select_wrapper_t wraps up the annoying bits of using select(): keeping
track of the max fd, passing null for boring parameters, and
constructing the timeout. Introduce a wrapper struct for this and
replace the existing uses of select() with the wrapper.
Previously iothread_perform could do something on a background thread, and
then do something on the main thread. But we no longer use that second
part: instead everything goes through debounce. Remove the completion
parameter from iothread_perform.
It may happen that the user types an abbreviation and then hits return.
Prior to this commit, we would perform a form of syntax highlighting
that does not require I/O, so as to not block the user. However this
could cause invalid commands to be colored as valid.
More generally if the user has e.g a slow NFS mount, then syntax
highlighting may lag behind the user's typing, and be incorrect at the
time the user hits return. This is an unavoidable race, since proper
syntax highlighting may take arbitrarily long.
Introduce a new function `finish_highlighting_before_exec`, which waits
for any outstanding syntax highlighting to complete, BUT has a timeout
(250 milliseconds). After this, it falls back to the no-I/O variant, which
colors all commands as valid and nothing as paths.
Fixes#7418Fixes#5912
debounce_t will be used to limit thread creation from background highlighting
and autosuggestion scenarios. This is a one-element queue backed by a
single thread. New requests displace any existing queued request; this
reflects the fact that autosuggestions and highlighting only care about
the most recent result.
A timeout allows for abandoning hung threads, which may happen if you
attempt to e.g. access a dead hard-mounted NFS server. We don't want
this to defeat autosuggestions and highlighting permanently, so allow
spawning a new thread after the timeout (here 500 ms).
Mostly line breaks, one instance of tabs!
For some reason clang-format insists on two spaces before a same-line comment?
(I continue to be unimpressed with super-strict line length limits,
but I continue to believe in automatic styling, so it is what it is)
[ci skip]
Sometimes we must spawn a new thread, to avoid the risk of deadlock.
Ensure we always spawn a thread in those cases. In particular this
includes the fillthread.
Improve the iothread behavior by enabling an iothread to stick around for
a while waiting for work. This reduces the amount of iothread churn, which
is useful on platforms where threads are expensive.
Also do other modernization like clean up the locking discipline and use
FLOG.
topic_monitor allows for querying changes posted to one or more topics,
initially sigchld. This will eventually replace the waitpid logic in
process_mark_finished_children().
Comment from the new header:
Topic monitoring support. Topics are conceptually "a thing that can
happen." For example, delivery of a SIGINT, a child process exits, etc. It
is possible to post to a topic, which means that that thing happened.
Associated with each topic is a current generation, which is a 64 bit
value. When you query a topic, you get back a generation. If on the next
query the generation has increased, then it indicates someone posted to
the topic.
For example, if you are monitoring a child process, you can query the
sigchld topic. If it has increased since your last query, it is possible
that your child process has exited.
Topic postings may be coalesced. That is there may be two posts to a given
topic, yet the generation only increases by 1. The only guarantee is that
after a topic post, the current generation value is larger than any value
previously queried.
Tying this all together is the topic_monitor_t. This provides the current
topic generations, and also provides the ability to perform a blocking
wait for any topic to change in a particular topic set. This is the real
power of topics: you can wait for a sigchld signal OR a thread exit.
Remove the "make iwyu" build target. Move the functionality into the
recently introduced lint.fish script. Fix a lot, but not all, of the
include-what-you-use errors. Specifically, it fixes all of the IWYU errors
on my OS X server but only removes some of them on my Ubuntu 14.04 server.
Fixes#2957
This change moves source files into a src/ directory,
and puts object files into an obj/ directory. The Makefile
and xcode project are updated accordingly.
Fixes#1866
