ensure safety for waitoncomplete when allocation failure is encountered

offloading-cacher/cache.hpp

@@ -149,11 +149,13 @@ namespace dsacache {
         size_t GetSize() const { return size_; }
         uint8_t* GetSource() const { return src_; }
         int32_t GetRefCount() const { return active_->load(); }
-        void SetCacheToSource() { cache_->store(src_); delete_ = false; }
+        void SetInvalidHandlersAndCacheToSource();
         void SetTaskHandlersAndCache(uint8_t* cache, std::vector<dml_handler>* handlers);
 
         // initializes the class after which it is thread safe
         // but may only be destroyed safely after setting handlers
+        // afterwards either SetTaskHandlersAndCache or
+        // SetCacheToSource must be called to prevent deadlocks
         void Init(std::vector<dml_handler>* invalid_handlers);
 
         friend Cache;
@@ -291,6 +293,9 @@ namespace dsacache {
         // source node for further usage
         // output may depend on the calling threads node assignment
         // as this is set as the "optimal placement" node
+        // TODO: it would be better to not handle any decisions regarding nodes in the cache
+        // TODO: and leave this entirely to the user, however, this idea came to me 3 days before
+        // TODO: submission date and there are more important things to do
         void GetCacheNode(uint8_t* src, const size_t size, int* OUT_DST_NODE, int* OUT_SRC_NODE) const;
 
         // checks whether the cache contains an entry for
@@ -409,7 +414,7 @@ inline std::unique_ptr<dsacache::CacheData> dsacache::Cache::Access(uint8_t* dat
     // data source location
 
     if (CheckFlag(flags, FLAG_ACCESS_WEAK)) {
-        task->SetCacheToSource();
+        task->SetInvalidHandlersAndCacheToSource();
         return std::move(task);
     }
 
@@ -454,6 +459,9 @@ inline void dsacache::Cache::SubmitTask(CacheData* task, const int dst_node, con
     uint8_t* dst = memory_allocate_function_(dst_node, task->GetSize());
 
     if (dst == nullptr) {
+        // allocation failure encountered, therefore submission is aborted
+        // which necessitates making the CacheData instance safe for usage
+        task->SetInvalidHandlersAndCacheToSource();
         return;
     }
 
@@ -794,6 +802,13 @@ void dsacache::CacheData::SetTaskHandlersAndCache(uint8_t* cache, std::vector<dm
     handlers_->notify_one();
 }
 
+void dsacache::CacheData::SetInvalidHandlersAndCacheToSource() {
+    cache_->store(src_);
+    delete_ = false;
+    handlers_->store(invalid_handlers_);
+    handlers_->notify_all();
+}
+
 void dsacache::CacheData::Init(std::vector<dml_handler>* invalid_handlers) {
     cache_->store(nullptr);
     delete_ = true;