Internal cleanup

PiperOrigin-RevId: 1001893419

absl/synchronization/notification.cc

diff --git a/absl/synchronization/notification.cc b/absl/synchronization/notification.cc
index 63da068..a84fc96 100644
--- a/absl/synchronization/notification.cc
+++ b/absl/synchronization/notification.cc
@@ -51,9 +51,9 @@
 void Notification::WaitForNotification() const {
   base_internal::TraceWait(this, TraceObjectKind());
   if (!HasBeenNotifiedInternal(&this->notified_yet_)) {
-    this->mutex_.LockWhen(
+    this->mutex_.ReaderLockWhen(
         Condition(&HasBeenNotifiedInternal, &this->notified_yet_));
-    this->mutex_.unlock();
+    this->mutex_.unlock_shared();
   }
   base_internal::TraceContinue(this, TraceObjectKind());
 }
@@ -63,9 +63,9 @@
   base_internal::TraceWait(this, TraceObjectKind());
   bool notified = HasBeenNotifiedInternal(&this->notified_yet_);
   if (!notified) {
-    notified = this->mutex_.LockWhenWithTimeout(
+    notified = this->mutex_.ReaderLockWhenWithTimeout(
         Condition(&HasBeenNotifiedInternal, &this->notified_yet_), timeout);
-    this->mutex_.unlock();
+    this->mutex_.unlock_shared();
   }
   base_internal::TraceContinue(notified ? this : nullptr, TraceObjectKind());
   return notified;
@@ -75,9 +75,9 @@
   base_internal::TraceWait(this, TraceObjectKind());
   bool notified = HasBeenNotifiedInternal(&this->notified_yet_);
   if (!notified) {
-    notified = this->mutex_.LockWhenWithDeadline(
+    notified = this->mutex_.ReaderLockWhenWithDeadline(
         Condition(&HasBeenNotifiedInternal, &this->notified_yet_), deadline);
-    this->mutex_.unlock();
+    this->mutex_.unlock_shared();
   }
   base_internal::TraceContinue(notified ? this : nullptr, TraceObjectKind());
   return notified;

absl/synchronization/notification_test.cc

diff --git a/absl/synchronization/notification_test.cc b/absl/synchronization/notification_test.cc
index ded80a5..e2a6c93 100644
--- a/absl/synchronization/notification_test.cc
+++ b/absl/synchronization/notification_test.cc
@@ -139,6 +139,41 @@
   BasicTests(true, &local_notification2);
 }
 
+TEST(NotificationTest, MultipleWaitersAndDestructionAfterWait) {
+  constexpr int kNumWaiters = 16;
+  auto* notification = new Notification();
+  ThreadSafeCounter ready_counter;
+  ThreadSafeCounter done_counter;
+
+  std::vector<std::thread> waiters;
+  waiters.reserve(kNumWaiters);
+  for (int i = 0; i < kNumWaiters; ++i) {
+    waiters.emplace_back([i, notification, &ready_counter, &done_counter]() {
+      ready_counter.Increment();
+      if (i % 3 == 0) {
+        notification->WaitForNotification();
+      } else if (i % 3 == 1) {
+        EXPECT_TRUE(
+            notification->WaitForNotificationWithTimeout(absl::Seconds(60)));
+      } else {
+        EXPECT_TRUE(notification->WaitForNotificationWithDeadline(
+            absl::Now() + absl::Seconds(60)));
+      }
+      done_counter.Increment();
+    });
+  }
+
+  ready_counter.WaitUntilGreaterOrEqual(kNumWaiters);
+  std::thread notifier([notification]() { notification->Notify(); });
+  done_counter.WaitUntilGreaterOrEqual(kNumWaiters);
+  delete notification;
+
+  notifier.join();
+  for (std::thread& waiter : waiters) {
+    waiter.join();
+  }
+}
+
 #if ABSL_HAVE_ATTRIBUTE_WEAK
 
 namespace base_internal {