Allow Blob::flush

implementations/onblocks/BlobOnBlocks.cpp

@@ -68,6 +68,10 @@ void BlobOnBlocks::write(const void *source, uint64_t offset, uint64_t size) {
   });
 }
 
+void BlobOnBlocks::flush() {
+  _datatree->flush();
+}
+
 void BlobOnBlocks::resizeIfSmallerThan(uint64_t neededSize) {
   //TODO This is inefficient, because size() and resizeNumBytes() both traverse the tree. Better: _datatree->ensureMinSize(x)
   if (neededSize > size()) {

implementations/onblocks/BlobOnBlocks.h

@@ -29,6 +29,8 @@ public:
   uint64_t tryRead(void *target, uint64_t offset, uint64_t size) const override;
   void write(const void *source, uint64_t offset, uint64_t size) override;
 
+  void flush() override;
+
   std::unique_ptr<cachingdatatreestore::CachedDataTreeRef> releaseTree();
 
 private:

implementations/onblocks/cachingdatatreestore/CachedDataTreeRef.h

@@ -36,6 +36,10 @@ public:
   uint64_t numStoredBytes() const {
     return _baseTree->numStoredBytes();
   }
+
+  void flush() {
+    return _baseTree->flush();
+  }
 private:
   datatreestore::DataTree *_baseTree;
 };

interface/Blob.h

@@ -22,6 +22,8 @@ public:
   virtual uint64_t tryRead(void *target, uint64_t offset, uint64_t size) const = 0;
   virtual void write(const void *source, uint64_t offset, uint64_t size) = 0;
 
+  virtual void flush() = 0;
+
   //TODO Test tryRead
 };