[test/statsd] add tests for cubicweb.statsd_logger

[utils] Implements __iter__ on QueryCache In order to be able to iterate over the currently cached queries (so that they may be inspected and invalidated), this changeset implementes __iter__ on QueryCache.

[utils] Added new get method to QueryCache The new get method enables the retrieval an item in the cache by specifying a default value so that in the absence of an item for the key, the default value is returned.

[test/rset] typo

[utils] Fixed issue in clearing QueryCache When trying to add an item in a full QueryCache, the cache tries to make room. It tries to list and remove non-permanent items with a transient counter (number of times it has been requested). However, there is a pathological case where items could be non-permanent but still not have a transient counter because they were added, but never requested. In some cases, the full cache could be flushed, including the permanent items. This changeset attempts to fix this issue by only dropping the non-permanent items that did not hav a transient counter.

[statsd] add a statsd_timethis context manager This context manager allows to report to statsd the execution time of any piece of code, without the need for it to be a function or a method, like:: def some_function(): do_stuff() with statsd_timethis('some context message'): do_that() ensure_this()

[test/rset] add tests for ResultSet.first() and .last() methods

[test/rset] flake8

[rset] update copyright

[rset] add convenient first() and last() methods on ResultSet These make life easier for the heavy user of the CW shell. Also aliases entities() with all(); so we end with a pretty consistant set: - .one() - .first() - .last() - .all()