Change repo sync to be more friendly when updating the treev1.6.6

We now try to sync all projects that can be done safely first, before
we start rebasing user commits over the upstream.  This has the nice
effect of making the local tree as close to the upstream as possible
before the user has to start resolving merge conflicts, as that extra
information in other projects may aid in the conflict resolution.

Informational output is buffered and delayed until calculation for
all projects has been done, so that the user gets one concise list
of notice messages, rather than it interrupting the progress meter.

Fast-forward output is now prefixed with the project header, so the
user can see which project that update is taking place in, and make
some relation of the diffstat back to the project name.

Rebase output is now prefixed with the project header, so that if
the rebase fails, the user can see which project we were operating
on and can try to address the failure themselves.

Since rebase sits on a detached HEAD, we now look for an in-progress
rebase during sync, so we can alert the user that the given project
is in a state we cannot handle.

Signed-off-by: Shawn O. Pearce <sop@google.com>

4 files changed, 175 insertions, 62 deletions

diff --git a/color.py b/color.py
index 07d1f6fd..7fa21d23 100644
--- a/color.py
+++ b/color.py
@@ -100,6 +100,9 @@ class Coloring(object):
     else:
       self._on = False
 
+  def redirect(self, out):
+    self._out = out
+
   @property
   def is_on(self):
     return self._on
diff --git a/project.py b/project.py
index 33cb3444..6621f1cb 100644
--- a/project.py
+++ b/project.py
@@ -38,14 +38,6 @@ def _error(fmt, *args):
   msg = fmt % args
   print >>sys.stderr, 'error: %s' % msg
 
-def _warn(fmt, *args):
-  msg = fmt % args
-  print >>sys.stderr, 'warn: %s' % msg
-
-def _info(fmt, *args):
-  msg = fmt % args
-  print >>sys.stderr, 'info: %s' % msg
-
 def not_rev(r):
   return '^' + r
 
@@ -576,13 +568,9 @@ class Project(object):
     for file in self.copyfiles:
       file._Copy()
 
-  def Sync_LocalHalf(self, detach_head=False):
+  def Sync_LocalHalf(self, syncbuf):
     """Perform only the local IO portion of the sync process.
        Network access is not required.
-
-       Return:
-         True:  the sync was successful
-         False: the sync requires user input
     """
     self._InitWorkTree()
     self.CleanPublishedCache()
@@ -597,19 +585,25 @@ class Project(object):
 
     branch = self.CurrentBranch
 
-    if branch is None or detach_head:
+    if branch is None or syncbuf.detach_head:
       # Currently on a detached HEAD.  The user is assumed to
       # not have any local modifications worth worrying about.
       #
+      if os.path.exists(os.path.join(self.worktree, '.dotest')) \
+      or os.path.exists(os.path.join(self.worktree, '.git', 'rebase-apply')):
+        syncbuf.fail(self, _PriorSyncFailedError())
+        return
+
       lost = self._revlist(not_rev(rev), HEAD)
       if lost:
-        _info("[%s] Discarding %d commits", self.name, len(lost))
+        syncbuf.info(self, "discarding %d commits", len(lost))
       try:
         self._Checkout(rev, quiet=True)
-      except GitError:
-        return False
+      except GitError, e:
+        syncbuf.fail(self, e)
+        return
       self._CopyFiles()
-      return True
+      return
 
     branch = self.GetBranch(branch)
     merge = branch.LocalMerge
@@ -618,16 +612,16 @@ class Project(object):
       # The current branch has no tracking configuration.
       # Jump off it to a deatched HEAD.
       #
-      _info("[%s] Leaving %s"
-            " (does not track any upstream)",
-            self.name,
-            branch.name)
+      syncbuf.info(self,
+                   "leaving %s; does not track upstream",
+                   branch.name)
       try:
         self._Checkout(rev, quiet=True)
-      except GitError:
-        return False
+      except GitError, e:
+        syncbuf.fail(self, e)
+        return
       self._CopyFiles()
-      return True
+      return
 
     upstream_gain = self._revlist(not_rev(HEAD), rev)
     pub = self.WasPublished(branch.name)
@@ -639,25 +633,24 @@ class Project(object):
           # commits are not yet merged upstream.  We do not want
           # to rewrite the published commits so we punt.
           #
-          _info("[%s] Branch %s is published,"
-                " but is now %d commits behind.",
-                self.name, branch.name, len(upstream_gain))
-          _info("[%s] Consider merging or rebasing the"
-                " unpublished commits.", self.name)
-        return True
+          syncbuf.info(self,
+                       "branch %s is published but is now %d commits behind",
+                       branch.name,
+                       len(upstream_gain))
+          syncbuf.info(self, "consider merging or rebasing the unpublished commits")
+        return
       elif upstream_gain:
         # We can fast-forward safely.
         #
-        try:
+        def _doff():
           self._FastForward(rev)
-        except GitError:
-          return False
-        self._CopyFiles()
-        return True
+          self._CopyFiles()
+        syncbuf.later1(self, _doff)
+        return
       else:
         # Trivially no changes in the upstream.
         #
-        return True
+        return
 
     if merge == rev:
       try:
@@ -672,8 +665,7 @@ class Project(object):
       # and pray that the old upstream also wasn't in the habit
       # of rebasing itself.
       #
-      _info("[%s] Manifest switched from %s to %s",
-            self.name, merge, rev)
+      syncbuf.info(self, "manifest switched %s...%s", merge, rev)
       old_merge = merge
 
     if rev == old_merge:
@@ -684,19 +676,19 @@ class Project(object):
     if not upstream_lost and not upstream_gain:
       # Trivially no changes caused by the upstream.
       #
-      return True
+      return
 
     if self.IsDirty(consider_untracked=False):
-      _warn('[%s] commit (or discard) uncommitted changes'
-            ' before sync', self.name)
-      return False
+      syncbuf.fail(self, _DirtyError())
+      return
 
     if upstream_lost:
       # Upstream rebased.  Not everything in HEAD
       # may have been caused by the user.
       #
-      _info("[%s] Discarding %d commits removed from upstream",
-            self.name, len(upstream_lost))
+      syncbuf.info(self,
+                   "discarding %d commits removed from upstream",
+                   len(upstream_lost))
 
     branch.remote = rem
     branch.merge = self.revision
@@ -704,23 +696,22 @@ class Project(object):
 
     my_changes = self._revlist(not_rev(old_merge), HEAD)
     if my_changes:
-      try:
+      def _dorebase():
         self._Rebase(upstream = old_merge, onto = rev)
-      except GitError:
-        return False
+        self._CopyFiles()
+      syncbuf.later2(self, _dorebase)
     elif upstream_lost:
       try:
         self._ResetHard(rev)
-      except GitError:
-        return False
+        self._CopyFiles()
+      except GitError, e:
+        syncbuf.fail(self, e)
+        return
     else:
-      try:
+      def _doff():
         self._FastForward(rev)
-      except GitError:
-        return False
-
-    self._CopyFiles()
-    return True
+        self._CopyFiles()
+      syncbuf.later1(self, _doff)
 
   def AddCopyFile(self, src, dest, absdest):
     # dest should already be an absolute path, but src is project relative
@@ -1212,6 +1203,113 @@ class Project(object):
       return runner
 
 
+class _PriorSyncFailedError(Exception):
+  def __str__(self):
+    return 'prior sync failed; rebase still in progress'
+
+class _DirtyError(Exception):
+  def __str__(self):
+    return 'contains uncommitted changes'
+
+class _InfoMessage(object):
+  def __init__(self, project, text):
+    self.project = project
+    self.text = text
+
+  def Print(self, syncbuf):
+    syncbuf.out.info('%s/: %s', self.project.relpath, self.text)
+    syncbuf.out.nl()
+
+class _Failure(object):
+  def __init__(self, project, why):
+    self.project = project
+    self.why = why
+
+  def Print(self, syncbuf):
+    syncbuf.out.fail('error: %s/: %s',
+                     self.project.relpath,
+                     str(self.why))
+    syncbuf.out.nl()
+
+class _Later(object):
+  def __init__(self, project, action):
+    self.project = project
+    self.action = action
+
+  def Run(self, syncbuf):
+    out = syncbuf.out
+    out.project('project %s/', self.project.relpath)
+    out.nl()
+    try:
+      self.action()
+      out.nl()
+      return True
+    except GitError, e:
+      out.nl()
+      return False
+
+class _SyncColoring(Coloring):
+  def __init__(self, config):
+    Coloring.__init__(self, config, 'reposync')
+    self.project   = self.printer('header', attr = 'bold')
+    self.info      = self.printer('info')
+    self.fail      = self.printer('fail', fg='red')
+
+class SyncBuffer(object):
+  def __init__(self, config, detach_head=False):
+    self._messages = []
+    self._failures = []
+    self._later_queue1 = []
+    self._later_queue2 = []
+
+    self.out = _SyncColoring(config)
+    self.out.redirect(sys.stderr)
+
+    self.detach_head = detach_head
+    self.clean = True
+
+  def info(self, project, fmt, *args):
+    self._messages.append(_InfoMessage(project, fmt % args))
+
+  def fail(self, project, err=None):
+    self._failures.append(_Failure(project, err))
+    self.clean = False
+
+  def later1(self, project, what):
+    self._later_queue1.append(_Later(project, what))
+
+  def later2(self, project, what):
+    self._later_queue2.append(_Later(project, what))
+
+  def Finish(self):
+    self._PrintMessages()
+    self._RunLater()
+    self._PrintMessages()
+    return self.clean
+
+  def _RunLater(self):
+    for q in ['_later_queue1', '_later_queue2']:
+      if not self._RunQueue(q):
+        return
+
+  def _RunQueue(self, queue):
+    for m in getattr(self, queue):
+      if not m.Run(self):
+        self.clean = False
+        return False
+    setattr(self, queue, [])
+    return True
+
+  def _PrintMessages(self):
+    for m in self._messages:
+      m.Print(self)
+    for m in self._failures:
+      m.Print(self)
+
+    self._messages = []
+    self._failures = []
+
+
 class MetaProject(Project):
   """A special project housed under .repo.
   """
diff --git a/subcmds/init.py b/subcmds/init.py
index a32eaae0..103a78d6 100644
--- a/subcmds/init.py
+++ b/subcmds/init.py
@@ -20,6 +20,7 @@ from color import Coloring
 from command import InteractiveCommand, MirrorSafeCommand
 from error import ManifestParseError
 from remote import Remote
+from project import SyncBuffer
 from git_command import git, MIN_GIT_VERSION
 
 class Init(InteractiveCommand, MirrorSafeCommand):
@@ -129,7 +130,10 @@ default.xml will be used.
       print >>sys.stderr, 'fatal: cannot obtain manifest %s' % r.url
       sys.exit(1)
 
-    m.Sync_LocalHalf()
+    syncbuf = SyncBuffer(m.config)
+    m.Sync_LocalHalf(syncbuf)
+    syncbuf.Finish()
+
     if is_new or m.CurrentBranch is None:
       if not m.StartBranch('default'):
         print >>sys.stderr, 'fatal: cannot create default in manifest'
diff --git a/subcmds/sync.py b/subcmds/sync.py
index f6eb2a08..ec5ada21 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -24,6 +24,7 @@ from project import HEAD
 from command import Command, MirrorSafeCommand
 from error import RepoChangedException, GitError
 from project import R_HEADS
+from project import SyncBuffer
 from progress import Progress
 
 class Sync(Command, MirrorSafeCommand):
@@ -112,7 +113,9 @@ revision is temporarily needed.
         return
 
       if mp.HasChanges:
-        if not mp.Sync_LocalHalf():
+        syncbuf = SyncBuffer(mp.config)
+        mp.Sync_LocalHalf(syncbuf)
+        if not syncbuf.Finish():
           sys.exit(1)
 
         self.manifest._Unload()
@@ -123,14 +126,17 @@ revision is temporarily needed.
             missing.append(project)
         self._Fetch(*missing)
 
+    syncbuf = SyncBuffer(mp.config,
+                         detach_head = opt.detach_head)
     pm = Progress('Syncing work tree', len(all))
     for project in all:
       pm.update()
       if project.worktree:
-        if not project.Sync_LocalHalf(
-            detach_head=opt.detach_head):
-          sys.exit(1)
+        project.Sync_LocalHalf(syncbuf)
     pm.end()
+    print >>sys.stderr
+    if not syncbuf.Finish():
+      sys.exit(1)
 
 
 def _PostRepoUpgrade(manifest):
@@ -143,7 +149,9 @@ def _PostRepoFetch(rp, no_repo_verify=False, verbose=False):
     print >>sys.stderr, 'info: A new version of repo is available'
     print >>sys.stderr, ''
     if no_repo_verify or _VerifyTag(rp):
-      if not rp.Sync_LocalHalf():
+      syncbuf = SyncBuffer(rp.config)
+      rp.Sync_LocalHalf(syncbuf)
+      if not syncbuf.Finish():
         sys.exit(1)
       print >>sys.stderr, 'info: Restarting repo with latest version'
       raise RepoChangedException(['--repo-upgraded'])