feat: use nwaku instead of go-waku

[richard-ramos]

This PR / branch will contain all the changes related to using nwaku instead of go-waku.
Once we achieve feature parity with current master, we need to reset that branch to point to the latest commit of this PR.

• Compile nwaku and generate bindings automagically
• Replace function calls to invoke nwaku's libwaku.h
• Create / Start / Stop node
• Relay Publish / Subscribe
• Event callback
• Result + Error handling

In separate PRs, the following functionality needs to be implemented

• Implement suggestions from Nwaku 2 event callback test #88
• Use Opaque type like in

  waku-rust-bindings/waku-bindings/src/node/mod.rs

  Lines 26 to 34 in 5abd9cc

  	pub struct OpaqueWakunodePtr {
  	obj_ptr: *mut c_void,
  	}
  	unsafe impl Send for OpaqueWakunodePtr {}
  	/// Handle to the underliying waku node
  	pub struct WakuNodeHandle {
  	ctx: Arc<Mutex<OpaqueWakunodePtr>>,

• Destroy node
• Add example program and docs
• Fix TODOs
• Expose any additional function

[richard-ramos]

This PR so far compiles waku-sys succesfully generating binding.rs

cd waku-sys
cargo build

The first time does take a while because it's building nim and downloading the submodules, so maybe we can consider generating .so/.a for different architectures and uploading them to the releases, if build times become a problem.

[richard-ramos]

waku-bindings now compiles succesfully and runs some basic tests

cd waku-bindings
cargo test

I added rln as a dependency so nwaku can run succesfully (it seems to no longer be an optional dependency). Also linked some other libraries and had to compile a libbacktrace_wrapper.o fike to link it succesfully. This has been tested on a linux machine. We should try on other architectures.

[richard-ramos]

We can now invoke the relay functions to publish and subscribe. I've run into some trouble setting up the event handler, which seems to work, but in the tests it fails when we attempt to push a value to a tokio channel (fails on line 48).

waku-rust-bindings/waku-bindings/tests/node.rs

Lines 45 to 53 in 24d7dd8

	println!("===============");
	println!("ID: {}", id);
	println!("Sending to channel....");
	futures::executor::block_on(tx.send(Response {
	id: id.to_string(),
	payload,
	}))
	.expect("send response to the receiver");
	println!("Sent!");

I'm investigating what's up with this.

[richard-ramos]

Thanks to @danielSanchezQ 's help, the event callback now works!

cd waku-bindings
cargo test default_echo -- --nocapture --exact

I'll now proceed to improve error handling as well as including suggestions from #88

[richard-ramos]

This PR is mostly complete.
Once waku-org/nwaku#2461 is merged, I'll fix the waku_flow test to use a rust node instead of using the fleet. I will not add more code to the PR, since it will get too complicated to review. Missing functionality will be done on a separate PR.

[richard-ramos]

@danielSanchezQ @Ivansete-status @SionoiS
I've marked this PR as ready for review. It contains a lot of changes (sorry!), but most of them are just deleting code or changing function signatures, with just a small section dedicated to actually use nwaku instead of go-waku

@danielSanchezQ , don't worry too much about all the deleted code. I'm going to add it back in future PRs towards this branch once the functionality is available in nwaku c-bindings :)

[SionoiS]

Nice base to build upon!

[SionoiS]

In the future we may want to do something like pubsub_topic: impl Into<WakuPubsubTopic> and impl From<String> for WakuPubsubTopic Or even better remove pubsub topic and use shards with the appropriate type constraints.

[Ivansete-status]

Wonderful! Thanks for it!
I just added some minor comments

[Ivansete-status]

I think we can use const in this particular case. Maybe we could check other fns and use the most restrictive option in each case.

Suggested change

	pub fn waku_version(ctx: *mut c_void) -> Result<String> {
	pub fn waku_version(ctx: *const c_void) -> Result<String> {

[richard-ramos]

Ah! in this case we're using bindgen to generate the bindings for libwaku.h automagically in https://github.com/waku-org/waku-rust-bindings/blob/nwaku/waku-sys/build.rs#L68-L79 and it translates *void to *mut c_void.
I could make the change and then cast the variable from *const to *mut right before interacting with nwaku, but since these functions are not exposed to the end user. We expose a friendlier API:

waku-rust-bindings/waku-bindings/src/node/mod.rs

Lines 48 to 50 in 646f6f0

	pub fn version(&self) -> Result<String> {
	management::waku_version(&self.ctx)
	}

)

I'm thinking we could accept to use a *mut in this case, just to not have to do the cast.

[Ivansete-status]

In a future PR we might need to add error handling ( it is actually pending to be implemented in libwaku.nim too .)