command: unify --job option & default values

Extend the Command class to support adding the --jobs option to the
parser if the command declares it supports running in parallel.  Also
pull the default value used for the number of local jobs into the
command module so local commands can share it.

Change-Id: I22b0f8d2cf69875013cec657b8e6c4385549ccac
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/297024
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Chris Mcdonald <cjmcdonald@google.com>

command.py

@@ -23,6 +23,11 @@ from error import NoSuchProjectError
 from error import InvalidProjectGroupsError
 
 
+# How many jobs to run in parallel by default?  This assumes the jobs are
+# largely I/O bound and do not hit the network.
+DEFAULT_LOCAL_JOBS = min(os.cpu_count(), 8)
+
+
 class Command(object):
   """Base class for any command line action in repo.
   """
@@ -32,6 +37,10 @@ class Command(object):
   manifest = None
   _optparse = None
 
+  # Whether this command supports running in parallel.  If greater than 0,
+  # it is the number of parallel jobs to default to.
+  PARALLEL_JOBS = None
+
   def WantPager(self, _opt):
     return False
 
@@ -72,6 +81,11 @@ class Command(object):
   def _Options(self, p):
     """Initialize the option parser.
     """
+    if self.PARALLEL_JOBS is not None:
+      p.add_option(
+          '-j', '--jobs',
+          type=int, default=self.PARALLEL_JOBS,
+          help='number of jobs to run in parallel (default: %s)' % self.PARALLEL_JOBS)
 
   def _RegisteredEnvironmentOptions(self):
     """Get options that can be set from environment variables.

subcmds/branches.py

@@ -16,7 +16,7 @@ import itertools
 import multiprocessing
 import sys
 from color import Coloring
-from command import Command
+from command import Command, DEFAULT_LOCAL_JOBS
 
 # Number of projects to submit to a single worker process at a time.
 # This number represents a tradeoff between the overhead of IPC and finer
@@ -103,17 +103,7 @@ the branch appears in, or does not appear in.  If no project list
 is shown, then the branch appears in all projects.
 
 """
-
-  def _Options(self, p):
-    """Add flags to CLI parser for this subcommand."""
-    default_jobs = min(multiprocessing.cpu_count(), 8)
-    p.add_option(
-        '-j',
-        '--jobs',
-        type=int,
-        default=default_jobs,
-        help='Number of worker processes to spawn '
-        '(default: %s)' % default_jobs)
+  PARALLEL_JOBS = DEFAULT_LOCAL_JOBS
 
   def Execute(self, opt, args):
     projects = self.GetProjects(args)

subcmds/forall.py

@@ -21,7 +21,7 @@ import sys
 import subprocess
 
 from color import Coloring
-from command import Command, MirrorSafeCommand
+from command import DEFAULT_LOCAL_JOBS, Command, MirrorSafeCommand
 import platform_utils
 
 _CAN_COLOR = [
@@ -113,8 +113,11 @@ terminal and are not redirected.
 If -e is used, when a command exits unsuccessfully, '%prog' will abort
 without iterating through the remaining projects.
 """
+  PARALLEL_JOBS = DEFAULT_LOCAL_JOBS
 
   def _Options(self, p):
+    super()._Options(p)
+
     def cmd(option, opt_str, value, parser):
       setattr(parser.values, option.dest, list(parser.rargs))
       while parser.rargs:
@@ -148,9 +151,6 @@ without iterating through the remaining projects.
     g.add_option('-v', '--verbose',
                  dest='verbose', action='store_true',
                  help='Show command error messages')
-    g.add_option('-j', '--jobs',
-                 dest='jobs', action='store', type='int', default=1,
-                 help='number of commands to execute simultaneously')
 
   def WantPager(self, opt):
     return opt.project_header and opt.jobs == 1

subcmds/status.py

@@ -17,7 +17,7 @@ import glob
 import multiprocessing
 import os
 
-from command import PagedCommand
+from command import DEFAULT_LOCAL_JOBS, PagedCommand
 
 from color import Coloring
 import platform_utils
@@ -76,11 +76,10 @@ the following meanings:
  d:  deleted       (    in index, not in work tree                )
 
 """
+  PARALLEL_JOBS = DEFAULT_LOCAL_JOBS
 
   def _Options(self, p):
-    p.add_option('-j', '--jobs',
-                 dest='jobs', action='store', type='int', default=2,
-                 help="number of projects to check simultaneously")
+    super()._Options(p)
     p.add_option('-o', '--orphans',
                  dest='orphans', action='store_true',
                  help="include objects in working directory outside of repo projects")

subcmds/sync.py

@@ -177,12 +177,14 @@ If the remote SSH daemon is Gerrit Code Review, version 2.0.10 or
 later is required to fix a server side protocol bug.
 
 """
+  PARALLEL_JOBS = 1
 
   def _Options(self, p, show_smart=True):
     try:
-      self.jobs = self.manifest.default.sync_j
+      self.PARALLEL_JOBS = self.manifest.default.sync_j
     except ManifestParseError:
-      self.jobs = 1
+      pass
+    super()._Options(p)
 
     p.add_option('-f', '--force-broken',
                  dest='force_broken', action='store_true',
@@ -222,9 +224,6 @@ later is required to fix a server side protocol bug.
     p.add_option('-q', '--quiet',
                  dest='output_mode', action='store_false',
                  help='only show errors')
-    p.add_option('-j', '--jobs',
-                 dest='jobs', action='store', type='int',
-                 help="projects to fetch simultaneously (default %d)" % self.jobs)
     p.add_option('-m', '--manifest-name',
                  dest='manifest_name',
                  help='temporary manifest to use for this sync', metavar='NAME.xml')