'a in spawn_blocking

[xuxiaocheng0201]

In many cases, the task is not 'static, but the params is 'a, so I have to clone the param to make the task 'static.
For example:

async fn hash(content: &str) -> anyhow::Result<String> {
    let content = content.to_string();
    tokio::task::spawn_blocking(move || util::hash::sha256::digest(&content)).await?
}

Is there any way to avoid clone the content?
I joined the future immediately so I think the task is not necessary to be 'static.
For some reasons, I don't want to use Arc, because the content may be zero-copied from other vec.

[wathenjiang]

You might use block on or run_util of the LocalSet. See https://tikv.github.io/doc/tokio/task/struct.LocalSet.html

[xuxiaocheng0201]

Thank for your suggestion.
But LocalSet::block_on is for !Send futures, it blocks on the current thread.
In my case, the task is Send. I want to send the task to the blocking thread to avoid blocking the current thread, just like spawn_blocking.

[Darksonn]

It's not possible. You'll have to clone the data.

[xuxiaocheng0201]

It's not possible. You'll have to clone the data.

@Darksonn Oh that's bad. Is there any plan to support this situation?

[Darksonn]

It's a limitation that has to be fixed in the language. There is nothing Tokio can do until the language changes. You can read more about why in this article: The scoped task trilemma