From bd8b5c709eef0793168a06eea1f9bfca55157ceb Mon Sep 17 00:00:00 2001
From: Matthias Richter <Matthias.Richter@scieq.net>
Date: Thu, 4 Nov 2021 08:36:07 +0100
Subject: [PATCH] DPL: using linear message store for the DataRelayer cache

---
 Framework/Core/include/Framework/MessageSet.h | 96 ++++++-------------
 Framework/Core/src/DataRelayer.cxx            |  2 +-
 2 files changed, 32 insertions(+), 66 deletions(-)

diff --git a/Framework/Core/include/Framework/MessageSet.h b/Framework/Core/include/Framework/MessageSet.h
index 7093486c6c888..c41bb46bfaefb 100644
--- a/Framework/Core/include/Framework/MessageSet.h
+++ b/Framework/Core/include/Framework/MessageSet.h
@@ -23,22 +23,28 @@ namespace framework
 
 /// A set of associated inflight messages.
 struct MessageSet {
-  std::vector<PartRef> parts;
+  struct Index {
+    Index(size_t p, size_t s) : position(p), size(s) {}
+    size_t position = 0;
+    size_t size = 0;
+  };
+  std::vector<FairMQMessagePtr> messages;
+  std::vector<Index> index;
 
   MessageSet()
-    : parts()
+    : messages(), index()
   {
   }
 
   template <typename F>
-  MessageSet(F&& getter, size_t size)
-    : parts()
+  MessageSet(F getter, size_t size)
+    : messages(), index()
   {
     add(std::forward<F>(getter), size);
   }
 
   MessageSet(MessageSet&& other)
-    : parts(std::move(other.parts))
+    : messages(std::move(other.messages)), index(std::move(other.index))
   {
     other.clear();
   }
@@ -48,25 +54,26 @@ struct MessageSet {
     if (&other == this) {
       return *this;
     }
-    parts = std::move(other.parts);
+    messages = std::move(other.messages);
+    index = std::move(other.index);
     other.clear();
     return *this;
   }
 
   size_t size() const
   {
-    return parts.size();
+    return index.size();
   }
 
   size_t getNumberOfPayloads(size_t part) const
   {
-    // this is for upcoming change of message store
-    return 1;
+    return index[part].size;
   }
 
   void clear()
   {
-    parts.clear();
+    messages.clear();
+    index.clear();
   }
 
   // this is more or less legacy
@@ -78,83 +85,42 @@ struct MessageSet {
 
   void add(PartRef&& ref)
   {
-    parts.emplace_back(std::move(ref));
+    index.emplace_back(messages.size(), 1);
+    messages.emplace_back(std::move(ref.header));
+    messages.emplace_back(std::move(ref.payload));
   }
 
   template <typename F>
   void add(F getter, size_t size)
   {
+    index.emplace_back(messages.size(), size - 1);
     for (size_t i = 0; i < size; ++i) {
-      PartRef ref{std::move(getter(i)), std::move(getter(i + 1))};
-      parts.emplace_back(std::move(ref));
-      ++i;
+      messages.emplace_back(std::move(getter(i)));
     }
   }
 
   FairMQMessagePtr& header(size_t partIndex)
   {
-    assert(partIndex < parts.size());
-    return parts[partIndex].header;
+    return messages[index[partIndex].position];
   }
 
   FairMQMessagePtr& payload(size_t partIndex, size_t payloadIndex = 0)
   {
-    assert(partIndex < parts.size());
-    // payload index will be supported in linear message store
-    assert(payloadIndex == 0);
-    return parts[partIndex].payload;
+    assert(partIndex < index.size());
+    assert(index[partIndex].position + payloadIndex + 1 < messages.size());
+    return messages[index[partIndex].position + payloadIndex + 1];
   }
 
   FairMQMessagePtr const& header(size_t partIndex) const
   {
-    assert(partIndex < parts.size());
-    return parts[partIndex].header;
+    return messages[index[partIndex].position];
   }
 
-  FairMQMessagePtr const& payload(size_t partIndex) const
+  FairMQMessagePtr const& payload(size_t partIndex, size_t payloadIndex = 0) const
   {
-    assert(partIndex < parts.size());
-    return parts[partIndex].payload;
-  }
-
-  PartRef& operator[](size_t index)
-  {
-    return parts[index];
-  }
-
-  PartRef const& operator[](size_t index) const
-  {
-    return parts[index];
-  }
-
-  PartRef& at(size_t index)
-  {
-    return parts.at(index);
-  }
-
-  PartRef const& at(size_t index) const
-  {
-    return parts.at(index);
-  }
-
-  decltype(auto) begin()
-  {
-    return parts.begin();
-  }
-
-  decltype(auto) begin() const
-  {
-    return parts.begin();
-  }
-
-  decltype(auto) end()
-  {
-    return parts.end();
-  }
-
-  decltype(auto) end() const
-  {
-    return parts.end();
+    assert(partIndex < index.size());
+    assert(index[partIndex].position + payloadIndex + 1 < messages.size());
+    return messages[index[partIndex].position + payloadIndex + 1];
   }
 };
 
diff --git a/Framework/Core/src/DataRelayer.cxx b/Framework/Core/src/DataRelayer.cxx
index 086411dd5ff0c..a6be13960ee3b 100644
--- a/Framework/Core/src/DataRelayer.cxx
+++ b/Framework/Core/src/DataRelayer.cxx
@@ -593,7 +593,7 @@ std::vector<o2::framework::MessageSet> DataRelayer::getInputsForTimeslice(Timesl
   // FIXME: what happens when we have enough timeslices to hit the invalid one?
   auto invalidateCacheFor = [&numInputTypes, &cachedStateMetrics = mCachedStateMetrics, &index, &cache](TimesliceSlot s) {
     for (size_t ai = s.index * numInputTypes, ae = ai + numInputTypes; ai != ae; ++ai) {
-      assert(std::accumulate(cache[ai].begin(), cache[ai].end(), true, [](bool result, auto const& element) { return result && element.header.get() == nullptr && element.payload.get() == nullptr; }));
+      assert(std::accumulate(cache[ai].messages.begin(), cache[ai].messages.end(), true, [](bool result, auto const& element) { return result && element.get() == nullptr; }));
       cache[ai].clear();
     }
     index.markAsInvalid(s);