extended interface for memory region params

Author: sy-c

src/MemoryPagesPool.cxx

@@ -50,15 +50,32 @@ size_t MemoryPagesPool::getNumberOfPagesAvailable() {
   return pagesAvailable->getNumberOfUsedSlots();
 }
 
+void *MemoryPagesPool::getBaseBlockAddress() {
+  return baseBlockAddress;
+}
+size_t MemoryPagesPool::getBaseBlockSize() {
+  return baseBlockSize;
+}
 
 
-std::shared_ptr<DataBlockContainer> MemoryPagesPool::getNewDataBlockContainer() {
-  // get a new page from the pool
-  void *newPage=getPage();
+std::shared_ptr<DataBlockContainer> MemoryPagesPool::getNewDataBlockContainer(void *newPage) {
   if (newPage==nullptr) {
-    return nullptr;
+    // get a new page from the pool
+    newPage=getPage();
+    if (newPage==nullptr) {
+      return nullptr;
+    }
   }
 
+  // fill header
+  DataBlock *b=(DataBlock *)newPage;
+  b->header.blockType=DataBlockType::H_BASE;
+  b->header.headerSize=sizeof(DataBlockHeaderBase);
+  b->header.dataSize=pageSize-sizeof(DataBlock);
+  b->header.id=0;
+  b->header.linkId=0;
+  b->data=&(((char *)b)[sizeof(DataBlock)]);
+
   // define a function to put it back in pool after use
   auto releaseCallback = [this, newPage] (void) -> void {
     this->releasePage(newPage);
@@ -72,5 +89,7 @@ std::shared_ptr<DataBlockContainer> MemoryPagesPool::getNewDataBlockContainer()
     return nullptr;
   }
 
+  //printf("create dbc %p with data=%p stored=%p\n",bc,newPage,bc->getData());
+  
   return bc;
 }

src/MemoryPagesPool.h

@@ -26,12 +26,14 @@ class MemoryPagesPool {
   void *getPage(); // get a new page from the pool (if available, nullptr if none)
   void releasePage(void *address); // insert back page to the pool after use, to make it available again
 
-  size_t getPageSize(); // retrieve the page size
-  size_t getTotalNumberOfPages(); // retrieve number of pages in pool
-  size_t getNumberOfPagesAvailable(); //retrieve number of pages currently available
-
-  std::shared_ptr<DataBlockContainer>getNewDataBlockContainer(); // returns an empty data block container (with data = a new page) from the pool. Page will be put back in pool after use.
-
+  size_t getPageSize(); // get the page size
+  size_t getTotalNumberOfPages(); // get number of pages in pool
+  size_t getNumberOfPagesAvailable(); //get number of pages currently available
+  void *getBaseBlockAddress(); // get the base address of memory pool block
+  size_t getBaseBlockSize(); // get the  size of memory pool block. All pages guaranteed to be within &baseBlockAddress[0] and &baseBlockAddress[baseBlockSize]
+  
+  std::shared_ptr<DataBlockContainer>getNewDataBlockContainer(void *page=nullptr); // returns an empty data block container (with data = a given page, retrieved previously by getPage(), or new page if null) from the pool. Page will be put back in pool after use.
+  
 private:
   std::unique_ptr<AliceO2::Common::Fifo<void *>> pagesAvailable;  // a buffer to keep track of individual pages