[GitHub] [nifi-minifi-cpp] adamdebreceni commented on a change in pull request #807: MINIFICPP-1228 - Resource ownership refactor + flowFile-owning processors.

[GitBox <gi...@apache.org>]

adamdebreceni commented on a change in pull request #807:
URL: https://github.com/apache/nifi-minifi-cpp/pull/807#discussion_r448208397



##########
File path: libminifi/include/core/FlowFile.h
##########
@@ -30,9 +30,56 @@ namespace minifi {
 namespace core {
 
 class FlowFile : public core::Connectable, public ReferenceContainer {
+ private:
+  class FlowFileOwnedResourceClaimPtr{
+   public:
+    FlowFileOwnedResourceClaimPtr() = default;
+    explicit FlowFileOwnedResourceClaimPtr(const std::shared_ptr<ResourceClaim>& claim) : claim_(claim) {
+      if (claim_) claim_->increaseFlowFileRecordOwnedCount();
+    }
+    explicit FlowFileOwnedResourceClaimPtr(std::shared_ptr<ResourceClaim>&& claim) : claim_(std::move(claim)) {
+      if (claim_) claim_->increaseFlowFileRecordOwnedCount();
+    }
+    FlowFileOwnedResourceClaimPtr(const FlowFileOwnedResourceClaimPtr& ref) : claim_(ref.claim_) {
+      if (claim_) claim_->increaseFlowFileRecordOwnedCount();
+    }
+    FlowFileOwnedResourceClaimPtr(FlowFileOwnedResourceClaimPtr&& ref) : claim_(std::move(ref.claim_)) {
+      // taking ownership of claim, no need to increment/decrement
+    }
+    FlowFileOwnedResourceClaimPtr& operator=(const FlowFileOwnedResourceClaimPtr& ref) = delete;
+    FlowFileOwnedResourceClaimPtr& operator=(FlowFileOwnedResourceClaimPtr&& ref) = delete;
+
+    FlowFileOwnedResourceClaimPtr& set(FlowFile& owner, const FlowFileOwnedResourceClaimPtr& ref) {
+      return set(owner, ref.claim_);
+    }
+    FlowFileOwnedResourceClaimPtr& set(FlowFile& owner, const std::shared_ptr<ResourceClaim>& newClaim) {
+      auto oldClaim = claim_;
+      claim_ = newClaim;
+      // the order of increase/release is important
+      if (claim_) claim_->increaseFlowFileRecordOwnedCount();
+      if (oldClaim) owner.releaseClaim(oldClaim);
+      return *this;
+    }
+    const std::shared_ptr<ResourceClaim>& get() const {
+      return claim_;
+    }
+    const std::shared_ptr<ResourceClaim>& operator->() const {
+      return claim_;
+    }
+    operator bool() const noexcept {
+      return static_cast<bool>(claim_);
+    }
+    ~FlowFileOwnedResourceClaimPtr() {
+      // allow the owner FlowFile to manually release the claim
+      // while logging stuff and removing it from repositories
+      assert(!claim_);
+    }
+   private:
+    std::shared_ptr<ResourceClaim> claim_;
+  };
  public:
   FlowFile();
-  ~FlowFile();
+  virtual ~FlowFile();

Review comment:
       since virtual destructors have different semantics from other virtual functions (they never actually override the base destructor but they are chained) they shouldn't be marked `override` imo




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