I consolidated the DB.Tx() and DB.RWTx() calls into a single
DB.Begin(writable bool) call. This is more consistent with the
database/sql library.
I also changed the DB.Do() and DB.With() call to DB.Update() and
DB.View(), respectively. This is more intuitive and more inline with
other database verbiage.
Commit/Rollback and mutable calls on Tx and Bucket now return ErrTxClosed
if the transaction has already been committed or rolled back. Non-mutable
calls have added an assertion to check if the transaction is closed which
will cause a panic. I don't want to introduce an error return for accessor
methods that are being used improperly so I think the panic is appropriate.
Functions such as DB.Put(), DB.Get(), and DB.Delete() were originally
added to be easy to use, however, after implementing Bolt in multiple
projects I have found these ease-of-use functions useless. Nearly
every use case requires multiple calls in a single transaction.
Using the DB ease of use functions turned out to be an antipattern.
@tv42 reported that creating a cursor on an empty bucket and then calling
Cursor.Last() causes an index out of range error and panics. This commit
adds a check for the page's item count being greater than zero.
Fixes#63.
Ben Johnson
Tommi Virtanen