cgen: add support for shared maps (#7042)

vlib/v/gen/cgen.v

@@ -2355,6 +2355,25 @@ fn (mut g Gen) expr(node ast.Expr) {
 			value_typ_str := g.typ(node.value_type)
 			value_typ := g.table.get_type_symbol(node.value_type)
 			size := node.vals.len
+			mut shared_styp := '' // only needed for shared &[]{...}
+			mut styp := ''
+			is_amp := g.is_amp
+			g.is_amp = false
+			if is_amp {
+				g.out.go_back(1) // delete the `&` already generated in `prefix_expr()
+				if g.is_shared {
+					mut shared_typ := node.typ.set_flag(.shared_f)
+					shared_styp = g.typ(shared_typ)
+					g.writeln('($shared_styp*)memdup(&($shared_styp){.val = ')
+				} else {
+					styp = g.typ(node.typ)
+					g.write('($styp*)memdup(&') // TODO: doesn't work with every compiler
+				}
+			} else {
+				if g.is_shared {
+					g.writeln('{.val = ($styp*)')
+				}
+			}
 			if size > 0 {
 				if value_typ.kind == .function {
 					g.write('new_map_init($size, sizeof(voidptr), _MOV(($key_typ_str[$size]){')
@@ -2378,6 +2397,14 @@ fn (mut g Gen) expr(node ast.Expr) {
 			} else {
 				g.write('new_map_1(sizeof($value_typ_str))')
 			}
+			if g.is_shared {
+				g.write(', .mtx = sync__new_rwmutex()}')
+				if is_amp {
+					g.write(', sizeof($shared_styp))')
+				}
+			} else if is_amp {
+				g.write(', sizeof($styp))')
+			}
 		}
 		ast.None {
 			g.write('opt_none()')
@@ -3715,10 +3742,17 @@ fn (mut g Gen) index_expr(node ast.IndexExpr) {
 				if g.is_assign_lhs && !g.is_array_set && !get_and_set_types {
 					g.is_array_set = true
 					g.write('map_set(')
-					if !left_is_ptr {
+					if !left_is_ptr || node.left_type.has_flag(.shared_f) {
 						g.write('&')
 					}
 					g.expr(node.left)
+					if node.left_type.has_flag(.shared_f) {
+						if left_is_ptr {
+							g.write('->val')
+						} else {
+							g.write('.val')
+						}
+					}
 					g.write(', ')
 					g.expr(node.index)
 					if elem_typ.kind == .function {
@@ -3744,10 +3778,17 @@ fn (mut g Gen) index_expr(node ast.IndexExpr) {
 					} else {
 						g.write('(*($elem_type_str*)map_get(')
 					}
-					if node.left_type.is_ptr() {
+					if node.left_type.is_ptr() && !node.left_type.has_flag(.shared_f) {
 						g.write('*')
 					}
 					g.expr(node.left)
+					if node.left_type.has_flag(.shared_f) {
+						if left_is_ptr {
+							g.write('->val')
+						} else {
+							g.write('.val')
+						}
+					}
 					g.write(', ')
 					g.expr(node.index)
 					if elem_typ.kind == .function {

vlib/v/tests/shared_map_test.v

@@ -0,0 +1,36 @@
+import sync
+
+fn incr(shared foo map[string]int, key string, sem sync.Semaphore) {
+	for _ in 0 .. 100000 {
+		lock foo {
+			foo[key] = foo[key] + 1
+		}
+	}
+	sem.post()
+}
+
+fn test_shared_array() {
+	shared foo := &{'p': 10, 'q': 20}
+	sem := sync.new_semaphore()
+	go incr(shared foo, 'p', sem)
+	go incr(shared foo, 'q', sem)
+	go incr(shared foo, 'p', sem)
+	go incr(shared foo, 'q', sem)
+	for _ in 0 .. 50000 {
+		lock foo {
+			unsafe {
+				foo['p'] = foo['p'] - 2
+				foo['q'] = foo['q'] + 3
+			}
+		}
+	}
+	for _ in 0..4 {
+		sem.wait()
+	}
+	rlock foo {
+		fp := unsafe { foo['p'] }
+		fq := unsafe { foo['q'] }
+		assert fp == 100010
+		assert fq == 350020
+	}
+}