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Remove a stack frame from .await calls #70831

Merged
merged 2 commits into from
Apr 16, 2020
Merged

Remove a stack frame from .await calls #70831

merged 2 commits into from
Apr 16, 2020

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sfackler
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@sfackler sfackler commented Apr 6, 2020

The stack frames when .awaiting one async fn from another currently look like this:

  12: foo::b::{{closure}}
             at src/main.rs:2
  13: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
             at /home/sfackler/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:66
  14: core::future::poll_with_context
             at /home/sfackler/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:84
  15: foo::a::{{closure}}
             at src/main.rs:6

Since the move away from using TLS to pass the Context around, it's now easy to remove frame 14 by removing poll_with_context in favor of calling Future::poll directly. This still leaves the GenFuture frame, but that seems significantly harder to deal with.

It also improves diagnostics a bit since they no longer talk about the private poll_with_context function.

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r? @matthewjasper

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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 6, 2020
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Centril commented Apr 6, 2020

@bors try @rust-timer queue

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Awaiting bors try build completion

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bors commented Apr 6, 2020

⌛ Trying commit 5dc8ec8 with merge c625e40f85b5b2f48f832564bf9dcdaeecc9a4fd...

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bors commented Apr 6, 2020

☀️ Try build successful - checks-azure
Build commit: c625e40f85b5b2f48f832564bf9dcdaeecc9a4fd (c625e40f85b5b2f48f832564bf9dcdaeecc9a4fd)

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Queued c625e40f85b5b2f48f832564bf9dcdaeecc9a4fd with parent b543afc, future comparison URL.

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sfackler commented Apr 9, 2020

It looks like the perf run finished but the bot didn't comment for some reason.

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Centril commented Apr 9, 2020

Yeah, that happens sometimes sadly.

matthewjasper
matthewjasper reviewed Apr 13, 2020
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r=me with nit addressed if we think that the perf is good enough.

src/librustc_span/symbol.rs Outdated
Poll,
poll_with_context,
get_context,
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Can this be moved up to be in order.

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Fixed

@Centril Centril added I-nominated T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 13, 2020
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@bors r+

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bors commented Apr 16, 2020

📌 Commit 3ba3bd5 has been approved by matthewjasper

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 16, 2020
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bors commented Apr 16, 2020

⌛ Testing commit 3ba3bd5 with merge 4e4d49d...

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bors commented Apr 16, 2020

☀️ Test successful - checks-azure
Approved by: matthewjasper
Pushing 4e4d49d to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Apr 16, 2020
@bors bors merged commit 4e4d49d into rust-lang:master Apr 16, 2020
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@sfackler sfackler deleted the shrink-future-stack branch April 16, 2020 22:23
@nikomatsakis nikomatsakis mentioned this pull request Apr 17, 2020
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@taiki-e taiki-e mentioned this pull request Apr 17, 2020
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bors bot added a commit to taiki-e/futures-async-stream that referenced this pull request Apr 17, 2020
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Merge #37
86d6917 
37: Remove poll*with_context functions r=taiki-e a=taiki-e

Based on rust-lang/rust#70831

Co-authored-by: Taiki Endo <[email protected]>
@senden9 senden9 mentioned this pull request Apr 20, 2020
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bors bot added a commit to taiki-e/futures-async-stream that referenced this pull request May 2, 2020
@bors @taiki-e
Merge #37
153093f 
37: Remove poll*with_context functions r=taiki-e a=taiki-e

Based on rust-lang/rust#70831


Co-authored-by: Taiki Endo <[email protected]>
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