Add class comments and resolve PR comments.

2 files changed, 17 insertions, 6 deletions

diff --git a/searchcore/src/vespa/searchcore/proton/common/feedtoken.h b/searchcore/src/vespa/searchcore/proton/common/feedtoken.h
index 363886b9f31..cf6c1f5a7e9 100644
--- a/searchcore/src/vespa/searchcore/proton/common/feedtoken.h
+++ b/searchcore/src/vespa/searchcore/proton/common/feedtoken.h
@@ -9,19 +9,23 @@ namespace proton {
 
 typedef std::unique_ptr<storage::spi::Result> ResultUP;
 
+namespace feedtoken {
+
 /**
  * This class is used by the FeedEngine to encapsulate the necessary information
  * for an IFeedHandler to perform an async reply to an operation. A unique
  * instance of this class is passed to every invokation of the IFeedHandler.
  */
-namespace feedtoken {
-
 class ITransport {
 public:
     virtual ~ITransport() { }
     virtual void send(ResultUP result, bool documentWasFound) = 0;
 };
 
+/**
+ * This holds the result of the feed operation until it is either failed or acked.
+ * Guarantees that the result is propagated back to the invoker via ITransport interface.
+ */
 class State : public search::IDestructorCallback {
 public:
     State(const State &) = delete;
@@ -42,6 +46,11 @@ private:
     bool                  _documentWasFound;
     std::atomic<bool>     _alreadySent;
 };
+
+/**
+ * This takes ownership ov the transport object, so that it can be used fully asynchronous
+ * without invoker needing to hold any state.
+ */
 class OwningState : public State {
 public:
     OwningState(std::unique_ptr<ITransport> transport)
diff --git a/searchcore/src/vespa/searchcore/proton/persistenceengine/transport_latch.h b/searchcore/src/vespa/searchcore/proton/persistenceengine/transport_latch.h
index b3b3bc43aa7..da4e19d3584 100644
--- a/searchcore/src/vespa/searchcore/proton/persistenceengine/transport_latch.h
+++ b/searchcore/src/vespa/searchcore/proton/persistenceengine/transport_latch.h
@@ -10,8 +10,7 @@
 namespace proton {
 
 /**
- * Implementation of FeedToken::ITransport for handling the async reply for an operation.
- * Uses an internal count down latch to keep track the number of outstanding replies.
+ * Base implementation for merging results from multiple sources.
  */
 
 class TransportMerger : public feedtoken::ITransport {
@@ -29,14 +28,17 @@ private:
     void mergeWithLock(ResultUP result, bool documentWasFound);
     std::unique_ptr<std::mutex> _lock;
 };
+
+/**
+ * Implementation of FeedToken::ITransport for handling the async reply for an operation.
+ * Uses an internal count down latch to keep track the number of outstanding replies.
+ */
 class TransportLatch : public TransportMerger {
 private:
-
     using UpdateResult = storage::spi::UpdateResult;
     using RemoveResult = storage::spi::RemoveResult;
     vespalib::CountDownLatch _latch;
 
-
 public:
     TransportLatch(uint32_t cnt);
     ~TransportLatch() override;