Created
February 18, 2018 01:31
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extern crate itoa; | |
extern crate smallvec; | |
macro_rules! print_time { | |
($start:expr, $end:expr) => (println!("time: {} ns", ($end - $start).subsec_nanos() as f32 / 1_000_000.0);) | |
} | |
// 189 ns | |
fn new_order_slow(stock: &str, price: i32, quantity: i32) -> String { | |
format!("NEW {} {} {}", stock, price, quantity) | |
} | |
// 117 ns | |
fn new_order_fast(stock: &str, price: i32, quantity: i32) -> String { | |
let mut s = Vec::<u8>::with_capacity(stock.len() + 6); | |
s.extend_from_slice(b"NEW "); | |
s.extend_from_slice(stock.as_bytes()); | |
s.push(b' '); | |
itoa::write(&mut s, price).unwrap(); | |
s.push(b' '); | |
itoa::write(&mut s, quantity).unwrap(); | |
unsafe { String::from_utf8_unchecked(s) } | |
} | |
// 78 ns | |
fn new_order_faster(stock: &str, price: i32, quantity: i32) -> String { | |
use smallvec::SmallVec; | |
let mut s = SmallVec::<[u8; 32]>::new(); | |
s.extend_from_slice(b"NEW "); | |
s.extend_from_slice(stock.as_bytes()); | |
s.push(b' '); | |
itoa::write(&mut s, price).unwrap(); | |
s.push(b' '); | |
itoa::write(&mut s, quantity).unwrap(); | |
unsafe { String::from_utf8_unchecked(s.to_vec()) } | |
} | |
fn main() { | |
{ | |
println!("new_order_slow:"); | |
let mut last = String::new(); | |
let time_start = ::std::time::Instant::now(); | |
for i in 0..1_000_000 { | |
last = new_order_slow("NVDA", i, i); | |
} | |
let time_end = ::std::time::Instant::now(); | |
println!("last: {}", last); | |
print_time!(time_start, time_end); | |
} | |
{ | |
println!("new_order_fast:"); | |
let mut last = String::new(); | |
let time_start = ::std::time::Instant::now(); | |
for i in 0..1_000_000 { | |
last = new_order_fast("NVDA", i, i); | |
} | |
let time_end = ::std::time::Instant::now(); | |
println!("last: {}", last); | |
print_time!(time_start, time_end); | |
} | |
{ | |
println!("new_order_faster:"); | |
let mut last = String::new(); | |
let time_start = ::std::time::Instant::now(); | |
for i in 0..1_000_000 { | |
last = new_order_faster("NVDA", i, i); | |
} | |
let time_end = ::std::time::Instant::now(); | |
println!("last: {}", last); | |
print_time!(time_start, time_end); | |
} | |
} |
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