external-software/github_OpenIdentityPlatform_OpenDJ.git

			@@ -15,25 +15,62 @@
			*/
			package org.opends.server.backends.jdbc;

			import org.forgerock.opendj.server.config.server.JDBCBackendCfg;
			import org.opends.server.DirectoryServerTestCase;
			import org.opends.server.backends.pluggable.spi.AccessMode;
			import org.opends.server.backends.pluggable.spi.StorageRuntimeException;
			import org.opends.server.backends.pluggable.spi.TreeName;
			import org.opends.server.backends.pluggable.spi.WriteOperation;
			import org.opends.server.types.DirectoryException;
			import org.testng.annotations.AfterClass;
			import org.testng.annotations.BeforeClass;
			import org.testng.annotations.DataProvider;
			import org.testng.annotations.Test;

			import java.sql.Connection;
			import java.sql.DatabaseMetaData;
			import java.sql.Driver;
			import java.sql.DriverManager;
			import java.sql.DriverPropertyInfo;
			import java.sql.PreparedStatement;
			import java.sql.ResultSet;
			import java.sql.SQLException;
			import java.sql.SQLNonTransientConnectionException;
			import java.sql.SQLRecoverableException;
			import java.sql.Statement;
			import java.util.Properties;
			import java.util.concurrent.TimeUnit;
			import java.util.concurrent.atomic.AtomicInteger;
			import java.util.logging.Logger;

			import static org.forgerock.i18n.LocalizableMessage.raw;
			import static org.forgerock.opendj.ldap.ResultCode.OTHER;
			import static org.mockito.Mockito.any;
			import static org.mockito.Mockito.anyBoolean;
			import static org.mockito.Mockito.anyInt;
			import static org.mockito.Mockito.anyString;
			import static org.mockito.Mockito.doNothing;
			import static org.mockito.Mockito.doThrow;
			import static org.mockito.Mockito.mock;
			import static org.mockito.Mockito.never;
			import static org.mockito.Mockito.startsWith;
			import static org.mockito.Mockito.times;
			import static org.mockito.Mockito.verify;
			import static org.mockito.Mockito.when;
			import static org.testng.Assert.assertEquals;
			import static org.testng.Assert.assertFalse;
			import static org.testng.Assert.assertNull;
			import static org.testng.Assert.assertTrue;
			import static org.testng.Assert.fail;

			/**
			* Tests how a failure is classified as a transaction conflict, which is what decides whether
			* {@link JDBCStorage#write} replays the operation, and how long it waits before it does.
			* Tests how a failure is classified - as a transaction conflict, or as a connection the database dropped - which
			* is what decides whether {@link JDBCStorage#write} replays the operation, and how long it waits before it does;
			* and what {@code write()} itself does with that verdict, replay and pool alike.
			* <p>
			* Runs without a database: the failures the drivers report are reproduced as synthetic
			* {@link SQLException}s carrying the same vendor error number and SQLState.
			* {@link SQLException}s carrying the same vendor error number and SQLState, and the writes that carry them run
			* against mocked connections handed out by a driver of this test.
			*/
			@Test(sequential = true)
			@SuppressWarnings("javadoc")
			@@ -45,6 +82,35 @@
			private static final String ORACLE = "oracle.jdbc.driver.T4CConnection";
			private static final String POSTGRES = "org.postgresql.jdbc.PgConnection";

			/** The tree every write of this test opens; the table name behind it is a hash of this name. */
			private static final TreeName TREE = new TreeName("dc=example,dc=com", "id2entry");

			private final StubDriver stub = new StubDriver();

			/** Every test gets a pool of its own: the pools and the distrust of a pool are keyed by the url. */
			private final AtomicInteger pools = new AtomicInteger();

			/** The statement a create of a test runs, so that a test can assert that it ran - or that it did not. */
			private PreparedStatement statements;

			/** The connection behind the pool of a test, so that a test can assert the statement it was asked to prepare. */
			private Connection engineConnection;

			/**
			* Connections whose class names carry the engine the way the drivers' own do - pgjdbc's
			* {@code org.postgresql.jdbc.PgConnection}, Connector/J's {@code com.mysql.cj.jdbc.ConnectionImpl}. That name
			* is what {@code driverNameOf()} matches an engine on, and the name of a mock is derived from the type it
			* mocks, so a mock of plain {@link Connection} reaches no engine branch of {@code openTree()} at all. Lowercase
			* because the match is case sensitive.
			*/
			interface postgresConnection extends Connection
			{
			}

			interface mysqlConnection extends Connection
			{
			}

			/** A failure whose cause chain is a cycle, to check that walking it terminates. */
			private static final class SelfCausedException extends RuntimeException
			{
			@@ -115,6 +181,155 @@
			assertEquals(JDBCStorage.isRetryableConflict(failure, driver), expected, name);
			}

			@DataProvider
			public Object[][] connectionFailures()
			{
			return new Object[][] {
			// class 08, connection exception: pgjdbc reports the next use of a connection the server dropped as 08003,
			// and a socket that failed under it as 08006, while a connect that never came up is 08001
			{ "connection does not exist", sql(0, "08003"), true },
			{ "connection failure", sql(0, "08006"), true },
			{ "unable to establish connection", sql(0, "08001"), true },
			// the FATAL message a pg_terminate_backend or a shutdown sends before the socket closes: the connection is
			// gone, and only its next use would be reported as class 08
			{ "admin shutdown", sql(0, "57P01"), true },
			{ "crash shutdown", sql(0, "57P02"), true },
			{ "cannot connect now", sql(0, "57P03"), true },
			// it reaches write() wrapped, exactly as a conflict does
			{ "wrapped once", new StorageRuntimeException(sql(0, "08006")), true },
			{ "wrapped twice",
			new DirectoryException(OTHER, raw("unchecked"), new StorageRuntimeException(sql(0, "08003"))), true },
			{ "wrapped 57P0x", new StorageRuntimeException(sql(0, "57P01")), true },
			// the types the JDBC contract gives a driver to say the connection is gone, whatever state it fills in:
			// oracle reports ORA-03113 and ORA-01089 as SQLRecoverableException, and only happens to map them to 08006
			{ "recoverable", new SQLRecoverableException("closed connection", "72000", 3113), true },
			{ "non transient connection", new SQLNonTransientConnectionException("socket closed", "S1000", 0), true },
			// a driver reports what happened as the next exception of a generic failure as readily as it reports it
			// as the cause, and mssql-jdbc chains every error of a message it received that way
			{ "next exception", chained(sql(0, "HY000"), sql(0, "08006")), true },
			// the drop of the rollback that releases a connection arrives suppressed into the failure of the operation
			{ "suppressed", suppressing(sql(2627, "23000"), sql(0, "08006")), true },

			// a statement the database answered, however badly, leaves the connection usable
			{ "deadlock victim", sql(1205, "40001"), false },
			{ "primary key violation", sql(2627, "23000"), false },
			// 53300 is the server refusing a further connection, not the loss of one already established
			{ "too many connections", sql(0, "53300"), false },
			// a killed session on SQL Server: generateStateCode maps neither 596 nor its siblings, so with xopenStates
			// off - the default - it arrives as "S"+errorState and no state tells it from a rejected statement. What
			// does tell it apart is the connection the driver closed behind it, see the test below
			{ "mssql killed session", sql(596, "S0001"), false },
			{ "no SQLState", sql(0, null), false },
			{ "not a SQLException", new IllegalStateException("connection closed"), false },
			{ "no failure at all", null, false },
			{ "cyclic cause chain", new SelfCausedException(), false },
			};
			}

			@Test(dataProvider = "connectionFailures")
			public void testIsConnectionFailure(String name, Throwable failure, boolean expected)
			{
			assertEquals(JDBCStorage.isConnectionFailure(failure), expected, name);
			}

			/**
			* A connection the database dropped is replayed on a connection the next attempt borrows of its own - but only
			* while the transaction has not been committed yet. A drop reported by {@code commit()} leaves the outcome of
			* the transaction unknown, and replaying a write that in fact committed applies it twice.
			*/
			@Test
			public void testADroppedConnectionIsReplayedOnlyBeforeTheCommit()
			{
			final SQLException dropped = sql(0, "08006");
			assertEquals(JDBCStorage.replayReason(dropped, POSTGRES, false, false, false),
			"a connection the database dropped");
			assertNull(JDBCStorage.replayReason(dropped, POSTGRES, true, false, false),
			"an in doubt transaction was replayed");
			}

			/**
			* A driver that closed the connection has said the connection is gone whatever SQLState it filled in - which is
			* the only way a killed SQL Server session is ever recognized, since it arrives as S0001.
			*/
			@Test
			public void testAConnectionTheDriverClosedIsADroppedOne()
			{
			final SQLException killed = sql(596, "S0001");
			assertNull(JDBCStorage.replayReason(killed, MSSQL, false, false, false), "S0001 was replayed on its own");
			assertEquals(JDBCStorage.replayReason(killed, MSSQL, false, false, true),
			"a connection the database dropped");
			assertNull(JDBCStorage.replayReason(killed, MSSQL, true, false, true),
			"an in doubt transaction was replayed");
			}

			/**
			* An attempt that committed part of its own work is not replayed, whatever the failure says: what it did no
			* longer rolls back as a whole, and a WriteOperation is only idempotent in the database. RootContainer.open
			* opens and registers the entry containers of every base DN in one write, and a replay of it fails with
			* ERR_ENTRY_CONTAINER_ALREADY_REGISTERED, masking the failure that caused the replay.
			*/
			@Test
			public void testAnAttemptThatCommittedPartOfItsWorkIsNotReplayed()
			{
			assertNull(JDBCStorage.replayReason(sql(0, "40001"), POSTGRES, false, true, false), "a conflict was replayed");
			assertNull(JDBCStorage.replayReason(sql(0, "08006"), POSTGRES, false, true, false), "a drop was replayed");
			assertNull(JDBCStorage.replayReason(sql(596, "S0001"), MSSQL, false, true, true), "a drop was replayed");
			}

			/**
			* A conflict is replayed on the strength of the engine having rolled the transaction back before it answered,
			* so it is read from the failure of the operation and not from the release of the connection: a class 40 the
			* release contributed - Oracle reports a transaction rolled back under it as ORA-02091, SQLState 40000 - would
			* otherwise re-authorise the replay of a commit whose outcome is unknown, past the guard that exists for it.
			* A drop is read from the release as well, which is the one place it is often stated at all.
			*/
			@Test
			public void testAConflictIsNotReadFromTheReleaseOfTheConnection()
			{
			final SQLException onRelease = suppressing(sql(2627, "23000"), sql(0, "40000"));
			assertFalse(JDBCStorage.isRetryableConflict(onRelease, POSTGRES), "a conflict was read from the release");
			assertNull(JDBCStorage.replayReason(onRelease, POSTGRES, true, false, false),
			"a transaction the commit left in doubt was replayed");

			// the same shape carrying a drop instead: read, since the release is where a drop is stated at all
			assertTrue(JDBCStorage.isConnectionFailure(suppressing(sql(2627, "23000"), sql(0, "08006"))),
			"a drop was not read from the release");
			}

			/** The connection is asked only where a state does not already say the connection is gone. */
			@Test
			public void testTheConnectionIsAskedWhetherTheDriverClosedIt() throws Exception
			{
			final Connection closed = mock(Connection.class);
			when(closed.isClosed()).thenReturn(true);
			final Connection alive = mock(Connection.class);
			when(alive.isClosed()).thenReturn(false);
			final Connection mute = mock(Connection.class);
			when(mute.isClosed()).thenThrow(new SQLException("the connection cannot say"));

			assertTrue(JDBCStorage.isConnectionFailure(sql(596, "S0001"), closed), "a killed session was not recognized");
			assertFalse(JDBCStorage.isConnectionFailure(sql(2627, "23000"), alive), "a rejected statement was a drop");
			assertTrue(JDBCStorage.isConnectionFailure(sql(0, "08006"), alive), "class 08 needs no connection to say so");
			assertTrue(JDBCStorage.isConnectionFailure(sql(2627, "23000"), mute), "a connection that cannot answer");
			}

			/** A conflict is a rollback the engine completed before it answered, whichever phase reported it. */
			@Test
			public void testAConflictIsReplayedFromEitherPhase()
			{
			final SQLException conflict = sql(0, "40001");
			assertEquals(JDBCStorage.replayReason(conflict, POSTGRES, false, false, false), "a conflict");
			assertEquals(JDBCStorage.replayReason(conflict, POSTGRES, true, false, false), "a conflict");
			}

			/** Everything else fails the operation, as it did before either replay existed. */
			@Test
			public void testAFailureOfTheStatementIsNotReplayed()
			{
			assertNull(JDBCStorage.replayReason(sql(2627, "23000"), MSSQL, false, false, false));
			assertNull(JDBCStorage.replayReason(sql(2627, "23000"), MSSQL, true, false, false));
			}

			/** The delay grows with the attempt, so that the replays outlast a contention lasting more than a few ms. */
			@Test
			public void testRetryDelayGrowsAndStaysBounded()
			@@ -143,23 +358,575 @@
			public void testConflictSummaryNamesTheStateAndTheNumber()
			{
			final String summary = JDBCStorage.conflictSummary(
			new DirectoryException(OTHER, raw("unchecked"), new StorageRuntimeException(sql(1205, "40001"))));
			new DirectoryException(OTHER, raw("unchecked"), new StorageRuntimeException(sql(1205, "40001"))), POSTGRES);
			assertTrue(summary.contains("40001"), summary);
			assertTrue(summary.contains("1205"), summary);
			assertTrue(summary.contains("synthetic failure"), summary);
			}

			/**
			* That line is the only record a replay leaves, so it names the failure the replay was decided on. A write whose
			* operation was rejected and whose release then reported a drop is replayed on the class 08 suppressed into the
			* rejection, and naming the state of the rejected statement would describe a replay that did not happen.
			*/
			@Test
			public void testConflictSummaryNamesTheFailureTheReplayWasDecidedOn()
			{
			final String summary = JDBCStorage.conflictSummary(
			new StorageRuntimeException(suppressing(sql(2627, "23000"), sql(0, "08006"))), POSTGRES);
			assertTrue(summary.contains("08006"), summary);
			assertFalse(summary.contains("23000"), summary);
			}

			/** A failure carrying no SQLException at all, and a cyclic cause chain, still have to yield something loggable. */
			@Test
			public void testConflictSummaryTerminatesWithoutASQLException()
			{
			assertTrue(JDBCStorage.conflictSummary(new IllegalStateException("connection closed")).contains("closed"));
			assertTrue(JDBCStorage.conflictSummary(new SelfCausedException()).contains("SelfCausedException"));
			assertEquals(JDBCStorage.conflictSummary(null), "null");
			assertTrue(JDBCStorage.conflictSummary(new IllegalStateException("connection closed"), POSTGRES).contains("closed"));
			assertTrue(JDBCStorage.conflictSummary(new SelfCausedException(), POSTGRES).contains("SelfCausedException"));
			assertEquals(JDBCStorage.conflictSummary(null, POSTGRES), "null");
			}

			/** A statement that carries neither a conflict nor a drop is still the one the summary names. */
			@Test
			public void testConflictSummaryFallsBackToTheFirstFailureOfTheChain()
			{
			final String summary = JDBCStorage.conflictSummary(new StorageRuntimeException(sql(2627, "23000")), POSTGRES);
			assertTrue(summary.contains("23000"), summary);

			// the fallback names the statement, not the rollback of the release behind it: this is where a replay
			// decided on the closed flag of the connection alone lands - neither chain carries a verdict of its own -
			// and the walk reaches the suppressed exceptions of a failure before its cause
			final StorageRuntimeException killedSession = new StorageRuntimeException(sql(596, "S0001"));
			killedSession.addSuppressed(sql(0, "25P02"));
			final String decidedOnTheConnection = JDBCStorage.conflictSummary(killedSession, MSSQL);
			assertTrue(decidedOnTheConnection.contains("S0001"), decidedOnTheConnection);
			assertFalse(decidedOnTheConnection.contains("25P02"), decidedOnTheConnection);
			}

			/**
			* The walk of a failure looks at a bounded number of links: mssql-jdbc chains every error of one message it
			* received through {@code setNextException}, and a budget spent on those would never reach the cause a wrapper
			* carries. Pinned from both sides - a drop on the last link of the budget is found and one link further is not
			* - since a number nothing pins drifts unnoticed in either direction.
			*/
			@Test
			public void testTheWalkOfAFailureStopsAtItsBudget()
			{
			assertTrue(JDBCStorage.isConnectionFailure(chainEndingInADrop(64)), "a drop on the last link of the budget");
			assertFalse(JDBCStorage.isConnectionFailure(chainEndingInADrop(65)), "a drop past the budget was walked to");
			}

			/**
			* Opening a tree that is already there commits nothing, so the attempt stays replayable. The create table is
			* guarded by a catalog read, and so is the create index on every engine but postgresql, so on an existing
			* backend {@code openTree(name, true)} issues no statement at all - while
			* {@code RootContainer.open()} opens every tree of every base DN in a single write whose first act is one of
			* these. A flag raised on the catalog read alone would leave that write unreplayable for the life of the
			* backend, the conflict replay of #867 included: {@code replayReason()} reads the flag before anything else.
			*/
			@Test
			public void testOpeningAnExistingTreeLeavesTheAttemptReplayable() throws Exception
			{
			final JDBCStorage storage = storageOverACatalogHolding(true);
			final AtomicInteger attempts = new AtomicInteger();

			storage.write(txn -> {
			txn.openTree(TREE, true);
			if (attempts.incrementAndGet() == 1)
			{
			throw new StorageRuntimeException(sql(0, "40001"));
			}
			});

			assertEquals(attempts.get(), 2, "a transaction that committed nothing was not replayed");
			verify(statements, never()).executeUpdate();
			}

			/**
			* A tree that had to be created did commit - the create table commits, and mysql and oracle commit before a DDL
			* statement of their own accord - so the attempt is out of the replay whatever the failure says: a
			* {@link WriteOperation} is only idempotent in the database, and {@code RootContainer.open()} replayed after the
			* trees of the first base DN were created registers that base DN a second time.
			*/
			@Test
			public void testCreatingATreeTakesTheAttemptOutOfTheReplay() throws Exception
			{
			final JDBCStorage storage = storageOverACatalogHolding(false);
			final AtomicInteger attempts = new AtomicInteger();

			try
			{
			storage.write(txn -> {
			txn.openTree(TREE, true);
			attempts.incrementAndGet();
			throw new StorageRuntimeException(sql(0, "40001"));
			});
			fail("a transaction that had committed a create table was replayed");
			}
			catch (StorageRuntimeException expected)
			{
			assertTrue(JDBCStorage.isRetryableConflict(expected, POSTGRES), "the conflict was not the failure raised");
			}
			assertEquals(attempts.get(), 1, "a transaction that committed part of its work was replayed");
			verify(statements).executeUpdate();
			}

			/**
			* The rollback that unwinds a failed attempt is often the first place a drop is stated outright, and on a
			* driver that reports a killed session as a plain vendor error it is the only one. It is joined to the failure
			* being unwound rather than dropped on the floor, so that the classifiers below read it: without it the attempt
			* would lean on the driver having flipped its closed flag already, and a driver that has not gives neither the
			* replay nor the distrust.
			*/
			@Test
			public void testTheRollbackOfAFailedAttemptIsNotSwallowed() throws Exception
			{
			final long window = CachedConnection.aliveBypassNanos;
			CachedConnection.aliveBypassNanos = TimeUnit.HOURS.toNanos(1);
			try
			{
			final Connection pooled = mock(Connection.class);
			when(pooled.isValid(anyInt())).thenReturn(true);
			final Connection dropped = mock(Connection.class);
			when(dropped.isValid(anyInt())).thenReturn(true);
			when(dropped.isClosed()).thenReturn(false); // the driver has not flipped its flag yet

			final JDBCStorage storage = storageOver(pooled, dropped);
			final Connection first = storage.getConnection();
			final Connection second = storage.getConnection();
			first.close();
			second.close();
			// proven alive by the connect itself, and inside the window ever since: nothing has validated
			verify(dropped, never()).isValid(anyInt());

			// only the rollback that unwinds the attempt says the connection is gone: the release behind it
			// goes through, so the dropped connection is back at the head of the pool - where the replay
			// borrows it again - with nothing else to report what it saw
			doThrow(new SQLException("connection reset", "08006")).doNothing().when(dropped).rollback();

			final AtomicInteger attempts = new AtomicInteger();
			storage.write(txn -> {
			if (attempts.incrementAndGet() == 1)
			{
			throw new StorageRuntimeException(sql(596, "S0001")); // a killed session, as mssql-jdbc reports it
			}
			});

			assertEquals(attempts.get(), 2, "the drop the rollback reported was not replayed");
			// the distrust reached the pool: the borrow of the replay validated instead of trusting the
			// last answer of a connection that predates the drop
			verify(dropped, times(1)).isValid(CachedConnection.VALIDATION_TIMEOUT_SECONDS);
			}
			finally
			{
			CachedConnection.aliveBypassNanos = window;
			}
			}

			/**
			* A drop the release of the connection reported reaches the pool as well as the replay. It is suppressed into
			* the failure of the operation (JLS 14.20.3.1) rather than replacing it, so the attempt sees it only on the
			* chains of that failure - and the pool has no other way of hearing of it: the rest of that generation would
			* otherwise be handed out unvalidated one by one until the pool runs out of it.
			*/
			@Test
			public void testADropReportedByTheReleaseReachesThePool() throws Exception
			{
			final long window = CachedConnection.aliveBypassNanos;
			CachedConnection.aliveBypassNanos = TimeUnit.HOURS.toNanos(1);
			try
			{
			final Connection pooled = mock(Connection.class);
			when(pooled.isValid(anyInt())).thenReturn(true);
			final Connection released = mock(Connection.class);
			when(released.isValid(anyInt())).thenReturn(true);

			final JDBCStorage storage = storageOver(pooled, released);
			// both are proven alive and back in the pool; the one released last is the one the write borrows
			final Connection first = storage.getConnection();
			final Connection second = storage.getConnection();
			first.close();
			second.close();

			// from here the database has dropped the connection at the head of the pool: the operation is
			// rejected for its own reasons, the rollback that unwinds the attempt goes through, and the release
			// behind it is where the drop surfaces. Chained, so that the drop lands on the second rollback: an
			// unchained stub fails the first one - the rollback of the attempt - and pins the sibling test above
			doNothing().doThrow(new SQLException("connection reset", "08006")).when(released).rollback();

			final AtomicInteger attempts = new AtomicInteger();
			storage.write(txn -> {
			if (attempts.incrementAndGet() == 1)
			{
			throw new StorageRuntimeException(sql(2627, "23000"));
			}
			});

			assertEquals(attempts.get(), 2, "the drop suppressed into the failure was not replayed");
			// the return to the pool that seeded it, the rollback of the attempt, and the release behind it - which
			// is the one that reported, since the stub above lets the rollback of the attempt through
			verify(released, times(3)).rollback();
			// the distrust reached the pool from the release: the borrow of the replay validated instead of
			// trusting the last answer of a connection established before the drop
			verify(pooled).isValid(CachedConnection.VALIDATION_TIMEOUT_SECONDS);
			}
			finally
			{
			CachedConnection.aliveBypassNanos = window;
			}
			}

			/**
			* A read is never replayed - two of the read operations of this server are not idempotent - but a drop it ran
			* into still has to reach the pool, which has no other way of hearing of one: a borrow inside the window asks
			* the database nothing, so the statement that broke is the only place the drop is ever seen. The release of
			* the connection counts as such a statement: its rollback is the one round trip a read that found nothing
			* makes.
			*/
			@Test
			public void testADropAReadRanIntoReachesThePool() throws Exception
			{
			final long window = CachedConnection.aliveBypassNanos;
			CachedConnection.aliveBypassNanos = TimeUnit.HOURS.toNanos(1);
			try
			{
			final Connection pooled = mock(Connection.class);
			when(pooled.isValid(anyInt())).thenReturn(true);
			final Connection released = mock(Connection.class);
			when(released.isValid(anyInt())).thenReturn(true);

			final JDBCStorage storage = storageOver(pooled, released);
			final Connection first = storage.getConnection();
			final Connection second = storage.getConnection();
			first.close();
			second.close();
			// both are proven alive and inside the window: nothing has validated
			verify(released, never()).isValid(anyInt());

			// the read is rejected for its own reasons, and the release behind it - a read issues no rollback of its
			// own - is where the connection the database dropped says so
			doThrow(new SQLException("connection reset", "08006")).when(released).rollback();
			try
			{
			storage.read(txn -> {
			throw new StorageRuntimeException(sql(2627, "23000"));
			});
			fail("the failure of the read was swallowed");
			}
			catch (StorageRuntimeException expected)
			{
			assertTrue(JDBCStorage.isConnectionFailure(expected), "the drop of the release did not reach the failure");
			}

			storage.getConnection().close(); // the borrow that follows it validates instead of trusting

			verify(pooled).isValid(CachedConnection.VALIDATION_TIMEOUT_SECONDS);
			}
			finally
			{
			CachedConnection.aliveBypassNanos = window;
			}
			}

			/**
			* The create index of the postgres branch is asked of the catalog first, although postgresql has "create index
			* if not exists": that statement commits whether it creates anything or not, and unguarded it would take every
			* write that opens a tree out of the replay - {@code RootContainer.open()} and its ~25 trees per suffix
			* included.
			*/
			@Test
			public void testThePostgresIndexIsAskedOfTheCatalogBeforeItIsCreated() throws Exception
			{
			final JDBCStorage storage = storageOverAnEngine(postgresConnection.class, true);
			final AtomicInteger attempts = new AtomicInteger();

			storage.write(txn -> {
			txn.openTree(TREE, true);
			if (attempts.incrementAndGet() == 1)
			{
			throw new StorageRuntimeException(sql(0, "40001"));
			}
			});

			assertEquals(attempts.get(), 2, "a transaction that committed nothing was not replayed");
			verify(statements, never()).executeUpdate();
			}

			/**
			* postgresql runs DDL inside the transaction, so a create index the engine rolled back has committed nothing:
			* {@code write()} rolls the attempt back whole and replays it. Raising the flag in front of the statement -
			* which is what mysql and oracle need, since they commit before a DDL of their own accord - would turn a
			* deadlock the engine itself undid into a hard failure of the open.
			*/
			@Test
			public void testACreateIndexPostgresRolledBackLeavesTheAttemptReplayable() throws Exception
			{
			final JDBCStorage storage = storageOverAnEngine(postgresConnection.class, false);
			when(statements.executeUpdate()).thenThrow(sql(0, "40P01")).thenReturn(0);
			final AtomicInteger attempts = new AtomicInteger();

			storage.write(txn -> {
			attempts.incrementAndGet();
			txn.openTree(TREE, true);
			});

			assertEquals(attempts.get(), 2, "a create index the engine rolled back was not replayed");
			verify(engineConnection, times(2)).prepareStatement(startsWith("create index if not exists k_"));
			}

			/**
			* mysql commits before a DDL statement whether asked to or not, so a create index that failed there has
			* committed everything the transaction did before it just as surely as one that succeeded: the attempt is out
			* of the replay whatever the failure says.
			*/
			@Test
			public void testACreateIndexMysqlCommittedBeforeTakesTheAttemptOutOfTheReplay() throws Exception
			{
			final JDBCStorage storage = storageOverAnEngine(mysqlConnection.class, false);
			when(statements.executeUpdate()).thenThrow(sql(1213, "40001"));
			final AtomicInteger attempts = new AtomicInteger();

			try
			{
			storage.write(txn -> {
			attempts.incrementAndGet();
			txn.openTree(TREE, true);
			});
			fail("a transaction whose create index had committed before it was replayed");
			}
			catch (StorageRuntimeException expected)
			{
			assertTrue(JDBCStorage.isRetryableConflict(expected, MYSQL), "the conflict was not the failure raised");
			}
			assertEquals(attempts.get(), 1, "an attempt that committed part of its work was replayed");
			verify(engineConnection).prepareStatement(startsWith("create index k_"));
			}

			/**
			* The connection the tree names are stamped on is closed as the attempt is unwound, and an unchecked throw out
			* of a driver's {@code close()} there would replace the exception being unwound (JLS 14.20.2) - the very one
			* the replay is decided on, and the only one that says what went wrong. The stamp is a diagnostic aid: it is
			* joined to the failure instead, and the replay goes ahead.
			*/
			@Test
			public void testAFailingCommentConnectionDoesNotReplaceTheFailureOfTheWrite() throws Exception
			{
			final Connection stamp = mock(Connection.class);
			when(stamp.createStatement()).thenReturn(mock(Statement.class)); // the lock bound of the stamp session
			// the readback of the stored comment fails, so the stamp is given up on - with its connection open
			when(stamp.prepareStatement(anyString())).thenThrow(new SQLException("no readback in this test", "42000"));
			doThrow(new IllegalStateException("the driver threw out of close()")).when(stamp).close();
			final JDBCStorage storage = storageOverAnEngine(postgresConnection.class, true, stamp);
			final AtomicInteger attempts = new AtomicInteger();

			storage.write(txn -> {
			txn.openTree(TREE, true); // opens the stamp session, which is closed as this attempt is unwound
			if (attempts.incrementAndGet() == 1)
			{
			throw new StorageRuntimeException(sql(0, "40001"));
			}
			});

			assertEquals(attempts.get(), 2, "the failure of the comment connection replaced the conflict being unwound");
			verify(stamp).close();
			}

			@BeforeClass
			public void registerStubDriver() throws Exception
			{
			DriverManager.registerDriver(stub);
			}

			@AfterClass
			public void deregisterStubDriver() throws Exception
			{
			DriverManager.deregisterDriver(stub);
			}

			/**
			* A storage whose pool hands out one connection of this test, over a catalog that either holds the table of
			* {@link #TREE} or does not. The connection is a mock of no recognized driver, which is how the engines that
			* guard their create index - and mssql, which has none - reach {@code openTree}.
			*/
			private JDBCStorage storageOverACatalogHolding(boolean theTable) throws Exception
			{
			final Connection con = mock(Connection.class);
			final JDBCStorage storage = storageOver(con);

			statements = mock(PreparedStatement.class);
			final String tableName = storage.getTableName(TREE);
			final DatabaseMetaData metaData = mock(DatabaseMetaData.class);
			// a result set of its own per call: the catalog is asked once per attempt, and a replayed attempt
			// reading a result set the previous one had already walked to its end would find no table there
			when(metaData.getTables(any(), any(), any(), any())).thenAnswer(invocation -> {
			final ResultSet tables = mock(ResultSet.class);
			when(tables.next()).thenReturn(theTable, false);
			when(tables.getString("TABLE_NAME")).thenReturn(tableName);
			return tables;
			});

			when(con.isValid(anyInt())).thenReturn(true);
			when(con.getMetaData()).thenReturn(metaData);
			when(con.prepareStatement(anyString())).thenReturn(statements);
			return storage;
			}

			/**
			* A storage whose pool hands out one connection of the given engine, over a catalog holding the table of
			* {@link #TREE} and either holding its {@code k_} index or not. The index guard and the statement behind it
			* are the branches {@code openTree()} takes per engine, and a mock of plain {@link Connection} reaches none
			* of them - so the name the mock ends up with is asserted here rather than assumed.
			*/
			private JDBCStorage storageOverAnEngine(Class<? extends Connection> engine, boolean theIndex,
			Connection... behind) throws Exception
			{
			final Connection con = mock(engine);
			final String engineName = engine.getSimpleName().replace("Connection", "");
			assertTrue(JDBCStorage.driverNameOf(con).contains(engineName),
			"a mock of " + engine.getSimpleName() + " reaches no " + engineName + " branch: "
			+ JDBCStorage.driverNameOf(con));
			engineConnection = con;
			// the connections behind it answer the connects the pool does not make: the stamp of a tree name opens one
			// of its own, straight through the driver, since the caller of openTree() is holding a pooled connection
			final Connection[] answers = new Connection[behind.length + 1];
			answers[0] = con;
			System.arraycopy(behind, 0, answers, 1, behind.length);
			final JDBCStorage storage = storageOver(answers);

			statements = mock(PreparedStatement.class);
			final String tableName = storage.getTableName(TREE);
			final DatabaseMetaData metaData = mock(DatabaseMetaData.class);
			// a result set of its own per call, for the reason the catalog of the test above hands out one: a replayed
			// attempt reading a result set the previous one had already walked to its end would find nothing there
			when(metaData.getTables(any(), any(), any(), any())).thenAnswer(invocation -> {
			final ResultSet tables = mock(ResultSet.class);
			when(tables.next()).thenReturn(true, false);
			when(tables.getString("TABLE_NAME")).thenReturn(tableName);
			return tables;
			});
			when(metaData.getIndexInfo(any(), any(), any(), anyBoolean(), anyBoolean())).thenAnswer(invocation -> {
			final ResultSet indexes = mock(ResultSet.class);
			when(indexes.next()).thenReturn(theIndex, false);
			when(indexes.getString("INDEX_NAME")).thenReturn("k_" + tableName.substring("opendj_".length()));
			return indexes;
			});

			when(con.isValid(anyInt())).thenReturn(true);
			when(con.getMetaData()).thenReturn(metaData);
			when(con.prepareStatement(anyString())).thenReturn(statements);
			// the tree name the sweep stamps the table with runs on a connection of its own and is a diagnostic aid: a
			// failure of it only logs, and this fixture is about the index statement rather than about the comment
			when(con.createStatement()).thenThrow(new SQLException("no session statement in this test", "42000"));
			return storage;
			}

			/**
			* A storage of a pool of its own, which connects to the given connections in turn and answers every connect
			* beyond them with the last. Every test gets a url of its own: both the pools and the distrust of a pool are
			* keyed by the connection string, so a shared one would carry the state of one test into the next.
			*/
			private JDBCStorage storageOver(Connection... connections) throws Exception
			{
			final JDBCBackendCfg cfg = mock(JDBCBackendCfg.class);
			when(cfg.getDBDirectory()).thenReturn(StubDriver.PREFIX + pools.incrementAndGet());
			final JDBCStorage storage = new JDBCStorage(cfg, null);
			storage.accessMode = AccessMode.READ_WRITE;
			stub.answerWith(connections);
			return storage;
			}

			/** A driver of this test, so that the pool the write borrows from needs no database behind it. */
			private static final class StubDriver implements Driver
			{
			static final String PREFIX = "jdbc:opendj-retry-stub:";

			private volatile Connection[] answers = new Connection[0];
			private final AtomicInteger connects = new AtomicInteger();

			void answerWith(Connection... answers)
			{
			this.answers = answers;
			this.connects.set(0);
			}

			@Override
			public Connection connect(String url, Properties info)
			{
			if (!acceptsURL(url) \|\| answers.length == 0)
			{
			return null;
			}
			// the last one answers every connect beyond the ones named, so a pool that opens more than the
			// test set up gets a working connection rather than a null the driver contract reads as "not mine"
			return answers[Math.min(connects.getAndIncrement(), answers.length - 1)];
			}

			@Override
			public boolean acceptsURL(String url)
			{
			return url != null && url.startsWith(PREFIX);
			}

			@Override
			public DriverPropertyInfo[] getPropertyInfo(String url, Properties info)
			{
			return new DriverPropertyInfo[0];
			}

			@Override
			public int getMajorVersion()
			{
			return 1;
			}

			@Override
			public int getMinorVersion()
			{
			return 0;
			}

			@Override
			public boolean jdbcCompliant()
			{
			return false;
			}

			@Override
			public Logger getParentLogger()
			{
			return Logger.getLogger(StubDriver.class.getName());
			}
			}

			private static SQLException sql(int errorCode, String sqlState)
			{
			return new SQLException("synthetic failure", sqlState, errorCode);
			}

			/** The second failure as the next exception of the first, the way a driver chains the errors of one message. */
			private static SQLException chained(SQLException first, SQLException next)
			{
			first.setNextException(next);
			return first;
			}

			/** A chain of the given number of next exceptions whose last link is a connection that broke. */
			private static SQLException chainEndingInADrop(int links)
			{
			final SQLException head = sql(2627, "23000");
			SQLException tail = head;
			for (int link = 2; link <= links; link++)
			{
			tail = chained(tail, sql(0, link == links ? "08006" : "23000")).getNextException();
			}
			return head;
			}

			/** The second failure suppressed into the first, the way a failing close() joins the failure of an operation. */
			private static SQLException suppressing(SQLException failure, SQLException onRelease)
			{
			failure.addSuppressed(onRelease);
			return failure;
			}
			}