patman: Run get_maintainer.pl in parallel

This script can take ages on some series. Try to limit the time by
using threads. If a few stubborn patches remain, show progress so the
user has some idea what is going on.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

tools/patman/func_test.py

@@ -240,6 +240,8 @@ class TestFunctional(unittest.TestCase):
         self.assertEqual('Change log missing for v3', next(lines))
         self.assertEqual('Change log for unknown version v4', next(lines))
         self.assertEqual("Alias 'pci' not found", next(lines))
+        while next(lines) != 'Cc processing complete':
+            pass
         self.assertIn('Dry run', next(lines))
         self.assertEqual('', next(lines))
         self.assertIn('Send a total of %d patches' % count, next(lines))

tools/patman/series.py

@@ -5,8 +5,11 @@
 from __future__ import print_function
 
 import collections
+import concurrent.futures
 import itertools
 import os
+import sys
+import time
 
 from patman import get_maintainer
 from patman import gitutil
@@ -303,10 +306,34 @@ class Series(dict):
         fd = open(fname, 'w', encoding='utf-8')
         all_ccs = []
         all_skips = set()
+        with concurrent.futures.ThreadPoolExecutor(max_workers=16) as executor:
+            for i, commit in enumerate(self.commits):
+                commit.seq = i
+                commit.future = executor.submit(
+                    self.GetCcForCommit, commit, process_tags, warn_on_error,
+                    add_maintainers, limit, get_maintainer_script, all_skips)
+
+            # Show progress any commits that are taking forever
+            lastlen = 0
+            while True:
+                left = [commit for commit in self.commits
+                        if not commit.future.done()]
+                if not left:
+                    break
+                names = ', '.join(f'{c.seq + 1}:{c.subject}'
+                                  for c in left[:2])
+                out = f'\r{len(left)} remaining: {names}'[:79]
+                spaces = ' ' * (lastlen - len(out))
+                if lastlen:  # Don't print anything the first time
+                    print(out, spaces, end='')
+                    sys.stdout.flush()
+                lastlen = len(out)
+                time.sleep(.25)
+            print(f'\rdone{" " * lastlen}\r', end='')
+            print('Cc processing complete')
+
         for commit in self.commits:
-            cc = self.GetCcForCommit(commit, process_tags, warn_on_error,
-                                     add_maintainers, limit,
-                                     get_maintainer_script, all_skips)
+            cc = commit.future.result()
             all_ccs += cc
             print(commit.patch, '\0'.join(sorted(set(cc))), file=fd)
             self._generated_cc[commit.patch] = cc