Moving swarms 'procCount' cache.

This was an attribute of the hdf5 file, now it's a dataset. Due to issue #749.

Author: julesghub

src/underworld/swarm/_swarm.py

@@ -359,7 +359,7 @@ def load( self, filename, collective=False, try_optimise=True ):
             size = dset.shape[0] # number of particles in h5 file
 
             if try_optimise:
-                procCount = h5f.attrs.get('proc_offset')
+                procCount = h5_get_dataset(h5f, 'proc_offset')
                 if procCount is not None and nProcs == len(procCount):
                     for p_i in range(rank):
                         offset += procCount[p_i]

src/underworld/swarm/_swarmvariable.py

@@ -491,7 +491,8 @@ def save( self, filename, collective=False, swarmHandle=None, units=None, **kwar
                 h5f["swarm"] = h5py.ExternalLink(sFilename, "./")
 
             # also write proc offsets - used for loading from checkpoint
-            h5f.attrs["proc_offset"] = procCount
+            pdata = h5_require_dataset(h5f, "proc_offset", shape=(len(procCount),), dtype=np.int64)
+            pdata[:] = procCount
             h5f.attrs["units"] = str(units)
 
             for kwarg, val in kwargs.items():