dirstate-v2: add flag to `debugstate` to print docket information stable

dirstate-v2: add flag to `debugstate` to print docket information

This is useful information that we don't easily have access to currently,
unless you speak fluent xxd.

This replaces `debugdirstateignorepatternshash`, which I'll remove in the next
changeset.

Differential Revision: https://phab.mercurial-scm.org/D12590

--- a/mercurial/debugcommands.py	Mon May 02 22:04:59 2022 -0400
+++ b/mercurial/debugcommands.py	Thu Apr 28 15:19:19 2022 +0200
@@ -47,6 +47,7 @@
     context,
     copies,
     dagparser,
+    dirstateutils,
     encoding,
     error,
     exchange,
@@ -940,6 +941,12 @@
         (b'', b'datesort', None, _(b'sort by saved mtime')),
         (
             b'',
+            b'docket',
+            False,
+            _(b'display the docket (metadata file) instead'),
+        ),
+        (
+            b'',
             b'all',
             False,
             _(b'display dirstate-v2 tree nodes that would not exist in v1'),
@@ -950,6 +957,33 @@
 def debugstate(ui, repo, **opts):
     """show the contents of the current dirstate"""
 
+    if opts.get("docket"):
+        if not repo.dirstate._use_dirstate_v2:
+            raise error.Abort(_(b'dirstate v1 does not have a docket'))
+
+        docket = repo.dirstate._map.docket
+        (
+            start_offset,
+            root_nodes,
+            nodes_with_entry,
+            nodes_with_copy,
+            unused_bytes,
+            _unused,
+            ignore_pattern,
+        ) = dirstateutils.v2.TREE_METADATA.unpack(docket.tree_metadata)
+
+        ui.write(_(b"size of dirstate data: %d\n") % docket.data_size)
+        ui.write(_(b"data file uuid: %s\n") % docket.uuid)
+        ui.write(_(b"start offset of root nodes: %d\n") % start_offset)
+        ui.write(_(b"number of root nodes: %d\n") % root_nodes)
+        ui.write(_(b"nodes with entries: %d\n") % nodes_with_entry)
+        ui.write(_(b"nodes with copies: %d\n") % nodes_with_copy)
+        ui.write(_(b"number of unused bytes: %d\n") % unused_bytes)
+        ui.write(
+            _(b"ignore pattern hash: %s\n") % binascii.hexlify(ignore_pattern)
+        )
+        return
+
     nodates = not opts['dates']
     if opts.get('nodates') is not None:
         nodates = True

--- a/tests/test-completion.t	Mon May 02 22:04:59 2022 -0400
+++ b/tests/test-completion.t	Thu Apr 28 15:19:19 2022 +0200
@@ -286,7 +286,7 @@
   debugdate: extended
   debugdeltachain: changelog, manifest, dir, template
   debugdirstateignorepatternshash: 
-  debugdirstate: nodates, dates, datesort, all
+  debugdirstate: nodates, dates, datesort, docket, all
   debugdiscovery: old, nonheads, rev, seed, local-as-revs, remote-as-revs, ssh, remotecmd, insecure, template
   debugdownload: output
   debugextensions: template

--- a/tests/test-hgignore.t	Mon May 02 22:04:59 2022 -0400
+++ b/tests/test-hgignore.t	Thu Apr 28 15:19:19 2022 +0200
@@ -418,14 +418,14 @@
   $ hg status > /dev/null
   $ cat .hg/testhgignore .hg/testhgignorerel .hgignore dir2/.hgignore dir1/.hgignore dir1/.hgignoretwo | $TESTDIR/f --sha1
   sha1=6e315b60f15fb5dfa02be00f3e2c8f923051f5ff
-  $ hg debugdirstateignorepatternshash
-  6e315b60f15fb5dfa02be00f3e2c8f923051f5ff
+  $ hg debugstate --docket | grep ignore
+  ignore pattern hash: 6e315b60f15fb5dfa02be00f3e2c8f923051f5ff
 
   $ echo rel > .hg/testhgignorerel
   $ hg status > /dev/null
   $ cat .hg/testhgignore .hg/testhgignorerel .hgignore dir2/.hgignore dir1/.hgignore dir1/.hgignoretwo | $TESTDIR/f --sha1
   sha1=dea19cc7119213f24b6b582a4bae7b0cb063e34e
-  $ hg debugdirstateignorepatternshash
-  dea19cc7119213f24b6b582a4bae7b0cb063e34e
+  $ hg debugstate --docket | grep ignore
+  ignore pattern hash: dea19cc7119213f24b6b582a4bae7b0cb063e34e
 
 #endif