fix: resolve condition promise on Close to break leak cycles

Author: beekld

libs/server-sdk/src/data_interfaces/source/ifdv2_condition.hpp

@@ -33,8 +33,12 @@ namespace launchdarkly::server_side::data_interfaces {
 class IFDv2Condition {
    public:
     enum class Type {
+        /** Stop the active synchronizer and start the next-preferred one. */
         kFallback,
+        /** Return to the most-preferred synchronizer. */
         kRecovery,
+        /** The condition was Close()d before firing; orchestrator ignores. */
+        kCancelled,
     };
 
     /**

libs/server-sdk/src/data_systems/fdv2/conditions.cpp

@@ -35,6 +35,7 @@ void TimedCondition::Close() {
         state_->timer_cancel->Cancel();
         state_->timer_cancel.reset();
     }
+    state_->promise.Resolve(IFDv2Condition::Type::kCancelled);
 }
 
 void TimedCondition::ArmTimer() {

libs/server-sdk/src/data_systems/fdv2/fdv2_data_system.cpp

@@ -260,6 +260,9 @@ void FDv2DataSystem::RunSynchronizerNext() {
 void FDv2DataSystem::OnConditionFired(
     data_interfaces::IFDv2Condition::Type type) {
     using Type = data_interfaces::IFDv2Condition::Type;
+    if (type == Type::kCancelled) {
+        return;
+    }
     {
         std::lock_guard<std::mutex> lock(mutex_);
         if (closed_) {

libs/server-sdk/tests/conditions_test.cpp

@@ -90,7 +90,7 @@ TEST(FallbackConditionTest, ChangeSetCancelsActiveTimer) {
     EXPECT_FALSE(future.IsFinished());
 }
 
-TEST(FallbackConditionTest, CloseCancelsActiveTimer) {
+TEST(FallbackConditionTest, CloseCancelsActiveTimerAndResolvesWithCancelled) {
     RunningIoContext ioc;
     FallbackCondition condition(ioc.GetExecutor(), /*timeout=*/100ms);
     auto future = condition.Execute();
@@ -103,8 +103,9 @@ TEST(FallbackConditionTest, CloseCancelsActiveTimer) {
     }});
     condition.Close();
 
-    std::this_thread::sleep_for(200ms);
-    EXPECT_FALSE(future.IsFinished());
+    auto result = future.WaitForResult(200ms);
+    ASSERT_TRUE(result.has_value());
+    EXPECT_EQ(IFDv2Condition::Type::kCancelled, *result);
 }
 
 // ============================================================================
@@ -148,15 +149,16 @@ TEST(RecoveryConditionTest, InformDoesNotAffectTimer) {
     EXPECT_EQ(IFDv2Condition::Type::kRecovery, *result);
 }
 
-TEST(RecoveryConditionTest, CloseCancelsActiveTimer) {
+TEST(RecoveryConditionTest, CloseCancelsActiveTimerAndResolvesWithCancelled) {
     RunningIoContext ioc;
     RecoveryCondition condition(ioc.GetExecutor(), /*timeout=*/100ms);
     auto future = condition.Execute();
 
     condition.Close();
 
-    std::this_thread::sleep_for(200ms);
-    EXPECT_FALSE(future.IsFinished());
+    auto result = future.WaitForResult(200ms);
+    ASSERT_TRUE(result.has_value());
+    EXPECT_EQ(IFDv2Condition::Type::kCancelled, *result);
 }
 
 // ============================================================================
@@ -226,5 +228,6 @@ TEST(ConditionsTest, CloseForwardsToAllUnderlyingConditions) {
     conditions.Close();
 
     auto result = conditions.GetFuture().WaitForResult(200ms);
-    EXPECT_FALSE(result.has_value());
+    ASSERT_TRUE(result.has_value());
+    EXPECT_EQ(IFDv2Condition::Type::kCancelled, *result);
 }