Merge bug

Hopefully found the ultimate cause of duplicated (completed) tasks.

The corresponding test case

 1. does not rely on the fact that there are modifications with equal
    timestamps and
 2. is a LOT simpler than the other ones.

src/TDB2.cpp

@@ -867,9 +867,27 @@ void TDB2::merge (const std::string& mergeFile)
       std::list<Taskmod>::iterator current = rmod_it++;
       Taskmod tmod = *current;
 
-      // new uuid?
+      if (uuid_left.find (tmod.getUuid ()) != uuid_left.end ())
-      if (tmod.isNew ())
       {
+        // check whether the remote side has added a task with the same UUID
+        //  this happens if it inserted a modification with an older timestamp
+        //  into the undo.data and thereby moved the branch point to an earlier
+        //  point in time. Normally this case will be solved by the merge logic,
+        //  BUT if the UUID is considered new the merge logic will be skipped.
+        //
+        //  This flaw resulted in a couple of duplication issues and bloated 
+        //  undo files (e.g. #1104).
+        //
+        //  This is just a "hack" which discards all the modifications of the
+        //  remote side to UUIDs that are considered new by both sides.
+        //  There may be more issues with the algorithm; probably a redesign
+        //  and proper encapsulation of the merge algorithm is due.
+
+        rmods.erase(current);
+      }
+      else if (tmod.isNew ())
+      {
+        // new uuid?
 /*
         // TODO Don't forget L10N.
         std::cout << "Adding new remote task             "

test/merge.simple_duplication.t

@@ -0,0 +1,133 @@
+#! /usr/bin/env perl
+################################################################################
+## taskwarrior - a command line task list manager.
+##
+## Copyright 2006-2012, Paul Beckingham, Federico Hernandez.
+##
+## Permission is hereby granted, free of charge, to any person obtaining a copy
+## of this software and associated documentation files (the "Software"), to deal
+## in the Software without restriction, including without limitation the rights
+## to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+## copies of the Software, and to permit persons to whom the Software is
+## furnished to do so, subject to the following conditions:
+##
+## The above copyright notice and this permission notice shall be included
+## in all copies or substantial portions of the Software.
+##
+## THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+## OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+## FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+## THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+## LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+## OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+## SOFTWARE.
+##
+## http://www.opensource.org/licenses/mit-license.php
+##
+################################################################################
+
+use strict;
+use warnings;
+use File::Copy;
+use File::Path;
+use Test::More tests => 16;
+
+mkdir("1",       0755);
+mkdir("2",       0755);
+mkdir("dropbox", 0755);
+
+ok (-e "1",       'Created directory 1/');
+ok (-e "2",       'Created directory 2/');
+ok (-e "dropbox", 'Created directory dropbox/');
+
+# Create the rc file.
+if (open my $fh, '>', '1.rc')
+{
+  print $fh "data.location=1/\n";
+  print $fh "confirmation=no\n";
+  print $fh "merge.autopush=yes\n";
+  print $fh "merge.default.uri=./dropbox/\n";
+  print $fh "push.default.uri=./dropbox/\n";
+  print $fh "pull.default.uri=./dropbox/\n";
+
+  close $fh;
+  ok (-r '1.rc', 'Created 1.rc');
+}
+
+# Create the rc file.
+if (open my $fh, '>', '2.rc')
+{
+  print $fh "data.location=2/\n";
+  print $fh "confirmation=no\n";
+  print $fh "merge.autopush=yes\n";
+  print $fh "merge.default.uri=./dropbox/\n";
+  print $fh "push.default.uri=./dropbox/\n";
+  print $fh "pull.default.uri=./dropbox/\n";
+
+  close $fh;
+  ok (-r '2.rc', 'Created 2.rc');
+}
+
+# Once-only push from 1 --> dropbox
+my $output = qx{../src/task rc:1.rc add one 2>&1};
+ok ($? == 0, 'Exit status check');
+$output = qx{../src/task rc:1.rc push 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Merges to 2
+$output = qx{../src/task rc:2.rc merge 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Add a task to 1
+$output = qx{../src/task rc:1.rc add two 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Add with a later timestamp to 2
+qx{sleep 1};
+$output = qx{../src/task rc:2.rc add three 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Only completing this task triggers duplications
+$output = qx{../src/task rc:2.rc three done 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Merge/update the dropbox
+$output = qx{../src/task rc:2.rc merge 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Merge to 1, which means that the new task on 1
+# will be inserted before the modifications of 2
+$output = qx{../src/task rc:1.rc merge 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Merging to 2 now triggers the duplications because
+# both sides have exactly the same modifications
+# (creation and deletion of a task) after
+# the branch point
+$output = qx{../src/task rc:2.rc merge 2>&1};
+ok ($? == 0, 'Exit status check');
+
+# Cleanup.
+unlink qw(1.rc 1/pending.data 1/completed.data 1/undo.data 1/backlog.data 1/synch.key 2/pending.data 2/completed.data 2/undo.data 2.rc 2/backlog.data 2/synch.key dropbox/completed.data dropbox/pending.data dropbox/undo.data);
+ok (! -r '1/pending.data'         &&
+    ! -r '1/completed.data'       &&
+    ! -r '1/undo.data'            &&
+    ! -r '1/backlog.data'         &&
+    ! -r '1/synch.key'            &&
+    ! -r '1.rc'                   &&
+    ! -r '2/pending.data'         &&
+    ! -r '2/completed.data'       &&
+    ! -r '2/undo.data'            &&
+    ! -r '2/backlog.data'         &&
+    ! -r '2/synch.key'            &&
+    ! -r '2.rc'                   &&
+    ! -r 'dropbox/pending.data'   &&
+    ! -r 'dropbox/completed.data' &&
+    ! -r 'dropbox/undo.data' , 'Cleanup');
+
+rmtree (['1', '2', 'dropbox'], 0, 1);
+ok (! -e '1'             &&
+    ! -e '2'             &&
+    ! -e 'dropbox', 'Removed directories');
+
+exit 0;