Expose natsjskv Watcher

[kobergj]

This PR bundles two related changes to the nats-js-kv store.

1. Expose natsjskv Watcher

Adds a Watch method to the nats-js-kv store. This exposes the underlying natsjs watcher and allows reacting to changes in the store.

2. Fix: treat a closed connection as no connection

hasConn() previously only checked n.conn != nil. Once the NATS client exhausts its reconnect attempts, the connection is permanently closed but n.conn stays non-nil. Since initConn() is gated on !hasConn(), it never re-runs, so every subsequent KV operation fails with nats: connection closed until the calling process is restarted.

func (n *natsStore) hasConn() bool {
    return n.conn != nil && !n.conn.IsClosed()
}

A closed connection is now treated as "no connection", so the next operation re-initializes it. This also adds a ClosedCB/resetConn() handler.

Note: the ClosedCB handler alone is not sufficient for consumers that pass nats.Options via context — Init() calls setOption() again, reassigning n.nopts from the context value before Connect(), which drops the callback. The IsClosed() check in hasConn() is therefore the load-bearing fix; resetConn() is complementary for direct callers.

[kobergj]

Pipelines broken unrelated?

go: open /home/runner/work/plugins/plugins/v5/acme/certmagic/go.mod: no such file or directory

[kobergj]

@asim is this something we would like to be merged?

[asim]

If the test pass and it's been go fmt then sure, why not

[kobergj]

If the test pass and it's been go fmt then sure, why not

@asim tests seem broken due to v5 update. Not sure what is going wrong. Unrelated to this PR:

go: open /home/runner/work/plugins/plugins/v5/acme/certmagic/go.mod: no such file or directory

[asim]

I think the acme dir is gone?

[kobergj]

I think the acme dir is gone?

I do not know to be honest. I was not involved in v5 update and also didn't see any PRs. So I do not know what the change between v4 and v5 is and neither do I know how this affects v4 builds.

[asim]

I don't know what you're doing in your branch but you need to merge main otherwise this won't work.

[kobergj]

It is up-to-date with main. Previous commit before this one is cc7e2f8

[asim]

I'm not near a computer but I'd do 'grep -r plugins/v5/acme' to see what's referencing this non existent path.

[gambitier]

@asim I am having same issue. Other ones are also missing

./v5/acme/certmagic
./v5/codec/bsonrpc
./v5/sync/consul
./v5/sync/etcd
./v5/sync/memory

If the test pass and it's been go fmt then sure, why not

@asim tests seem broken due to v5 update. Not sure what is going wrong. Unrelated to this PR:

go: open /home/runner/work/plugins/plugins/v5/acme/certmagic/go.mod: no such file or directory

[asim]

So it's a go work issue then. Fixing in a separate PR #146

[kobergj]

There still seems to be something wrong:

go: downloading github.com/Microsoft/go-winio v0.5.2
     | pattern ./...: directory prefix . does not contain modules listed in go.work or their selected dependencies

I tried go mod tidy but it doesn't help.

[asim]

Try delete and reinitialise go work

[kobergj]

Seems to be even more broken after the go work sync.

go: github.com/micro/go-micro@v1.18.0 requires
	github.com/micro/protoc-gen-micro@v1.0.0: reading github.com/micro/protoc-gen-micro/go.mod at revision v1.0.0: git ls-remote -q origin in /home/runner/go/pkg/mod/cache/vcs/28cfbca4f5e41691076780b2017d5a1000b007b1d3d37b7a9d3b562c7adc9377: exit status 128:
	fatal: could not read Username for 'https://github.com/': terminal prompts disabled

I think this is somehow related to the v5 update. Pipelines were green before it. Did we change build mechanics with v5?