Golang Error.StripErrorTransaction方法代碼示例

// Exec executes fn in the context of a distributed transaction.
// Execution is controlled by opt (see comments in TxnExecOptions).
//
// opt is passed to fn, and it's valid for fn to modify opt as it sees
// fit during each execution attempt.
//
// It's valid for txn to be nil (meaning the txn has already aborted) if fn
// can handle that. This is useful for continuing transactions that have been
// aborted because of an error in a previous batch of statements in the hope
// that a ROLLBACK will reset the state. Neither opt.AutoRetry not opt.AutoCommit
// can be set in this case.
//
// If an error is returned, the txn has been aborted.
func (txn *Txn) Exec(
	opt TxnExecOptions,
	fn func(txn *Txn, opt *TxnExecOptions) *roachpb.Error) *roachpb.Error {
	// Run fn in a retry loop until we encounter a success or
	// error condition this loop isn't capable of handling.
	var pErr *roachpb.Error
	var retryOptions retry.Options
	if txn == nil && (opt.AutoRetry || opt.AutoCommit) {
		panic("asked to retry  or commit a txn that is already aborted")
	}
	if opt.AutoRetry {
		retryOptions = txn.db.txnRetryOptions
	}
RetryLoop:
	for r := retry.Start(retryOptions); r.Next(); {
		pErr = fn(txn, &opt)
		if (pErr == nil) && opt.AutoCommit && (txn.Proto.Status == roachpb.PENDING) {
			// fn succeeded, but didn't commit.
			pErr = txn.commit(nil)
		}

		if pErr == nil {
			break
		}

		// Make sure the txn record that pErr carries is for this txn.
		// We check only when txn.Proto.ID has been initialized after an initial successful send.
		if pErr.GetTxn() != nil && txn.Proto.ID != nil {
			if errTxn := pErr.GetTxn(); !errTxn.Equal(&txn.Proto) {
				return roachpb.NewErrorf("mismatching transaction record in the error:\n%s\nv.s.\n%s",
					errTxn, txn.Proto)
			}
		}

		if !opt.AutoRetry {
			break RetryLoop
		}
		switch pErr.TransactionRestart {
		case roachpb.TransactionRestart_IMMEDIATE:
			r.Reset()
		case roachpb.TransactionRestart_BACKOFF:
		default:
			break RetryLoop
		}
		if log.V(2) {
			log.Infof("automatically retrying transaction: %s because of error: %s",
				txn.DebugName(), pErr)
		}
	}
	if txn != nil {
		// TODO(andrei): don't do Cleanup() on retriable errors here.
		// Let the sql executor do it.
		txn.Cleanup(pErr)
	}
	if pErr != nil {
		pErr.StripErrorTransaction()
	}
	return pErr
}

// Exec executes fn in the context of a distributed transaction.
// Execution is controlled by opt (see comments in TxnExecOptions).
//
// opt is passed to fn, and it's valid for fn to modify opt as it sees
// fit during each execution attempt.
//
// It's valid for txn to be nil (meaning the txn has already aborted) if fn
// can handle that. This is useful for continuing transactions that have been
// aborted because of an error in a previous batch of statements in the hope
// that a ROLLBACK will reset the state. Neither opt.AutoRetry not opt.AutoCommit
// can be set in this case.
//
// When this method returns, txn might be in any state; Exec does not attempt
// to clean up the transaction before returning an error. In case of
// TransactionAbortedError, txn is reset to a fresh transaction, ready to be
// used.
//
// TODO(andrei): Make Exec() return error; make fn return an error + a retriable
// bit. There's no reason to propagate roachpb.Error (protos) above this point.
func (txn *Txn) Exec(
	opt TxnExecOptions,
	fn func(txn *Txn, opt *TxnExecOptions) *roachpb.Error) *roachpb.Error {
	// Run fn in a retry loop until we encounter a success or
	// error condition this loop isn't capable of handling.
	var pErr *roachpb.Error
	var retryOptions retry.Options
	if txn == nil && (opt.AutoRetry || opt.AutoCommit) {
		panic("asked to retry or commit a txn that is already aborted")
	}

	if opt.AutoRetry {
		retryOptions = txn.db.txnRetryOptions
	}
RetryLoop:
	for r := retry.Start(retryOptions); r.Next(); {
		if txn != nil {
			// If we're looking at a brand new transaction, then communicate
			// what should be used as initial timestamp for the KV txn created
			// by TxnCoordSender.
			if txn.Proto.OrigTimestamp == roachpb.ZeroTimestamp {
				txn.Proto.OrigTimestamp = opt.MinInitialTimestamp
			}
		}

		pErr = fn(txn, &opt)
		if txn != nil {
			txn.retrying = true
			defer func() {
				txn.retrying = false
			}()
		}
		if (pErr == nil) && opt.AutoCommit && (txn.Proto.Status == roachpb.PENDING) {
			// fn succeeded, but didn't commit.
			pErr = txn.Commit()
		}

		if pErr == nil {
			break
		}

		// Make sure the txn record that pErr carries is for this txn.
		// We check only when txn.Proto.ID has been initialized after an initial successful send.
		if pErr.GetTxn() != nil && txn.Proto.ID != nil {
			if errTxn := pErr.GetTxn(); !errTxn.Equal(&txn.Proto) {
				return roachpb.NewErrorf("mismatching transaction record in the error:\n%s\nv.s.\n%s",
					errTxn, txn.Proto)
			}
		}

		if !opt.AutoRetry {
			break RetryLoop
		}
		switch pErr.TransactionRestart {
		case roachpb.TransactionRestart_IMMEDIATE:
			r.Reset()
		case roachpb.TransactionRestart_BACKOFF:
		default:
			break RetryLoop
		}
		if log.V(2) {
			log.Infof("automatically retrying transaction: %s because of error: %s",
				txn.DebugName(), pErr)
		}
	}

	if pErr != nil {
		pErr.StripErrorTransaction()
	}
	return pErr
}