setAutoCommit(false);
+				// The second transaction tries to read the value
+				try {
+					getCounter(txn2);
+					fail();
+				} catch (SQLException expected) {
+					// Expected: the table is locked by the first transaction
+				}
+				// Abort the transactions
+				txn1.rollback();
+				txn2.rollback();
+			} finally {
+				txn2.close();
+			}
+		} finally {
+			txn1.close();
+		}
+	}
+
+	private Connection openConnection(boolean mvcc) throws SQLException {
+		return DriverManager.getConnection(mvcc ? withMvcc : withoutMvcc);
+	}
+
+	private void createTableAndInsertRow(Connection c) throws SQLException {
+		Statement s = c.createStatement();
+		s.executeUpdate(DROP_TABLE);
+		s.executeUpdate(CREATE_TABLE);
+		s.executeUpdate(INSERT_ROW);
+		s.close();
+	}
+
+	private int getCounter(Connection c) throws SQLException {
+		Statement s = c.createStatement();
+		ResultSet rs = s.executeQuery(GET_COUNTER);
+		assertTrue(rs.next());
+		int counter = rs.getInt(1);
+		assertFalse(rs.next());
+		rs.close();
+		s.close();
+		return counter;
+	}
+
+	private int setCounter(Connection c, int counter)
+			throws SQLException {
+		PreparedStatement ps = c.prepareStatement(SET_COUNTER);
+		ps.setInt(1, counter);
+		int rowsAffected = ps.executeUpdate();
+		ps.close();
+		return rowsAffected;
+	}
+}