[server] Make connection pooler configurable and set better default values
Drop the configuration connections-pool-size and add new configurations options:
* connections-pool-min-size. Set to 0 by default so we open connections only
when needed. This avoid opening min-size*processes connections at startup,
which is, it think, a good default.
* connections-pool-max-size. Set to 0 (unlimited) by default, so we move the
bottleneck to postgresql.
* connections-idle-timeout. Set to 10 minutes. I don't have arguments about
this except that this is the default in pgbouncer.
Creating a new cube from scratch
--------------------------------
Let's start by creating the cube environment in which we will develop ::
cd ~/myproject
# use cubicweb-ctl to generate a template for the cube
# will ask some questions, most with nice default
cubicweb-ctl newcube mycube
# makes the cube source code managed by mercurial
cd cubicweb-mycube
hg init
hg add .
hg ci
If all went well, you should see the cube you just created in the list
returned by ``cubicweb-ctl list`` in the *Available cubes* section.
If not, please refer to :ref:`ConfigurationEnv`.
To reuse an existing cube, add it to the list named
``__depends_cubes__`` which is defined in :file:`__pkginfo__.py`.
This variable is used for the instance packaging (dependencies handled
by system utility tools such as APT) and to find used cubes when the
database for the instance is created.