Commit failure unhandled, database left in unusable state

[kornelski]

When sqlite is used from multiple processes at the same time, COMMIT may fail with "database is locked" error.

After that happens, all subsequent transactions in rusqlite fail with "cannot start a transaction within a transaction".

I think this is because:

    fn commit_(&mut self) -> Result<()> {
        self.committed = true;
        self.conn.execute_batch("COMMIT")
    }

Sets self.committed = true; without checking whether commit has succeeded, and when COMMIT fails, the transaction remains open — forever.

It should probably be:

    fn commit_(&mut self) -> Result<()> {        
        self.conn.execute_batch("COMMIT")?;
        self.committed = true;
        Ok(())
    }

[gwenn]

Random thoughts:

• either use the sqlite3_get_autocommit method and remove the committed flag.
• or do a rollback when a COMMIT fails.