• Sarah Adams's avatar
    database/sql: proper prepared statement support in transactions · 82e1732f
    Sarah Adams authored
    This change was originally written by Marko Tiikkaja <marko@joh.to>.
    https://go-review.googlesource.com/#/c/2035/
    
    Previously *Tx.Stmt always prepared a new statement, even if an
    existing one was available on the connection the transaction was on.
    Now we first see if the statement is already available on the
    connection and only prepare if it isn't. Additionally, when we do
    need to prepare one, we store it in the parent *Stmt to allow it to be
    later reused by other calls to *Tx.Stmt on that statement or just
    straight up by *Stmt.Exec et al.
    
    To make sure that the statement doesn't disappear unexpectedly, we
    record a dependency from the statement returned by *Tx.Stmt to the
    *Stmt it came from and set a new field, parentStmt, to point to the
    originating *Stmt. When the transaction's *Stmt is closed, we remove
    the dependency. This way the "parent" *Stmt can be closed by the user
    without her having to know whether any transactions are still using it
    or not.
    
    Fixes #15606
    
    Change-Id: I41b5056847e117ac61130328b0239d1e000a4a08
    Reviewed-on: https://go-review.googlesource.com/35476
    Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: 's avatarDaniel Theophanes <kardianos@gmail.com>
    82e1732f
sql.go 69.3 KB