add multithreading

Cargo.toml

@@ -9,7 +9,6 @@ edition = "2021"
 num-bigint = { default-features = false, version = "0.4.3" }
 
 [profile.release]
-opt-level = 'z'     # Optimize for size
 lto = true          # Enable link-time optimization
 codegen-units = 1   # Reduce number of codegen units to increase optimizations
 panic = 'abort'     # Abort on panic

src/main.rs

@@ -1,9 +1,22 @@
 pub mod is_prime;
 
-use std::{time::SystemTime,sync::mpsc,thread};
+use std::{time::SystemTime,thread};
 use num_bigint::BigUint;
 use crate::is_prime::is_prime::is_prime;
 
+fn p(n: f64) -> f64 {
+    let ln_n = n.ln();
+    let ln_ln_n = ln_n.ln();
+    let ln_ln_ln_n = ln_ln_n.ln();
+
+    n * (
+        ln_n + ln_ln_n - 1.0
+        + (ln_ln_ln_n - 2.0) / ln_n
+        - ((ln_ln_n).powi(2) - 6.0 * ln_ln_n + 11.0) / (2.0 * 2.0f64.log2() * ln_n)
+        + ((ln_ln_n / ln_n).powi(3)) * (1.0 / ln_n)
+    )
+}
+
 
 fn main() {
     /* 
@@ -32,15 +45,69 @@ fn main() {
     //     tx.send(val).unwrap();
     // });
     // TODO: multithreading
+    let n:f64 = 1_000_000f64;
+    let nthprime_approx = p(n*1.01) as u128;
+    const THREADS: u128 = 12;
+    let workloads = nthprime_approx/THREADS;
 
-    let mut number = BigUint::from(0u8);
-    let inc = BigUint::from(1u8);
     let mut primes: Vec<BigUint> = vec![];
+    let mut joins = vec![];
+    for i in 0..THREADS {
+        let tprimes = thread::spawn(move || {
+            let mut lprimes = vec![];
+            let mut number = BigUint::from(i)*BigUint::from(workloads);
+            let inc = BigUint::from(1u8);
+            
+            let max = BigUint::from(i+1)*BigUint::from(workloads);
+            
+            loop {
+                number = number + inc.clone();
+                if is_prime(number.clone()) {
+                    lprimes.push(number.clone());
+                }
+                if number == max {
+                    break;
+                }
+            }
+            lprimes
+        });
+        joins.push(tprimes);
+    }
+
+    loop {
+        let mut njoins = vec![];
+        for join in joins {
+            if join.is_finished() {
+                let tp = join.join();
+                if let Ok(mut tprimes) = tp {
+                    primes.append(&mut tprimes);
+                }
+            } else {
+                njoins.push(join);
+            }
+        }
+        joins = njoins;
+        if joins.len()==0 {
+            break;
+        }
+    }
+    let removed = (primes.len()-n as usize).clamp(0, n as usize);
+    if primes.len() > n as usize {
+        for _ in 0..removed {
+            primes.pop();
+        }
+    }
+
+    let added = (n as usize-primes.len()).clamp(0, n as usize);
+    if primes.len() < n as usize {
+        let mut number = BigUint::from(THREADS+1)*BigUint::from(workloads);
+        let inc = BigUint::from(1u8);
         loop {
             number = number + inc.clone();
             if is_prime(number.clone()) {
                 primes.push(number.clone());
-            if primes.len() >= 1_000_000 {
+            }
+            if primes.len() == n as usize {
                 break;
             }
         }
@@ -52,6 +119,9 @@ fn main() {
 
     println!("{:?}", primes);
 
+    println!("prime count: {}, expected: {}, primes removed: {} | {}%, primes added: {} | {}%",primes.len(),n,removed,(removed as f64)/primes.len() as f64*100.0,added,(added as f64)/primes.len() as f64*100.0);
+    println!("last prime approx: {}",nthprime_approx);
+
     println!("And that's time: {difference:?}");