[GitHub] [jena] afs commented on a change in pull request #707: JENA-1857: DatasetGraphInMemory.size.

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

afs commented on a change in pull request #707: JENA-1857: DatasetGraphInMemory.size.
URL: https://github.com/apache/jena/pull/707#discussion_r391733804
 
 

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 File path: jena-arq/src/main/java/org/apache/jena/sparql/core/mem/DatasetGraphInMemory.java
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 @@ -400,7 +400,9 @@ public DatasetPrefixStorage prefixes() {
 
     @Override
     public long size() {
-        return quadsIndex().listGraphNodes().count() ;
+        return isInTransaction() 
+                ? quadsIndex().listGraphNodes().count()
+                : calculateRead(this, ()->quadsIndex().listGraphNodes().count());
 
 Review comment:
   `access` returns `Iterator<T>`.
   
   I had tried `quadsIndex().listGraphNodes()::count` -- it does not work.
   
   It is different because is `quadsIndex().listGraphNodes()` is called as a plain argument (i.e. early), the method pointer calculated with `::count` and that passed in so only `count()` is delayed to inside the R transaction.
   
   `()->quadsIndex().listGraphNodes().count()` delays calling `quadsIndex().listGraphNodes()` to inside the R transaction and `listGraphNodes()` is the critical step.
   

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