Instead of parsing the DSN for each external libpq program we
are going to execute, provide a function that feeds them all
necessary parameters through the environment.
osm2pgsql is the first user.
Psycopg2 has changed the kind of exception that is emitted on
deadlocks between versions 2.7 and 2.8. The code was already
trying to catch both kind of errors but because the
psycopg2.errors package is unknown in 2.7 and below, the
code would throw an exception on anything but a deadlock error.
This commit wraps the deadlock handling into a context manager
to avoid code duplication and uses module imports to detect if
the new error codes are available.
Also sets the required psycopg2 version to 2.7 or bigger as
versions below are difficult to test.
With the website directory now tied to the project directory instead
of the build directory, it is no longer possible to use make for
running the web server.
Given that the module is now copied to the project directory
when no module path is set, we need the information that the
module path is empty. Therefore hand in the default module path
in a separate variable.
This is a exception to be thrown when the error occures because
of bad user data. We don't want to print a full stack trace in
these cases but just tell the user what went wrong.
The new functions always creates normal and partitioned functions.
Also adds specialised connection and cursor classes for adding
frequently used helper functions.
Given that only one command will be executed in the end, it is
not necessary to import what amounts to the whole library. This
becomes in particular important for update functions that have
a dependency on pyosmium. The dependency can remain optional for
people not using updates.
