Because an exported universal variable must be exported in all variable
stacks, explicit invalidation is infeasible. Switch the universal variables
to a generation count.
Prior to this fix, fish would invalidate the exported variable list
whenever an exported variable changes. However we soon will not have a
single "exported variable list." If a global variable changes, it is
infeasible to find all exported variable lists and invalidate them.
Switch to a new model where we store a list of generation counts. Every
time an exported variable changes, the node gets a new generation. If the
current generation list does not match the cached one, then we know that
our exported variable list is stale.
We also might want to remove the mailing list and/or IRC channel as I
think most devs aren't on them anymore, but let's just add the channel
that I prefer first.
[ci skip]
This was undocumented, not all that useful and potentially unwanted.
In particular it means that things like
mysql -p(read)
will still keep the password in history.
Also it allows us to simply implement asking for the history deletion
term.
See #5791.
This makes the following changes:
1. Events in background threads are executed in those threads, instead of
being silently dropped
2. Blocked events are now per-parser instead of global
3. Events are posted in builtin_set instead of within the environment stack
The last one means that we no longer support event handlers for implicit
sets like (example) argv. Instead only the `set` builtin (and also `cd`)
post variable-change events.
Events from universal variable changes are still not fully rationalized.
This cuts down on the wcs2string here by ~25%.
The better solution would be to cache narrow versions of $PATH, since
we compute that over and over and over and over again, while it rarely changes.
Or we could add a full path-cache (where which command is), but that's
much harder to invalidate.
See #5905.
This sets the explicit path to the default one, which should be okay,
since the default path never changes (not even if $XDG_CONFIG_HOME
does).
Then it saves a narrow version of that, which saves most of the time
needed to `sync` in most cases.
Fixes#5905.
Note that this isn't technically *w*util, but the differences between
the functions are basically just whether they do the wcs2string
themselves or not.
This fixes a race condition in the topic monitor. A thread may decide to
enter the wait queue, but before it does the generation list changes, and
so our thread will wait forever, resulting in a hang.
It also simplifies the implementation of the topic monitor considerably;
on reflection the whole "metagen" thing isn't providing any value and we
should just compare generations directly.
In the new design, we have a lock-protected list of current generations,
along with a boolean as to whether someone is reading from the pipe. The
reader (only one at a time) is responsible for broadcasting notifications
via a condition variable.
