example: add mutexes

examples/CMakeLists.txt

@@ -6,4 +6,5 @@ add_executable(channel-directions channel-directions.cpp)
 add_executable(select select.cpp)
 add_executable(non-blocking-channel-operations non-blocking-channel-operations.cpp)
 add_executable(waitgroups waitgroups.cpp)
+add_executable(mutexes mutexes.cpp)
 add_executable(defer defer.cpp)

examples/mutexes.cpp

@@ -0,0 +1,81 @@
+// package main
+//
+// import (
+//     "fmt"
+//     "sync"
+// )
+//
+// type Container struct {
+//     mu       sync.Mutex
+//     counters map[string]int
+// }
+//
+// func (c *Container) inc(name string) {
+//
+//     c.mu.Lock()
+//     defer c.mu.Unlock()
+//     c.counters[name]++
+// }
+//
+// func main() {
+//     c := Container{
+//         counters: map[string]int{"a": 0, "b": 0},
+//     }
+//
+//     var wg sync.WaitGroup
+//
+//     doIncrement := func(name string, n int) {
+//         for i := 0; i < n; i++ {
+//             c.inc(name)
+//         }
+//         wg.Done()
+//     }
+//
+//     wg.Add(3)
+//     go doIncrement("a", 10000)
+//     go doIncrement("a", 10000)
+//     go doIncrement("b", 10000)
+//
+//     wg.Wait()
+//     fmt.Println(c.counters)
+// }
+
+#include <eo/fmt.h>
+#include <eo/sync.h>
+
+using namespace eo;
+
+struct Container {
+  std::mutex mu;
+  std::map<std::string, int> counters;
+
+  void inc(const std::string& name) {
+    std::scoped_lock g{mu};
+    counters[name]++;
+  }
+};
+
+func<> eo_main() {
+  auto c = Container{
+    .counters = {{"a", 0}, {"b", 0}},
+  };
+
+  auto wg = sync::WaitGroup();
+
+  auto do_increment = [&](const std::string& name, int n) {
+    for (auto i = 0; i < n; i++) {
+      c.inc(name);
+    }
+    wg.done();
+  };
+
+  wg.add(3);
+  go([&]() { do_increment("a", 10000); });
+  go([&]() { do_increment("a", 10000); });
+  go([&]() { do_increment("b", 10000); });
+
+  wg.wait();
+  fmt::println(c.counters);
+
+  co_return;
+}