Soft commit on reindexes

Allow data to be saved and ready to be used by Solr.

Note that at the end of reindex a hard commit is done which will save
the changes on the disk.

See:
http://wiki.apache.org/solr/UpdateXmlMessages#A.22commit.22_and_.22optimize.22

docs/CHANGES.rst

@@ -26,6 +26,9 @@ Changelog
 - Add zopectl.command for reindexing. Do not rely on positional arguments in _get_site.
   [tschorr]
 
+- Soft commit changes while reindexing.
+  This allows to get results on searches while reindexing is taking place.
+  [gforcada]
 
 4.1.0 (2015-02-19)
 ------------------

src/collective/solr/browser/maintenance.py

@@ -119,7 +119,7 @@ def reindex(self, batch=1000, skip=0, limit=0, ignore_portal_types=None,
         schema = manager.getSchema()
         key = schema.uniqueKey
         updates = {}            # list to hold data to be updated
-        flush = lambda: conn.flush()
+        flush = lambda: conn.commit(soft=True)
         flush = notimeout(flush)
 
         def checkPoint():

src/collective/solr/solr.py

@@ -240,12 +240,13 @@ def add(self, boost_values=None, **fields):
         xstr = ''.join(lst)
         return self.doUpdateXML(xstr)
 
-    def commit(self, waitSearcher=True, optimize=False):
+    def commit(self, waitSearcher=True, optimize=False, soft=False):
         data = {
             'committype': optimize and 'optimize' or 'commit',
             'nowait': not waitSearcher and ' waitSearcher="false"' or '',
+            'soft': soft and ' softCommit="true"' or '',
         }
-        xstr = '<%(committype)s%(nowait)s/>' % data
+        xstr = '<%(committype)s%(soft)s%(nowait)s/>' % data
         self.doUpdateXML(xstr)
         return self.flush()