TrustDB: Make it possible to use transactions (#2251)

go/lib/infra/modules/trust/trustdb/trustdb.go

@@ -12,52 +12,85 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package trustdb provides wrappers for SQL calls for managing a database
+// containing TRCs and Certificate Chains.
 package trustdb
 
 import (
 	"context"
+	"database/sql"
 	"io"
 
 	"github.com/scionproto/scion/go/lib/addr"
 	"github.com/scionproto/scion/go/lib/scrypto/cert"
 	"github.com/scionproto/scion/go/lib/scrypto/trc"
 )
 
+// TrustDB is a database containing Certificates, Chains and TRCs, stored in JSON format.
 // TrustDB is the interface that all trust databases have to implement.
+// Read and Write interactions with this interface have to happen in individual transactions
+// (either explicit or implicit).
 type TrustDB interface {
+	Read
+	Write
+	BeginTransaction(ctx context.Context, opts *sql.TxOptions) (Transaction, error)
+	io.Closer
+}
+
+// Read contains all read operation of the trust DB.
+// On errors, GetXxx methods return nil and the error. If no error occurred,
+// but the database query yielded 0 results, the first returned value is nil.
+type Read interface {
 	// GetIssCertVersion returns the specified version of the issuer certificate for
 	// ia. If version is scrypto.LatestVer, this is equivalent to GetIssCertMaxVersion.
 	GetIssCertVersion(ctx context.Context, ia addr.IA, version uint64) (*cert.Certificate, error)
 	// GetIssCertMaxVersion returns the max version of the issuer certificate for ia.
 	GetIssCertMaxVersion(ctx context.Context, ia addr.IA) (*cert.Certificate, error)
-	// InsertIssCert inserts the issuer certificate.
-	InsertIssCert(ctx context.Context, crt *cert.Certificate) (int64, error)
 	// GetLeafCertVersion returns the specified version of the leaf certificate for
 	// ia. If version is scrypto.LatestVer, this is equivalent to GetLeafCertMaxVersion.
 	GetLeafCertVersion(ctx context.Context, ia addr.IA, version uint64) (*cert.Certificate, error)
 	// GetLeafCertMaxVersion returns the max version of the leaf certificate for ia.
 	GetLeafCertMaxVersion(ctx context.Context, ia addr.IA) (*cert.Certificate, error)
-	// InsertLeafCert inserts the leaf certificate.
-	InsertLeafCert(ctx context.Context, crt *cert.Certificate) (int64, error)
 	// GetChainVersion returns the specified version of the certificate chain for
 	// ia. If version is scrypto.LatestVer, this is equivalent to GetChainMaxVersion.
 	GetChainVersion(ctx context.Context, ia addr.IA, version uint64) (*cert.Chain, error)
 	// GetChainMaxVersion returns the max version of the chain for ia.
 	GetChainMaxVersion(ctx context.Context, ia addr.IA) (*cert.Chain, error)
 	// GetAllChains returns all chains in the database.
 	GetAllChains(ctx context.Context) ([]*cert.Chain, error)
-	// InsertChain inserts chain into the database. The first return value is the
-	// number of rows affected.
-	InsertChain(ctx context.Context, chain *cert.Chain) (int64, error)
 	// GetTRCVersion returns the specified version of the TRC for
 	// isd. If version is scrypto.LatestVer, this is equivalent to GetTRCMaxVersion.
 	GetTRCVersion(ctx context.Context, isd addr.ISD, version uint64) (*trc.TRC, error)
 	// GetTRCMaxVersion returns the max version of the TRC for ia.
 	GetTRCMaxVersion(ctx context.Context, isd addr.ISD) (*trc.TRC, error)
+	// GetAllTRCs fetches all TRCs from the database.
+	GetAllTRCs(ctx context.Context) ([]*trc.TRC, error)
+}
+
+// Write contains all write operations fo the trust DB.
+type Write interface {
+	// InsertIssCert inserts the issuer certificate.
+	InsertIssCert(ctx context.Context, crt *cert.Certificate) (int64, error)
+	// InsertLeafCert inserts the leaf certificate.
+	InsertLeafCert(ctx context.Context, crt *cert.Certificate) (int64, error)
+	// InsertChain inserts chain into the database. The first return value is the
+	// number of rows affected.
+	InsertChain(ctx context.Context, chain *cert.Chain) (int64, error)
 	// InsertTRC inserts trcobj into the database. The first return value is the
 	// number of rows affected.
 	InsertTRC(ctx context.Context, trcobj *trc.TRC) (int64, error)
-	// GetAllTRCs fetches all TRCs from the database.
-	GetAllTRCs(ctx context.Context) ([]*trc.TRC, error)
-	io.Closer
+}
+
+// Transaction represents a trust DB transaction with an ongoing transaction.
+// To end the transaction either Rollback or Commit should be called. Calling Commit or Rollback
+// multiple times will result in an error.
+type Transaction interface {
+	Read
+	Write
+	// Commit commits the transaction.
+	// Returns the underlying TrustDB connection.
+	Commit() error
+	// Rollback rollbacks the transaction.
+	// Returns the underlying TrustDB connection.
+	Rollback() error
 }