Provide a `Scope` per server call (#3197) #3276

987Nabil · 2025-01-18T19:57:20Z

zio-http/jvm/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala

guersam · 2025-01-20T10:27:56Z

zio-http-testkit/src/main/scala/zio/http/TestServer.scala

@@ -98,7 +98,7 @@ final case class TestServer(driver: Driver, bindPort: Int) extends Server {
      _ <- driver.addApp(provided, r)
    } yield ()

-  override def install[R](routes: Routes[R, Response])(implicit
+  override def install[R](routes: Routes[Scope & R, Response])(implicit


What's the purpose of this Scope requirement?

I'd prefer hiding it from the Routes because it makes users to provide Scope that is not actually used.

The Scope has to be here, so that it is "eaten" up by the method. The effect that is returned has no more requirement of scope. That means, it is not possible to use a Scope that extends over a single request from inside a request. That is intentionally

I see. I misinterpreted the code due to this line.

I also wondered if we could do the elimination earlier, RoutePattern#->, Routes.apply or etc. for example, but it could be error prone and let the compiler do more work.

No, the routes is the right place. We need to close the Scope in the driver, after netty write is over.
If we eliminate the Scope earlier, we would need to close the scope earlier too.
Else you do route.run(..) and your scope is not closed/provided. That would be a bug

By 'eliminating', I mean something like this:

trait Route[-Env, +Err] { def apply(request: Request): ZIO[Scope & Env, Response, Response] = ??? } case class RoutePattern[A](...) { def ->[Env, Err, I](handler: Handler[Scope & Env, Err, I, Response]): Route[Env, Err] = ??? }

Unlike the other environments, Scope is a local requirement per request. I think this encoding reveals the relationship more clearly, but there's two downsides that we need to modify every route forming function including Endpoint DSL and the burden to the compiler of the added type calculation per route . In this respect, I think the current design in this PR is still good.

@guersam I tried that out. It complicates the code, has negative impact on type inference and all just to save Scope on the type of Routes seems like a bad trade off

@guersam I tried that out. It complicates the code, has negative impact on type inference and all just to save Scope on the type of Routes seems like a bad trade off

This was my conclusion on #3229 as well, I agree with @987Nabil this is the best approach to not make it very convoluted.

jgranstrom · 2025-01-22T21:05:48Z

FWIW I tested this on the real world case of #3197 and it looks good.

987Nabil · 2025-02-03T08:40:50Z

@guersam @jgranstrom @kyri-petrou I changed the design after talking to @jdegoes
please take a look again.

guersam · 2025-02-03T08:50:01Z

I'm excited to see how the new design looks in idiomatic ZIO. It must have involved subtle internal design decisions and thorough changes across a wide range of the codebase. I really appreciate your continuous efforts to improve it!

jdegoes · 2025-02-05T16:35:00Z

zio-http/shared/src/main/scala/zio/http/Handler.scala

@@ -1051,6 +1058,9 @@ object Handler extends HandlerPlatformSpecific with HandlerVersionSpecific {
  def fromResponseZIO[R, Err](getResponse: ZIO[R, Err, Response]): Handler[R, Err, Any, Response] =
    fromZIO(getResponse)

+  def scoped[R]: ScopedPartiallyApplied[R] =
+    new ScopedPartiallyApplied[R]()


Make:

_scopedPartiallyApplied.asInstanceOf[ScopePartiallyApplied[R]]

where:

private val _scopedPartiallyApplied = new ScopedPartiallyApplied[Any]()

jdegoes · 2025-02-05T16:37:11Z

zio-http/shared/src/main/scala/zio/http/Middleware.scala

@@ -181,7 +181,7 @@ object Middleware extends HandlerAspects {
          handler { (req: Request) =>
            if (req.headers.contains(header.name)) h(req)
            else h(req.addHeader(make))
-          }
+          }.asInstanceOf[Handler[Env1, Response, Request, Response]]


Handler.scoped here and elsewhere

jdegoes · 2025-02-05T16:38:02Z

zio-http/shared/src/main/scala/zio/http/Route.scala

+      Handler
+        .fromZIO(handler(routePattern).map(_.sandbox))
+        .flatten
+        .asInstanceOf[Handler[Env, Response, Request, Response]]


jdegoes · 2025-02-05T16:43:02Z

Ideally this would NOT allow R to extend Scope:

trait Server {

  /**
   * Installs the given HTTP application into the server.
   */
  def install[R](routes: Routes[R, Response])(implicit trace: Trace, tag: EnvironmentTag[R]): URIO[R, Unit]

Using a macro (making this old version private so it's there for backward compatibility only).

987Nabil requested review from jdegoes, vigoo and kyri-petrou as code owners January 18, 2025 19:57

algora-pbc bot mentioned this pull request Jan 18, 2025

It is not possible to express a per-request Scope in a Handler that covers the entire request/response lifetime #3197

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algora-pbc bot added the 🙋 Bounty claim label Jan 18, 2025

987Nabil force-pushed the sope-per-request branch from e7140d6 to 631581e Compare January 18, 2025 20:02

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zio-http/jvm/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala Outdated Show resolved Hide resolved

987Nabil force-pushed the sope-per-request branch 7 times, most recently from 6d31d72 to a5d85d1 Compare January 19, 2025 12:19

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987Nabil force-pushed the sope-per-request branch 2 times, most recently from d3c02e3 to 5ccb804 Compare February 3, 2025 08:39

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Provide a Scope per server call (zio#3197)

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987Nabil force-pushed the sope-per-request branch from d96627b to b4f472e Compare February 3, 2025 14:12

Scope handling for handlers (zio#3197)

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987Nabil force-pushed the sope-per-request branch from b4f472e to 0f28d82 Compare February 3, 2025 18:17

kyri-petrou approved these changes Feb 5, 2025

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Provide a `Scope` per server call (#3197) #3276

Provide a `Scope` per server call (#3197) #3276

987Nabil commented Jan 18, 2025

guersam Jan 20, 2025

987Nabil Jan 20, 2025

guersam Jan 20, 2025

987Nabil Jan 20, 2025

guersam Jan 21, 2025

987Nabil Jan 22, 2025

jgranstrom Jan 22, 2025

jgranstrom commented Jan 22, 2025

987Nabil commented Feb 3, 2025

guersam commented Feb 3, 2025

jdegoes Feb 5, 2025

jdegoes Feb 5, 2025

jdegoes Feb 5, 2025

jdegoes commented Feb 5, 2025

Provide a Scope per server call (#3197) #3276

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Provide a Scope per server call (#3197) #3276

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987Nabil commented Jan 18, 2025

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jgranstrom commented Jan 22, 2025

987Nabil commented Feb 3, 2025

guersam commented Feb 3, 2025

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jdegoes commented Feb 5, 2025

Provide a `Scope` per server call (#3197) #3276

Provide a `Scope` per server call (#3197) #3276