Fix zodb analyze with empty reports

Fix for this kind of errors:

```
(env)$ zodb analyze demo.fs ffffffffffffffff..
# ø
Processed 0 records in 0 transactions
Traceback (most recent call last):
  File "/srv/slapgrid/slappart8/srv/runner/project/zodbtools/env/bin/zodb", line 11, in <module>
    load_entry_point('zodbtools', 'console_scripts', 'zodb')()
  File "/srv/slapgrid/slappart8/srv/runner/project/zodbtools/zodbtools/zodb.py", line 130, in main
    return command_module.main(argv)
  File "/srv/slapgrid/slappart8/srv/runner/project/zodbtools/zodbtools/zodbanalyze.py", line 305, in main
    report(analyze(path, use_dbm, delta_fs, tidmin, tidmax), csv)
  File "/srv/slapgrid/slappart8/srv/runner/project/zodbtools/zodbtools/zodbanalyze.py", line 102, in report
    print "Average record size is %7.2f bytes" % (rep.DBYTES * 1.0 / rep.OIDS)
ZeroDivisionError: float division by zero
```

and also small fixes for python3 compatibility

/reviewed-on !9

zodbtools/test/test_analyze.py

+# -*- coding: utf-8 -*-
+# Copyright (C) 2019 Nexedi SA and Contributors.
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+
+from zodbtools.zodbanalyze import analyze, report
+import os.path
+
+
+def test_zodbanalyze(capsys):
+    for use_dbm in (False, True):
+        report(
+            analyze(
+                os.path.join(os.path.dirname(__file__), "testdata", "1.fs"),
+                use_dbm=use_dbm,
+                delta_fs=False,
+                tidmin=None,
+                tidmax=None,
+            ),
+            csv=False,
+        )
+        captured = capsys.readouterr()
+        assert "Processed 68 records in 59 transactions" in captured.out
+        assert captured.err == ""
+
+    # csv output
+    report(
+        analyze(
+            os.path.join(os.path.dirname(__file__), "testdata", "1.fs"),
+            use_dbm=False,
+            delta_fs=False,
+            tidmin=None,
+            tidmax=None,
+        ),
+        csv=True,
+    )
+    captured = capsys.readouterr()
+    assert (
+        """Class Name,T.Count,T.Bytes,Pct,AvgSize,C.Count,C.Bytes,O.Count,O.Bytes
+persistent.mapping.PersistentMapping,10,1578,45.633314%,157.800000,1,213,9,1365
+__main__.Object,56,1880,54.366686%,33.571429,9,303,47,1577
+"""
+        == captured.out
+    )
+    assert captured.err == ""
+
+    # empty range
+    report(
+        analyze(
+            os.path.join(os.path.dirname(__file__), "testdata", "1.fs"),
+            use_dbm=False,
+            delta_fs=False,
+            tidmin="ffffffffffffffff",
+            tidmax=None,
+        ),
+        csv=False,
+    )
+    captured = capsys.readouterr()
+    assert "# ø\nNo transactions processed\n" == captured.out.encode('utf-8')
+    assert captured.err == ""

zodbtools/zodbanalyze.py

@@ -4,10 +4,12 @@
 
 # Based on a transaction analyzer by Matt Kromer.
 
+from __future__ import print_function
+
 import sys
 import os
 import getopt
-import anydbm as dbm
+from six.moves import dbm_gnu as dbm
 import tempfile
 import shutil
 from ZODB.FileStorage import FileIterator, packed_version
@@ -29,7 +31,7 @@ class DeltaFileStorage(
         pass
 
 class DeltaFileIterator(FileIterator):
-    def __init__(self, filename, start=None, stop=None, pos=0L):
+    def __init__(self, filename, start=None, stop=None, pos=0):
         assert isinstance(filename, str)
         file = open(filename, 'rb')
         self._file = file
@@ -95,15 +97,17 @@ def report(rep, csv=False):
     delta_fs = rep.delta_fs
     if not csv:
         if rep.TIDS == 0:
-            print "# ø"
-        else:
-            print "# %s..%s" % (ashex(rep.tidmin), ashex(rep.tidmax))
-        print "Processed %d records in %d transactions" % (rep.OIDS, rep.TIDS)
-        print "Average record size is %7.2f bytes" % (rep.DBYTES * 1.0 / rep.OIDS)
+            print ("# ø")
+            print ("No transactions processed")
+            return
+
+        print ("# %s..%s" % (ashex(rep.tidmin), ashex(rep.tidmax)))
+        print ("Processed %d records in %d transactions" % (rep.OIDS, rep.TIDS))
+        print ("Average record size is %7.2f bytes" % (rep.DBYTES * 1.0 / rep.OIDS))
         print ("Average transaction size is %7.2f bytes" %
                (rep.DBYTES * 1.0 / rep.TIDS))
 
-        print "Types used:"
+        print ("Types used:")
     if delta_fs:
         if csv:
             fmt = "%s,%s,%s,%s,%s"
@@ -111,9 +115,9 @@ def report(rep, csv=False):
         else:
             fmt = "%-46s %7s %9s %6s %7s"
             fmtp = "%-46s %7d %9d %5.1f%% %7.2f" # per-class format
-        print fmt % ("Class Name", "T.Count", "T.Bytes", "Pct", "AvgSize")
+        print (fmt % ("Class Name", "T.Count", "T.Bytes", "Pct", "AvgSize"))
         if not csv:
-            print fmt % ('-'*46, '-'*7, '-'*9, '-'*5, '-'*7)
+            print (fmt % ('-'*46, '-'*7, '-'*9, '-'*5, '-'*7))
     else:
         if csv:
             fmt = "%s,%s,%s,%s,%s,%s,%s,%s,%s"
@@ -121,15 +125,13 @@ def report(rep, csv=False):
         else:
             fmt = "%-46s %7s %9s %6s %7s %7s %9s %7s %9s"
             fmtp = "%-46s %7d %9d %5.1f%% %7.2f %7d %9d %7d %9d" # per-class format
-        print fmt % ("Class Name", "T.Count", "T.Bytes", "Pct", "AvgSize",
-                     "C.Count", "C.Bytes", "O.Count", "O.Bytes")
+        print (fmt % ("Class Name", "T.Count", "T.Bytes", "Pct", "AvgSize",
+                      "C.Count", "C.Bytes", "O.Count", "O.Bytes"))
         if not csv:
-            print fmt % ('-'*46, '-'*7, '-'*9, '-'*5, '-'*7, '-'*7, '-'*9, '-'*7, '-'*9)
+            print (fmt % ('-'*46, '-'*7, '-'*9, '-'*5, '-'*7, '-'*7, '-'*9, '-'*7, '-'*9))
     fmts = "%46s %7d %8dk %5.1f%% %7.2f" # summary format
-    typemap = rep.TYPEMAP.keys()
-    typemap.sort(key=lambda a:rep.TYPESIZE[a])
     cumpct = 0.0
-    for t in typemap:
+    for t in sorted(rep.TYPEMAP.keys(), key=lambda a:rep.TYPESIZE[a]):
         pct = rep.TYPESIZE[t] * 100.0 / rep.DBYTES
         cumpct += pct
         if csv:
@@ -137,37 +139,37 @@ def report(rep, csv=False):
         else:
             t_display = shorten(t, 46)
         if delta_fs:
-            print fmtp % (t_display, rep.TYPEMAP[t], rep.TYPESIZE[t],
-                          pct, rep.TYPESIZE[t] * 1.0 / rep.TYPEMAP[t])
+            print (fmtp % (t_display, rep.TYPEMAP[t], rep.TYPESIZE[t],
+                           pct, rep.TYPESIZE[t] * 1.0 / rep.TYPEMAP[t]))
         else:
-            print fmtp % (t_display, rep.TYPEMAP[t], rep.TYPESIZE[t],
+            print (fmtp % (t_display, rep.TYPEMAP[t], rep.TYPESIZE[t],
                            pct, rep.TYPESIZE[t] * 1.0 / rep.TYPEMAP[t],
                            rep.COIDSMAP[t], rep.CBYTESMAP[t],
-                          rep.FOIDSMAP.get(t, 0), rep.FBYTESMAP.get(t, 0))
+                           rep.FOIDSMAP.get(t, 0), rep.FBYTESMAP.get(t, 0)))
 
     if csv:
         return
 
     if delta_fs:
-        print fmt % ('='*46, '='*7, '='*9, '='*5, '='*7)
-        print "%46s %7d %9s %6s %6.2f" % ('Total Transactions', rep.TIDS, ' ',
-                                          ' ', rep.DBYTES * 1.0 / rep.TIDS)
-        print fmts % ('Total Records', rep.OIDS, rep.DBYTES, cumpct,
-                      rep.DBYTES * 1.0 / rep.OIDS)
+        print (fmt % ('='*46, '='*7, '='*9, '='*5, '='*7))
+        print ("%46s %7d %9s %6s %6.2f" % ('Total Transactions', rep.TIDS, ' ',
+                                          ' ', rep.DBYTES * 1.0 / rep.TIDS))
+        print (fmts % ('Total Records', rep.OIDS, rep.DBYTES, cumpct,
+                       rep.DBYTES * 1.0 / rep.OIDS))
     else:
-        print fmt % ('='*46, '='*7, '='*9, '='*5, '='*7, '='*7, '='*9, '='*7, '='*9)
-        print "%46s %7d %9s %6s %6.2fk" % ('Total Transactions', rep.TIDS, ' ',
-            ' ', rep.DBYTES * 1.0 / rep.TIDS / 1024.0)
-        print fmts % ('Total Records', rep.OIDS, rep.DBYTES / 1024.0, cumpct,
-                      rep.DBYTES * 1.0 / rep.OIDS)
+        print (fmt % ('='*46, '='*7, '='*9, '='*5, '='*7, '='*7, '='*9, '='*7, '='*9))
+        print ("%46s %7d %9s %6s %6.2fk" % ('Total Transactions', rep.TIDS, ' ',
+            ' ', rep.DBYTES * 1.0 / rep.TIDS / 1024.0))
+        print (fmts % ('Total Records', rep.OIDS, rep.DBYTES / 1024.0, cumpct,
+                       rep.DBYTES * 1.0 / rep.OIDS))
 
-        print fmts % ('Current Objects', rep.COIDS, rep.CBYTES / 1024.0,
+        print (fmts % ('Current Objects', rep.COIDS, rep.CBYTES / 1024.0,
                        rep.CBYTES * 100.0 / rep.DBYTES,
-                      rep.CBYTES * 1.0 / rep.COIDS)
+                       rep.CBYTES * 1.0 / rep.COIDS))
         if rep.FOIDS:
-            print fmts % ('Old Objects', rep.FOIDS, rep.FBYTES / 1024.0,
+            print (fmts % ('Old Objects', rep.FOIDS, rep.FBYTES / 1024.0,
                            rep.FBYTES * 100.0 / rep.DBYTES,
-                          rep.FBYTES * 1.0 / rep.FOIDS)
+                           rep.FBYTES * 1.0 / rep.FOIDS))
 
 @func
 def analyze(path, use_dbm, delta_fs, tidmin, tidmax):
@@ -238,8 +240,8 @@ def analyze_rec(report, record):
                 report.CBYTESMAP[type] = report.CBYTESMAP.get(type, 0) + size - fsize
             report.TYPEMAP[type] = report.TYPEMAP.get(type, 0) + 1
             report.TYPESIZE[type] = report.TYPESIZE.get(type, 0) + size
-    except Exception, err:
-        print err
+    except Exception as err:
+        print (err, file=sys.stderr)
 
 __doc__ = """%(program)s: Analyzer for ZODB data or repozo deltafs
 
@@ -261,9 +263,9 @@ summary = "analyze ZODB database or repozo deltafs usage"
 
 def usage(stream, msg=None):
     if msg:
-        print >>stream, msg
-        print >>stream
-    print >>stream, __doc__ % {"program": "zodb analyze"}
+        print (msg, file=stream)
+        print (file=stream)
+    print (__doc__ % {"program": "zodb analyze"}, file=stream)
 
 
 def main(argv):
@@ -271,7 +273,7 @@ def main(argv):
         opts, args = getopt.getopt(argv[1:],
                                    'hcd', ['help', 'csv', 'dbm'])
         path = args[0]
-    except (getopt.GetoptError, IndexError), msg:
+    except (getopt.GetoptError, IndexError) as msg:
         usage(sys.stderr, msg)
         sys.exit(2)