map: optimize free() and keys() (#7152)

vlib/builtin/map.v

@@ -56,7 +56,6 @@ find the index for their meta's in the new array. Instead of rehashing compl-
 etely, it simply uses the cached-hashbits stored in the meta, resulting in
 much faster rehashing.
 */
-
 const (
 	// Number of bits from the hash stored for each entry
 	hashbits            = 24
@@ -224,9 +223,7 @@ fn new_map_1(value_bytes int) map {
 fn new_map_init(n int, value_bytes int, keys &string, values voidptr) map {
 	mut out := new_map_1(value_bytes)
 	for i in 0 .. n {
-		unsafe {
-			out.set(keys[i], byteptr(values) + i * value_bytes)
-		}
+		unsafe {out.set(keys[i], byteptr(values) + i * value_bytes)}
 	}
 	return out
 }
@@ -261,13 +258,11 @@ fn (mut m map) meta_greater(_index u32, _metas u32, kvi u32) {
 				tmp_meta := m.metas[index]
 				m.metas[index] = meta
 				meta = tmp_meta
-			}
-			tmp_index := unsafe {m.metas[index + 1]}
-			unsafe {
+				tmp_index := m.metas[index + 1]
 				m.metas[index + 1] = kv_index
-			}
 				kv_index = tmp_index
 			}
+		}
 		index += 2
 		meta += probe_inc
 	}
@@ -335,8 +330,7 @@ fn (mut m map) expand() {
 		m.shift += max_cached_hashbits
 		m.cached_hashbits = max_cached_hashbits
 		m.rehash()
-	}
-	else {
+	} else {
 		m.cached_rehash(old_cap)
 		m.cached_hashbits--
 	}
@@ -385,9 +379,7 @@ fn (mut m map) cached_rehash(old_cap u32) {
 		kv_index := unsafe {old_metas[i + 1]}
 		m.meta_greater(index, meta, kv_index)
 	}
-	unsafe{
-		free(old_metas)
-	}
+	unsafe {free(old_metas)}
 }
 
 // This method is used for assignment operators. If the argument-key
@@ -406,7 +398,9 @@ fn (mut m map) get_and_set(key string, zero voidptr) voidptr {
 			}
 			index += 2
 			meta += probe_inc
-			if meta > unsafe {m.metas[index]} { break }
+			if meta > unsafe {m.metas[index]} {
+				break
+			}
 		}
 		// Key not found, insert key with zero-value
 		m.set(key, zero)
@@ -430,7 +424,9 @@ fn (m map) get(key string, zero voidptr) voidptr {
 		}
 		index += 2
 		meta += probe_inc
-		if meta > unsafe {m.metas[index]} { break }
+		if meta > unsafe {m.metas[index]} {
+			break
+		}
 	}
 	return zero
 }
@@ -448,7 +444,9 @@ fn (m map) exists(key string) bool {
 		}
 		index += 2
 		meta += probe_inc
-		if meta > unsafe {m.metas[index]} { break }
+		if meta > unsafe {m.metas[index]} {
+			break
+		}
 	}
 	return false
 }
@@ -496,10 +494,17 @@ pub fn (mut m map) delete(key string) {
 }
 
 // Returns all keys in the map.
-// TODO: add optimization in case of no deletes
 pub fn (m &map) keys() []string {
 	mut keys := []string{len: m.len}
 	mut j := 0
+	if m.key_values.deletes == 0 {
+		for i := 0; i < m.key_values.len; i++ {
+			pkey := unsafe {&string(m.key_values.key(i))}
+			keys[j] = pkey.clone()
+			j++
+		}
+		return keys
+	}
 	for i := 0; i < m.key_values.len; i++ {
 		if !m.key_values.has_index(i) {
 			continue
@@ -539,17 +544,21 @@ pub fn (m map) clone() map {
 		extra_metas: m.extra_metas
 		len: m.len
 	}
-	unsafe {
-		C.memcpy(res.metas, m.metas, metasize)
-	}
+	unsafe {C.memcpy(res.metas, m.metas, metasize)}
 	return res
 }
 
 [unsafe]
 pub fn (m &map) free() {
+	unsafe {free(m.metas)}
+	if m.key_values.deletes == 0 {
+		for i := 0; i < m.key_values.len; i++ {
 			unsafe {
-		free(m.metas)
+				pkey := &string(m.key_values.key(i))
+				(*pkey).free()
 			}
+		}
+	} else {
 		for i := 0; i < m.key_values.len; i++ {
 			if !m.key_values.has_index(i) {
 				continue
@@ -559,22 +568,6 @@ pub fn (m &map) free() {
 				(*pkey).free()
 			}
 		}
-	unsafe {
-		free(m.key_values.data)
 	}
+	unsafe {free(m.key_values.data)}
 }
-
-/*
-pub fn (m map_string) str() string {
-	if m.len == 0 {
-		return '{}'
-	}
-	mut sb := strings.new_builder(50)
-	sb.writeln('{')
-	for key, val in m {
-		sb.writeln('  "$key" => "$val"')
-	}
-	sb.writeln('}')
-	return sb.str()
-}
-*/

vlib/v/gen/cgen.v

@@ -1234,6 +1234,7 @@ fn (mut g Gen) for_in(it ast.ForInStmt) {
 		g.expr(it.cond)
 		g.writeln(';')
 		g.writeln('for (int $idx = 0; $idx < ${atmp}.key_values.len; ++$idx) {')
+		// TODO: don't have this check when the map has no deleted elements
 		g.writeln('\tif (!DenseArray_has_index(&${atmp}.key_values, $idx)) {continue;}')
 		if it.key_var != '_' {
 			key_styp := g.typ(it.key_type)