prime number profiling

main.rs

use std::fs::File;

use std::io::Write;

use pprof::protos::Message;

#[inline(never)]

fn is_prime_number1(v: usize, prime_numbers: &[usize]) -> bool {

    if v < 10000 {

        let r = prime_numbers.binary_search(&v);

        return r.is_ok();

    }

    for n in prime_numbers {

        if v % n == 0 {

            return false;

        }

    }

    true

}

#[inline(never)]

fn is_prime_number2(v: usize, prime_numbers: &[usize]) -> bool {

    if v < 10000 {

        let r = prime_numbers.binary_search(&v);

        return r.is_ok();

    }

    for n in prime_numbers {

        if v % n == 0 {

            return false;

        }

    }

    true

}

#[inline(never)]

fn prepare_prime_numbers() -> Vec<usize> {

    // bootstrap: Generate a prime table of 0..10000

    let mut prime_number_table: [bool; 10000] = [true; 10000];

    prime_number_table[0] = false;

    prime_number_table[1] = false;

    for i in 2..10000 {

        if prime_number_table[i] {

            let mut v = i * 2;

            while v < 10000 {

                prime_number_table[v] = false;

                v += i;

            }

        }

    }

    let mut prime_numbers = vec![];

    for i in 2..10000 {

        if prime_number_table[i] {

            prime_numbers.push(i);

        }

    }

    prime_numbers

}

fn main() {

    let prime_numbers = prepare_prime_numbers();

    let guard = pprof::ProfilerGuardBuilder::default()

        .frequency(100)

        .build()

        .unwrap();

    let mut v = 0;

    for i in 0..50000 {

        if i % 3 == 0 {

            if is_prime_number1(i, &prime_numbers) {

                v += 1;

            }

        } 

         else {

            if is_prime_number2(i, &prime_numbers) {

                v += 1;

            }

        }

    }

    println!("Prime numbers: {}", v);

    if let Ok(report) = guard.report().build() {

        let mut file = File::create("profile.pb").unwrap();

        let profile = report.pprof().unwrap();

        let mut content = Vec::new();

        profile.write_to_vec(&mut content).unwrap();

        file.write_all(&content).unwrap();

    };

}