Fix DeadlineRegistration to be reusable after expiration

PiperOrigin-RevId: 702664862
Change-Id: I9656622abe49e26209840c75760e1e4f90d66210

sandboxed_api/sandbox2/util/deadline_manager.cc

@@ -100,6 +100,8 @@ void DeadlineManager::AdjustDeadline(DeadlineRegistration& registration,
                                      absl::Time deadline) {
   absl::MutexLock lock(&queue_mutex_);
   queue_.erase(registration.data_.get());
+  absl::MutexLock data_lock(&registration.data_->mutex);
+  registration.data_->expired = false;
   registration.data_->deadline = RoundUpTo(deadline, kResolution);
   if (deadline != absl::InfiniteFuture()) {
     queue_.insert(registration.data_.get());

sandboxed_api/sandbox2/util/deadline_manager.h

@@ -71,7 +71,7 @@ class DeadlineRegistration {
 
   struct Data {
     absl::Mutex mutex;
-    // Changed only under DeadlineManager::queue_mutex_.
+    // Changed only under both DeadlineManager::queue_mutex_ and Data::mutex.
     absl::Time deadline = absl::InfiniteFuture();
     pid_t ABSL_GUARDED_BY(mutex) tid = -1;
     bool ABSL_GUARDED_BY(mutex) in_blocking_fn = false;

sandboxed_api/sandbox2/util/deadline_manager_test.cc

@@ -112,5 +112,20 @@ TEST(DeadlineManagerTest, DeadlineReset) {
   EXPECT_GE(elapsed, absl::Milliseconds(200));
 }
 
+TEST(DeadlineManagerTest, CanBeReusedAfterExpiration) {
+  DeadlineManager manager("test");
+  DeadlineRegistration registration(manager);
+  for (int i = 0; i < 3; ++i) {
+    absl::Time start_time = absl::Now();
+    struct timespec ts = absl::ToTimespec(absl::Seconds(1));
+    registration.SetDeadline(start_time + absl::Milliseconds(100));
+    registration.ExecuteBlockingSyscall(
+        [&] { ASSERT_EQ(nanosleep(&ts, nullptr), -1); });
+    absl::Duration elapsed = absl::Now() - start_time;
+    EXPECT_GE(elapsed, absl::Milliseconds(100));
+    EXPECT_LE(elapsed, absl::Milliseconds(200));
+  }
+}
+
 }  // namespace
 }  // namespace sandbox2