builder,util: add convenience methods for boxing services by davidpdrsn · Pull Request #616 · tower-rs/tower

davidpdrsn · 2021-11-11T09:32:48Z

This adds a couple of new methods to ServiceBuilder and ServiceExt:

ServiceBuilder::boxed
ServiceExt::boxed
ServiceBuilder::clone_boxed
ServiceExt::clone_boxed

This adds a couple of new methods to `ServiceBuilder` and `ServiceExt`: - `ServiceBuilder::boxed` - `ServiceExt::boxed` - `ServiceBuilder::clone_boxed` - `ServiceExt::clone_boxed` They apply `BoxService::layer` and `CloneBoxService::layer` respectively.

hawkw

I commented on some docs nits and stuff, but I'm mostly good with this. It would be nice to fix the wrong syntax in links before merging, though.

hawkw · 2021-11-11T20:59:41Z

tower/src/builder/mod.rs

+            tower_layer::LayerFn<
+                fn(
+                    L::Service,
+                ) -> crate::util::BoxService<
+                    R,
+                    <L::Service as Service<R>>::Response,
+                    <L::Service as Service<R>>::Error,
+                >,
+            >,


yeesh...i feel like it's almost worth introducing a named Layer type for BoxService just to avoid having this type signature...but, I think that might be a breaking change...

I went down that route initially actually but you end up having to have the request type as a type param on the layer:

// have to have `T` here otherwise its unconstrained in the layer impl pub struct CloneBoxServiceLayer<T> { _request: PhantomData<T>, } impl<S, T> Layer<S> for CloneBoxServiceLayer<T> where S: Service<T> + Clone + Send + 'static, S::Future: Send + 'static, { type Service = CloneBoxService<T, S::Response, S::Error>; fn layer(&self, inner: S) -> Self::Service { CloneBoxService::new(inner) } }

That could be workable to leads to inference issues when actually using the builder method:

---- src/builder/mod.rs - builder::ServiceBuilder<L>::clone_boxed (line 754) stdout ---- error[E0284]: type annotations needed --> src/builder/mod.rs:765:6 | 14 | .clone_boxed() | ^^^^^^^^^^^ cannot infer type for type parameter `S` | = note: cannot satisfy `<_ as Service<Request>>::Future == _`

ugh, never mind. it's probably better to avoid introducing phantomdata anyway, as they will result in rustc having to typecheck a larger type, potentially impacting build time... this is fine, then.

hawkw · 2021-11-11T21:01:29Z

tower/src/builder/mod.rs

+    /// [`CloneBoxService:layer()`]: crate::util::CloneBoxService::layer()
+    #[cfg(feature = "util")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "util")))]
+    pub fn clone_boxed<S, R>(


TIOLI but I might have called this boxed_clone? although on the other hand, this isn't consistent with the name of the return type...idk.

Right I went with this name because it matches the service name, which we can rename since its not released. CloneBoxService or BoxCloneService seem kinda same same to me though.

tower/src/util/mod.rs

tower/src/builder/mod.rs

hawkw · 2021-11-11T21:06:27Z

tower/src/builder/mod.rs

+    }
+
+    /// Convert the resulting service into a [`Service`] + [`Clone`] + [`Send`] trait object.
+    ///


nit, take it or leave it: maybe worth adding a note comparing this with box_service, like I mentioned on the ServiceExt methods? not a blocker...

hawkw · 2021-11-11T21:10:36Z

tower/src/builder/mod.rs

+            tower_layer::LayerFn<
+                fn(
+                    L::Service,
+                ) -> crate::util::CloneBoxService<
+                    R,
+                    <L::Service as Service<R>>::Response,
+                    <L::Service as Service<R>>::Error,
+                >,
+            >,
+            L,


gosh... since the CloneBoxService::layer() method hasn't been released yet, we could potentially replace the LayerFn with a named Layer type. IDK if it's worth it just to get rid of this type signature, but...wow.

tower/CHANGELOG.md

Co-authored-by: Eliza Weisman <[email protected]>

hawkw · 2021-11-17T23:54:21Z

tower/src/builder/mod.rs

+            tower_layer::LayerFn<
+                fn(
+                    L::Service,
+                ) -> crate::util::BoxService<
+                    R,
+                    <L::Service as Service<R>>::Response,
+                    <L::Service as Service<R>>::Error,
+                >,
+            >,


ugh, never mind. it's probably better to avoid introducing phantomdata anyway, as they will result in rustc having to typecheck a larger type, potentially impacting build time... this is fine, then.

Added - **util**: Add `CloneBoxService` which is a `Clone + Send` boxed `Service` ([#615]) - **util**: Add `ServiceExt::boxed` and `ServiceExt::clone_boxed` for applying the `BoxService` and `CloneBoxService` middleware ([#616]) - **builder**: Add `ServiceBuilder::boxed` and `ServiceBuilder::clone_boxed` for applying `BoxService` and `CloneBoxService` layers ([#616]) Fixed - **balance**: Remove redundant `Req: Clone` bound from `Clone` impls for `MakeBalance`, and `MakeBalanceLayer` ([#607]) - **balance**: Remove redundant `Req: Debug` bound from `Debug` impls for `MakeBalance`, `MakeFuture`, `Balance`, and `Pool` ([#607]) - **ready-cache**: Remove redundant `Req: Debug` bound from `Debug` impl for `ReadyCache` ([#607]) - **steer**: Remove redundant `Req: Debug` bound from `Debug` impl for `Steer` ([#607]) - **util**: Remove redundant `F: Clone` bound from `ServiceExt::map_request` ([#607]) - **docs**: Fix `doc(cfg(...))` attributes of `PeakEwmaDiscover`, and `PendingRequestsDiscover` ([#610]) - **util**: Remove unnecessary `Debug` bounds from `impl Debug for BoxService` ([#617]) - **util**: Remove unnecessary `Debug` bounds from `impl Debug for UnsyncBoxService` ([#617]) [#607]: #607 [#610]: #610 [#616]: #616 [#617]: #617 [#615]: #615

* tower: prepare to release 0.4.11 Added - **util**: Add `CloneBoxService` which is a `Clone + Send` boxed `Service` ([#615]) - **util**: Add `ServiceExt::boxed` and `ServiceExt::clone_boxed` for applying the `BoxService` and `CloneBoxService` middleware ([#616]) - **builder**: Add `ServiceBuilder::boxed` and `ServiceBuilder::clone_boxed` for applying `BoxService` and `CloneBoxService` layers ([#616]) Fixed - **balance**: Remove redundant `Req: Clone` bound from `Clone` impls for `MakeBalance`, and `MakeBalanceLayer` ([#607]) - **balance**: Remove redundant `Req: Debug` bound from `Debug` impls for `MakeBalance`, `MakeFuture`, `Balance`, and `Pool` ([#607]) - **ready-cache**: Remove redundant `Req: Debug` bound from `Debug` impl for `ReadyCache` ([#607]) - **steer**: Remove redundant `Req: Debug` bound from `Debug` impl for `Steer` ([#607]) - **util**: Remove redundant `F: Clone` bound from `ServiceExt::map_request` ([#607]) - **docs**: Fix `doc(cfg(...))` attributes of `PeakEwmaDiscover`, and `PendingRequestsDiscover` ([#610]) - **util**: Remove unnecessary `Debug` bounds from `impl Debug for BoxService` ([#617]) - **util**: Remove unnecessary `Debug` bounds from `impl Debug for UnsyncBoxService` ([#617]) [#607]: #607 [#610]: #610 [#616]: #616 [#617]: #617 [#615]: #615 * sorting * Rename `CloneBoxService` to `BoxCloneService` * formatting * also update changelog

davidpdrsn added 3 commits November 11, 2021 10:32

fix doc links

d16373f

add missing cfgs

ef9066b

davidpdrsn marked this pull request as ready for review November 11, 2021 09:46

davidpdrsn requested review from hawkw and olix0r November 11, 2021 09:47

hawkw approved these changes Nov 11, 2021

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davidpdrsn and others added 7 commits November 17, 2021 18:36

Update tower/CHANGELOG.md

9ab3cce

Co-authored-by: Eliza Weisman <[email protected]>

Apply suggestions from code review

a140604

Co-authored-by: Eliza Weisman <[email protected]>

not sure why rustdoc cannot infer these

407823c

line breaks

e5dabd5

trailing whitespace

56be5c4

make docs a bit more consistent

a596a90

Merge branch 'master' into david/boxed-helper-methods

c7883d5

davidpdrsn requested a review from hawkw November 17, 2021 17:47

hawkw approved these changes Nov 17, 2021

View reviewed changes

davidpdrsn added 4 commits November 18, 2021 09:55

fix doc links

b4c983c

update tokio

decccad

don't pull in old version of tower

34600d3

Don't run cargo deny check bans as it hangs

03066dd

davidpdrsn merged commit 4d80f7e into master Nov 18, 2021

davidpdrsn deleted the david/boxed-helper-methods branch November 18, 2021 12:56

This was referenced Nov 18, 2021

tower: prepare to release 0.4.11 #618

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cargo deny check bans hangs when run in the tower repo #619

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builder,util: add convenience methods for boxing services#616

builder,util: add convenience methods for boxing services#616
davidpdrsn merged 14 commits intomasterfrom
david/boxed-helper-methods

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