feat: oneshot channel returns `Pkid` #806

de-sh · 2024-02-22T16:15:43Z

Fixes #349, implements #805

Type of change

New feature (non-breaking change which adds functionality)

Allows user access to pkid information once it is assigned by rumqttc internals during run.

Checklist:

Formatted with cargo fmt
Make an entry to CHANGELOG.md if it's relevant to the users of the library. If it's not relevant mention why.

Tests performed

Ran this against provided example async code, output looks as follows

Event = Incoming(ConnAck(ConnAck { session_present: false, code: Success }))
Event = Outgoing(Subscribe(1))
Pkid: 1
Event = Outgoing(Publish(2))
Pkid: 2
Event = Incoming(SubAck(SubAck { pkid: 1, return_codes: [Success(AtMostOnce)] }))
Event = Outgoing(PubRel(2))
Event = Incoming(PubRec(PubRec { pkid: 2 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 1))
Event = Incoming(PubComp(PubComp { pkid: 2 }))
Event = Outgoing(Publish(3))
Pkid: 3
Event = Outgoing(PubRel(3))
Event = Incoming(PubRec(PubRec { pkid: 3 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 2))
Event = Incoming(PubComp(PubComp { pkid: 3 }))
Event = Outgoing(Publish(4))
Pkid: 4
Event = Outgoing(PubRel(4))
Event = Incoming(PubRec(PubRec { pkid: 4 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 3))
Event = Incoming(PubComp(PubComp { pkid: 4 }))
Event = Outgoing(Publish(5))
Pkid: 5
Event = Outgoing(PubRel(5))
Event = Incoming(PubRec(PubRec { pkid: 5 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 4))
Event = Incoming(PubComp(PubComp { pkid: 5 }))
Event = Outgoing(Publish(6))
Pkid: 6
Event = Outgoing(PubRel(6))
Event = Incoming(PubRec(PubRec { pkid: 6 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 5))
Event = Incoming(PubComp(PubComp { pkid: 6 }))
Event = Outgoing(PingReq)
Event = Outgoing(Publish(7))
Pkid: 7
Event = Incoming(PingResp)
Event = Outgoing(PubRel(7))
Event = Incoming(PubRec(PubRec { pkid: 7 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 6))
Event = Incoming(PubComp(PubComp { pkid: 7 }))
Event = Outgoing(Publish(8))
Pkid: 8
Event = Outgoing(PubRel(8))
Event = Incoming(PubRec(PubRec { pkid: 8 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 7))
Event = Incoming(PubComp(PubComp { pkid: 8 }))
Event = Outgoing(Publish(9))
Pkid: 9
Event = Outgoing(PubRel(9))
Event = Incoming(PubRec(PubRec { pkid: 9 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 8))
Event = Incoming(PubComp(PubComp { pkid: 9 }))
Event = Outgoing(Publish(10))
Pkid: 10
Event = Outgoing(PubRel(10))
Event = Incoming(PubRec(PubRec { pkid: 10 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 9))
Event = Incoming(PubComp(PubComp { pkid: 10 }))
Event = Outgoing(Publish(11))
Pkid: 11
Event = Outgoing(PubRel(11))
Event = Incoming(PubRec(PubRec { pkid: 11 }))
Event = Incoming(Publish(Topic = hello/world, Qos = AtMostOnce, Retain = false, Pkid = 0, Payload Size = 10))
Event = Incoming(PubComp(PubComp { pkid: 11 }))
Event = Outgoing(PingReq)
Event = Incoming(PingResp)

Thus the implementation is complete.

coveralls · 2024-02-23T02:03:06Z

Pull Request Test Coverage Report for Build 8478057404

Details

80 of 351 (22.79%) changed or added relevant lines in 6 files are covered.
No unchanged relevant lines lost coverage.
Overall first build on pkid at 36.187%

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rumqttc/src/state.rs	27	37	72.97%
rumqttc/src/v5/state.rs	26	38	68.42%
rumqttc/src/lib.rs	3	18	16.67%
rumqttc/src/v5/mod.rs	0	29	0.0%
rumqttc/src/client.rs	16	101	15.84%
rumqttc/src/v5/client.rs	8	128	6.25%

Totals
Change from base Build 8432798356:	36.2%
Covered Lines:	6020
Relevant Lines:	16636

💛 - Coveralls

swanandx

I like the idea and also tried it out, with both sync & async, and it works nicely!

Here is my feedback:

we should avoid placing the pkid_tx directly in packets, mqttbytes should strictly be related to protocol parsing. We can maybe put it in request like Request::Publish(tx, publish) ?
just Pkid seems intuitive than PkidPromise
users don't need to know about the oneshot channel, thus instead of just type alias, we should impl / rename some methods. e.g. async client is fine, but when in sync, using pkid.blocking_recv() isn't. maybe we can rename that recv to something else?
if we fail to send the pkid from state, maybe we can log some debug lvl info? not sure how often we will fail though.
examples can be simplified, we just want to show how user can get pkid. So we can simply await right after getting Pkid. Using joinsets / delay queues in unnecessarily adding complexity. Also, users want to associate the publish with the pkid right? awaiting em later via joinset or something will be same as checking for Outgoing event.
as you suggested in RFC, having many open oneshot channels might addup perf impact which we are unsure of as of now. Whether to feature gate this or not is your call ( as you would know better haha )

de-sh · 2024-02-25T09:29:56Z

as you suggested in RFC, having many open oneshot channels might addup perf impact which we are unsure of as of now. Whether to feature gate this or not is your call ( as you would know better haha )

It doesn't seem to have much of an impact on perf, I believe it is safe to ignore for now. Cost of feature gating is expensive on the code readability front.

will be same as checking for Outgoing event.

Not really, I got the idea from the user comment in the RFC, it's just to give users an idea of what is possible, they can choose to not go the route we illustrate, but we can try and educate them about the possibilities.

if we fail to send the pkid from state, maybe we can log some debug lvl info? not sure how often we will fail though.

This should be fine, the only reason we couldn't send was because of rx drop, which means the user doesn't want to do anything with the pkid.

just Pkid seems intuitive than PkidPromise

From a user perspective, you wouldn't want them to confuse between the awaiting and the occupied state.

we should avoid placing the pkid_tx directly in packets, mqttbytes should strictly be related to protocol parsing. We can maybe put it in request like Request::Publish(tx, publish) ?

users don't need to know about the oneshot channel, thus instead of just type alias, we should impl / rename some methods. e.g. async client is fine, but when in sync, using pkid.blocking_recv() isn't. maybe we can rename that recv to something else?

✅

de-sh · 2024-02-25T09:54:58Z

rumqttc/src/v5/state.rs

@@ -183,21 +186,21 @@ impl MqttState {
    /// be put on to the network by the eventloop
    pub fn handle_outgoing_packet(&mut self, request: Request) -> Result<(), StateError> {
        match request {
-            Request::Publish(publish) => {
+            Request::Publish(tx, publish) => {
                self.check_size(publish.size())?;


EventLoop drops the pkid_tx here if size is not valid

de-sh · 2024-02-25T09:56:21Z

I have a few comments about the PkidError type, it needs to be more descriptive of why it failed to resolve into a valid number. This could be one of many:

EventLoop was shutdown, hence the tx was dropped.
EventLoop rejected the packet and hence did not assign it a pkid

We should probably handle this in a separate PR, I believe the current PR is a good to merge now.

swanandx · 2024-02-27T11:28:10Z

it's just to give users an idea of what is possible, they can choose to not go the route we illustrate, but we can try and educate them about the possibilities.

my thinking was, the examples should show them how they can get the pkid in general. for simple examples sake, getting pkid one by one should be fine imo ( in async & in sync )

we can make separate examples tailored toward why they might want to use joinset ( or something else ). There we should also explain why it is used and when they should and shouldn't use it.

From a user perspective, you wouldn't want them to confuse between the awaiting and the occupied state.

I didn't get this completely, but i would like to differ. Adding Promise to name is too verbose(? idk correct word). e.g. the receiver is Receiver not ReceiverPromise.

de-sh · 2024-03-05T11:38:01Z

e.g. the receiver is Receiver not ReceiverPromise.

That's because the receiver is a generic term for receiving data, here we are adding context that we are promising deliver of a Pkid specifically. Naming is the most contentious thing in software, believe me when I tell you that this is the right term 😂

de-sh added 2 commits February 22, 2024 15:59

feat: oneshot channel returns Pkid

e29b9ad

fulfill promise on handling packets

44a7090

de-sh changed the title ~~fulfill promise on handling packets~~ feat: oneshot channel returns Pkid Feb 22, 2024

de-sh added 5 commits February 22, 2024 16:24

handle QoS 0

941fa54

doc: example usecase

8fc2d4a

get tests to compile, partially

0b3406f

ci: fix missing dep feature

c7ac03d

make example fun

408b01c

de-sh requested review from tekjar and swanandx February 23, 2024 01:51

de-sh added 3 commits February 23, 2024 02:21

implement feature for v5

76af76d

doc: v5 example

4999ae3

add entry into changelog

20eca90

de-sh marked this pull request as ready for review February 23, 2024 02:28

swanandx reviewed Feb 23, 2024

View reviewed changes

de-sh added 4 commits February 23, 2024 22:59

Abstract true nature of PkidPromise

8a06b11

fix example

ad34d6e

move tx out of mqttbytes

f090555

PkidError when no pkid

1949c2a

don't expose oneshot

33346a1

de-sh commented Feb 25, 2024

View reviewed changes

de-sh added 2 commits March 29, 2024 06:01

Merge remote-tracking branch 'origin/main' into pkid

ac261eb

test: remove test

de57cf1

de-sh closed this May 22, 2024

de-sh deleted the pkid branch July 31, 2024 06:20

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feat: oneshot channel returns `Pkid` #806

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feat: oneshot channel returns Pkid #806

feat: oneshot channel returns Pkid #806

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Type of change

Checklist:

Tests performed

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Pull Request Test Coverage Report for Build 8478057404

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feat: oneshot channel returns `Pkid` #806

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