upload: search local projects in parallel

Search for project branches to upload in parallel.  This can cut the
lookup time in half for large projects.  We still run the actual hooks
in serial once we have the list of projects to process, but we would
need to rethink things quite a bit before we could handle running them
in parallel too.

Change-Id: I8da0cbc5010566aa860e1a158f3dc07f0709dcff
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/304842
Reviewed-by: Raman Tenneti <rtenneti@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

subcmds/upload.py

@@ -13,10 +13,11 @@
 # limitations under the License.
 
 import copy
+import functools
 import re
 import sys
 
-from command import InteractiveCommand
+from command import DEFAULT_LOCAL_JOBS, InteractiveCommand
 from editor import Editor
 from error import UploadError
 from git_command import GitCommand
@@ -145,6 +146,7 @@ https://gerrit-review.googlesource.com/Documentation/user-upload.html#notify
 Gerrit Code Review:  https://www.gerritcodereview.com/
 
 """
+  PARALLEL_JOBS = DEFAULT_LOCAL_JOBS
 
   def _Options(self, p):
     p.add_option('-t',
@@ -165,9 +167,9 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
     p.add_option('--cc',
                  type='string', action='append', dest='cc',
                  help='Also send email to these email addresses.')
-    p.add_option('--br',
+    p.add_option('--br', '--branch',
                  type='string', action='store', dest='branch',
-                 help='Branch to upload.')
+                 help='(Local) branch to upload.')
     p.add_option('--cbr', '--current-branch',
                  dest='current_branch', action='store_true',
                  help='Upload current git branch.')
@@ -502,40 +504,46 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
     merge_branch = p.stdout.strip()
     return merge_branch
 
+  @staticmethod
+  def _GatherOne(opt, project):
+    """Figure out the upload status for |project|."""
+    if opt.current_branch:
+      cbr = project.CurrentBranch
+      up_branch = project.GetUploadableBranch(cbr)
+      avail = [up_branch] if up_branch else None
+    else:
+      avail = project.GetUploadableBranches(opt.branch)
+    return (project, avail)
+
   def Execute(self, opt, args):
-    project_list = self.GetProjects(args)
-    pending = []
-    reviewers = []
-    cc = []
-    branch = None
+    projects = self.GetProjects(args)
 
-    if opt.branch:
-      branch = opt.branch
-
-    for project in project_list:
-      if opt.current_branch:
-        cbr = project.CurrentBranch
-        up_branch = project.GetUploadableBranch(cbr)
-        if up_branch:
-          avail = [up_branch]
-        else:
-          avail = None
+    def _ProcessResults(_pool, _out, results):
+      pending = []
+      for result in results:
+        project, avail = result
+        if avail is None:
           print('repo: error: %s: Unable to upload branch "%s". '
                 'You might be able to fix the branch by running:\n'
                 '  git branch --set-upstream-to m/%s' %
-                (project.relpath, str(cbr), self.manifest.branch),
+                (project.relpath, project.CurrentBranch, self.manifest.branch),
                 file=sys.stderr)
-      else:
-        avail = project.GetUploadableBranches(branch)
-      if avail:
-        pending.append((project, avail))
+        elif avail:
+          pending.append(result)
+      return pending
+
+    pending = self.ExecuteInParallel(
+        opt.jobs,
+        functools.partial(self._GatherOne, opt),
+        projects,
+        callback=_ProcessResults)
 
     if not pending:
-      if branch is None:
+      if opt.branch is None:
         print('repo: error: no branches ready for upload', file=sys.stderr)
       else:
         print('repo: error: no branches named "%s" ready for upload' %
-              (branch,), file=sys.stderr)
+              (opt.branch,), file=sys.stderr)
       return 1
 
     pending_proj_names = [project.name for (project, available) in pending]
@@ -548,10 +556,8 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
         worktree_list=pending_worktrees):
       return 1
 
-    if opt.reviewers:
-      reviewers = _SplitEmails(opt.reviewers)
-    if opt.cc:
-      cc = _SplitEmails(opt.cc)
+    reviewers = _SplitEmails(opt.reviewers) if opt.reviewers else []
+    cc = _SplitEmails(opt.cc) if opt.cc else []
     people = (reviewers, cc)
 
     if len(pending) == 1 and len(pending[0][1]) == 1: