repo: Add a new "command" event type to git trace2 logging in repo.

Add a new "event": "command", which is emitted at when all command
arguments have been processed.

Additional fields:

"name": Name of the primary command (ex: repo, git)

"subcommands"': List of the sub-commands once command-line arguments
                are processed

Examples:

Command: repo --version

Event: {"event": "command", <common fields>,
        "name": "repo",
	"subcommands": ["version"]
	}

Bug: [google internal] b/178507266
Testing:
- Unit tests
- Verified repo git trace2 logs had expected data

Change-Id: I825bd0ecedee45135382461a4ba10f987f09aef3
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/300343
Reviewed-by: Ian Kasprzak <iankaz@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Raman Tenneti <rtenneti@google.com>

git_trace2_event_log.py

@@ -132,6 +132,18 @@ class EventLog(object):
     exit_event['code'] = result
     self._log.append(exit_event)
 
+  def CommandEvent(self, name, subcommands):
+    """Append a 'command' event to the current log.
+
+    Args:
+      name: Name of the primary command (ex: repo, git)
+      subcommands: List of the sub-commands (ex: version, init, sync)
+    """
+    command_event = self._CreateEventDict('command')
+    command_event['name'] = name
+    command_event['subcommands'] = subcommands
+    self._log.append(command_event)
+
   def DefParamRepoEvents(self, config):
     """Append a 'def_param' event for each repo.* config key to the current log.
 

main.py

@@ -254,6 +254,7 @@ class _Repo(object):
     cmd_event = cmd.event_log.Add(name, event_log.TASK_COMMAND, start)
     cmd.event_log.SetParent(cmd_event)
     git_trace2_event_log.StartEvent()
+    git_trace2_event_log.CommandEvent(name='repo', subcommands=[name])
 
     try:
       cmd.ValidateOptions(copts, cargs)

tests/test_git_trace2_event_log.py

@@ -161,6 +161,30 @@ class EventLogTestCase(unittest.TestCase):
     self.assertIn('code', exit_event)
     self.assertEqual(exit_event['code'], 2)
 
+  def test_command_event(self):
+    """Test and validate 'command' event data is valid.
+
+    Expected event log:
+    <version event>
+    <command event>
+    """
+    name = 'repo'
+    subcommands = ['init' 'this']
+    self._event_log_module.CommandEvent(name='repo', subcommands=subcommands)
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 2)
+    command_event = self._log_data[1]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+    self.verifyCommonKeys(command_event, expected_event_name='command')
+    # Check for 'command' event specific fields.
+    self.assertIn('name', command_event)
+    self.assertIn('subcommands', command_event)
+    self.assertEqual(command_event['name'], name)
+    self.assertEqual(command_event['subcommands'], subcommands)
+
   def test_def_params_event_repo_config(self):
     """Test 'def_params' event data outputs only repo config keys.