for SETs via DL, compare write timestamp with existing item creation …

…time

Summary: as title

Reviewed By: stuclar

Differential Revision: D65797021

fbshipit-source-id: 4e48c7d03837e345176dd794c52abbdf9948c5a1

mcrouter/lib/carbon/RequestCommon.h

@@ -102,10 +102,14 @@ class RequestCommon : public MessageCommon {
     sourceIpAddr_ = sourceIpAddr;
   }
 
-  void setWriteTimestamp(uint64_t writeTimestamp) noexcept {
+  void setWriteTimestampNs(uint64_t writeTimestamp) noexcept {
     writeTimestamp_ = writeTimestamp;
   }
 
+  std::optional<uint64_t> getWriteTimestampNs() const noexcept {
+    return writeTimestamp_;
+  }
+
  protected:
   void markBufferAsDirty() {
     serializedBuffer_ = nullptr;