fxhashmap faster afterall...

src/main/rust/src/implementations/libraries.rs

@@ -1,10 +1,10 @@
 use crate::models::station_measurements::StationMeasurements;
 use crate::utils::{hash, parse};
 use memmap2::MmapOptions;
-use std::collections::HashMap;
 use std::sync::mpsc;
 use std::time::Instant;
 use std::{fs::File, thread};
+use rustc_hash::{FxHashMap as HashMap, FxBuildHasher};
 
 const DEFAULT_HASHMAP_LENGTH: usize = 10000;
 
@@ -14,8 +14,9 @@ pub fn run() {
     let file = File::open(FILE_PATH).expect("File measurements.txt not found");
     let mmap = unsafe { MmapOptions::new().map(&file).unwrap() };
     let file_length = mmap.len();
-    let mut stations: HashMap<usize, (String, StationMeasurements)> =
-        HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
+    let hasher = FxBuildHasher::default();
+    let mut stations: HashMap<u64, (String, StationMeasurements)> =
+        HashMap::with_capacity_and_hasher(DEFAULT_HASHMAP_LENGTH, hasher);
     let (tx, rx) = mpsc::channel();
     let cores = thread::available_parallelism().unwrap().into();
     let chunk_length = file_length / cores;
@@ -40,8 +41,8 @@ pub fn run() {
             let (start, end) = *bounds.get(i).unwrap();
             let mmap_slice = &mmap[start..end];
             s.spawn(move || {
-                let mut t_stations: HashMap<usize, (String, StationMeasurements)> =
-                    HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
+                let mut t_stations: HashMap<u64, (String, StationMeasurements)> =
+                    HashMap::with_capacity_and_hasher(DEFAULT_HASHMAP_LENGTH, hasher);
                 for line in mmap_slice.split(|&byte| byte == b'\n') {
                     if line.len() == 0 {
                         break;

src/main/rust/src/implementations/multi_threaded.rs

@@ -12,7 +12,7 @@ pub fn run() {
     const FILE_PATH: &str = "../../../measurements.txt";
     let now = Instant::now();
     thread::scope(|s| {
-        let mut stations: HashMap<usize, (String, StationMeasurements)> =
+        let mut stations: HashMap<u64, (String, StationMeasurements)> =
             HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
         let (tx, rx) = mpsc::channel();
         let cores = thread::available_parallelism().unwrap().into();
@@ -44,7 +44,7 @@ pub fn run() {
                 let file = File::open(FILE_PATH).expect("File measurements.txt not found");
                 let mut reader = BufReader::new(&file);
                 reader.seek(SeekFrom::Start(currposition)).unwrap();
-                let mut t_stations: HashMap<usize, (String, StationMeasurements)> =
+                let mut t_stations: HashMap<u64, (String, StationMeasurements)> =
                     HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
                 let mut line = Vec::with_capacity(108);
                 loop {

src/main/rust/src/implementations/multi_threaded_smol.rs

@@ -13,7 +13,7 @@ const DEFAULT_HASHMAP_LENGTH: usize = 10000;
 pub fn run() {
     const FILE_PATH: &str = "../../../measurements.txt";
     let now = Instant::now();
-    let mut stations: HashMap<usize, (String, StationMeasurements)> =
+    let mut stations: HashMap<u64, (String, StationMeasurements)> =
         HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
     let cores = thread::available_parallelism().unwrap().into();
     let bounds = smol::block_on(async {
@@ -53,7 +53,7 @@ pub fn run() {
                     .expect("File measurements.txt not found");
                 let mut reader = BufReader::new(&mut file);
                 reader.seek(SeekFrom::Start(currposition)).await.unwrap();
-                let mut t_stations: HashMap<usize, (String, StationMeasurements)> =
+                let mut t_stations: HashMap<u64, (String, StationMeasurements)> =
                     HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
                 let mut line = Vec::with_capacity(108);
                 loop {

src/main/rust/src/implementations/single_thread.rs

@@ -9,7 +9,7 @@ const DEFAULT_HASHMAP_LENGTH: usize = 10000;
 
 pub fn run() {
     let now = Instant::now();
-    let mut stations: HashMap<usize, (String, StationMeasurements)> =
+    let mut stations: HashMap<u64, (String, StationMeasurements)> =
         HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
 
     let file = File::open("../../../measurements.txt").expect("File measurements.txt not found");

src/main/rust/src/implementations/smol.rs

@@ -10,7 +10,7 @@ const DEFAULT_HASHMAP_LENGTH: usize = 10000;
 
 pub fn run() {
     let now = Instant::now();
-    let mut stations: HashMap<usize, (String, StationMeasurements)> =
+    let mut stations: HashMap<u64, (String, StationMeasurements)> =
         HashMap::with_capacity(DEFAULT_HASHMAP_LENGTH);
 
     smol::block_on(async {

src/main/rust/src/utils/hash.rs

@@ -1,9 +1,15 @@
 #[inline]
-pub fn bytes(bytes: &[u8]) -> usize {
-    let mut hash: usize = 0;
+pub fn bytes(bytes: &[u8]) -> u64 {
+    // hash from https://curiouscoding.nl/posts/1brc/ still wrong for measurements3.txt (and slower?)
+    //let mut key = [0u8; 8];
+    //let l = bytes.len().min(8);
+    //key[..l].copy_from_slice(&bytes[..l]);
+    //key[0] ^= bytes.len() as u8;
+    //u64::from_ne_bytes(key)
+    let mut hash: u64 = 0;
     let (chunks, remainder) = bytes.as_chunks::<8>();
     for &chunk in chunks {
-        hash = hash.wrapping_add(usize::from_be_bytes(chunk));
+        hash = hash.wrapping_add(u64::from_be_bytes(chunk));
     }
     let mut r = [0_u8; 8];
     r[0] = remainder.len() as u8;
@@ -12,7 +18,7 @@ pub fn bytes(bytes: &[u8]) -> usize {
         r[idx] = byte;
         idx += 1;
     }
-    hash += usize::from_be_bytes(r);
+    hash += u64::from_be_bytes(r);
     hash
 }