// Test that we fail to lease a table that was marked for deletion.
func TestCantLeaseDeletedTable(testingT *testing.T) {
	defer leaktest.AfterTest(testingT)()
	defer csql.TestDisableAsyncSchemaChangeExec()()

	var execKnobs csql.ExecutorTestingKnobs
	var mu sync.Mutex
	clearSchemaChangers := false
	execKnobs.SyncSchemaChangersFilter =
		func(tscc csql.TestingSchemaChangerCollection) {
			mu.Lock()
			defer mu.Unlock()
			if clearSchemaChangers {
				tscc.ClearSchemaChangers()
			}
		}
	ctx, _ := createTestServerContext()
	ctx.TestingKnobs.SQLExecutor = &execKnobs
	t := newLeaseTest(testingT, ctx)
	defer t.cleanup()

	sql := `
CREATE DATABASE test;
CREATE TABLE test.t(a INT PRIMARY KEY);
`
	_, err := t.db.Exec(sql)
	if err != nil {
		t.Fatal(err)
	}

	// Block schema changers so that the table we're about to DROP is not actually
	// dropped; it will be left in a "deleted" state.
	mu.Lock()
	clearSchemaChangers = true
	mu.Unlock()

	// DROP the table
	_, err = t.db.Exec(`DROP TABLE test.t`)
	if err != nil {
		t.Fatal(err)
	}

	// Make sure we can't get a lease on the descriptor.
	tableDesc := getTableDescriptor(t.kvDB, "test", "t")
	// try to acquire at a bogus version to make sure we don't get back a lease we
	// already had.
	_, err = t.acquire(1, tableDesc.ID, tableDesc.Version+1)
	if !testutils.IsError(err, "descriptor deleted") {
		t.Fatalf("got a different error than expected: %s", err)
	}
}

func TestCommandsWithPendingMutations(t *testing.T) {
	defer leaktest.AfterTest(t)
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	defer csql.TestDisableAsyncSchemaChangeExec()()
	server, sqlDB, kvDB := setup(t)
	defer cleanup(server, sqlDB)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (a CHAR PRIMARY KEY, b CHAR, c CHAR, INDEX foo (c));
`); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor
	nameKey := csql.MakeNameMetadataKey(keys.MaxReservedDescID+1, "test")
	gr, err := kvDB.Get(nameKey)
	if err != nil {
		t.Fatal(err)
	}
	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}
	descKey := csql.MakeDescMetadataKey(csql.ID(gr.ValueInt()))
	desc := &csql.Descriptor{}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}

	mt := mutationTest{
		T:       t,
		kvDB:    kvDB,
		sqlDB:   sqlDB,
		descKey: descKey,
		desc:    desc,
	}

	// Test CREATE INDEX in the presence of mutations.

	// Add index DROP mutation "foo""
	mt.writeIndexMutation("foo", csql.DescriptorMutation{Direction: csql.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`CREATE INDEX foo ON t.test (c)`); !testutils.IsError(err, `index "foo" being dropped, try again later`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()

	// "foo" is being added.
	mt.writeIndexMutation("foo", csql.DescriptorMutation{Direction: csql.DescriptorMutation_ADD})
	if _, err := sqlDB.Exec(`CREATE INDEX foo ON t.test (c)`); !testutils.IsError(err, `duplicate index name: "foo"`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// Add column DROP mutation "b"
	mt.writeColumnMutation("b", csql.DescriptorMutation{Direction: csql.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`CREATE INDEX bar ON t.test (b)`); !testutils.IsError(err, `index "bar" contains unknown column "b"`) {
		t.Fatal(err)
	}
	// Make "b" live.
	mt.makeMutationsActive()
	// "b" is being added.
	mt.writeColumnMutation("b", csql.DescriptorMutation{Direction: csql.DescriptorMutation_ADD})
	// An index referencing a column mutation that is being added
	// is allowed to be added.
	if _, err := sqlDB.Exec(`CREATE INDEX bar ON t.test (b)`); err != nil {
		t.Fatal(err)
	}
	// Make "b" live.
	mt.makeMutationsActive()

	// Test DROP INDEX in the presence of mutations.

	// Add index DROP mutation "foo""
	mt.writeIndexMutation("foo", csql.DescriptorMutation{Direction: csql.DescriptorMutation_DROP})
	// Noop.
	if _, err := sqlDB.Exec(`DROP INDEX [email protected]`); err != nil {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// "foo" is being added.
	mt.writeIndexMutation("foo", csql.DescriptorMutation{Direction: csql.DescriptorMutation_ADD})
	if _, err := sqlDB.Exec(`DROP INDEX [email protected]`); !testutils.IsError(err, `index "foo" in the middle of being added, try again later`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// Test ALTER TABLE ADD/DROP column in the presence of mutations.

	// Add column DROP mutation "b"
	mt.writeColumnMutation("b", csql.DescriptorMutation{Direction: csql.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`ALTER TABLE t.test ADD b CHAR`); !testutils.IsError(err, `column "b" being dropped, try again later`) {
		t.Fatal(err)
	}
	// Noop.
	if _, err := sqlDB.Exec(`ALTER TABLE t.test DROP b`); err != nil {
//.........这里部分代码省略.........

func TestOperationsWithIndexMutation(t *testing.T) {
	defer leaktest.AfterTest(t)
	// The descriptor changes made must have an immediate effect.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	defer csql.TestDisableAsyncSchemaChangeExec()()
	server, sqlDB, kvDB := setup(t)
	defer cleanup(server, sqlDB)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR, INDEX foo (v));
`); err != nil {
		t.Fatal(err)
	}

	// read table descriptor
	nameKey := csql.MakeNameMetadataKey(keys.MaxReservedDescID+1, "test")
	gr, err := kvDB.Get(nameKey)
	if err != nil {
		t.Fatal(err)
	}
	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}
	descKey := csql.MakeDescMetadataKey(csql.ID(gr.ValueInt()))
	desc := &csql.Descriptor{}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}

	mTest := mutationTest{
		T:       t,
		kvDB:    kvDB,
		sqlDB:   sqlDB,
		descKey: descKey,
		desc:    desc,
	}

	starQuery := `SELECT * FROM t.test`
	indexQuery := `SELECT * FROM [email protected]`
	// See the effect of the operations depending on the state.
	for _, state := range []csql.DescriptorMutation_State{csql.DescriptorMutation_DELETE_ONLY, csql.DescriptorMutation_WRITE_ONLY} {
		// Init table with some entries.
		if _, err := sqlDB.Exec(`TRUNCATE TABLE t.test`); err != nil {
			t.Fatal(err)
		}
		initRows := [][]string{{"a", "z"}, {"b", "y"}}
		for _, row := range initRows {
			if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ($1, $2)`, row[0], row[1]); err != nil {
				t.Fatal(err)
			}
		}
		_ = mTest.checkQueryResponse(starQuery, initRows)
		// Index foo is visible.
		_ = mTest.checkQueryResponse(indexQuery, [][]string{{"y"}, {"z"}})

		// Index foo is invisible once it's a mutation.
		mTest.writeIndexMutation("foo", csql.DescriptorMutation{State: state})
		if _, err := sqlDB.Query(indexQuery); !testutils.IsError(err, `index "foo" not found`) {
			t.Fatal(err)
		}

		// Insert a new entry.
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ('c', 'x')`); err != nil {
			t.Fatal(err)
		}
		_ = mTest.checkQueryResponse(starQuery, [][]string{{"a", "z"}, {"b", "y"}, {"c", "x"}})

		// Make index "foo" live so that we can read it.
		mTest.makeMutationsActive()
		if state == csql.DescriptorMutation_DELETE_ONLY {
			// "x" didn't get added to the index.
			_ = mTest.checkQueryResponse(indexQuery, [][]string{{"y"}, {"z"}})
		} else {
			// "x" got added to the index.
			_ = mTest.checkQueryResponse(indexQuery, [][]string{{"x"}, {"y"}, {"z"}})
		}

		// Make "foo" a mutation.
		mTest.writeIndexMutation("foo", csql.DescriptorMutation{State: state})
		// Update.
		if _, err := sqlDB.Exec(`UPDATE t.test SET v = 'w' WHERE k = 'c'`); err != nil {
			t.Fatal(err)
		}
		// Update "v" to its current value "z" in row "a".
		if _, err := sqlDB.Exec(`UPDATE t.test SET v = 'z' WHERE k = 'a'`); err != nil {
			t.Fatal(err)
		}
		_ = mTest.checkQueryResponse(starQuery, [][]string{{"a", "z"}, {"b", "y"}, {"c", "w"}})

		// Make index "foo" live so that we can read it.
		mTest.makeMutationsActive()
		if state == csql.DescriptorMutation_DELETE_ONLY {
			// updating "x" -> "w" is a noop on the index,
			// updating "z" -> "z" results in "z" being deleted from the index.
			_ = mTest.checkQueryResponse(indexQuery, [][]string{{"y"}, {"z"}})
		} else {
			// updating "x" -> "w" results in the index updating from "x" -> "w",
			// updating "z" -> "z" is a noop on the index.
//.........这里部分代码省略.........

func TestOperationsWithColumnMutation(t *testing.T) {
	defer leaktest.AfterTest(t)
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	defer csql.TestDisableAsyncSchemaChangeExec()()
	server, sqlDB, kvDB := setup(t)
	defer cleanup(server, sqlDB)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR, i CHAR DEFAULT 'i');
`); err != nil {
		t.Fatal(err)
	}

	// read table descriptor
	nameKey := csql.MakeNameMetadataKey(keys.MaxReservedDescID+1, "test")
	gr, err := kvDB.Get(nameKey)
	if err != nil {
		t.Fatal(err)
	}
	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}
	descKey := csql.MakeDescMetadataKey(csql.ID(gr.ValueInt()))
	desc := &csql.Descriptor{}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}

	mTest := mutationTest{
		T:       t,
		kvDB:    kvDB,
		sqlDB:   sqlDB,
		descKey: descKey,
		desc:    desc,
	}

	starQuery := `SELECT * FROM t.test`
	// Run the tests for both states.
	for _, state := range []csql.DescriptorMutation_State{csql.DescriptorMutation_DELETE_ONLY, csql.DescriptorMutation_WRITE_ONLY} {
		// Init table to start state.
		if _, err := sqlDB.Exec(`TRUNCATE TABLE t.test`); err != nil {
			t.Fatal(err)
		}
		initRows := [][]string{{"a", "z", "q"}}
		for _, row := range initRows {
			if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ($1, $2, $3)`, row[0], row[1], row[2]); err != nil {
				t.Fatal(err)
			}
		}
		// Check that the table only contains the initRows.
		_ = mTest.checkQueryResponse(starQuery, initRows)

		// Add column "i" as a mutation.
		mTest.writeColumnMutation("i", csql.DescriptorMutation{State: state})
		// A direct read of column "i" fails.
		if _, err := sqlDB.Query(`SELECT i FROM t.test`); err == nil {
			t.Fatalf("Read succeeded despite column being in %v state", csql.DescriptorMutation{State: state})
		}
		// The table only contains columns "k" and "v".
		_ = mTest.checkQueryResponse(starQuery, [][]string{{"a", "z"}})

		// Inserting a row into the table while specifying column "i" results in an error.
		if _, err := sqlDB.Exec(`INSERT INTO t.test (k, v, i) VALUES ('b', 'y', 'i')`); !testutils.IsError(err, `column "i" does not exist`) {
			t.Fatal(err)
		}
		// Repeating the same without specifying the columns results in a different error.
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ('b', 'y', 'i')`); !testutils.IsError(err, "INSERT has more expressions than target columns: 3/2") {
			t.Fatal(err)
		}
		// Make column "i" live so that it is read.
		mTest.makeMutationsActive()
		// Check that we can read all the rows and columns.
		_ = mTest.checkQueryResponse(starQuery, initRows)

		var afterInsert, afterUpdate, afterDelete [][]string
		if state == csql.DescriptorMutation_DELETE_ONLY {
			// The default value of "i" for column "i" is not written.
			afterInsert = [][]string{{"a", "z", "q"}, {"c", "x", "NULL"}}
			// Update is a noop for column "i".
			afterUpdate = [][]string{{"a", "u", "q"}, {"c", "x", "NULL"}}
			// Delete also deletes column "i".
			afterDelete = [][]string{{"c", "x", "NULL"}}
		} else {
			// The default value of "i" for column "i" is written.
			afterInsert = [][]string{{"a", "z", "q"}, {"c", "x", "i"}}
			// Update is a noop for column "i".
			afterUpdate = [][]string{{"a", "u", "q"}, {"c", "x", "i"}}
			// Delete also deletes column "i".
			afterDelete = [][]string{{"c", "x", "i"}}
		}
		// Make column "i" a mutation.
		mTest.writeColumnMutation("i", csql.DescriptorMutation{State: state})
		// Insert a row into the table.
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ('c', 'x')`); err != nil {
			t.Fatal(err)
		}
//.........这里部分代码省略.........

func TestSchemaChangeProcess(t *testing.T) {
	defer leaktest.AfterTest(t)
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	defer csql.TestDisableAsyncSchemaChangeExec()()
	server, sqlDB, kvDB := setup(t)
	defer cleanup(server, sqlDB)
	var id = csql.ID(keys.MaxReservedDescID + 2)
	var node = roachpb.NodeID(2)
	db := server.DB()
	leaseMgr := csql.NewLeaseManager(0, *db, hlc.NewClock(hlc.UnixNano))
	changer := csql.NewSchemaChangerForTesting(id, 0, node, *db, leaseMgr)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR, INDEX foo(v));
INSERT INTO t.test VALUES ('a', 'b'), ('c', 'd');
`); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor for version.
	nameKey := csql.MakeNameMetadataKey(keys.MaxReservedDescID+1, "test")
	gr, err := kvDB.Get(nameKey)
	if err != nil {
		t.Fatal(err)
	}
	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}
	descKey := csql.MakeDescMetadataKey(csql.ID(gr.ValueInt()))
	desc := &csql.Descriptor{}

	// Check that MaybeIncrementVersion doesn't increment the version
	// when the up_version bit is not set.
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}
	expectedVersion := desc.GetTable().Version

	if err := changer.MaybeIncrementVersion(); err != nil {
		t.Fatal(err)
	}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}
	newVersion := desc.GetTable().Version
	if newVersion != expectedVersion {
		t.Fatalf("bad version; e = %d, v = %d", expectedVersion, newVersion)
	}
	isDone, err := changer.IsDone()
	if err != nil {
		t.Fatal(err)
	}
	if !isDone {
		t.Fatalf("table expected to not have an outstanding schema change: %v", desc.GetTable())
	}

	// Check that MaybeIncrementVersion increments the version
	// correctly.
	expectedVersion++
	desc.GetTable().UpVersion = true
	if err := kvDB.Put(descKey, desc); err != nil {
		t.Fatal(err)
	}
	isDone, err = changer.IsDone()
	if err != nil {
		t.Fatal(err)
	}
	if isDone {
		t.Fatalf("table expected to have an outstanding schema change: %v", desc.GetTable())
	}
	if err := changer.MaybeIncrementVersion(); err != nil {
		t.Fatal(err)
	}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}
	newVersion = desc.GetTable().Version
	if newVersion != expectedVersion {
		t.Fatalf("bad version; e = %d, v = %d", expectedVersion, newVersion)
	}
	isDone, err = changer.IsDone()
	if err != nil {
		t.Fatal(err)
	}
	if !isDone {
		t.Fatalf("table expected to not have an outstanding schema change: %v", desc.GetTable())
	}

	// Check that RunStateMachineBeforeBackfill doesn't do anything
	// if there are no mutations queued.
	if err := changer.RunStateMachineBeforeBackfill(); err != nil {
		t.Fatal(err)
	}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}
//.........这里部分代码省略.........

// Test schema change backfills are not affected by various operations
// that run simultaneously.
func TestRaceWithBackfill(t *testing.T) {
	defer leaktest.AfterTest(t)()

	// Disable asynchronous schema change execution to allow synchronous path
	// to trigger start of backfill notification.
	defer csql.TestDisableAsyncSchemaChangeExec()()
	var execKnobs csql.ExecutorTestingKnobs
	var backfillNotification chan bool
	execKnobs.SchemaChangersStartBackfillNotification =
		func() {
			if backfillNotification != nil {
				// Close channel to notify that the backfill has started.
				close(backfillNotification)
			}
		}
	ctx, _ := createTestServerContext()
	ctx.TestingKnobs.SQLExecutor = &execKnobs
	server, sqlDB, kvDB := setupWithContext(t, ctx)
	defer cleanup(server, sqlDB)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k INT PRIMARY KEY, v INT, pi DECIMAL DEFAULT (DECIMAL '3.14'));
CREATE UNIQUE INDEX vidx ON t.test (v);
`); err != nil {
		t.Fatal(err)
	}

	// Bulk insert.
	maxValue := 4000
	insert := fmt.Sprintf(`INSERT INTO t.test VALUES (%d, %d)`, 0, maxValue)
	for i := 1; i <= maxValue; i++ {
		insert += fmt.Sprintf(` ,(%d, %d)`, i, maxValue-i)
	}
	if _, err := sqlDB.Exec(insert); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor for version.
	nameKey := sqlbase.MakeNameMetadataKey(keys.MaxReservedDescID+1, "test")
	gr, err := kvDB.Get(nameKey)
	if err != nil {
		t.Fatal(err)
	}
	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}
	descKey := sqlbase.MakeDescMetadataKey(sqlbase.ID(gr.ValueInt()))
	desc := &sqlbase.Descriptor{}
	if err := kvDB.GetProto(descKey, desc); err != nil {
		t.Fatal(err)
	}
	tableDesc := desc.GetTable()
	tablePrefix := roachpb.Key(keys.MakeTablePrefix(uint32(tableDesc.ID)))
	tableEnd := tablePrefix.PrefixEnd()
	// number of keys == 4 * number of rows; 3 columns and 1 index entry for
	// each row.
	if kvs, err := kvDB.Scan(tablePrefix, tableEnd, 0); err != nil {
		t.Fatal(err)
	} else if e := 4 * (maxValue + 1); len(kvs) != e {
		t.Fatalf("expected %d key value pairs, but got %d", e, len(kvs))
	}

	// Run some schema changes with operations.

	// Add column.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"ALTER TABLE t.test ADD COLUMN x DECIMAL DEFAULT (DECIMAL '1.4')",
		maxValue,
		5,
		descKey,
		backfillNotification)

	// Drop column.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"ALTER TABLE t.test DROP pi",
		maxValue,
		4,
		descKey,
		backfillNotification)

	// Add index.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"CREATE UNIQUE INDEX foo ON t.test (v)",
		maxValue,
		5,
//.........这里部分代码省略.........

// Test that once a table is marked as deleted, a lease's refcount dropping to 0
// means the lease is released immediately, as opposed to being released only
// when it expires.
func TestLeasesOnDeletedTableAreReleasedImmediately(t *testing.T) {
	defer leaktest.AfterTest(t)()
	defer csql.TestDisableAsyncSchemaChangeExec()()

	var execKnobs csql.ExecutorTestingKnobs
	var lmKnobs csql.LeaseManagerTestingKnobs
	var mu sync.Mutex
	clearSchemaChangers := false
	execKnobs.SyncSchemaChangersFilter =
		func(tscc csql.TestingSchemaChangerCollection) {
			mu.Lock()
			defer mu.Unlock()
			if clearSchemaChangers {
				tscc.ClearSchemaChangers()
			}
		}
	var waitTableID sqlbase.ID
	deleted := make(chan bool)
	lmKnobs.TestingLeasesRefreshedEvent =
		func(cfg config.SystemConfig) {
			mu.Lock()
			defer mu.Unlock()
			if waitTableID != 0 {
				if isDeleted(waitTableID, cfg) {
					close(deleted)
					waitTableID = 0
				}
			}
		}
	ctx, _ := createTestServerContext()
	ctx.TestingKnobs.SQLExecutor = &execKnobs
	ctx.TestingKnobs.SQLLeaseManager = &lmKnobs
	s, db, kvDB := setupWithContext(t, ctx)
	defer cleanup(s, db)

	sql := `
CREATE DATABASE test;
CREATE TABLE test.t(a INT PRIMARY KEY);
`
	_, err := db.Exec(sql)
	if err != nil {
		t.Fatal(err)
	}

	tableDesc := getTableDescriptor(kvDB, "test", "t")

	lease1, err := acquire(s.TestServer, tableDesc.ID, 0)
	if err != nil {
		t.Fatal(err)
	}
	lease2, err := acquire(s.TestServer, tableDesc.ID, 0)
	if err != nil {
		t.Fatal(err)
	}

	// Block schema changers so that the table we're about to DROP is not actually
	// dropped; it will be left in a "deleted" state.
	// Also install a way to wait for the config update to be processed.
	mu.Lock()
	clearSchemaChangers = true
	waitTableID = tableDesc.ID
	mu.Unlock()

	// DROP the table
	_, err = db.Exec(`DROP TABLE test.t`)
	if err != nil {
		t.Fatal(err)
	}

	// Block until the LeaseManager has processed the gossip update.
	<-deleted

	// We should still be able to acquire, because we have an active lease.
	lease3, err := acquire(s.TestServer, tableDesc.ID, 0)
	if err != nil {
		t.Fatal(err)
	}

	// Release everything.
	if err := s.LeaseManager().Release(lease1); err != nil {
		t.Fatal(err)
	}
	if err := s.LeaseManager().Release(lease2); err != nil {
		t.Fatal(err)
	}
	if err := s.LeaseManager().Release(lease3); err != nil {
		t.Fatal(err)
	}
	// Now we shouldn't be able to acquire any more.
	_, err = acquire(s.TestServer, tableDesc.ID, 0)
	if !testutils.IsError(err, "descriptor deleted") {
		t.Fatalf("got a different error than expected: %s", err)
	}
}