hashmap: change hash-function to wyhash and add benchmarks

tools/bench/hashmap.v

@@ -0,0 +1,112 @@
+import rand
+import time
+import builtin.hashmap
+
+fn hashmap_set_bench(arr []string, repeat int) {
+	start_time := time.ticks()
+	for _ in 0..repeat {
+		mut b := hashmap.new_hashmap()
+		for x in arr {
+			b.set(x, 1)
+		}
+	}
+	end_time := time.ticks() - start_time
+	println("* hashmap_set: ${end_time} ms")
+}
+
+fn map_set_bench(arr []string, repeat int) {
+	start_time := time.ticks()
+	for _ in 0..repeat {
+		mut b := map[string]int
+		for x in arr {
+			b[x] = 1
+		}
+	}
+	end_time := time.ticks() - start_time
+	println("* map_set: ${end_time} ms")
+}
+
+fn hashmap_get_bench(arr []string, repeat int) {
+	mut b := hashmap.new_hashmap()
+	for x in arr {
+		b.set(x, 1)
+	}
+	start_time := time.ticks()
+	for _ in 0..repeat {
+		for x in arr {
+			b.get(x)
+		}
+	}
+	end_time := time.ticks() - start_time
+	println("* hashmap_get: ${end_time} ms")
+}
+
+fn map_get_bench(arr []string, repeat int) {
+	mut b := map[string]int
+	for x in arr {
+		b[x] = 1
+	}
+	start_time := time.ticks()
+	for _ in 0..repeat {
+		for x in arr {
+			b[x]
+		}
+	}
+	end_time := time.ticks() - start_time
+	println("* map_get: ${end_time} ms")
+}
+
+fn benchmark_many_keys() {
+	key_len := 30
+	repeat := 1
+	for i := 2048; i <= 10000000; i = i * 2 {
+		mut arr := []string
+		for _ in 0..i {
+			mut buf := []byte
+			for j in 0..key_len {
+				buf << byte(rand.next(int(`z`) - int(`a`)) + `a`)
+			}
+			s := string(buf)
+			arr << s
+		}
+		println("$arr.len keys of length $key_len")
+		// Uncomment the benchmark you would like to benchmark
+		// Run one or two at a time while memory leaks is a thing
+		hashmap_get_bench(arr, repeat)
+		map_get_bench(arr, repeat)
+		// hashmap_set_bench(arr, repeat)
+		// map_set_bench(arr, repeat)
+		println('')
+	}
+}
+
+fn benchmark_few_keys() {
+	key_len := 30
+	repeat := 10000
+	println("Benchmarks are repeated $repeat times")
+	for i := 16; i <= 2048; i = i * 2 {
+		mut arr := []string
+		for _ in 0..i {
+			mut buf := []byte
+			for j in 0..key_len {
+				buf << byte(rand.next(int(`z`) - int(`a`)) + `a`)
+			}
+			s := string(buf)
+			arr << s
+		}
+		println("$arr.len keys of length $key_len")
+		// Uncomment the benchmark you would like to benchmark
+		// Run one or two  at a time while memory leaks is a thing
+		hashmap_get_bench(arr, repeat)
+		map_get_bench(arr, repeat)
+		// hashmap_set_bench(arr, repeat)
+		// map_set_bench(arr, repeat)
+		println('')
+	}
+}
+
+fn main() {
+	// Uncomment below to benchmark on many keys
+	// benchmark_many_keys()
+	benchmark_few_keys()
+}

vlib/builtin/hashmap/hashmap.v

@@ -3,6 +3,8 @@
 // that can be found in the LICENSE file.
 module hashmap
 
+import hash.wyhash
+
 const (
 	initial_size = 2 << 4
 	initial_cap = initial_size - 1
@@ -10,23 +12,6 @@ const (
 	load_factor = 0.8
 )
 
-// hash-function should not be in this file
-const (
-	fnv64_prime = 1099511628211
-	fnv64_offset_basis = 14695981039346656037
-	fnv32_offset_basis = u32(2166136261)
-	fnv32_prime = u32(16777619)
-)
-
-[inline]
-fn fnv1a64(data string) u64 {
-	mut hash := fnv64_offset_basis
-	for i := 0; i < data.len; i++ {
-		hash = (hash ^ u64(data[i])) * fnv64_prime
-	}
-	return hash
-}
-
 pub struct Hashmap {
 mut:
 	info        &u16
@@ -54,14 +39,11 @@ pub fn new_hashmap() Hashmap {
 }
 
 pub fn (h mut Hashmap) set(key string, value int) {
-	// The load factor is 0.5.
+	// load_factor can be adjusted.
-	// It will be adjustable  in the future and with
-	// a higher default settings to lower memory usage.
 	if (f32(h.size) / f32(h.cap)) > h.load_factor {
 		h.rehash()
 	}
-	// Hash-function will be swapped for wyhash
+	hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
-	hash := fnv1a64(key)
 	mut info := u16((hash >> 56) | probe_offset)
 	mut index := hash & h.cap
 	// While probe count is less
@@ -115,7 +97,7 @@ fn (h mut Hashmap) rehash() {
 	for i in 0 .. (old_cap + 1) {
 		if h.info[i] != 0 {
 			mut kv := h.key_values[i]
-			hash := fnv1a64(kv.key)
+			hash := wyhash.wyhash_c(kv.key.str, u64(kv.key.len), 0)
 			mut info := u16((hash >> 56) | probe_offset)
 			mut index := hash & h.cap
 			// While probe count is less
@@ -154,7 +136,7 @@ fn (h mut Hashmap) rehash() {
 }
 
 pub fn (h mut Hashmap) delete(key string) {
-	hash := fnv1a64(key)
+	hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
 	mut index := hash & h.cap
 	mut info := u16((hash >> 56) | probe_offset)
 	for info < h.info[index] {
@@ -184,7 +166,7 @@ pub fn (h mut Hashmap) delete(key string) {
 }
 
 pub fn (h Hashmap) get(key string) int {
-	hash := fnv1a64(key)
+	hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
 	mut index := hash & h.cap
 	mut info := u16((hash >> 56) | probe_offset)
 	for info < h.info[index] {
@@ -202,7 +184,7 @@ pub fn (h Hashmap) get(key string) int {
 }
 
 pub fn (h Hashmap) exists(key string) bool {
-	hash := fnv1a64(key)
+	hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
 	mut index := hash & h.cap
 	mut info := u16((hash >> 56) | probe_offset)
 	for info < h.info[index] {