This mega patch primarily introduces a new function engine. The main
reasons for this new engine are:
1) Massively improved performance with lock-contended graphs.
Certain large function graphs could have very high lock-contention which
turned out to be much slower than I would have liked. This new algorithm
happens to be basically lock-free, so that's another helpful
improvement.
2) Glitch-free function graphs.
The function graphs could "glitch" (an FRP term) which could be
undesirable in theory. In practice this was never really an issue, and
I've not explicitly guaranteed that the new graphs are provably
glitch-free, but in practice things are a lot more consistent.
3) Simpler graph shape.
The new graphs don't require the private channels. This makes
understanding the graphs a lot easier.
4) Branched graphs only run half.
Previously we would run two pure side of an if statement, and while this
was mostly meant as an early experiment, it stayed in for far too long
and now was the right time to remove this. This also means our graphs
are much smaller and more efficient too.
Note that this changed the function API slightly. Everything has been
ported. It's possible that we introduce a new API in the future, but it
is unexpected to cause removal of the two current APIs.
In addition, we finally split out the "schedule" aspect from
world.schedule(). The "pick me" aspects now happen in a separate
resource, rather than as a yucky side-effect in the function. This also
lets us more precisely choose when we're scheduled, and we can observe
without being chosen too.
As usual many thanks to Sam for helping through some of the algorithmic
graph shape issues!
This is a bit tricky, and we should nuke and redo some of this API. The
sneaky bit has to do with whether we've already added the namespace
magic into our etcd client or not.
This was rather tricky, but I think I've learned a lot more about how
SSH actually works. We now only offer up to the server what we can
actually support, which lets us actually get back a host key we have a
chance of actually authenticating against.
Needed a new version of the ssh code and had to mess with go mod
garbage.
I inverted the logic for complex setups and forgot to handle the zero
cases. I also didn't notice my loop continue error. This cleans all this
up so that we can have proper exported resource matching.
These two small bugs would allow thrashing to occur since we'd
constantly delete and re-add exports, and constantly think that a noop
etcd operation made a change.
I've been waiting to write this patch for a long time. I firmly believe
that the idea of "exported resources" was truly a brilliant one, but
which was never even properly understood by its original inventors! This
patch set aims to show how it should have been done.
The main differences are:
* Real-time modelling, since "once per run" makes no sense.
* Filter with code/functions not language syntax.
* Directed exporting to limit the intended recipients.
The next step is to add more "World" reading and filtering functions to
make it easy and expressive to make your selection of resources to
collect!
This provides a new kind of "world" backend, one that runs etcd over an
SSH connection. This is useful for situations where you want to run an
etcd cluster somewhere for clients across the net, but where you don't
want to expose the ports publicly.
If SSH authentication is setup correctly (using public keys) this will
tunnel over SSH for etcd to connect.
This patch does not yet support deploys over SSH, but that should be
fixed in the future as the world code gets cleaned up more.
Instead of constantly making these updates, let's just remove the year
since things are stored in git anyways, and this is not an actual modern
legal risk anymore.
This is at least a stop-gap until we redo the whole filesystem API mess.
I think golang is partly to blame because they don't have proper API's
merged yet.
With the recent merging of embedded package imports and the entry CLI
package, it is now possible for users to build in mcl code into a single
binary. This additional permission makes it explicitly clear that this
is permitted to make it easier for those users. The condition is phrased
so that the terms can be "patched" by the original author if it's
necessary for the project. For example, if the name of the language
(mcl) changes, has a differently named new version, someone finds a
phrasing improvement or a legal loophole, or for some other
reasonable circumstance. Now go write some beautiful embedded tools!
The new version of the urfave/cli library is moving to generics, and
it's completely unclear to me why this is an improvement. Their new API
is very complicated to understand, which for me, defeats the purpose of
golang.
In parallel, I needed to do some upcoming cli API refactoring, so this
was a good time to look into new libraries. After a review of the
landscape, I found the alexflint/go-arg library which has a delightfully
elegant API. It does have a few rough edges, but it's otherwise very
usable, and I think it would be straightforward to add features and fix
issues.
Thanks Alex!
Previously the resource could only set values in a per-hostname
namespace, but for single, user-managed values, we'd like to be able to
control things entirely. Now this resource can do that.
When mgmt is in etcd-client-only mode and using an external etcd server,
we don't want to unset our only known endpoint since this would deadlock
our etcd client since it can't connect to anyone. This could have
happened because a plain etcd server didn't set any endpoints to follow,
and as a result we noticed it was empty and decided to use that instead.
To workaround this issue on an earlier version of mgmt, you would have
had to run:
etcdctl put /_mgmt/endpoints/etcd http://localhost:2379
to set this magic key on the initial etcd server.
Not sure how this snuck in!
I've now ran a quick grep across the code base, and I can't find any
similar mistakes.
ack '.Done()' | grep -v defer | grep -iv ctx # then check these
The old system with vendor/ and git submodules worked great,
unfortunately FUD around git submodules seemed to scare people away and
golang moved to a go.mod system that adds a new lock file format instead
of using the built-in git version. It's now almost impossible to use
modern golang without this, so we've switched.
So much for the golang compatibility promise-- turns out it doesn't
apply to the useful parts that I actually care about like this.
Thanks to frebib for his incredibly valuable contributions to this
patch. This snide commit message is mine alone.
This patch also mixes in some changes due to legacy golang as we've also
bumped the minimum version to 1.16 in the docs and tests.
Lastly, we had to disable some tests and fix up a few other misc things
to get this passing. We've definitely hot bugs in the go.mod system, and
our Makefile tries to workaround those.
