Make config state atomic to allow for well-defined polling

2 files changed, 5 insertions, 3 deletions

diff --git a/config/src/vespa/config/subscription/configsubscriptionset.cpp b/config/src/vespa/config/subscription/configsubscriptionset.cpp
index f120272edcf..9b3ef32a128 100644
--- a/config/src/vespa/config/subscription/configsubscriptionset.cpp
+++ b/config/src/vespa/config/subscription/configsubscriptionset.cpp
@@ -42,7 +42,7 @@ ConfigSubscriptionSet::acquireSnapshot(uint64_t timeoutInMillis, bool ignoreChan
     bool inSync = false;
 
     LOG(debug, "Going into nextConfig loop, time left is %d", timeLeft);
-    while ((_state != CLOSED) && (timeLeft >= 0) && !inSync) {
+    while (!isClosed() && (timeLeft >= 0) && !inSync) {
         size_t numChanged = 0;
         size_t numGenerationChanged = 0;
         bool generationsInSync = true;
@@ -117,7 +117,7 @@ ConfigSubscriptionSet::close()
 bool
 ConfigSubscriptionSet::isClosed() const
 {
-    return (_state == CLOSED);
+    return (_state.load(std::memory_order_relaxed) == CLOSED);
 }
 
 ConfigSubscription::SP
diff --git a/config/src/vespa/config/subscription/configsubscriptionset.h b/config/src/vespa/config/subscription/configsubscriptionset.h
index cebd3007b19..ce1f45b0eb8 100644
--- a/config/src/vespa/config/subscription/configsubscriptionset.h
+++ b/config/src/vespa/config/subscription/configsubscriptionset.h
@@ -9,6 +9,8 @@
 #include "configsubscription.h"
 #include "configprovider.h"
 
+#include <atomic>
+
 namespace config {
 
 /**
@@ -60,7 +62,7 @@ private:
     int64_t               _currentGeneration;     // Holds the current config generation.
     SubscriptionList      _subscriptionList;      // List of current subscriptions.
 
-    SubscriberState _state;              // Current state of this subscriber.
+    std::atomic<SubscriberState> _state;              // Current state of this subscriber.
 };
 
 } // namespace config