feat: expose transaction failure stages and conservative outcomes

database/mysqlConnector_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"database/sql"
+	"database/sql/driver"
 	"errors"
 	"net"
 	"os"
@@ -166,11 +167,64 @@ func TestMySQLConnectorTLSAndPoolIsolation(t *testing.T) {
 		return rollbackErr
 	}); !errors.Is(err, rollbackErr) {
 		t.Fatal(err)
+	} else {
+		var txErr *database.TxError
+		if !errors.As(err, &txErr) || txErr.Stage != database.TxStageWork || txErr.Outcome != database.TxOutcomeRolledBack {
+			t.Fatal("real MySQL rollback was not classified", err)
+		}
 	}
 	var count int
 	if err := second.QueryRowContext(ctx, "SELECT COUNT(*) FROM connector_check").Scan(&count); err != nil || count != 1 {
 		t.Fatalf("transaction count=%d err=%v", count, err)
 	}
+	// Commit/Rollback run against real MySQL, then a driver-boundary wrapper
+	// suppresses the acknowledgement. This is deterministic fault injection,
+	// not a claim to reproduce every wire-level disconnect timing.
+	for _, loseCommit := range []bool{true, false} {
+		name, id := "commitAcknowledgementLost", 3
+		if !loseCommit {
+			name, id = "rollbackAcknowledgementLost", 4
+		}
+		t.Run(name, func(t *testing.T) {
+			connector, err := mysql.NewConnector(cfg.Clone())
+			if err != nil {
+				t.Fatal(err)
+			}
+			ackErr, workErr := errors.New("injected lost acknowledgement"), errors.New("work rejected")
+			fault := &ackLossConnector{Connector: connector, loseCommit: loseCommit, ackErr: ackErr}
+			faultPool, err := database.OpenConnector(ctx, fault, pool)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer faultPool.Close()
+			err = faultPool.InTx(ctx, nil, func(tx *sql.Tx) error {
+				if _, err := tx.ExecContext(ctx, "INSERT INTO connector_check VALUES (?)", id); err != nil {
+					return err
+				}
+				if !loseCommit {
+					return workErr
+				}
+				return nil
+			})
+			var txErr *database.TxError
+			if !errors.As(err, &txErr) || txErr.Outcome != database.TxOutcomeUnknown || !errors.Is(err, ackErr) {
+				t.Fatal("unknown acknowledgement was treated as definite outcome", err)
+			}
+			wantCount := 0
+			if loseCommit {
+				wantCount = 1
+				if txErr.Stage != database.TxStageCommit || txErr.Err != ackErr || txErr.RollbackErr != sql.ErrTxDone || fault.commits.Load() != 1 || fault.rollbacks.Load() != 0 {
+					t.Fatal("commit failure was retried or misclassified", err)
+				}
+			} else if txErr.Stage != database.TxStageWork || !errors.Is(err, workErr) || txErr.RollbackErr != ackErr || fault.commits.Load() != 0 || fault.rollbacks.Load() != 1 {
+				t.Fatal("rollback failure lost its primary/secondary causes", err)
+			}
+			var stored int
+			if err := second.QueryRowContext(ctx, "SELECT COUNT(*) FROM connector_check WHERE id = ?", id).Scan(&stored); err != nil || stored != wantCount {
+				t.Fatal("independent connection observed unexpected persistence", stored, err)
+			}
+		})
+	}
 	if err := first.Close(); err != nil {
 		t.Fatal(err)
 	}
@@ -178,3 +232,58 @@ func TestMySQLConnectorTLSAndPoolIsolation(t *testing.T) {
 		t.Fatal("closing first pool affected second:", err)
 	}
 }
+
+type ackLossConnector struct {
+	driver.Connector
+	loseCommit         bool
+	ackErr             error
+	commits, rollbacks atomic.Int32
+}
+
+func (c *ackLossConnector) Connect(ctx context.Context) (driver.Conn, error) {
+	conn, err := c.Connector.Connect(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return &ackLossConn{Conn: conn, owner: c}, nil
+}
+
+type ackLossConn struct {
+	driver.Conn
+	owner *ackLossConnector
+}
+
+func (c *ackLossConn) Ping(ctx context.Context) error { return c.Conn.(driver.Pinger).Ping(ctx) }
+func (c *ackLossConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	tx, err := c.Conn.(driver.ConnBeginTx).BeginTx(ctx, opts)
+	if err != nil {
+		return nil, err
+	}
+	return &ackLossTx{Tx: tx, owner: c.owner}, nil
+}
+
+type ackLossTx struct {
+	driver.Tx
+	owner *ackLossConnector
+}
+
+func (tx *ackLossTx) Commit() error {
+	tx.owner.commits.Add(1)
+	if err := tx.Tx.Commit(); err != nil {
+		return err
+	}
+	if tx.owner.loseCommit {
+		return tx.owner.ackErr
+	}
+	return nil
+}
+func (tx *ackLossTx) Rollback() error {
+	tx.owner.rollbacks.Add(1)
+	if err := tx.Tx.Rollback(); err != nil {
+		return err
+	}
+	if !tx.owner.loseCommit {
+		return tx.owner.ackErr
+	}
+	return nil
+}