Add primes program

.gitignore

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+/target
+**/*.rs.bk
+primes.txt
+*.tar.gz

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "hermit-abi"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.66"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "num_cpus"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "hermit-abi 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "primes"
+version = "0.1.0"
+dependencies = [
+ "num_cpus 1.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[metadata]
+"checksum hermit-abi 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "eff2656d88f158ce120947499e971d743c05dbcbed62e5bd2f38f1698bbc3772"
+"checksum libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)" = "d515b1f41455adea1313a4a2ac8a8a477634fbae63cc6100e3aebb207ce61558"
+"checksum num_cpus 1.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "46203554f085ff89c235cd12f7075f3233af9b11ed7c9e16dfe2560d03313ce6"

Cargo.toml

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+[package]
+name = "primes"
+version = "0.1.0"
+authors = ["trivernis <trivernis@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+num_cpus = "1.0"

src/main.rs

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+extern crate num_cpus;
+use std::thread;
+use std::fs::{OpenOptions};
+use std::io::prelude::*;
+use std::sync::mpsc::{sync_channel, SyncSender};
+use std::env;
+
+fn main() {
+    let (tx, rx) = sync_channel::<u64>(0);
+    let num_threads: u64 = num_cpus::get() as u64;
+    let mut start: u64 = 1;
+    let args: Vec<String> = env::args().collect();
+    if args.len() > 1 {
+        start = *(&args[1].parse::<u64>().unwrap());
+    }
+    if &start % 2 == 0 {
+        start += 1;
+    }
+    let mut file = OpenOptions::new()
+        .write(true)
+        .append(true)
+        .create(true)
+        .open("primes.txt")
+        .unwrap();
+    println!("Starting {} threads", num_threads);
+    for i in 0u64..num_threads {
+        let tx = tx.clone();
+        let _child = thread::spawn(move || {
+            get_primes(&start + (2*&i), &num_threads * 2, &tx);
+        });
+    }
+    loop {
+        let prime = rx.recv().unwrap();
+        println!("{}", prime);
+        if let Err(e) = writeln!(file, "{}", prime) {
+            panic!(e);
+        }
+    }
+}
+
+fn get_primes(start: u64, incr: u64, tx: &SyncSender<u64>) {
+    let mut num = start;
+    loop {
+        let mut is_prime = true;
+        if (num < 3) | (&num % 2 == 0) {
+            num += incr;
+            continue;
+        }
+        for i in (3u64..&num/2).step_by(2) {
+            if &num % i == 0 {
+                is_prime = false;
+            }
+        }
+        if is_prime {
+            if let Err(e) = (*tx).send(num) {
+                panic!(e);
+            }
+        }
+        num += incr;
+    }
+}