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[services] Tunnelbroker - Rust APNS push notifications A2 library wrapper
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Authored by max on Jul 14 2022, 8:18 AM.
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Details

Summary

This is a Rust a2 apns push notifications library wrapper for using the library in the C++ codebase to send the push notifications to iOS devices.

Linear task: ENG-1303

Test Plan
  1. Rust:

Patch to D4807 (top of the stack) using arc patch D4807.
Run cargo build from services/tunnelbroker/rust-notifications directory.
Rust library will be successfully built.

  1. C++ (Docker):

Patch to D4807 (top of the stack) using arc patch D4807.
Running run run-tunnelbroker-service successfully built the Rust library and link it.

  1. C++ (Nix):

Patch to D4807 (top of the stack) using arc patch D4807.
Call cd services/tunnelbroker.
Running rm -dfr build && cmake -B build . && make -C build -j4 successfully built the Rust library and link it.

Library apns notifications push method can be called from the C++ as:

#include "rust-notifications/src/lib.rs.h"
#include "rust/cxx.h"
...

const unsigned short responseCode = sendNotifToAPNS(
    char const *certificatePath,
    char const *certificatePassword,
    char const *deviceToken,
    char const *message,
    bool const *sandbox
);

Diff Detail

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apns-rust-wrapper
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Event Timeline

There are a very large number of changes, so older changes are hidden. Show Older Changes

Remove old corrosion integration.

services/tunnelbroker/CMakeLists.txt
70 ↗(On Diff #15594)

Corrosion integration was removed in a favor of Corrosion+CXX integration in D4807.

tomek requested changes to this revision.Aug 12 2022, 4:11 AM

The first line of crate documentation https://crates.io/crates/a2 says that

HTTP/2 Apple Push Notification Service for Rust using Tokio and async sending.

So this is only for APN, which is reflected in function name sendNotifToAPNS.
The Linear task is about handling all the notifs

Rust notification library integration into the C++ codebase including helper functions.

E.g. in a comment there

We should be able to communicate directly with APNs and FCM.

So what is the plan for FCM? I can't see any info about it.

services/tunnelbroker/rust-notifications/src/apns.rs
9–12 ↗(On Diff #15594)

Is it something cxx-specific to use &String? I guess we should prefer using &str, then String, but &String should be used only when necessary.

30 ↗(On Diff #15594)

Why do we hardcode this value?

services/tunnelbroker/rust-notifications/src/lib.rs
37–40 ↗(On Diff #15594)

Why not to_string()?

46–59 ↗(On Diff #15594)

What about this?

This revision now requires changes to proceed.Aug 12 2022, 4:11 AM

Changes to use &str instead of String.
Remove sound and badge hardcoding.

max retitled this revision from [services] Tunnelbroker - Rust push notifications library wrapper to [services] Tunnelbroker - Rust APNS push notifications A2 library wrapper.Aug 22 2022, 3:55 AM
max edited the summary of this revision. (Show Details)
max edited the test plan for this revision. (Show Details)
In D4540#139298, @tomek wrote:

The first line of crate documentation https://crates.io/crates/a2 says that

HTTP/2 Apple Push Notification Service for Rust using Tokio and async sending.

So this is only for APN, which is reflected in function name sendNotifToAPNS.
The Linear task is about handling all the notifs

Rust notification library integration into the C++ codebase including helper functions.

E.g. in a comment there

We should be able to communicate directly with APNs and FCM.

So what is the plan for FCM? I can't see any info about it.

I've split APNS and FCM into two diffs, FCM will be a follow-up on this one. Sorry I didn't update this diff title and description.
Thanks, Fixed it!

max marked 4 inline comments as done.
max added inline comments.
services/tunnelbroker/rust-notifications/src/apns.rs
9–12 ↗(On Diff #15594)

Is it something cxx-specific to use &String? I guess we should prefer using &str, then String, but &String should be used only when necessary.

I've missed this difference between String and str in case of performance we definitely must use &str here, according to this article also.
I've changed to use &str and we can use it with CXX!

30 ↗(On Diff #15594)

Why do we hardcode this value?

I think we should remove this two of set_sound and set_badge and go with the default for the notifications for the app. So I've removed them.

services/tunnelbroker/rust-notifications/src/lib.rs
37–40 ↗(On Diff #15594)

Why not to_string()?

I've changed to using just &str instead.

46–59 ↗(On Diff #15594)

What about this?

A good practice is to return at the end if possible, I would prefer to live it here.

max added 1 blocking reviewer(s): tomek.
tomek requested changes to this revision.Aug 22 2022, 6:22 AM
tomek added inline comments.
services/tunnelbroker/rust-notifications/src/lib.rs
22 ↗(On Diff #15801)

Are we sure that default configuration is good for us?

35 ↗(On Diff #15801)

Are there any downsides of blocking here?

This revision now requires changes to proceed.Aug 22 2022, 6:22 AM
max marked 6 inline comments as done.
max added inline comments.
services/tunnelbroker/rust-notifications/src/lib.rs
22 ↗(On Diff #15801)

Are we sure that default configuration is good for us?

We are using the lazy initialization here. According to the tokio documentation, there are no parameters to new. Instead, we can use runtime builder, but I don't think we should define a number of workers, thread name, or thread stack in our scenario.

35 ↗(On Diff #15801)

Are there any downsides of blocking here?

According to the documentation this will block the current thread execution. The reason to block here is that we will call this from the C++ thread and will wait for a result there. In the case of non-blocking here we will have a future -> in the future results, because of calling the non-blocking future result from the C++ thread. The case with spawning and non-blocking seems reasonable when calling not from the C++ thread or just from the Rust app, or from C++ but from the blocking execution in case we don't want to block... Hope the answer is not messy.

varun requested changes to this revision.EditedAug 22 2022, 8:10 PM

Can we create an Error type for this library and avoid panicking? It's fine in the lazy_static block, but I don't like the use of unwrap elsewhere

Edit: Alternatively we can use anyhow. See this example: https://cxx.rs/binding/result.html#returning-result-from-rust-to-c

services/tunnelbroker/rust-notifications/src/apns.rs
7 ↗(On Diff #15801)

what's wrong with snake case?

services/tunnelbroker/rust-notifications/src/lib.rs
22 ↗(On Diff #15801)

but I don't think we should define a number of workers, thread name, or thread stack in our scenario.

Curious why you think this

32 ↗(On Diff #15801)

We can change the signature of this function to return a Result. See: https://cxx.rs/binding/result.html

Gives us more flexibility with error handling than a bool

This revision now requires changes to proceed.Aug 22 2022, 8:10 PM
services/tunnelbroker/rust-notifications/src/apns.rs
7 ↗(On Diff #15801)

It doesn't look like the function is exposed in the ffi module, but if you're trying to follow C++ conventions, check this out: https://cxx.rs/attributes.html#rust_name-cxx_name

max marked 2 inline comments as done.

Using Anyhow and Result instead of bool as a return.
Remove unwrap()ing.
Using snake_case in Rust code, export to C++ as a camelCase.
Simplify the code.

In D4540#142224, @varun wrote:

Can we create an Error type for this library and avoid panicking? It's fine in the lazy_static block, but I don't like the use of unwrap elsewhere

Edit: Alternatively we can use anyhow. See this example: https://cxx.rs/binding/result.html#returning-result-from-rust-to-c

Good catch! I've changed to use Result and Anyhow. The code is much simpler with this approach by the way.

services/tunnelbroker/rust-notifications/src/apns.rs
7 ↗(On Diff #15801)

what's wrong with snake case?

I've used our C++ naming convention with camelCase, but now it's removed in a favor of #[cxx_name = "..."] to export to C++ as a camelCase and use snake_case in a Rust.

7 ↗(On Diff #15801)

It doesn't look like the function is exposed in the ffi module, but if you're trying to follow C++ conventions, check this out: https://cxx.rs/attributes.html#rust_name-cxx_name

Wow! Thanks a lot @varun!

services/tunnelbroker/rust-notifications/src/lib.rs
32 ↗(On Diff #15801)

We can change the signature of this function to return a Result. See: https://cxx.rs/binding/result.html

Gives us more flexibility with error handling than a bool

That's a good point to change! I've changed it to use Result and Anyhow.

max marked 2 inline comments as done.
max added a subscriber: varun.

Removing @varun and @ashoat because of the vacation.

services/tunnelbroker/CMakeLists.txt
12 ↗(On Diff #16143)

This space is added by the Cmake linter.

Overall looks pretty standard for rust (at least from my intermediate knowledge of rust).

Would be nice to get some CI with tests involved so we can we can get away from having people do larger test plans (different issue).

I was unable to arc patch from master, but that's likely to be an issue which can be solved with a rebase.

Removing of wraping result in Ok.

Android build fail isn't related to this diff:

error An unexpected error occurred: "https://registry.yarnpkg.com/setprototypeof/-/setprototypeof-1.2.0.tgz: Request failed \"503 Service Unavailable\"".

Android build fail isn't related to this diff:

You should be able to click on the gate, then select "restart build" on the right hand side.

In D4540#145965, @jon wrote:

Android build fail isn't related to this diff:

You should be able to click on the gate, then select "restart build" on the right hand side.

Oh, I thought the state in phabricator will not update on this (it's linked to some unique id of the build run). That's cool, thanks!

In D4540#146008, @max wrote:
In D4540#145965, @jon wrote:

Android build fail isn't related to this diff:

You should be able to click on the gate, then select "restart build" on the right hand side.

Oh, I thought the state in phabricator will not update on this (it's linked to some unique id of the build run). That's cool, thanks!

The tricky thing here is if you restart a job from the Buildkite UI it won't be reflected in Phabricator, but if you restart a build from Phabricator (via Harbormaster) it will be reflected

In D4540#146009, @atul wrote:
In D4540#146008, @max wrote:
In D4540#145965, @jon wrote:

Android build fail isn't related to this diff:

You should be able to click on the gate, then select "restart build" on the right hand side.

Oh, I thought the state in phabricator will not update on this (it's linked to some unique id of the build run). That's cool, thanks!

The tricky thing here is if you restart a job from the Buildkite UI it won't be reflected in Phabricator, but if you restart a build from Phabricator (via Harbormaster) it will be reflected

That makes sense because Harbormaster will link to a new unique build id (or something like that). Thanks for a clarification @atul ;)

tomek requested changes to this revision.Sep 2 2022, 1:39 AM
tomek added inline comments.
services/tunnelbroker/rust-notifications/src/apns.rs
21–22 ↗(On Diff #16210)

Is it a recommended approach to create new client for every notification? Seems really wasteful.

services/tunnelbroker/rust-notifications/src/lib.rs
22 ↗(On Diff #15801)

but I don't think we should define a number of workers, thread name, or thread stack in our scenario.

Curious why you think this

@max this comment was probably missed. What about it?

This revision now requires changes to proceed.Sep 2 2022, 1:39 AM
max marked 3 inline comments as done.
max added inline comments.
services/tunnelbroker/rust-notifications/src/apns.rs
21–22 ↗(On Diff #16210)

Is it a recommended approach to create new client for every notification? Seems really wasteful.

There is no point here to use a shared client and reuse it because we will call this function from the different C++ threads and in this case, we will need to use a synchronization mechanism for the shared access and this will level out benefits and makes the code more complex on this simple call.
Also, this can be a bottleneck in the case of the performance while parallel sending because we use only one client.

Same thing in D4894#146223

services/tunnelbroker/rust-notifications/src/lib.rs
22 ↗(On Diff #15801)

but I don't think we should define a number of workers, thread name, or thread stack in our scenario.

Curious why you think this

@max this comment was probably missed. What about it?

According to the Tokio documentation using a Multi-Thread Scheduler is the best default point because of:

By default, it will start a worker thread for each CPU core available on the system. This tends to be the ideal configuration for most applications.

Using a current-thread-scheduler can make a problem when the Rust call spawns threads that don't need to be blocked and run in parallel. Seems to be in this case they can be blocked by each other.

tomek added inline comments.
services/tunnelbroker/rust-notifications/src/apns.rs
21–22 ↗(On Diff #16210)

Ok, but how about thread local? How expensive is it to create a new client?

This revision is now accepted and ready to land.Sep 2 2022, 5:57 AM
max added inline comments.
services/tunnelbroker/rust-notifications/src/apns.rs
21–22 ↗(On Diff #16210)

Ok, but how about thread local? How expensive is it to create a new client?

I'm not a big fan of thread_local because we will copy the instance every time instead of creating which is quite light, but there is room for improvement. I've created a possible follow-up for this.

Thanks @tomek !

max marked an inline comment as done.

Rebase on master and merge.

Android build error is unrelated to this diff (it doesn't touch any Android stuff), it fails with the downloading timeout.

This revision was landed with ongoing or failed builds.Sep 6 2022, 4:59 AM
This revision was automatically updated to reflect the committed changes.