actions: calculate what all parts does the operation touches

To make upgrade work less in certain situations, we need to teach it to find out
what all parts of repository current operation is touching.

This patch starts doing that. In next patch we will be setting values in
improvement objects. For now, we assume everything touches everything.

Differential Revision: https://phab.mercurial-scm.org/D9771

mercurial/upgrade_utils/actions.py

@@ -66,6 +66,18 b' class improvement(object):'
     postdowngrademessage
        Message intended for humans which will be shown post an upgrade
        operation in which this improvement was removed
+
+    touches_filelogs (bool)
+        Whether this improvement touches filelogs
+
+    touches_manifests (bool)
+        Whether this improvement touches manifests
+
+    touches_changelog (bool)
+        Whether this improvement touches changelog
+
+    touches_requirements (bool)
+        Whether this improvement changes repository requirements
     """
 
     def __init__(self, name, type, description, upgrademessage):
@@ -75,6 +87,12 b' class improvement(object):'
         self.upgrademessage = upgrademessage
         self.postupgrademessage = None
         self.postdowngrademessage = None
+        # By default for now, we assume every improvement touches
+        # all the things
+        self.touches_filelogs = True
+        self.touches_manifests = True
+        self.touches_changelog = True
+        self.touches_requirements = True
 
     def __eq__(self, other):
         if not isinstance(other, improvement):
@@ -128,6 +146,12 b' class formatvariant(improvement):'
     # operation in which this improvement was removed
     postdowngrademessage = None
 
+    # By default for now, we assume every improvement touches all the things
+    touches_filelogs = True
+    touches_manifests = True
+    touches_changelog = True
+    touches_requirements = True
+
     def __init__(self):
         raise NotImplementedError()
 
@@ -674,6 +698,72 b' class UpgradeOperation(object):'
         # should this operation create a backup of the store
         self.backup_store = backup_store
 
+        # whether the operation touches different revlogs at all or not
+        self.touches_filelogs = self._touches_filelogs()
+        self.touches_manifests = self._touches_manifests()
+        self.touches_changelog = self._touches_changelog()
+        # whether the operation touches requirements file or not
+        self.touches_requirements = self._touches_requirements()
+        self.touches_store = (
+            self.touches_filelogs
+            or self.touches_manifests
+            or self.touches_changelog
+        )
+        # does the operation only touches repository requirement
+        self.requirements_only = (
+            self.touches_requirements and not self.touches_store
+        )
+
+    def _touches_filelogs(self):
+        for a in self.upgrade_actions:
+            # in optimisations, we re-process the revlogs again
+            if a.type == OPTIMISATION:
+                return True
+            elif a.touches_filelogs:
+                return True
+        for a in self.removed_actions:
+            if a.touches_filelogs:
+                return True
+        return False
+
+    def _touches_manifests(self):
+        for a in self.upgrade_actions:
+            # in optimisations, we re-process the revlogs again
+            if a.type == OPTIMISATION:
+                return True
+            elif a.touches_manifests:
+                return True
+        for a in self.removed_actions:
+            if a.touches_manifests:
+                return True
+        return False
+
+    def _touches_changelog(self):
+        for a in self.upgrade_actions:
+            # in optimisations, we re-process the revlogs again
+            if a.type == OPTIMISATION:
+                return True
+            elif a.touches_changelog:
+                return True
+        for a in self.removed_actions:
+            if a.touches_changelog:
+                return True
+        return False
+
+    def _touches_requirements(self):
+        for a in self.upgrade_actions:
+            # optimisations are used to re-process revlogs and does not result
+            # in a requirement being added or removed
+            if a.type == OPTIMISATION:
+                pass
+            elif a.touches_requirements:
+                return True
+        for a in self.removed_actions:
+            if a.touches_requirements:
+                return True
+
+        return False
+
     def _write_labeled(self, l, label):
         """
         Utility function to aid writing of a list under one label