Allow playback of patchfiles (wrapper for git am)

CHANGELOG

@@ -1,3 +1,6 @@
+3.12.4
+  Provide a wrapper to apply patches and play back the affected objects.
+
 3.12.3
   Fix python3 crash in read_pdata, source might be bytes or string.
 

README.md

@@ -112,11 +112,16 @@ marked as `unsupported`, which are ignored if found in the ZODB. If only a
 given object itself should be updated (properties, security settings etc.),
 `--no-recurse` can be used.
 
-If using `--pick`, the given paths are not interpreted as object paths, but as
-git commits. This is useful if the repository the Data.FS is recorded to is
-tracked by git and some development has been done on a remote system that has
-to be deployed to the current system. It then becomes possible to do something
-like
+There are two other modes to use with `perfact-zopeplayback`, selected by
+passing `--pick` or `--apply`. These assume the file system representation is
+stored in a git repository and provide wrappers for `git cherry-pick` and `git
+am`, respectively. They also change the interpretation of the positional `path`
+arguments.
+
+If using `--pick`, the given paths are interpreted as git commits. This is
+useful if some development has been done in a branch or on a remote system that
+has to be deployed to the current system. It then becomes possible to do
+something like
 
     git fetch origin
     perfact-zopeplayback --pick origin/master
@@ -127,6 +132,10 @@ for example, to pull all commits where the commit message starts with T12345:
 
     perfact-zopeplayback --pick $(git log origin/master --reverse --pretty=%H --grep="^T12345" )
 
+
+Similarly, `--apply` allows to pass patch files that are to be applied, playing
+back all objects that are changed by these patches.
+
 ## Compatibility
 This package aims to replace similar functionality that was previously found in
 python-perfact and perfact-dbutils-zope2. For backwards compatibility, those

bin/perfact-zopeplayback

@@ -42,20 +42,31 @@ if __name__ == '__main__':
             '--skip-errors', action='store_true',
             help="Skip failed objects and continue",
             default=False)
-    parser.add_argument(
+    group = parser.add_mutually_exclusive_group()
+    group.add_argument(
         '--pick', action='store_true',
         help='''
         Switch to cherry-pick mode. The positional arguments are then
         interpreted as commits, which are checked for compatibility and
         applied, playing back all affected paths at the end.
         ''',
     )
+    group.add_argument(
+        '--apply', action='store_true',
+        help='''
+        Switch to apply mode. The positional arguments are then interpreted as
+        patch files which are applied to the repository (using git am). If
+        successful, the changed objects are played back. Else, the am session
+        is automatically rolled back.
+        ''',
+    )
+
     parser.add_argument(
         'path', nargs='+', type=str,
         help='''
         In default mode, paths of Data.FS objects to be played back. With
-        --pick, commits to be applied. The object list is then determined
-        automatically.
+        --pick, commits to be applied. With --apply, patch files to be applied.
+        The object list is then determined automatically.
         ''',
         )
     if 'perfact.loggingtools' in sys.modules:
@@ -71,16 +82,17 @@ if __name__ == '__main__':
     recurse = not args.no_recurse
 
     pickmode = args.pick
+    applymode = args.apply
 
     # Setup sync toolkit
     sync = perfact.zodbsync.ZODBSync(conffile=args.config, logger=logger)
 
     sync.acquire_lock()
 
-    def gitcmd(*args):
-        return ['git', '-C', sync.base_dir] + list(args)
+    if pickmode or applymode:
+        def gitcmd(*args):
+            return ['git', '-C', sync.base_dir] + list(args)
 
-    if pickmode:
         # Check that there are no unstaged changes
         dirty_workdir = len(subprocess.check_output(
             gitcmd('status', '--porcelain'),
@@ -89,15 +101,51 @@ if __name__ == '__main__':
             print("You have unstaged changes. Please commit or stash them")
             sys.exit(1)
 
-        commits = paths
-        paths = set()
-
         orig_commit = subprocess.check_output(
             gitcmd('show-ref', '--head', 'HEAD'),
             universal_newlines=True
         ).split()[0]
         print('Original commit: %s' % orig_commit)
 
+        changed_files = set()
+
+        # compatibility since python2 has no subprocess.DEVNULL
+        fnull = open(os.devnull, 'w')
+
+        # recurse and override are set automatically for these modes
+        recurse = False
+        override = True
+
+    if applymode:
+        # somehow, if we pass relative filenames to git while it is called with
+        # '-C' or even with '--git-dir' and '--work-tree', they are no longer
+        # interpreted relative to the current work dir. Therefore, we open the
+        # files ourselves and pass them via stdin
+        proc = subprocess.Popen(gitcmd('am'),
+            stdin=subprocess.PIPE
+        )
+        for path in paths:
+            print("Reading from %s" % path)
+            with open(path) as f:
+                proc.stdin.write(f.read())
+
+        proc.stdin.close()
+        proc.wait()
+        if proc.returncode:
+            print('Error applying patches. Rolling back')
+            subprocess.call(gitcmd('am', '--abort'))
+            sys.exit(1)
+
+        changed_files.update(set(subprocess.check_output(
+            gitcmd('diff-tree', '--no-commit-id', '--name-only', '-r',
+                orig_commit, 'HEAD'),
+            universal_newlines=True,
+        ).strip().split('\n')))
+
+    if pickmode:
+        commits = paths
+        paths = set()
+
         for commit in commits:
             print('Checking and applying %s.' % commit)
             # obtain files affected by the commit
@@ -122,27 +170,25 @@ if __name__ == '__main__':
                 subprocess.check_call(gitcmd('reset', '--hard', orig_commit))
                 sys.exit(1)
 
-            paths.update({
-                filename[len('__root__'):].rsplit('/', 1)[0]
-                for filename in files
-            })
-            # compatibility since python2 has no subprocess.DEVNULL
-            fnull = open(os.devnull, 'w')
+            changed_files.update(files)
             subprocess.check_call(
                 gitcmd('cherry-pick', commit),
                 stdout=fnull
             )
 
-        paths = sorted(paths)
-        recurse = False
-        override = True
+    if applymode or pickmode:
+        paths = sorted({
+            filename[len('__root__'):].rsplit('/', 1)[0]
+            for filename in changed_files
+        })
+    else:
+        paths.sort()
 
     note = 'perfact-zopeplayback'
     if len(paths) == 1:
         note += ': ' + paths[0]
     txn_mgr = sync.start_transaction(note=note)
 
-    paths.sort()
     try:
         for path in paths:
             sync.playback(path=path,

setup.py

@@ -4,7 +4,7 @@
 
 from setuptools import setup
 setup(name='perfact-zodbsync',
-      version='3.12.3',
+      version='3.12.4',
       description='Zope Recorder and Playback',
       long_description=''' ''',
       author='Ján Jockusch et.al.',