// maybeRejectClientLocked checks whether the (transactional) request is in a
// state that prevents it from continuing, such as the coordinator having
// considered the client abandoned, or a heartbeat having reported an error.
func (tc *TxnCoordSender) maybeRejectClientLocked(
	ctx context.Context,
	txn roachpb.Transaction,
) *roachpb.Error {

	if !txn.Writing {
		return nil
	}
	txnMeta, ok := tc.txns[*txn.ID]
	// Check whether the transaction is still tracked and has a chance of
	// completing. It's possible that the coordinator learns about the
	// transaction having terminated from a heartbeat, and GC queue correctness
	// (along with common sense) mandates that we don't let the client
	// continue.
	switch {
	case !ok:
		// TODO(spencerkimball): Could add coordinator node ID to the
		// transaction session so that we can definitively return the right
		// error between these possible errors. Or update the code to make an
		// educated guess based on the incoming transaction timestamp.
		return roachpb.NewError(errNoState)
	case txnMeta.txn.Status == roachpb.ABORTED:
		txn := txnMeta.txn.Clone()
		tc.cleanupTxnLocked(ctx, txn)
		return roachpb.NewErrorWithTxn(roachpb.NewTransactionAbortedError(),
			&txn)
	case txnMeta.txn.Status == roachpb.COMMITTED:
		txn := txnMeta.txn.Clone()
		tc.cleanupTxnLocked(ctx, txn)
		return roachpb.NewErrorWithTxn(roachpb.NewTransactionStatusError(
			"transaction is already committed"), &txn)
	default:
		return nil
	}
}

// TestEndWriteRestartReadOnlyTransaction verifies that if
// a transaction writes, then restarts and turns read-only,
// an explicit EndTransaction call is still sent if retry-
// able didn't, regardless of whether there is an error
// or not.
func TestEndWriteRestartReadOnlyTransaction(t *testing.T) {
	defer leaktest.AfterTest(t)()
	for _, success := range []bool{true, false} {
		expCalls := []roachpb.Method{roachpb.BeginTransaction, roachpb.Put, roachpb.EndTransaction}
		var calls []roachpb.Method
		db := NewDB(newTestSender(func(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
			calls = append(calls, ba.Methods()...)
			return ba.CreateReply(), nil
		}, nil))
		ok := false
		if err := db.Txn(context.TODO(), func(txn *Txn) error {
			if !ok {
				if err := txn.Put("consider", "phlebas"); err != nil {
					t.Fatal(err)
				}
				ok = true
				// Return an immediate txn retry error. We need to go through the pErr
				// and back to get a RetryableTxnError.
				return roachpb.NewErrorWithTxn(roachpb.NewTransactionRetryError(), &txn.Proto).GoError()
			}
			if !success {
				return errors.New("aborting on purpose")
			}
			return nil
		}); err == nil != success {
			t.Errorf("expected error: %t, got error: %v", !success, err)
		}
		if !reflect.DeepEqual(expCalls, calls) {
			t.Fatalf("expected %v, got %v", expCalls, calls)
		}
	}
}

// Tests that a retryable error for an inner txn doesn't cause the outer txn to
// be retried.
func TestWrongTxnRetry(t *testing.T) {
	defer leaktest.AfterTest(t)()
	db := NewDB(newTestSender(nil, nil))

	var retries int
	txnClosure := func(outerTxn *Txn) error {
		log.Infof(context.Background(), "outer retry")
		retries++
		// Ensure the KV transaction is created.
		if err := outerTxn.Put("a", "b"); err != nil {
			t.Fatal(err)
		}
		var execOpt TxnExecOptions
		execOpt.AutoRetry = false
		err := outerTxn.Exec(
			execOpt,
			func(innerTxn *Txn, opt *TxnExecOptions) error {
				// Ensure the KV transaction is created.
				if err := innerTxn.Put("x", "y"); err != nil {
					t.Fatal(err)
				}
				return roachpb.NewErrorWithTxn(&roachpb.TransactionPushError{
					PusheeTxn: outerTxn.Proto}, &innerTxn.Proto).GoError()
			})
		return err
	}

	if err := db.Txn(context.TODO(), txnClosure); !testutils.IsError(err, "failed to push") {
		t.Fatal(err)
	}
	if retries != 1 {
		t.Fatalf("unexpected retries: %d", retries)
	}
}

// TestNonRetryableError verifies that a non-retryable error from the
// execution of EndTransactionRequests is propagated to the client.
func TestNonRetryableErrorFromCommit(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, cmdFilters := createTestServerParams()
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	hitError := false
	cleanupFilter := cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if req, ok := args.Req.(*roachpb.EndTransactionRequest); ok {
				if bytes.Contains(req.Key, []byte(keys.DescIDGenerator)) {
					hitError = true
					return roachpb.NewErrorWithTxn(fmt.Errorf("testError"), args.Hdr.Txn)
				}
			}
			return nil
		}, false)
	defer cleanupFilter()

	if _, err := sqlDB.Exec("CREATE DATABASE t;"); !testutils.IsError(err, "pq: testError") {
		t.Errorf("unexpected error %v", err)
	}
	if !hitError {
		t.Errorf("expected to hit error, but it didn't happen")
	}
}

// Verifies that an inner transaction in a nested transaction strips the transaction
// information in its error when propagating it to an other transaction.
func TestNestedTransaction(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, db := setup()
	defer s.Stop()

	pErr := db.Txn(func(txn1 *client.Txn) *roachpb.Error {
		if pErr := txn1.Put("a", "1"); pErr != nil {
			t.Fatalf("unexpected put error: %s", pErr)
		}
		iPErr := db.Txn(func(txn2 *client.Txn) *roachpb.Error {
			txnProto := roachpb.NewTransaction("test", roachpb.Key("a"), 1, roachpb.SERIALIZABLE, roachpb.Timestamp{}, 0)
			return roachpb.NewErrorWithTxn(util.Errorf("inner txn error"), txnProto)
		})

		if iPErr.GetTxn() != nil {
			t.Errorf("error txn must be stripped: %s", iPErr)
		}
		return iPErr

	})
	if pErr == nil {
		t.Fatal("unexpected success of txn")
	}
	if !testutils.IsPError(pErr, "inner txn error") {
		t.Errorf("unexpected failure: %s", pErr)
	}
}

// TestNonRetryableError verifies that a non-retryable error is propagated to the client.
func TestNonRetryableError(t *testing.T) {
	defer leaktest.AfterTest(t)()

	ctx, cmdFilters := createTestServerContext()
	server, sqlDB, _ := setupWithContext(t, &ctx)
	defer cleanup(server, sqlDB)

	testKey := []byte("test_key")
	hitError := false
	cleanupFilter := cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if req, ok := args.Req.(*roachpb.ScanRequest); ok {
				if bytes.Contains(req.Key, testKey) {
					hitError = true
					return roachpb.NewErrorWithTxn(fmt.Errorf("testError"), args.Hdr.Txn)
				}
			}
			return nil
		}, false)
	defer cleanupFilter()

	sqlDB.SetMaxOpenConns(1)
	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k TEXT PRIMARY KEY, v TEXT);
INSERT INTO t.test (k, v) VALUES ('test_key', 'test_val');
SELECT * from t.test WHERE k = 'test_key';
`); !testutils.IsError(err, "pq: testError") {
		t.Errorf("unexpected error %s", err)
	}
	if !hitError {
		t.Errorf("expected to hit error, but it didn't happen")
	}
}

// TestRunTransactionRetryOnErrors verifies that the transaction
// is retried on the correct errors.
func TestRunTransactionRetryOnErrors(t *testing.T) {
	defer leaktest.AfterTest(t)()
	testCases := []struct {
		err   error
		retry bool // Expect retry?
	}{
		{roachpb.NewReadWithinUncertaintyIntervalError(hlc.ZeroTimestamp, hlc.ZeroTimestamp), true},
		{&roachpb.TransactionAbortedError{}, true},
		{&roachpb.TransactionPushError{}, true},
		{&roachpb.TransactionRetryError{}, true},
		{&roachpb.WriteTooOldError{}, true},
		{&roachpb.RangeNotFoundError{}, false},
		{&roachpb.RangeKeyMismatchError{}, false},
		{&roachpb.TransactionStatusError{}, false},
	}

	for i, test := range testCases {
		count := 0
		dbCtx := DefaultDBContext()
		dbCtx.TxnRetryOptions.InitialBackoff = 1 * time.Millisecond
		db := NewDBWithContext(newTestSender(
			func(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {

				if _, ok := ba.GetArg(roachpb.Put); ok {
					count++
					if count == 1 {
						return nil, roachpb.NewErrorWithTxn(test.err, ba.Txn)
					}
				}
				return ba.CreateReply(), nil
			}, nil), dbCtx)
		err := db.Txn(context.TODO(), func(txn *Txn) error {
			return txn.Put("a", "b")
		})
		if test.retry {
			if count != 2 {
				t.Errorf("%d: expected one retry; got %d", i, count-1)
			}
			if err != nil {
				t.Errorf("%d: expected success on retry; got %s", i, err)
			}
		} else {
			if count != 1 {
				t.Errorf("%d: expected no retries; got %d", i, count)
			}
			if reflect.TypeOf(err) != reflect.TypeOf(test.err) {
				t.Errorf("%d: expected error of type %T; got %T", i, test.err, err)
			}
		}
	}
}

func TestAbortCountConflictingWrites(t *testing.T) {
	defer leaktest.AfterTest(t)()

	ctx, cmdFilters := createTestServerContext()
	s, sqlDB, _ := setupWithContext(t, ctx)
	defer cleanup(s, sqlDB)

	if _, err := sqlDB.Exec("CREATE DATABASE db"); err != nil {
		t.Fatal(err)
	}
	if _, err := sqlDB.Exec("CREATE TABLE db.t (k TEXT PRIMARY KEY, v TEXT)"); err != nil {
		t.Fatal(err)
	}

	// Inject errors on the INSERT below.
	restarted := false
	cmdFilters.AppendFilter(func(args storageutils.FilterArgs) *roachpb.Error {
		switch req := args.Req.(type) {
		// SQL INSERT generates ConditionalPuts for unique indexes (such as the PK).
		case *roachpb.ConditionalPutRequest:
			if bytes.Contains(req.Value.RawBytes, []byte("marker")) && !restarted {
				restarted = true
				return roachpb.NewErrorWithTxn(
					roachpb.NewTransactionAbortedError(), args.Hdr.Txn)
			}
		}
		return nil
	}, false)

	txn, err := sqlDB.Begin()
	if err != nil {
		t.Fatal(err)
	}
	_, err = txn.Exec("INSERT INTO db.t VALUES ('key', 'marker')")
	if !testutils.IsError(err, "aborted") {
		t.Fatal(err)
	}

	if err = txn.Rollback(); err != nil {
		t.Fatal(err)
	}

	checkCounterEQ(t, s, "txn.abort.count", 1)
	checkCounterEQ(t, s, "txn.begin.count", 1)
	checkCounterEQ(t, s, "txn.rollback.count", 0)
	checkCounterEQ(t, s, "txn.commit.count", 0)
	checkCounterEQ(t, s, "insert.count", 1)
}

// TestTxnResetTxnOnAbort verifies transaction is reset on abort.
func TestTxnResetTxnOnAbort(t *testing.T) {
	defer leaktest.AfterTest(t)
	db := newDB(newTestSender(func(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
		return nil, roachpb.NewErrorWithTxn(&roachpb.TransactionAbortedError{}, ba.Txn)
	}, nil))

	txn := NewTxn(*db)
	_, pErr := txn.db.sender.Send(context.Background(), testPut())
	if _, ok := pErr.GetDetail().(*roachpb.TransactionAbortedError); !ok {
		t.Fatalf("expected TransactionAbortedError, got %v", pErr)
	}

	if txn.Proto.ID != nil {
		t.Errorf("expected txn to be cleared")
	}
}

// TestTransactionKeyNotChangedInRestart verifies that if the transaction already has a key (we're
// in a restart), the key in the begin transaction request is not changed.
func TestTransactionKeyNotChangedInRestart(t *testing.T) {
	defer leaktest.AfterTest(t)()
	tries := 0
	db := NewDB(newTestSender(nil, func(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
		var bt *roachpb.BeginTransactionRequest
		if args, ok := ba.GetArg(roachpb.BeginTransaction); ok {
			bt = args.(*roachpb.BeginTransactionRequest)
		} else {
			t.Fatal("failed to find a begin transaction request")
		}

		// In the first try, the transaction key is the key of the first write command. Before the
		// second try, the transaction key is set to txnKey by the test sender. In the second try, the
		// transaction key is txnKey.
		var expectedKey roachpb.Key
		if tries == 1 {
			expectedKey = testKey
		} else {
			expectedKey = txnKey
		}
		if !bt.Key.Equal(expectedKey) {
			t.Fatalf("expected transaction key %v, got %v", expectedKey, bt.Key)
		}

		return ba.CreateReply(), nil
	}))

	if err := db.Txn(context.TODO(), func(txn *Txn) error {
		tries++
		b := txn.NewBatch()
		b.Put("a", "b")
		if err := txn.Run(b); err != nil {
			t.Fatal(err)
		}
		if tries == 1 {
			return roachpb.NewErrorWithTxn(roachpb.NewTransactionRetryError(), &txn.Proto).GoError()
		}
		return nil
	}); err != nil {
		t.Errorf("unexpected error on commit: %s", err)
	}
	minimumTries := 2
	if tries < minimumTries {
		t.Errorf("expected try count >= %d, got %d", minimumTries, tries)
	}
}

// TestRollbackInRestartWait ensures that a ROLLBACK while the txn is in the
// RetryWait state works.
func TestRollbackInRestartWait(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, cmdFilters := createTestServerParams()
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

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

	// Set up error injection that causes retries.
	magicVals := createFilterVals(nil, nil)
	magicVals.endTxnRestartCounts = map[string]int{
		"boulanger": 1,
	}
	defer cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if err := injectErrors(args.Req, args.Hdr, magicVals); err != nil {
				return roachpb.NewErrorWithTxn(err, args.Hdr.Txn)
			}
			return nil
		}, false)()

	tx, err := sqlDB.Begin()
	if err != nil {
		t.Fatal(err)
	}
	if _, err := tx.Exec("SAVEPOINT cockroach_restart"); err != nil {
		t.Fatal(err)
	}
	if _, err := tx.Exec(
		"INSERT INTO t.test (k, v) VALUES ('g', 'boulanger')"); err != nil {
		t.Fatal(err)
	}
	if _, err := tx.Exec("RELEASE SAVEPOINT cockroach_restart"); err == nil {
		t.Fatal("expected RELEASE to fail")
	}
	if err := tx.Rollback(); err != nil {
		t.Fatal(err)
	}
}

// Verifies that a nested transaction returns an error if an inner txn
// propagates an error to an outer txn.
func TestNestedTransaction(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, db := setup()
	defer s.Stop()

	txnProto := roachpb.NewTransaction("test", roachpb.Key("a"), 1, roachpb.SERIALIZABLE, roachpb.Timestamp{}, 0)
	pErr := db.Txn(func(txn1 *client.Txn) *roachpb.Error {
		if pErr := txn1.Put("a", "1"); pErr != nil {
			t.Fatalf("unexpected put error: %s", pErr)
		}
		return db.Txn(func(txn2 *client.Txn) *roachpb.Error {
			return roachpb.NewErrorWithTxn(util.Errorf("err"), txnProto)
		})
	})
	if pErr == nil {
		t.Fatal("unexpected success of txn")
	}
	if !testutils.IsPError(pErr, "mismatching transaction record in the error") {
		t.Errorf("unexpected failure: %s", pErr)
	}
}

// TestNonRetryableError verifies that a non-retryable error is propagated to the client.
func TestNonRetryableError(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, cmdFilters := createTestServerParams()
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	testKey := []byte("test_key")
	hitError := false
	cleanupFilter := cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if req, ok := args.Req.(*roachpb.ScanRequest); ok {
				if bytes.Contains(req.Key, testKey) {
					hitError = true
					return roachpb.NewErrorWithTxn(fmt.Errorf("testError"), args.Hdr.Txn)
				}
			}
			return nil
		}, false)
	defer cleanupFilter()

	// We need to do everything on one connection as we'll want to observe the
	// connection state after a COMMIT.
	sqlDB.SetMaxOpenConns(1)
	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k TEXT PRIMARY KEY, v TEXT);
INSERT INTO t.test (k, v) VALUES ('test_key', 'test_val');
SELECT * from t.test WHERE k = 'test_key';
`); !testutils.IsError(err, "pq: testError") {
		t.Errorf("unexpected error %v", err)
	}
	if !hitError {
		t.Errorf("expected to hit error, but it didn't happen")
	}
}

//.........这里部分代码省略.........
			status:     roachpb.COMMITTED,
			orig:       gcTxnAndAC - 1,
			newStatus:  -1,
			expResolve: true,
			expAbortGC: true,
		},
		// Same as the previous one, but we've rigged things so that the intent
		// resolution here will fail and consequently no GC is expected.
		"g": {
			status:      roachpb.COMMITTED,
			orig:        gcTxnAndAC - 1,
			newStatus:   roachpb.COMMITTED,
			failResolve: true,
			expResolve:  true,
			expAbortGC:  true,
		},
	}

	resolved := map[string][]roachpb.Span{}

	tc := testContext{}
	tsc := TestStoreContext()
	tsc.TestingKnobs.TestingCommandFilter =
		func(filterArgs storagebase.FilterArgs) *roachpb.Error {
			if resArgs, ok := filterArgs.Req.(*roachpb.ResolveIntentRequest); ok {
				id := string(resArgs.IntentTxn.Key)
				resolved[id] = append(resolved[id], roachpb.Span{
					Key:    resArgs.Key,
					EndKey: resArgs.EndKey,
				})
				// We've special cased one test case. Note that the intent is still
				// counted in `resolved`.
				if testCases[id].failResolve {
					return roachpb.NewErrorWithTxn(util.Errorf("boom"), filterArgs.Hdr.Txn)
				}
			}
			return nil
		}
	tc.StartWithStoreContext(t, tsc)
	defer tc.Stop()
	tc.manualClock.Set(int64(now))

	outsideKey := tc.rng.Desc().EndKey.Next().AsRawKey()
	testIntents := []roachpb.Span{{Key: roachpb.Key("intent")}}

	txns := map[string]roachpb.Transaction{}
	for strKey, test := range testCases {
		baseKey := roachpb.Key(strKey)
		txnClock := hlc.NewClock(hlc.NewManualClock(int64(test.orig)).UnixNano)
		txn := newTransaction("txn1", baseKey, 1, enginepb.SERIALIZABLE, txnClock)
		txn.Status = test.status
		txn.Intents = testIntents
		if test.hb > 0 {
			txn.LastHeartbeat = &hlc.Timestamp{WallTime: int64(test.hb)}
		}
		// Set a high Timestamp to make sure it does not matter. Only
		// OrigTimestamp (and heartbeat) are used for GC decisions.
		txn.Timestamp.Forward(hlc.MaxTimestamp)
		txns[strKey] = *txn
		for _, addrKey := range []roachpb.Key{baseKey, outsideKey} {
			key := keys.TransactionKey(addrKey, txn.ID)
			if err := engine.MVCCPutProto(context.Background(), tc.engine, nil, key, hlc.ZeroTimestamp, nil, txn); err != nil {
				t.Fatal(err)
			}
		}
		entry := roachpb.AbortCacheEntry{Key: txn.Key, Timestamp: txn.LastActive()}

// send runs the specified calls synchronously in a single batch and
// returns any errors. If the transaction is read-only or has already
// been successfully committed or aborted, a potential trailing
// EndTransaction call is silently dropped, allowing the caller to
// always commit or clean-up explicitly even when that may not be
// required (or even erroneous). Returns (nil, nil) for an empty batch.
func (txn *Txn) send(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {

	if txn.Proto.Status != roachpb.PENDING || txn.IsFinalized() {
		return nil, roachpb.NewErrorf(
			"attempting to use transaction with wrong status or finalized: %s", txn.Proto.Status)
	}

	// It doesn't make sense to use inconsistent reads in a transaction. However,
	// we still need to accept it as a parameter for this to compile.
	if ba.ReadConsistency != roachpb.CONSISTENT {
		return nil, roachpb.NewErrorf("cannot use %s ReadConsistency in txn",
			ba.ReadConsistency)
	}

	lastIndex := len(ba.Requests) - 1
	if lastIndex < 0 {
		return nil, nil
	}

	// firstWriteIndex is set to the index of the first command which is
	// a transactional write. If != -1, this indicates an intention to
	// write. This is in contrast to txn.Proto.Writing, which is set by
	// the coordinator when the first intent has been created, and which
	// lives for the life of the transaction.
	firstWriteIndex := -1
	var firstWriteKey roachpb.Key

	for i, ru := range ba.Requests {
		args := ru.GetInner()
		if i < lastIndex {
			if _, ok := args.(*roachpb.EndTransactionRequest); ok {
				return nil, roachpb.NewErrorf("%s sent as non-terminal call", args.Method())
			}
		}
		if roachpb.IsTransactionWrite(args) && firstWriteIndex == -1 {
			firstWriteKey = args.Header().Key
			firstWriteIndex = i
		}
	}

	haveTxnWrite := firstWriteIndex != -1
	endTxnRequest, haveEndTxn := ba.Requests[lastIndex].GetInner().(*roachpb.EndTransactionRequest)
	needBeginTxn := !txn.Proto.Writing && haveTxnWrite
	needEndTxn := txn.Proto.Writing || haveTxnWrite
	elideEndTxn := haveEndTxn && !needEndTxn

	// If we're not yet writing in this txn, but intend to, insert a
	// begin transaction request before the first write command.
	if needBeginTxn {
		// If the transaction already has a key (we're in a restart), make
		// sure we set the key in the begin transaction request to the original.
		bt := &roachpb.BeginTransactionRequest{
			Span: roachpb.Span{
				Key: firstWriteKey,
			},
		}
		if txn.Proto.Key != nil {
			bt.Key = txn.Proto.Key
		}
		// Inject the new request before position firstWriteIndex, taking
		// care to avoid unnecessary allocations.
		oldRequests := ba.Requests
		ba.Requests = make([]roachpb.RequestUnion, len(ba.Requests)+1)
		copy(ba.Requests, oldRequests[:firstWriteIndex])
		ba.Requests[firstWriteIndex].MustSetInner(bt)
		copy(ba.Requests[firstWriteIndex+1:], oldRequests[firstWriteIndex:])
	}

	if elideEndTxn {
		ba.Requests = ba.Requests[:lastIndex]
	}

	br, pErr := txn.db.send(ba)
	if elideEndTxn && pErr == nil {
		// Check that read only transactions do not violate their deadline. This can NOT
		// happen since the txn deadline is normally updated when it is about to expire
		// or expired. We will just keep the code for safety (see TestReacquireLeaseOnRestart).
		if endTxnRequest.Deadline != nil {
			if endTxnRequest.Deadline.Less(txn.Proto.Timestamp) {
				return nil, roachpb.NewErrorWithTxn(roachpb.NewTransactionAbortedError(), &txn.Proto)
			}
		}
		// This normally happens on the server and sent back in response
		// headers, but this transaction was optimized away. The caller may
		// still inspect the transaction struct, so we manually update it
		// here to emulate a true transaction.
		if endTxnRequest.Commit {
			txn.Proto.Status = roachpb.COMMITTED
		} else {
			txn.Proto.Status = roachpb.ABORTED
		}
		txn.finalized = true
	}

//.........这里部分代码省略.........

// Verifies that an expired lease is released and a new lease is acquired on transaction
// restart.
//
// This test triggers the above scenario by making ReadWithinUncertaintyIntervalError advance
// the clock, so that the transaction timestamp exceeds the deadline of the EndTransactionRequest.
func TestReacquireLeaseOnRestart(t *testing.T) {
	defer leaktest.AfterTest(t)()

	var cmdFilters CommandFilters
	cmdFilters.AppendFilter(checkEndTransactionTrigger, true)

	var clockUpdate int32
	testKey := []byte("test_key")
	testingKnobs := &storage.StoreTestingKnobs{
		TestingCommandFilter: cmdFilters.runFilters,
		ClockBeforeSend: func(c *hlc.Clock, ba roachpb.BatchRequest) {
			if atomic.LoadInt32(&clockUpdate) > 0 {
				return
			}

			// Hack to advance the transaction timestamp on a transaction restart.
			for _, union := range ba.Requests {
				if req, ok := union.GetInner().(*roachpb.ScanRequest); ok {
					if bytes.Contains(req.Key, testKey) {
						atomic.AddInt32(&clockUpdate, 1)
						now := c.Now()
						now.WallTime += int64(5 * sql.LeaseDuration)
						c.Update(now)
						break
					}
				}
			}
		},
	}

	params, _ := createTestServerParams()
	params.Knobs.Store = testingKnobs
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	var restartDone int32
	cleanupFilter := cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if atomic.LoadInt32(&restartDone) > 0 {
				return nil
			}

			if req, ok := args.Req.(*roachpb.ScanRequest); ok {
				if bytes.Contains(req.Key, testKey) {
					atomic.AddInt32(&restartDone, 1)
					// Return ReadWithinUncertaintyIntervalError to update the transaction timestamp on retry.
					txn := args.Hdr.Txn
					txn.ResetObservedTimestamps()
					now := s.Clock().Now()
					txn.UpdateObservedTimestamp(
						s.(*server.TestServer).Gossip().GetNodeID(), now)
					return roachpb.NewErrorWithTxn(roachpb.NewReadWithinUncertaintyIntervalError(now, now), txn)
				}
			}
			return nil
		}, false)
	defer cleanupFilter()

	// Use a large max offset to avoid rejecting a transaction whose timestanp is in
	// future (as we will advance the transaction timestamp with ReadWithinUncertaintyIntervalError).
	s.Clock().SetMaxOffset(sql.LeaseDuration * 10)

	sqlDB.SetMaxOpenConns(1)
	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k TEXT PRIMARY KEY, v TEXT);
INSERT INTO t.test (k, v) VALUES ('test_key', 'test_val');
`); err != nil {
		t.Fatal(err)
	}
	// Acquire the lease and enable the auto-retry. The first read attempt will trigger ReadWithinUncertaintyIntervalError
	// and advance the transaction timestamp. The transaction timestamp will exceed the lease expiration
	// time, and the second read attempt will re-acquire the lease.
	if _, err := sqlDB.Exec(`
SELECT * from t.test WHERE k = 'test_key';
`); err != nil {
		t.Fatal(err)
	}

	if u := atomic.LoadInt32(&clockUpdate); u != 1 {
		t.Errorf("expected exacltly one clock update, but got %d", u)
	}
	if u := atomic.LoadInt32(&restartDone); u != 1 {
		t.Errorf("expected exactly one restart, but got %d", u)
	}
}

// updateState updates the transaction state in both the success and
// error cases, applying those updates to the corresponding txnMeta
// object when adequate. It also updates certain errors with the
// updated transaction for use by client restarts.
func (tc *TxnCoordSender) updateState(ctx context.Context, ba roachpb.BatchRequest, br *roachpb.BatchResponse, pErr *roachpb.Error) *roachpb.Error {
	sp, cleanupSp := tracing.SpanFromContext(opTxnCoordSender, tc.tracer, ctx)
	defer cleanupSp()

	newTxn := &roachpb.Transaction{}
	newTxn.Update(ba.Txn)
	if pErr == nil {
		newTxn.Update(br.Txn)
	} else {
		newTxn.Update(pErr.GetTxn())
	}

	// If the request was successful but we're in a transaction which needs to
	// restart but doesn't know it yet, let it restart now (as opposed to
	// waiting until EndTransaction).
	if pErr == nil && newTxn.Isolation == roachpb.SERIALIZABLE &&
		!newTxn.OrigTimestamp.Equal(newTxn.Timestamp) {
		pErr = roachpb.NewErrorWithTxn(roachpb.NewTransactionRetryError(), br.Txn)
		br = nil
	}

	switch t := pErr.GetDetail().(type) {
	case *roachpb.TransactionStatusError:
		// Likely already committed or more obscure errors such as epoch or
		// timestamp regressions; consider txn dead.
		defer tc.cleanupTxn(sp, *pErr.GetTxn())
	case *roachpb.OpRequiresTxnError:
		panic("OpRequiresTxnError must not happen at this level")
	case *roachpb.ReadWithinUncertaintyIntervalError:
		// If the reader encountered a newer write within the uncertainty
		// interval, we advance the txn's timestamp just past the last observed
		// timestamp from the node.
		restartTS, ok := newTxn.GetObservedTimestamp(pErr.OriginNode)
		if !ok {
			pErr = roachpb.NewError(util.Errorf("no observed timestamp for node %d found on uncertainty restart", pErr.OriginNode))
		} else {
			newTxn.Timestamp.Forward(restartTS)
			newTxn.Restart(ba.UserPriority, newTxn.Priority, newTxn.Timestamp)
		}
	case *roachpb.TransactionAbortedError:
		// Increase timestamp if applicable.
		newTxn.Timestamp.Forward(pErr.GetTxn().Timestamp)
		newTxn.Priority = pErr.GetTxn().Priority
		// Clean up the freshly aborted transaction in defer(), avoiding a
		// race with the state update below.
		defer tc.cleanupTxn(sp, *newTxn)
	case *roachpb.TransactionPushError:
		// Increase timestamp if applicable, ensuring that we're
		// just ahead of the pushee.
		newTxn.Timestamp.Forward(t.PusheeTxn.Timestamp.Add(0, 1))
		newTxn.Restart(ba.UserPriority, t.PusheeTxn.Priority-1, newTxn.Timestamp)
	case *roachpb.TransactionRetryError:
		newTxn.Restart(ba.UserPriority, pErr.GetTxn().Priority, newTxn.Timestamp)
	case nil:
		// Nothing to do here, avoid the default case.
	default:
		if pErr.GetTxn() != nil {
			if pErr.CanRetry() {
				panic("Retryable internal error must not happen at this level")
			} else {
				// Do not clean up the transaction here since the client might still
				// want to continue the transaction. For example, a client might
				// continue its transaction after receiving ConditionFailedError, which
				// can come from a unique index violation.
			}
		}
	}

	if pErr != nil && pErr.GetTxn() != nil {
		// Avoid changing existing errors because sometimes they escape into
		// goroutines and then there are races. Fairly sure there isn't one
		// here, but better safe than sorry.
		pErrShallow := *pErr
		pErrShallow.SetTxn(newTxn)
		pErr = &pErrShallow
	}

	if newTxn.ID == nil {
		return pErr
	}
	txnID := *newTxn.ID
	tc.Lock()
	defer tc.Unlock()
	txnMeta := tc.txns[txnID]
	// For successful transactional requests, keep the written intents and
	// the updated transaction record to be sent along with the reply.
	// The transaction metadata is created with the first writing operation.
	// A tricky edge case is that of a transaction which "fails" on the
	// first writing request, but actually manages to write some intents
	// (for example, due to being multi-range). In this case, there will
	// be an error, but the transaction will be marked as Writing and the
	// coordinator must track the state, for the client's retry will be
	// performed with a Writing transaction which the coordinator rejects
	// unless it is tracking it (on top of it making sense to track it;
	// after all, it **has** laid down intents and only the coordinator
	// can augment a potential EndTransaction call). See #3303.
//.........这里部分代码省略.........

// Test that a COMMIT getting an error, retryable or not, leaves the txn
// finalized and not in Aborted/RestartWait (i.e. COMMIT, like ROLLBACK, is
// always final).
func TestCommitFinalizesTxnOnError(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, cmdFilters := createTestServerParams()
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t; CREATE TABLE t.test (k INT PRIMARY KEY, v TEXT);
`); err != nil {
		t.Fatal(err)
	}
	// We need to do everything on one connection as we'll want to observe the
	// connection state after a COMMIT.
	sqlDB.SetMaxOpenConns(1)

	// Set up error injection that causes retries.
	magicVals := createFilterVals(nil, nil)
	magicVals.endTxnRestartCounts = map[string]int{
		"boulanger": 1000, // restart many times, for all the tests below
	}
	defer cmdFilters.AppendFilter(
		func(args storagebase.FilterArgs) *roachpb.Error {
			if err := injectErrors(args.Req, args.Hdr, magicVals); err != nil {
				return roachpb.NewErrorWithTxn(err, args.Hdr.Txn)
			}
			return nil
		}, false)()

	// We're going to test both errors that would leave the transaction in the
	// RestartWait state and errors that would leave the transaction in Aborted,
	// if they were to happen on any other statement than COMMIT.
	// We do that by always injecting a retryable error at COMMIT, but once in a
	// txn that had a "retry intent" (SAVEPOINT cockroach_restart), and once in a
	// txn without it.
	testCases := []struct {
		retryIntent bool
	}{
		{false},
		{true},
	}
	for _, tc := range testCases {
		if _, err := sqlDB.Exec("BEGIN;"); err != nil {
			t.Fatal(err)
		}
		if tc.retryIntent {
			if _, err := sqlDB.Exec("SAVEPOINT cockroach_restart;"); err != nil {
				t.Fatal(err)
			}
		}
		if _, err := sqlDB.Exec("INSERT INTO t.test (k, v) VALUES (0, 'boulanger');"); err != nil {
			t.Fatal(err)
		}
		if _, err := sqlDB.Exec("COMMIT;"); !testutils.IsError(err, "pq: restart transaction") {
			t.Fatalf("unexpected error: %v", err)
		}

		// Check that we can start another txn on the (one and only) connection.
		if _, err := sqlDB.Exec("BEGIN;END;"); err != nil {
			t.Fatal(err)
		}
	}
}

// TestPropagateTxnOnError verifies that DistSender.sendChunk properly
// propagates the txn data to a next iteration. Use txn.Writing field to
// verify that.
func TestPropagateTxnOnError(t *testing.T) {
	defer leaktest.AfterTest(t)()

	// Set up a filter to so that the first CPut operation will
	// get a ReadWithinUncertaintyIntervalError.
	targetKey := roachpb.Key("b")
	var numGets int32

	ctx := server.NewTestContext()
	ctx.TestingKnobs.StoreTestingKnobs.TestingCommandFilter =
		func(fArgs storageutils.FilterArgs) *roachpb.Error {
			_, ok := fArgs.Req.(*roachpb.ConditionalPutRequest)
			if ok && fArgs.Req.Header().Key.Equal(targetKey) {
				if atomic.AddInt32(&numGets, 1) == 1 {
					z := roachpb.ZeroTimestamp
					pErr := roachpb.NewReadWithinUncertaintyIntervalError(z, z)
					return roachpb.NewErrorWithTxn(pErr, fArgs.Hdr.Txn)
				}
			}
			return nil
		}
	s := server.StartTestServerWithContext(t, ctx)
	defer s.Stop()
	db := setupMultipleRanges(t, s, "b")

	// Set the initial value on the target key "b".
	origVal := "val"
	if pErr := db.Put(targetKey, origVal); pErr != nil {
		t.Fatal(pErr)
	}

	// The following txn creates a batch request that is split
	// into two requests: Put and CPut. The CPut operation will
	// get a ReadWithinUncertaintyIntervalError and the txn will be
	// retried.
	epoch := 0
	if pErr := db.Txn(func(txn *client.Txn) *roachpb.Error {
		epoch++
		if epoch >= 2 {
			// Writing must be true since we ran the BeginTransaction command.
			if !txn.Proto.Writing {
				t.Errorf("unexpected non-writing txn")
			}
		} else {
			// Writing must be false since we haven't run any write command.
			if txn.Proto.Writing {
				t.Errorf("unexpected writing txn")
			}
		}

		b := txn.NewBatch()
		b.Put("a", "val")
		b.CPut(targetKey, "new_val", origVal)
		pErr := txn.CommitInBatch(b)
		if epoch == 1 {
			if _, ok := pErr.GetDetail().(*roachpb.ReadWithinUncertaintyIntervalError); ok {
				if !pErr.GetTxn().Writing {
					t.Errorf("unexpected non-writing txn on error")
				}
			} else {
				t.Errorf("expected ReadWithinUncertaintyIntervalError, but got: %s", pErr)
			}
		}
		return pErr
	}); pErr != nil {
		t.Errorf("unexpected error on transactional Puts: %s", pErr)
	}

	if epoch != 2 {
		t.Errorf("unexpected epoch; the txn must be retried exactly once, but got %d", epoch)
	}
}

// TestUserTxnRestart tests user-directed txn restarts.
// The test will inject and otherwise create retriable errors of various kinds
// and checks that we still manage to run a txn despite them.
func TestTxnUserRestart(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, cmdFilters := createTestServerParams()
	params.Knobs.SQLExecutor = &sql.ExecutorTestingKnobs{FixTxnPriority: true}
	s, sqlDB, _ := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

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

	// Set up error injection that causes retries.
	testCases := []struct {
		magicVals   *filterVals
		expectedErr string
	}{
		{
			magicVals: createFilterVals(
				map[string]int{"boulanger": 2}, // restartCounts
				nil),
			expectedErr: ".*encountered previous write with future timestamp.*",
		},
		{
			magicVals: createFilterVals(
				nil,
				map[string]int{"boulanger": 2}), // abortCounts
			expectedErr: ".*txn aborted.*",
		},
	}

	for _, tc := range testCases {
		for _, rs := range []rollbackStrategy{rollbackToSavepoint, declareSavepoint} {
			cleanupFilter := cmdFilters.AppendFilter(
				func(args storagebase.FilterArgs) *roachpb.Error {
					if err := injectErrors(args.Req, args.Hdr, tc.magicVals); err != nil {
						return roachpb.NewErrorWithTxn(err, args.Hdr.Txn)
					}
					return nil
				}, false)

			// Also inject an error at RELEASE time, besides the error injected by magicVals.
			injectReleaseError := true

			commitCount := s.MustGetSQLCounter(sql.MetaTxnCommit.Name)
			// This is