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package txinfo
import (
"context"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"gitlab.com/gitlab-org/gitaly/v16/internal/grpc/backchannel"
"google.golang.org/grpc/metadata"
)
const (
// TransactionMetadataKey is the key used to store transaction
// information in the gRPC metadata.
TransactionMetadataKey = "gitaly-reference-transaction"
)
// ErrTransactionNotFound indicates the transaction metadata could not
// be found
var ErrTransactionNotFound = errors.New("transaction not found")
// Transaction stores parameters required to identify a reference
// transaction.
type Transaction struct {
// BackchannelID is the ID of the backchannel that corresponds to the Praefect
// that is handling the transaction. This field is filled in by the Gitaly.
BackchannelID backchannel.ID `json:"backchannel_id,omitempty"`
// ID is the unique identifier of a transaction
ID uint64 `json:"id"`
// Node is the name used to cast a vote
Node string `json:"node"`
// Primary identifies the node's role in this transaction
Primary bool `json:"primary"`
}
// serialize serializes a `Transaction` into a string.
func (t Transaction) serialize() (string, error) {
marshalled, err := json.Marshal(t)
if err != nil {
return "", err
}
return base64.StdEncoding.EncodeToString(marshalled), nil
}
// transactionFromSerialized creates a transaction from a `serialize()`d string.
func transactionFromSerialized(serialized string) (Transaction, error) {
decoded, err := base64.StdEncoding.DecodeString(serialized)
if err != nil {
return Transaction{}, err
}
var tx Transaction
if err := json.Unmarshal(decoded, &tx); err != nil {
return Transaction{}, err
}
return tx, nil
}
// InjectTransaction injects reference transaction metadata into an incoming context
func InjectTransaction(ctx context.Context, transactionID uint64, node string, primary bool) (context.Context, error) {
transaction := Transaction{
ID: transactionID,
Node: node,
Primary: primary,
}
serialized, err := transaction.serialize()
if err != nil {
return nil, err
}
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
md = metadata.New(map[string]string{})
} else {
md = md.Copy()
}
md.Set(TransactionMetadataKey, serialized)
return metadata.NewIncomingContext(ctx, md), nil
}
// TransactionFromContext extracts `Transaction` from an incoming context. In
// case the metadata key is not set, the function will return
// `ErrTransactionNotFound`.
func TransactionFromContext(ctx context.Context) (Transaction, error) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
return Transaction{}, ErrTransactionNotFound
}
serialized := md[TransactionMetadataKey]
if len(serialized) == 0 {
return Transaction{}, ErrTransactionNotFound
}
transaction, err := transactionFromSerialized(serialized[0])
if err != nil {
return Transaction{}, fmt.Errorf("from serialized: %w", err)
}
// For backwards compatibility during an upgrade, we still need to accept transactions
// from non-multiplexed connections. From 14.0 onwards, we can expect every transaction to
// originate from a multiplexed connection and should drop the error check below.
transaction.BackchannelID, err = backchannel.GetPeerID(ctx)
if err != nil && !errors.Is(err, backchannel.ErrNonMultiplexedConnection) {
return Transaction{}, fmt.Errorf("get peer id: %w", err)
}
return transaction, nil
}
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