Let me clarify: I am truly grateful for the community's help and even feel ashamed for benefiting from it without contributing in return.
I did not mean to convey, āReaching a different outcome than the one you expected and putting the blame on the community for not helping you to reach that outcome are two different things.ā I was simply confused and frustrated by the issues I encountered during the process. If the translation made it seem otherwise, I sincerely apologize.
What I want to express is that, regardless of how "correct" or "wrong" my approach may have been in this process, I just wanted to understand how to avoid performance issues or whether my usage pattern could impact performance. Thatās why I used a method that closely resembled a real-world scenario for testing. Whatever the performance issue was, I needed to identify and resolve it instead of using a more scientific method to test. This āmicrobenchmarkā was already very close to my actual code, which merely has more functions and loops. I wasnāt trying to prove that "returning tuples affects performance," nor was I trying to claim that C++ is better than Rust. I just wanted to know what I should do if I encountered similar issues in my code. At that point, I instinctively thought I could find an answer online or, perhaps shamefully, seek help from the community. But when I was repeatedly told that my testing method was incorrect or that assembly-level knowledge was required to solve the issue, I couldnāt help but feel frustrated...
Regardless, I deeply appreciate the time and effort youāve spent addressing my question. I am in no position to blame anyone, nor was it ever my intention.
The latest replies have provided new insights, and based on those suggestions, I removed the impact of black_box. After doing so, I observed similar performance across all approaches.
This is the latest code:
use std::time::Instant;
use criterion::black_box;
use rand::{Rng, thread_rng};
// Define a simple structure
#[derive(Debug, Copy, Clone)]
struct RandomStruct {
flag: bool,
value: u8,
}
// First function: returns a u8 value
fn return_u8(rng: &mut impl Rng) -> u8 {
let test: u8 = rng.gen();
test
}
// Second function: returns a tuple (bool, u8)
fn return_tuple(rng: &mut impl Rng) -> (bool, u8) {
let test: u8 = rng.gen();
(test > 10, test)
}
// Third function: returns a RandomStruct
fn return_struct(rng: &mut impl Rng) -> RandomStruct {
let test: u8 = rng.gen();
RandomStruct {
flag: test > 10,
value: test,
}
}
// Benchmark the performance of random number generation
fn benchmark_rng(iterations: usize, rng: &mut impl Rng) -> u32 {
let mut result: u32 = 0;
let start = Instant::now();
for _ in 0..iterations {
let value: u8 = rng.gen();
result += value as u32; // Accumulate values as u32
}
let duration = start.elapsed();
println!(
"Random number generation: {:?} (for {} iterations)",
duration, iterations
);
result // Return result to ensure it is used
}
fn main() {
let iterations = 1000_000_000; // Test 100 million iterations
let mut rng = thread_rng(); // Initialize a global random number generator once
// Benchmark: random number generation
let rng_result = benchmark_rng(iterations, &mut rng);
black_box(rng_result); // Use black_box after the test to prevent optimization
// Test: returning a RandomStruct
let mut struct_sum: u32 = 0;
let start = Instant::now();
for _ in 0..iterations {
let result = return_struct(&mut rng);
struct_sum += if result.flag { 1 } else { 2 }; // Add 1 or 2 based on `flag`
}
let duration_struct = start.elapsed();
black_box(struct_sum);
// Test: returning a u8 value
let mut u8_sum: u32 = 0;
let start = Instant::now();
for _ in 0..iterations {
let result = return_u8(&mut rng);
let flag =result > 10;
u8_sum += if flag { 1 } else { 2 }; // Add 1 or 2 based on `>10`
}
let duration_u8 = start.elapsed();
black_box(u8_sum);
// Test: returning a tuple (bool, u8)
let mut tuple_sum: u32 = 0;
let start = Instant::now();
for _ in 0..iterations {
let result = return_tuple(&mut rng);
tuple_sum += if result.0 { 1 } else { 2 }; // Add 1 or 2 based on `result.0`
}
let duration_tuple = start.elapsed();
black_box(tuple_sum);
// Print results
println!("\nResults:");
println!("RandomStruct sum: {}", struct_sum);
println!("u8 sum: {}", u8_sum);
println!("Tuple sum: {}", tuple_sum);
println!(
"Durations - return_u8: {:?}, return_tuple: {:?}, return_struct: {:?}",
duration_u8, duration_tuple, duration_struct
);
}
Result:
Random number generation: 1.066217523s (for 1000000000 iterations)
Results:
RandomStruct sum: 1042965858
u8 sum: 1042976607
Tuple sum: 1042966964
Durations - return_u8: 1.264039853s, return_tuple: 1.264772937s, return_struct: 1.264900587s