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sync: doc of watch::Sender::send improved #4959

Merged
merged 4 commits into from
Sep 1, 2022
Merged

sync: doc of watch::Sender::send improved #4959

merged 4 commits into from
Sep 1, 2022

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JanBeh
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@JanBeh JanBeh commented Aug 30, 2022

Current documentation of sync::watch::Sender::send may be intepreted as the method failing if at some point in past the channel has been closed because every receiver has been dropped. This isn't true, however, as the channel could have been reopened by using sync::watch::Sender::subscribe.

This fix clarifies the behavior. Moreover, it is noted that on failure, the value isn't made available to future subscribers (but returned as part of the SendError).

Fixes #4957.

@JanBeh
sync: doc of watch::Sender::send improved
d2bd60b 
Current documentation of `sync::watch::Sender::send` may be intepreted
as the method failing if at some point in past the channel has been
closed because every receiver has been dropped. This isn't true,
however, as the channel could have been reopened by using
`sync::watch::Sender::subscribe`.

This fix clarifies the behavior. Moreover, it is noted that on failure,
the value isn't made available to future subscribers (but returned as
part of the `SendError`).

Fixes tokio-rs#4957.
@github-actions github-actions bot added the R-loom Run loom tests on this PR label Aug 30, 2022
@Darksonn Darksonn added T-docs Topic: documentation A-tokio Area: The main tokio crate M-sync Module: tokio/sync labels Aug 30, 2022
Darksonn
Darksonn reviewed Aug 30, 2022
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tokio/src/sync/watch.rs
@@ -604,8 +604,14 @@ impl<T> Drop for Receiver<T> {
impl<T> Sender<T> {
/// Sends a new value via the channel, notifying all receivers.
///
/// This method fails if the channel has been closed, which happens when
/// every receiver has been dropped.
/// This method fails if the channel is closed, which is the case when
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Maybe it would be worth adding something like "unlike the other methods for sending" to emphasize that only this method fails in this way.

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@JanBeh JanBeh Aug 30, 2022 •
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Thank you for pointing that out; I added another note, mentioning that the other send methods can be used to send a value even if there isn't any receiver.

JanBeh added 2 commits August 30, 2022 22:54
@JanBeh
amend! sync: doc of watch::Sender::send improved
da8b888 
sync: doc of watch::Sender::send improved

Current documentation of `sync::watch::Sender::send` may be intepreted
as the method failing if at some point in past the channel has been
closed because every receiver has been dropped. This isn't true,
however, as the channel could have been reopened by using
`sync::watch::Sender::subscribe`.

This fix clarifies the behavior. Moreover, it is noted that on failure,
the value isn't made available to future subscribers (but returned as
part of the `SendError`), and that the other send methods
(`send_if_modified`, `send_modify`, or `send_replace`) can be used to
always make a new value available for future receivers, even if no
receiver currently exists.

Fixes tokio-rs#4957.
@JanBeh
fixup! amend! sync: doc of watch::Sender::send improved
202db6e
@Darksonn Darksonn enabled auto-merge (squash) August 31, 2022 10:25
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Thanks!

@Darksonn Darksonn disabled auto-merge August 31, 2022 10:27
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You'll need to merge master to pass CI.

@JanBeh
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JanBeh commented Aug 31, 2022

You'll need to merge master to pass CI.

Should I create a merge commit or rebase?

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hds commented Sep 1, 2022

Once a PR is open, it is preferable to create a merge commit, the changes will be squashed when they're merged.

Darksonn
Darksonn approved these changes Sep 1, 2022
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Thanks.

@Darksonn Darksonn merged commit 431ec68 into tokio-rs:master Sep 1, 2022
@Darksonn Darksonn mentioned this pull request Sep 1, 2022
Merged
crapStone pushed a commit to Calciumdibromid/CaBr2 that referenced this pull request Sep 11, 2022
Update Rust crate tokio to 1.21.0 (#1532)
62b6b26 
This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dependencies | minor | `1.20.1` -> `1.21.0` |
| [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dev-dependencies | minor | `1.20.1` -> `1.21.0` |

---

### Release Notes

<details>
<summary>tokio-rs/tokio</summary>

### [`v1.21.0`](https://github.com/tokio-rs/tokio/releases/tag/tokio-1.21.0)

[Compare Source](tokio-rs/tokio@tokio-1.20.1...tokio-1.21.0)

##### 1.21.0 (September 2, 2022)

This release is the first release of Tokio to intentionally support WASM. The `sync,macros,io-util,rt,time` features are stabilized on WASM. Additionally the wasm32-wasi target is given unstable support for the `net` feature.

##### Added

-   net: add `device` and `bind_device` methods to TCP/UDP sockets ([#&#8203;4882])
-   net: add `tos` and `set_tos` methods to TCP and UDP sockets ([#&#8203;4877])
-   net: add security flags to named pipe `ServerOptions` ([#&#8203;4845])
-   signal: add more windows signal handlers ([#&#8203;4924])
-   sync: add `mpsc::Sender::max_capacity` method ([#&#8203;4904])
-   sync: implement Weak version of `mpsc::Sender` ([#&#8203;4595])
-   task: add `LocalSet::enter` ([#&#8203;4765])
-   task: stabilize `JoinSet` and `AbortHandle` ([#&#8203;4920])
-   tokio: add `track_caller` to public APIs ([#&#8203;4805], [#&#8203;4848], [#&#8203;4852])
-   wasm: initial support for `wasm32-wasi` target ([#&#8203;4716])

##### Fixed

-   miri: improve miri compatibility by avoiding temporary references in `linked_list::Link` impls ([#&#8203;4841])
-   signal: don't register write interest on signal pipe ([#&#8203;4898])
-   sync: add `#[must_use]` to lock guards ([#&#8203;4886])
-   sync: fix hang when calling `recv` on closed and reopened broadcast channel ([#&#8203;4867])
-   task: propagate attributes on task-locals ([#&#8203;4837])

##### Changed

-   fs: change panic to error in `File::start_seek` ([#&#8203;4897])
-   io: reduce syscalls in `poll_read` ([#&#8203;4840])
-   process: use blocking threadpool for child stdio I/O ([#&#8203;4824])
-   signal: make `SignalKind` methods const ([#&#8203;4956])

##### Internal changes

-   rt: extract `basic_scheduler::Config` ([#&#8203;4935])
-   rt: move I/O driver into `runtime` module ([#&#8203;4942])
-   rt: rename internal scheduler types ([#&#8203;4945])

##### Documented

-   chore: fix typos and grammar ([#&#8203;4858], [#&#8203;4894], [#&#8203;4928])
-   io: fix typo in `AsyncSeekExt::rewind` docs ([#&#8203;4893])
-   net: add documentation to `try_read()` for zero-length buffers ([#&#8203;4937])
-   runtime: remove incorrect panic section for `Builder::worker_threads` ([#&#8203;4849])
-   sync: doc of `watch::Sender::send` improved ([#&#8203;4959])
-   task: add cancel safety docs to `JoinHandle` ([#&#8203;4901])
-   task: expand on cancellation of `spawn_blocking` ([#&#8203;4811])
-   time: clarify that the first tick of `Interval::tick` happens immediately ([#&#8203;4951])

##### Unstable

-   rt: add unstable option to disable the LIFO slot ([#&#8203;4936])
-   task: fix incorrect signature in `Builder::spawn_on` ([#&#8203;4953])
-   task: make `task::Builder::spawn*` methods fallible ([#&#8203;4823])

[#&#8203;4595]: tokio-rs/tokio#4595

[#&#8203;4716]: tokio-rs/tokio#4716

[#&#8203;4765]: tokio-rs/tokio#4765

[#&#8203;4805]: tokio-rs/tokio#4805

[#&#8203;4811]: tokio-rs/tokio#4811

[#&#8203;4823]: tokio-rs/tokio#4823

[#&#8203;4824]: tokio-rs/tokio#4824

[#&#8203;4837]: tokio-rs/tokio#4837

[#&#8203;4840]: tokio-rs/tokio#4840

[#&#8203;4841]: tokio-rs/tokio#4841

[#&#8203;4845]: tokio-rs/tokio#4845

[#&#8203;4848]: tokio-rs/tokio#4848

[#&#8203;4849]: tokio-rs/tokio#4849

[#&#8203;4852]: tokio-rs/tokio#4852

[#&#8203;4858]: tokio-rs/tokio#4858

[#&#8203;4867]: tokio-rs/tokio#4867

[#&#8203;4877]: tokio-rs/tokio#4877

[#&#8203;4882]: tokio-rs/tokio#4882

[#&#8203;4886]: tokio-rs/tokio#4886

[#&#8203;4893]: tokio-rs/tokio#4893

[#&#8203;4894]: tokio-rs/tokio#4894

[#&#8203;4897]: tokio-rs/tokio#4897

[#&#8203;4898]: tokio-rs/tokio#4898

[#&#8203;4901]: tokio-rs/tokio#4901

[#&#8203;4904]: tokio-rs/tokio#4904

[#&#8203;4920]: tokio-rs/tokio#4920

[#&#8203;4924]: tokio-rs/tokio#4924

[#&#8203;4928]: tokio-rs/tokio#4928

[#&#8203;4935]: tokio-rs/tokio#4935

[#&#8203;4936]: tokio-rs/tokio#4936

[#&#8203;4937]: tokio-rs/tokio#4937

[#&#8203;4942]: tokio-rs/tokio#4942

[#&#8203;4945]: tokio-rs/tokio#4945

[#&#8203;4951]: tokio-rs/tokio#4951

[#&#8203;4953]: tokio-rs/tokio#4953

[#&#8203;4956]: tokio-rs/tokio#4956

[#&#8203;4959]: tokio-rs/tokio#4959

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about these updates again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, click this checkbox.

---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzMi4xODcuMCIsInVwZGF0ZWRJblZlciI6IjMyLjE4Ny4wIn0=-->

Co-authored-by: cabr2-bot <cabr2.help@gmail.com>
Reviewed-on: https://codeberg.org/Calciumdibromid/CaBr2/pulls/1532
Reviewed-by: crapStone <crapstone@noreply.codeberg.org>
Co-authored-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org>
Co-committed-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org>
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Documentation of watch::Sender implies that channel is closed forever when all receivers are dropped
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