dbstore: refactor sqlfs and tx, add tx tests

1 files changed, 105 insertions, 0 deletions

diff --git a/dbstore/tx.go b/dbstore/tx.go
new file mode 100644
index 0000000..460bbe1
--- /dev/null
+++ b/dbstore/tx.go
@@ -0,0 +1,105 @@
+// database storage
+package dbstore
+
+import (
+  "context"
+  db_sql "database/sql"
+  "fmt"
+  _ "github.com/mattn/go-sqlite3"
+)
+
+type Tx struct {
+  tx      *db_sql.Tx // underlying transaction
+  sts     map[string]*db_sql.Stmt // prepared statements
+  closed  bool // are the statements closed?
+  done    bool // is the transaction done?
+  err     error // last error
+}
+
+func newTx(ctx context.Context, db *db_sql.DB, queryIds []string) (Tx, error) {
+  var r Tx
+
+  // begin context
+  if tx, err := db.BeginTx(ctx, nil); err != nil {
+    return r, err
+  } else {
+    r.tx = tx
+  }
+
+  // build query map
+  queries, err := getQueries(queryIds)
+  if err != nil {
+    return r, err
+  }
+
+  // build statements
+  sts := make(map[string]*db_sql.Stmt)
+  for id, sql := range(queries) {
+    if st, err := r.tx.PrepareContext(ctx, sql); err != nil {
+      return r, err
+    } else {
+      sts[id] = st
+    }
+  }
+  r.sts = sts
+
+  // return success
+  return r, nil
+}
+
+// Finalize statements.
+func (tx Tx) Close() {
+  if !tx.closed {
+    for id, st := range(tx.sts) {
+      // close statement
+      st.Close()
+
+      // delete key
+      delete(tx.sts, id)
+    }
+
+    // mark transaction as closed
+    tx.closed = true
+  }
+}
+
+// Finalize statements, commit transaction.
+func (tx Tx) Commit() error {
+  // close statements
+  // FIXME: this isn't really necessary, rollback and commit will take
+  // care of it according to the database/sql docs
+  tx.Close()
+
+  if !tx.done {
+    tx.err = tx.tx.Commit()
+    tx.done = true
+  }
+
+  // return last error
+  return tx.err
+}
+
+// Finalize statements, rollback transaction.
+func (tx Tx) Rollback() error {
+  // close statements
+  // FIXME: this isn't really necessary, rollback and commit will take
+  // care of it according to the database/sql docs
+  tx.Close()
+
+  if !tx.done {
+    tx.err = tx.tx.Rollback()
+    tx.done = true
+  }
+
+  // return last error
+  return tx.err
+}
+
+// execute given prepared statement
+func (tx Tx) Exec(ctx context.Context, id string, args... interface{}) (db_sql.Result, error) {
+  if st, ok := tx.sts[id]; !ok {
+    return nil, fmt.Errorf("unknown statement: %s", id)
+  } else {
+    return st.ExecContext(ctx, args...)
+  }
+}