This better reflects the request handling, since the headers are sent
before the request is fully processed. This status code just indicates
that we successfully accepted the request but is not guaranteed that all
the subsequent actions will also be successful.
This commit refactors the ValueGenerator class to be a template that can
work with any container type. Previously, one has to manually take care
of the used container by lazily iterating over it within a lambda. Now,
the `ValueGenerator` class itself takes care of all the iteration,
making it easier to use and less error-prone. The new base `Generator`
class is required to allow the `JsonEncoder` to handle generators in a
type-erased manner.
The wait group gets passed to HttpServerConnection, then down to the
HttpHandlers. For those handlers that modify the program state, the
wait group is locked so ApiListener will wait on Stop() for the
request to complete. If the request iterates over config objects,
a further check on the state of the wait group is added to abort early
and not delay program shutdown. In that case, 503 responses will be
sent to the client.
Additionally, in HttpServerConnection, no further requests than the
one already started will be allowed once the wait group is joining.
for (const T& needle : haystack) creates the illusion that haystack is a
container of T and we're just borrowing needle. In these cases that's not true.
The .ti files call `DependencyGraph::AddDependency(this, service.get())`. Obviously, `service.get()` is the parent and `this` (Downtime, Notification, ...) is the child. The DependencyGraph terminology should reflect this not to confuse its future users.
What does this change?
* Remove use of spaces for formatting
These could be found by using `grep -r -l -P '^\t+ +[^*]'
* Removal of training whitespaces
* A few lines longer than 120 chars
