pprof example does not compile

[LanHikari22]

The example in https://github.com/tikv/pprof-rs?tab=readme-ov-file#use-with-pprof does not compile. I had to make some changes:

First, we need to enable the prost-codec instead of protobuf feature in Cargo.toml (but documentation mentions to use protobuf):

pprof = { version = "0.15.0", features = ["prost-codec"] }

for the report println, had to change {} to {:?} because the report does not implement Display

Then in the code,

use pprof::protos::Message;
use std::fs::File;
use std::io::Write;

[...]

// Added in program start
let guard = pprof::ProfilerGuardBuilder::default().frequency(1000).blocklist(&["libc", "libgcc", "pthread", "vdso"]).build().unwrap();

[...]

// For output in profile.proto format:
match guard.report().build() {
    Ok(report) => {
        let mut file = File::create("profile.pb").unwrap();
        let profile = report.pprof().unwrap();

        let mut content = Vec::new();
        profile.encode(&mut content).unwrap();
        file.write_all(&content).unwrap();

        println!("report: {:?}", &report);
    }
    Err(_) => {}
};

This works. But if we had used protobuf feature, or did not include pprof::protos::Message we would have issue with profile.encode not being found.