Remove some stack frames from .async calls #66398
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The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. 
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bors added S-waiting-on-bors tmandry added a commit to tmandry/rust that referenced this pull request Nov 14, 2019
Remove some stack frames from `.async` calls The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. tmandry added a commit to tmandry/rust that referenced this pull request Nov 14, 2019
Remove some stack frames from `.async` calls The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. JohnTitor added a commit to JohnTitor/rust that referenced this pull request Nov 15, 2019
Remove some stack frames from `.async` calls The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. JohnTitor added a commit to JohnTitor/rust that referenced this pull request Nov 15, 2019
Remove some stack frames from `.async` calls The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. bors added a commit that referenced this pull request Nov 15, 2019
Rollup of 12 pull requests Successful merges: - #65557 (rename Error::iter_chain() and remove Error::iter_sources()) - #66013 (Avoid hashing the key twice in `get_query()`.) - #66306 (Remove cannot mutate statics in initializer of another static error) - #66338 (Update mdbook.) - #66388 (Do not ICE on recovery from unmet associated type bound obligation) - #66390 (Fix ICE when trying to suggest `Type<>` instead of `Type()`) - #66391 (Do not ICE in `if` without `else` in `async fn`) - #66394 (Fix two OOM issues related to `ConstProp`) - #66398 (Remove some stack frames from `.async` calls) - #66410 (miri: helper methods for max values of machine's usize/isize) - #66418 (Link to tracking issue in HIR const-check error code description) - #66419 (Don't warn labels beginning with `_` on unused_labels lint) Failed merges: r? @ghost
JohnTitor added a commit to JohnTitor/rust that referenced this pull request Nov 15, 2019
Remove some stack frames from `.async` calls The `Context` argument is currently smuggled through TLS for async-generated futures. The current infrastructure is closure-based, and results in an extra 6 stack frames when .awaiting an async-generated future! ``` 12: foo::async_b::{{closure}} at src/main.rs:10 13: <std::future::GenFuture<T> as core::future::future::Future>::poll::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 14: std::future::set_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:79 15: <std::future::GenFuture<T> as core::future::future::Future>::poll at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:43 16: std::future::poll_with_tls_context::{{closure}} at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 17: std::future::get_task_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:111 18: std::future::poll_with_tls_context at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/future.rs:121 19: foo::async_a::{{closure}} at src/main.rs:6 ``` While the long (medium?) term solution is to remove the use of TLS entirely, we can improve things a bit in the meantime. In particular, this commit does 2 things: 1. `get_task_context` has been inlined into `poll_with_tls_context`, removing 2 frames (16 and 17 above). 2. `set_task_context` now returns a guard type that resets the TLS rather than taking a closure, removing 2 frames (13 and 14 above). We can also remove frame 18 by removing `poll_with_tls_context` in favor of a `get_task_context` function which returns a guard, but that requires adjusting the code generated for .await, so I've left that off for now. bors added a commit that referenced this pull request Nov 15, 2019
Rollup of 12 pull requests Successful merges: - #65557 (rename Error::iter_chain() and remove Error::iter_sources()) - #66013 (Avoid hashing the key twice in `get_query()`.) - #66306 (Remove cannot mutate statics in initializer of another static error) - #66338 (Update mdbook.) - #66388 (Do not ICE on recovery from unmet associated type bound obligation) - #66390 (Fix ICE when trying to suggest `Type<>` instead of `Type()`) - #66391 (Do not ICE in `if` without `else` in `async fn`) - #66398 (Remove some stack frames from `.async` calls) - #66410 (miri: helper methods for max values of machine's usize/isize) - #66418 (Link to tracking issue in HIR const-check error code description) - #66419 (Don't warn labels beginning with `_` on unused_labels lint) - #66428 (Cleanup unused function) Failed merges: r? @ghost
| @sfackler, was the visibility change to |
| Yes, it was intentional. The TLS interface is not a public API and will be removed entirely in the future. |
AerialX added a commit to AerialX/core-futures-tls that referenced this pull request Dec 6, 2019
bors bot added a commit to taiki-e/futures-async-stream that referenced this pull request Dec 10, 2019
31: Fix build failure on latest nightly r=taiki-e a=taiki-e This fixes breakage due to rust-lang/rust#66398. Fixes #30 Co-authored-by: Taiki Endo <te316e89@gmail.com>
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The
Contextargument is currently smuggled through TLS forasync-generated futures. The current infrastructure is closure-based,
and results in an extra 6 stack frames when .awaiting an async-generated
future!
While the long (medium?) term solution is to remove the use of TLS
entirely, we can improve things a bit in the meantime. In particular,
this commit does 2 things:
get_task_contexthas been inlined intopoll_with_tls_context,removing 2 frames (16 and 17 above).
set_task_contextnow returns a guard type that resets the TLSrather than taking a closure, removing 2 frames (13 and 14 above).
We can also remove frame 18 by removing
poll_with_tls_contextin favorof a
get_task_contextfunction which returns a guard, but thatrequires adjusting the code generated for .await, so I've left that off
for now.