morph petrify: Avoid petrifying chunks that have already been edited

This change causes 'morph petrify' to avoid petrifying any chunk whose
ref matches the current system branch, because it makes no sense to
petrify something that is also being edited. It also improves efficiency
slightly and adds warning where different systems point to different
refs of the same stratum.

A non-obvious effect of this is that if you try to petrify 'master',
many of the chunks won't get petrified because they are built from
'master'. However, petrifying master makes no sense so I'm not sure
that we need to worry.

5 files changed, 130 insertions, 23 deletions

diff --git a/morphlib/plugins/branch_and_merge_plugin.py b/morphlib/plugins/branch_and_merge_plugin.py
index 384f0550..050410d4 100644
--- a/morphlib/plugins/branch_and_merge_plugin.py
+++ b/morphlib/plugins/branch_and_merge_plugin.py
@@ -722,7 +722,8 @@ class BranchAndMergePlugin(cliapp.Plugin):
         Strata refs are not petrified, because they must all be edited to set
         the new chunk refs, which requires branching them all for the current
         branch - so they will not be updated outside of the user's control in
-        any case.
+        any case. Chunks that have already been edited on the current branch
+        are also not petrified.
 
         '''
 
@@ -733,9 +734,11 @@ class BranchAndMergePlugin(cliapp.Plugin):
         branch, branch_path = self.deduce_system_branch()
         root_repo = self.get_branch_config(branch_path, 'branch.root')
         root_repo_dir = self.find_repository(branch_path, root_repo)
-
         self.lrc, self.rrc = morphlib.util.new_repo_caches(self.app)
 
+        # We must first get the full set of strata. One same stratum may be
+        # in multiple systems and each system may use a different ref.
+        strata = {}
         for f in glob.glob(os.path.join(root_repo_dir, '*.morph')):
             name = os.path.basename(f)[:-len('.morph')]
             morphology = self.load_morphology(root_repo_dir, name)
@@ -743,24 +746,42 @@ class BranchAndMergePlugin(cliapp.Plugin):
                 continue
 
             for stratum_info in morphology['strata']:
-                repo_dir = self.edit_stratum(
-                    branch, branch_path, root_repo, root_repo_dir,
-                    stratum_info)
-
-                stratum = self.load_morphology(repo_dir, stratum_info['morph'])
-
-                for chunk_info in stratum['chunks']:
-                    if 'unpetrify-ref' not in chunk_info:
-                        commit_sha1, tree_sha1 = self.app.resolve_ref(
-                            self.lrc, self.rrc, chunk_info['repo'],
-                            chunk_info['ref'],
-                            update=not self.app.settings['no-git-update'])
-                        chunk_info['unpetrify-ref'] = chunk_info['ref']
-                        chunk_info['ref'] = commit_sha1
-                self.save_morphology(repo_dir, stratum_info['morph'], stratum)
-
+                key = (stratum_info['repo'], stratum_info['morph'])
+                if key in strata:
+                    original_ref = strata[key]
+                    if stratum_info['ref'] == branch:
+                        strata[key] = branch
+                    elif stratum_info['ref'] != original_ref:
+                        if original_ref != branch:
+                            self.app.output.write(
+                                'WARNING: not merging any differences from '
+                                'ref %s into %s of stratum %s\n' %
+                                (stratum_info['ref'], original_ref,
+                                 stratum_info['morph']))
+                        stratum_info['ref'] = branch
+                else:
+                    strata[key] = stratum_info['ref']
+                    stratum_info['ref'] = branch
             self.save_morphology(root_repo_dir, name, morphology)
 
+        for (repo, morph), ref in strata.iteritems():
+            repo_dir = self.edit_stratum(
+                branch, branch_path, root_repo, root_repo_dir,
+                { 'repo': repo, 'ref': ref, 'morph': morph})
+
+            stratum = self.load_morphology(repo_dir, morph)
+
+            for chunk_info in stratum['chunks']:
+                if chunk_info['ref'] != branch and \
+                        'unpetrify-ref' not in chunk_info:
+                    commit_sha1, tree_sha1 = self.app.resolve_ref(
+                        self.lrc, self.rrc, chunk_info['repo'],
+                        chunk_info['ref'],
+                        update=not self.app.settings['no-git-update'])
+                    chunk_info['unpetrify-ref'] = chunk_info['ref']
+                    chunk_info['ref'] = commit_sha1
+            self.save_morphology(repo_dir, morph, stratum)
+
         self.print_changelog('The following changes were made but have not '
                              'been comitted')
 
diff --git a/tests.branching/petrify-no-double-petrify.script b/tests.branching/petrify-no-double-petrify.script
index 3e7ac412..9fc00d39 100755
--- a/tests.branching/petrify-no-double-petrify.script
+++ b/tests.branching/petrify-no-double-petrify.script
@@ -31,9 +31,9 @@ fi
 
 cd "$DATADIR/workspace"
 "$SRCDIR/scripts/test-morph" init
-"$SRCDIR/scripts/test-morph" checkout baserock:morphs master
+"$SRCDIR/scripts/test-morph" branch baserock:morphs test/petrify
 
-cd master/baserock:morphs
+cd test/petrify/baserock:morphs
 "$SRCDIR/scripts/test-morph" petrify
 "$SRCDIR/scripts/test-morph" petrify
 "$SRCDIR/scripts/test-morph" petrify
diff --git a/tests.branching/petrify.script b/tests.branching/petrify.script
index 0b5ff018..c1828bf3 100755
--- a/tests.branching/petrify.script
+++ b/tests.branching/petrify.script
@@ -15,7 +15,8 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 
-# Verify that "morph petrify" works.
+# Verify "morph petrify", and ensure it doesn't petrify chunks that have
+# already been edited.
 
 
 set -eu
@@ -28,11 +29,15 @@ then
     exit 0
 fi
 
+. "$SRCDIR/tests.branching/setup-second-chunk"
+
 cd "$DATADIR/workspace"
 "$SRCDIR/scripts/test-morph" init
-"$SRCDIR/scripts/test-morph" checkout baserock:morphs master
+"$SRCDIR/scripts/test-morph" branch baserock:morphs test/petrify master
+
+cd test/petrify/baserock:morphs
+"$SRCDIR/scripts/test-morph" edit hello-system hello-stratum goodbye
 
-cd master/baserock:morphs
 "$SRCDIR/scripts/test-morph" petrify
 echo "Petrified:"
 cat hello-stratum.morph
diff --git a/tests.branching/petrify.stdout b/tests.branching/petrify.stdout
index 249a8f59..6219c84e 100644
--- a/tests.branching/petrify.stdout
+++ b/tests.branching/petrify.stdout
@@ -9,6 +9,12 @@ Petrified:
             "ref": "f4d032b42c0134e67bdf19a43fa99072493667d7",
             "build-depends": [],
             "unpetrify-ref": "master"
+        },
+        {
+            "name": "goodbye",
+            "repo": "baserock:goodbye",
+            "ref": "test/petrify",
+            "build-depends": []
         }
     ]
 }
@@ -23,6 +29,12 @@ Unpetrified:
             "repo": "baserock:hello",
             "ref": "master",
             "build-depends": []
+        },
+        {
+            "name": "goodbye",
+            "repo": "baserock:goodbye",
+            "ref": "test/petrify",
+            "build-depends": []
         }
     ]
 }
diff --git a/tests.branching/setup-second-chunk b/tests.branching/setup-second-chunk
new file mode 100755
index 00000000..9f7aa419
--- /dev/null
+++ b/tests.branching/setup-second-chunk
@@ -0,0 +1,69 @@
+#!/bin/sh
+# Copyright (C) 2012  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+# Add a second chunk to hello-stratum.
+
+. "$SRCDIR/scripts/fix-committer-info"
+
+create_chunk() {
+    REPO="$1"
+    NAME="$2"
+
+    mkdir "$1"
+    ln -s "$1" "$1.git"
+    cd "$1"
+
+    cat <<EOF > "$1/$2.morph"
+{
+    "name": "$2",
+    "kind": "chunk",
+    "build-system": "dummy"
+}
+EOF
+
+    git init --quiet
+    git add  .
+    git commit --quiet -m "Initial commit"
+}
+
+create_chunk "$DATADIR/goodbye" "hello"
+
+cd "$DATADIR/morphs"
+cat <<EOF > hello-stratum.morph
+{
+    "name": "hello-stratum",
+    "kind": "stratum",
+    "chunks": [
+        {
+            "name": "hello",
+            "repo": "baserock:hello",
+            "ref": "master",
+            "build-depends": []
+        },
+        {
+            "name": "goodbye",
+            "repo": "baserock:goodbye",
+            "ref": "master",
+            "build-depends": []
+        }
+    ]
+}
+EOF
+
+git commit -q --all -m "Add goodbye to hello-stratum"
+
+cd "$DATADIR/workspace"