SparseIntDirectedGraph returns inconsistent edge information

[vigna]

While converting one of our graphs (http://law.di.unimi.it/webdata/enwiki-2013/) to a SparseIntDirectedGraph I ran into inconsistent edge information. More precisely, for some edges returned by outgoingEdgesOf(), getAllEdges() called on the edge endpoints returns the empty set, which is inconsistent, since the edge was returned by outgoingEdgesOf() in the first place.

There is a class reproducing this behavior:

https://github.com/vigna/jgrapht/blob/sux4j-test/jgrapht-unimi-dsi/src/main/java/org/jgrapht/sux4j/SparseGraphTest.java

To reproduce the bug, you have to download enwiki-2013 from the link above (.graph, and .properties files). Then, generate offsets with

java it.unimi.dsi.webgraph.BVGraph -O enwiki-2013

Finally, run the class above with assertions enabled and as only argument the basename of the graph (enwiki-2013, if it is in the current directory):

java -ea org.jgrapht.sux4j.SparseGraphTest enwiki-2013
Exception in thread "main" java.lang.AssertionError: 14395206 (469192 -> 66589)
	at org.jgrapht.sux4j.SparseGraphTest.main(SparseGraphTest.java:128)

The test simply enumerates the edges outgoing of node 469192 and for each edge calls getAllEdges() between the edge endpoints.

[d-michail]

Thanks, I will take a look.

[d-michail]

After 3' minutes I noticed that I am performing an equality test with == instead of .equals().