notify: optional mail threading based on obsmarker

notify: optional mail threading based on obsmarker

When notify.reply is set and a changeset has a predecessor in the
repository, include In-Reply-To pointing to the message-id that would
have been generated for the oldest predecessor. This allows mail
threading like Phabricator for common cases like rebasing changes, but
will be optimal for cases like folding.

Differential Revision: https://phab.mercurial-scm.org/D8172

--- a/hgext/notify.py	Fri Mar 27 10:39:59 2020 -0400
+++ b/hgext/notify.py	Wed Feb 26 22:35:39 2020 +0100
@@ -133,6 +133,15 @@
   the "From" field of the notification mail. If not set, take the user
   from the pushing repo.  Default: False.
 
+notify.reply-to-predecessor (EXPERIMENTAL)
+  If set and the changeset has a predecessor in the repository, try to thread
+  the notification mail with the predecessor. This adds the "In-Reply-To" header
+  to the notification mail with a reference to the predecessor with the smallest
+  revision number. Mail threads can still be torn, especially when changesets
+  are folded.
+
+  This option must  be used in combination with ``notify.messageidseed``.
+
 If set, the following entries will also be used to customize the
 notifications:
 
@@ -160,6 +169,7 @@
     error,
     logcmdutil,
     mail,
+    obsutil,
     patch,
     pycompat,
     registrar,
@@ -219,6 +229,9 @@
     b'notify', b'outgoing', default=None,
 )
 configitem(
+    b'notify', b'reply-to-predecessor', default=False,
+)
+configitem(
     b'notify', b'sources', default=b'serve',
 )
 configitem(
@@ -281,6 +294,16 @@
         self.merge = self.ui.configbool(b'notify', b'merge')
         self.showfunc = self.ui.configbool(b'notify', b'showfunc')
         self.messageidseed = self.ui.config(b'notify', b'messageidseed')
+        self.reply = self.ui.configbool(b'notify', b'reply-to-predecessor')
+
+        if self.reply and not self.messageidseed:
+            raise error.Abort(
+                _(
+                    b'notify.reply-to-predecessor used without '
+                    b'notify.messageidseed'
+                )
+            )
+
         if self.showfunc is None:
             self.showfunc = self.ui.configbool(b'diff', b'showfunc')
 
@@ -437,6 +460,26 @@
         msg['X-Hg-Notification'] = 'changeset %s' % ctx
         if not msg['Message-Id']:
             msg['Message-Id'] = messageid(ctx, self.domain, self.messageidseed)
+        if self.reply:
+            unfi = self.repo.unfiltered()
+            has_node = unfi.changelog.index.has_node
+            predecessors = [
+                unfi[ctx2]
+                for ctx2 in obsutil.allpredecessors(unfi.obsstore, [ctx.node()])
+                if ctx2 != ctx.node() and has_node(ctx2)
+            ]
+            if predecessors:
+                # There is at least one predecessor, so which to pick?
+                # Ideally, there is a unique root because changesets have
+                # been evolved/rebased one step at a time. In this case,
+                # just picking the oldest known changeset provides a stable
+                # base. It doesn't help when changesets are folded. Any
+                # better solution would require storing more information
+                # in the repository.
+                pred = min(predecessors, key=lambda ctx: ctx.rev())
+                msg['In-Reply-To'] = messageid(
+                    pred, self.domain, self.messageidseed
+                )
         msg['To'] = ', '.join(sorted(subs))
 
         msgtext = msg.as_bytes() if pycompat.ispy3 else msg.as_string()

--- a/tests/test-notify.t	Fri Mar 27 10:39:59 2020 -0400
+++ b/tests/test-notify.t	Wed Feb 26 22:35:39 2020 +0100
@@ -6,8 +6,15 @@
   > EOF
 
   $ cat <<EOF >> $HGRCPATH
+  > [experimental]
+  > evolution = true
+  > 
   > [extensions]
   > notify=
+  > strip=
+  > 
+  > [phases]
+  > publish=False
   > 
   > [hooks]
   > incoming.notify = python:hgext.notify.hook
@@ -15,6 +22,8 @@
   > [notify]
   > sources = pull
   > diffstat = False
+  > reply-to-predecessor = True
+  > messageidseed = notifyseed
   > 
   > [usersubs]
   > foo@bar = *
@@ -151,6 +160,15 @@
     "From" field of the notification mail. If not set, take the user from the
     pushing repo.  Default: False.
   
+  notify.reply-to-predecessor (EXPERIMENTAL)
+    If set and the changeset has a predecessor in the repository, try to thread
+    the notification mail with the predecessor. This adds the "In-Reply-To"
+    header to the notification mail with a reference to the predecessor with the
+    smallest revision number. Mail threads can still be torn, especially when
+    changesets are folded.
+  
+    This option must  be used in combination with "notify.messageidseed".
+  
   If set, the following entries will also be used to customize the
   notifications:
   
@@ -205,7 +223,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 2 changes to 2 files
-  new changesets 00a13f371396
+  new changesets 00a13f371396 (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -266,7 +284,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 2 changes to 2 files
-  new changesets 00a13f371396
+  new changesets 00a13f371396 (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -316,7 +334,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 2 changes to 2 files
-  new changesets 00a13f371396
+  new changesets 00a13f371396 (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -369,7 +387,7 @@
   adding manifests
   adding file changes
   added 2 changesets with 0 changes to 0 files
-  new changesets 3332653e1f3c:fccf66cd0c35
+  new changesets 3332653e1f3c:fccf66cd0c35 (2 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -436,7 +454,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
-  new changesets 0f25f9c22b4c
+  new changesets 0f25f9c22b4c (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 8bit
@@ -480,7 +498,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
-  new changesets a846b5f6ebb7
+  new changesets a846b5f6ebb7 (1 drafts)
   notify: sending 2 subscribers 1 changes
   (run 'hg update' to get a working copy)
   $ cat b/mbox | "$PYTHON" $TESTDIR/unwrap-message-id.py | "$PYTHON" $TESTTMP/filter.py
@@ -493,7 +511,7 @@
   Subject: long line
   From: [e-mail]
   X-Hg-Notification: changeset a846b5f6ebb7
-  Message-Id: <hg.a846b5f6ebb7.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset a846b5f6ebb7 in b
@@ -543,6 +561,8 @@
   (branches are permanent and global, did you want a bookmark?)
   $ echo a >> a/a
   $ hg --cwd a ci -m test -d '1 0'
+  $ echo a >> a/a
+  $ hg --cwd a ci -m test -d '1 0'
   $ hg --traceback --cwd b pull ../a | \
   >  "$PYTHON" $TESTDIR/unwrap-message-id.py | \
   >  "$PYTHON" $TESTTMP/filter.py
@@ -551,8 +571,8 @@
   adding changesets
   adding manifests
   adding file changes
-  added 1 changesets with 1 changes to 1 files
-  new changesets f7e5aaed4080
+  added 2 changesets with 2 changes to 1 files
+  new changesets f7e5aaed4080:485bf79b9464 (2 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -561,11 +581,24 @@
   Subject: test
   From: [e-mail]
   X-Hg-Notification: changeset f7e5aaed4080
-  Message-Id: <hg.f7e5aaed4080.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar, [e-mail]
   
   changeset f7e5aaed4080 in b
   description: test
+  MIME-Version: 1.0
+  Content-Type: text/plain; charset="us-ascii"
+  Content-Transfer-Encoding: 7bit
+  X-Test: foo
+  Date: * (glob)
+  Subject: test
+  From: [e-mail]
+  X-Hg-Notification: changeset 485bf79b9464
+  Message-Id: <hg.[e-mail]>
+  To: [e-mail], foo@bar, [e-mail]
+  
+  changeset 485bf79b9464 in b
+  description: test
   (run 'hg update' to get a working copy)
 
 revset selection: don't send to address that waits for mails
@@ -584,7 +617,7 @@
   adding manifests
   adding file changes
   added 1 changesets with 0 changes to 0 files (+1 heads)
-  new changesets 645eb6690ecf
+  new changesets 645eb6690ecf (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -593,7 +626,7 @@
   Subject: test
   From: [e-mail]
   X-Hg-Notification: changeset 645eb6690ecf
-  Message-Id: <hg.645eb6690ecf.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset 645eb6690ecf in b
@@ -616,7 +649,7 @@
   Subject: changeset in b: default template
   From: [e-mail]
   X-Hg-Notification: changeset 5cd4346eed47
-  Message-Id: <hg.5cd4346eed47.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset 5cd4346eed47 in $TESTTMP/b
@@ -647,7 +680,7 @@
   Subject: with style
   From: [e-mail]
   X-Hg-Notification: changeset ec8d9d852f56
-  Message-Id: <hg.ec8d9d852f56.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset ec8d9d852f56
@@ -672,7 +705,7 @@
   Subject: 14721b538ae3: with template
   From: [e-mail]
   X-Hg-Notification: changeset 14721b538ae3
-  Message-Id: <hg.14721b538ae3.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   with template
@@ -695,6 +728,8 @@
   > EOF
   $ hg commit -Am addfunction
   adding f1
+  $ hg debugobsolete eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee b86bc16ff894f057d023b306936f290954857187
+  1 new obsolescence markers
   $ hg --cwd ../b pull ../a | \
   >  "$PYTHON" $TESTDIR/unwrap-message-id.py
   pulling from ../a
@@ -703,7 +738,8 @@
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
-  new changesets b86bc16ff894
+  1 new obsolescence markers
+  new changesets b86bc16ff894 (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -711,7 +747,7 @@
   Subject: addfunction
   From: [e-mail]
   X-Hg-Notification: changeset b86bc16ff894
-  Message-Id: <hg.b86bc16ff894.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset b86bc16ff894
@@ -739,6 +775,9 @@
   > }
   > EOF
   $ hg commit -m changefunction
+  $ hg debugobsolete 485bf79b9464197b2ed2debd0b16252ad64ed458 e81040e9838c704d8bf17658cb11758f24e40b6b
+  1 new obsolescence markers
+  obsoleted 1 changesets
   $ hg --cwd ../b --config notify.showfunc=True pull ../a | \
   >  "$PYTHON" $TESTDIR/unwrap-message-id.py
   pulling from ../a
@@ -747,7 +786,9 @@
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
-  new changesets e81040e9838c
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  new changesets e81040e9838c (1 drafts)
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -755,7 +796,8 @@
   Subject: changefunction
   From: [e-mail]
   X-Hg-Notification: changeset e81040e9838c
-  Message-Id: <hg.e81040e9838c.*.*@*> (glob)
+  Message-Id: <hg.[e-mail]>
+  In-Reply-To: <hg.[e-mail]>
   To: [e-mail], foo@bar
   
   changeset e81040e9838c
@@ -774,3 +816,50 @@
   +    return a + b + c + e;
    }
   (run 'hg update' to get a working copy)
+
+Retry the In-Reply-To, but make sure the oldest known change is older.
+This can happen when folding commits that have been rebased by another user.
+
+  $ hg --cwd ../b strip tip
+  saved backup bundle to $TESTTMP/b/.hg/strip-backup/e81040e9838c-10aad4de-backup.hg
+  $ hg debugobsolete f7e5aaed408029cfe9890318245e87ef44739fdd e81040e9838c704d8bf17658cb11758f24e40b6b
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  $ hg --cwd ../b --config notify.showfunc=True pull ../a | \
+  >  "$PYTHON" $TESTDIR/unwrap-message-id.py
+  pulling from ../a
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  2 new obsolescence markers
+  obsoleted 2 changesets
+  new changesets e81040e9838c (1 drafts)
+  MIME-Version: 1.0
+  Content-Type: text/plain; charset="us-ascii"
+  Content-Transfer-Encoding: 7bit
+  Date: * (glob)
+  Subject: changefunction
+  From: [e-mail]
+  X-Hg-Notification: changeset e81040e9838c
+  Message-Id: <hg.[e-mail]>
+  In-Reply-To: <hg.[e-mail]>
+  To: [e-mail], foo@bar
+  
+  changeset e81040e9838c
+  diffs (12 lines):
+  
+  diff -r b86bc16ff894 -r e81040e9838c f1
+  --- a/f1	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/f1	Thu Jan 01 00:00:00 1970 +0000
+  @@ -2,6 +2,6 @@ int main() {
+       int a = 0;
+       int b = 1;
+       int c = 2;
+  -    int d = 3;
+  -    return a + b + c + d;
+  +    int e = 3;
+  +    return a + b + c + e;
+   }
+  (run 'hg update' to get a working copy)