These iterfaces are similar but ultimately unrelated! Unfortunately
we are stuck with a joined class hiearchy because of DBObjectMap.
Someday it would be nice to break this link.

Signed-off-by: Sage Weil <sage@redhat.com>

This uses the most general class as the type for the Iterator
shared_ptr typedef, and makes the class that filters by prefix
private.

Signed-off-by: Sage Weil <sage@redhat.com>

get_wholespace_iterator() and get_iterator().  This gets rid of
the goofy _get_iterator() indirection and avoids colliding on names w/
virtual methods.

Signed-off-by: Sage Weil <sage@redhat.com>

Signed-off-by: Sage Weil <sage@redhat.com>

Signed-off-by: Jianjian Huo <jianjian.huo@ssi.samsung.com>
Signed-off-by: Sage Weil <sage@redhat.com>

Signed-off-by: Sage Weil <sage@redhat.com>

- detect and use existing CFs on open

Signed-off-by: Jianjian Huo <jianjian.huo@ssi.samsung.com>
Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
Signed-off-by: Sage Weil <sage@redhat.com>

Merge operators always map to a prefix, just like a CF, so we can link
directly to the operator without doing any lookup.

Signed-off-by: Sage Weil <sage@redhat.com>

This was hard-coded to 'b'.

Signed-off-by: Sage Weil <sage@redhat.com>

Signed-off-by: Sage Weil <sage@redhat.com>

We need to close the default CF handle *only* if we explicitly opened it.

Also, take care to use that handle wherever we can.  This is mostly
paranoia--I'm not sure if rocksdb cares if you mix the handle you opened
with DefaultColumnFamily(), which is different.

Signed-off-by: Sage Weil <sage@redhat.com>