Make Event to be not 'static

[tomocrafter]

I want to customize the Event with before_send callback and adding the fingerprint that getting from event.contexts.
but since Event is Event<'static> so it needs static lifetime, therefore adding dynamic string to fingerprint is not straightforward (by using Box::leak, we can make string to be 'static lifetime but as name suggests, it causes memory leak).

sentry-rust/sentry/examples/before-send.rs

Line 6 in 8c701e8

event.request = Some(sentry::protocol::Request {

            before_send: Some(Arc::new(|mut event| {
                let tracing_fields = event.contexts.get("Rust Tracing Fields");
                if let Some(Context::Other(fields)) = tracing_fields {
                    let fingerprint = fields.get("fingerprint");
                    if let Some(Value::String(fingerprint)) = fingerprint {
                        event.fingerprint = Cow::Borrowed(&[
                            Cow::Borrowed("{{ default }}"),
                            Cow::Borrowed(&fingerprint), // <-- Here, fingerprint is not 'static, therefore error occurs.
                        ])
                    }
                }
                Some(event)
            })),

I would like to have Event as not 'static, and allow me to modify it dynamically.
Thank you.

[loewenheim]

Hi! All the references with lifetime 'a in Event are behind Cow smart pointers. For example, fingerprint has the type Cow<'a, [Cow<'a, str>]>. In case you're not familiar, a Cow<'a, T> is either a reference &'a T or the "owned form" of T. For example, a Cow<'a, str> is either a &'a str or a String. You can always get a Cow<'static, T> by using the owned form of T. For fingerprint, that means using Vec and String.

Here is a small example on the Rust playground that shows how it works: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=e9a894986b86e0d2a2540f96b1142718

Please let me know if that resolves your issue.

Edited to add: Here is your example snippet with my suggestion applied:

            before_send: Some(Arc::new(|mut event| {
                let tracing_fields = event.contexts.get("Rust Tracing Fields");
                if let Some(Context::Other(fields)) = tracing_fields {
                    let fingerprint = fields.get("fingerprint");
                    if let Some(Value::String(fingerprint)) = fingerprint {
                        event.fingerprint = Cow::Owned(vec![ // <-- This needs to be Owned because it's dynamic
                            Cow::Borrowed("{{ default }}"), // <-- This can be Borrowed because it's hardcoded
                            Cow::Owned(fingerprint.clone()), // <-- This needs to be Owned because it's dynamic
                        ])
                    }
                }
                Some(event)
            })),

[tomocrafter]

Wow, I misunderstood Cow smart pointer. Your suggestion compiled and worked as expected!
Thank you!