This commit adds performance counters for each transaction which are rolled
up to the database level on each commit/rollback. Counters are meant to be
a very fast way to track what is going on in the database. A few timers are
also added in areas where the time.Now() overhead is not noticible.
The DB.Stat() function is now deprecated since the `bolt` CLI now performs
similar functions.
Fixes#108.
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.
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.
I changed the Transaction/RWTransaction types to Tx/RWTx, respectively. This makes the naming
more consistent with other packages such as database/sql. The txnid is changed to txid as well.