%contact-store is responsible for sending updates about contacts, eg
profile color. When it hears an update, it fans that out to its
subsribers, unless that update is stale. If you reguarly fan out stale
updates, then they reverberate across the network indefinitely -- we
call this "echoing".
To cut off this echoing, all edits have a timestamp, and we consider any
updates from before this timestamp to be stale. Additions are separate
from edits, and for them we instead do a value comparison on the contact
-- if it didn't change, we consider the update stale.
The problem with this scheme is that if an addition and edit happen one
after the other in quick succession, you might have the following
sequence:
- add comes in with timestamp T1
- edit comes in with timestamp T2 after T1
- we hear an echo of the add, and that errantly applies because it
passes our "did the contact actually change" check
- we hear an echo of the edit, which applies because T2 is after T1
- GOTO 3
Each time we apply the stale update, we fan that out to our subscribers,
and if any two hosts subscribe to each other, this will loop. This may
even loop unconditionally because the ship that made the profile changes
seems like it might not recognize that those changes didn't come from
itself, so it sends them to all the groups it's in. If so, that's an
important issue to fix.
Fixestloncorp/landscape-issues#1442
when +apse sees a link, it presume that the following a batch comment,
and stops parsing so that it can be picked up by apex:docs next
this required a change to +leap, which has been rewritten to pretty much
look like +gap but stop parsing when encountering doccords.
previously we just threw them out and wasn't sure whether it was the
right answer. this violates the principle of least surprise - even
though it hard to see the value of attaching multiple empty $cuff notes
to an arm, we shouldn't stop the programmer from doing it without any
indication or explanation as to why. its the behaviour you'd expect
given how doccords is structured.
it is desirable for both apex:docs and apse:docs to parse into an
intermediate representation that never ends up in an AST so that it is
clear that these parsed representations may be altered in the future
without worrying about old types nesting with new types. this was
already the case for $whit, but apse:docs parsed directly as a $help,
which is used in ASTs. so apse:docs now parses as a $whiz, which is
simply a cord. in the future, if postfix comments are used for something
like invariants, or allow $links, we may want to change this.
this also changes $whit to remove .use, which was unused. similarly,
+glom is removed since its not used anywhere.
