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Lack of documentation regarding cancel safety on TcpStream::peek #7303

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cvengler opened this issue May 3, 2025 · 3 comments · May be fixed by #7305
Open

Lack of documentation regarding cancel safety on TcpStream::peek #7303

cvengler opened this issue May 3, 2025 · 3 comments · May be fixed by #7305
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A-tokio Area: The main tokio crate C-bug Category: This is a bug. M-net Module: tokio/net T-docs Topic: documentation

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@cvengler
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cvengler commented May 3, 2025

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Some methods in TcpStream contain a note regarding their cancel safety, such as TcpStream::readable. However, this information is not present with the TcpStream::peek method. The only reference I could find there, is that it uses the recv system call with the MSG_PEEK argument, potentially referring the user to dig into the abyss of the respective Unix manual pages.

I expected to see this happen: A subsection on cancel safety for the TcpStream::peek method.
@cvengler cvengler added A-tokio Area: The main tokio crate C-bug Category: This is a bug. labels May 3, 2025
@cvengler
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cvengler commented May 3, 2025

I hope lack of documentation is considered a bug in this project. I tend to consider it as such myself but many projects handle this differently.

@cvengler
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cvengler commented May 3, 2025

I assume it is cancel safe, because the documentation points out that it is just a recv system call with the MSG_PEEK flag. Given that an abortion of that single system call does not create a faulty state or something, my intuition would argue it being cancel safe.

@maminrayej
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Yes, I believe TcpStream::peek is cancel safe. A PR to update the documentation is welcome.

cvengler added a commit to cvengler/tokio that referenced this issue May 4, 2025
@cvengler
docs: add cancel safety section to TcpStream::peek
7e1f56f 
Fix tokio-rs#7303
@cvengler cvengler linked a pull request May 4, 2025 that will close this issue
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@Darksonn Darksonn added T-docs Topic: documentation M-net Module: tokio/net labels May 5, 2025
cvengler added a commit to cvengler/tokio that referenced this issue May 6, 2025
@cvengler
docs: add cancel safety section to TcpStream::peek
02f6d2f 
Fix tokio-rs#7303
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A-tokio Area: The main tokio crate C-bug Category: This is a bug. M-net Module: tokio/net T-docs Topic: documentation
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docs: add cancel safety section to TcpStream::peek cvengler/tokio
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@Darksonn @cvengler @maminrayej