Fix submodule initialization in interleaved sync mode

With the introduction of interleaved sync mode, the submodule activation
logic broke because the 'has_submodules' attribute was no longer being
populated when needed. With this change, each submodule is initialized
when it enters the Sync_LocalHalf stage, whereas previously all
submodules were initialized at once when the parent repository entered
the Sync_LocalHalf stage. The init is now retried if it fails, as
submodules may concurrently modify the parent’s git config, potentially
causing contention when attempting to obtain a lock on it.

This change makes the submodule activation logic more robust and less
prone to breakage.

Bug: 444366154
Change-Id: I25eca4ea2a6868219045cfa088988eb01ded47d2
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/509041
Reviewed-by: Gavin Mak <[email protected]>
Tested-by: Kaushik Lingarkar <[email protected]>
Reviewed-by: Nasser Grainawi <[email protected]>
Commit-Queue: Kaushik Lingarkar <[email protected]>
Reviewed-by: Scott Lee <[email protected]>

Author: quic-kaushikl

project.py

@@ -642,10 +642,6 @@ def __init__(
         # project containing repo hooks.
         self.enabled_repo_hooks = []
 
-        # This will be updated later if the project has submodules and
-        # if they will be synced.
-        self.has_subprojects = False
-
     def RelPath(self, local=True):
         """Return the path for the project relative to a manifest.
 
@@ -1563,8 +1559,8 @@ def fail(error: Exception):
         # TODO(https://git-scm.com/docs/git-worktree#_bugs): Re-evaluate if
         # submodules can be init when using worktrees once its support is
         # complete.
-        if self.has_subprojects and not self.use_git_worktrees:
-            self._InitSubmodules()
+        if self.parent and not self.use_git_worktrees:
+            self._InitSubmodule()
         all_refs = self.bare_ref.all
         self.CleanPublishedCache(all_refs)
         revid = self.GetRevisionId(all_refs)
@@ -2359,8 +2355,6 @@ def GetDerivedSubprojects(self):
             )
             result.append(subproject)
             result.extend(subproject.GetDerivedSubprojects())
-        if result:
-            self.has_subprojects = True
         return result
 
     def EnableRepositoryExtension(self, key, value="true", version=1):
@@ -3030,16 +3024,39 @@ def _SyncSubmodules(self, quiet=True):
                 project=self.name,
             )
 
-    def _InitSubmodules(self, quiet=True):
-        """Initialize the submodules for the project."""
+    def _InitSubmodule(self, quiet=True):
+        """Initialize the submodule."""
         cmd = ["submodule", "init"]
         if quiet:
             cmd.append("-q")
-        if GitCommand(self, cmd).Wait() != 0:
-            raise GitError(
-                f"{self.name} submodule init",
-                project=self.name,
+        cmd.extend(["--", self.worktree])
+        max_retries = 3
+        base_delay_secs = 1
+        jitter_ratio = 1 / 3
+        for attempt in range(max_retries):
+            git_cmd = GitCommand(
+                None,
+                cmd,
+                cwd=self.parent.worktree,
+                capture_stdout=True,
+                capture_stderr=True,
             )
+            if git_cmd.Wait() == 0:
+                return
+            error = git_cmd.stderr or git_cmd.stdout
+            if "lock" in error:
+                delay = base_delay_secs * (2**attempt)
+                delay += random.uniform(0, delay * jitter_ratio)
+                logger.warning(
+                    f"Attempt {attempt+1}/{max_retries}: "
+                    + f"git {' '.join(cmd)} failed."
+                    + f" Error: {error}."
+                    + f" Sleeping {delay:.2f}s before retrying."
+                )
+                time.sleep(delay)
+            else:
+                break
+        git_cmd.VerifyCommand()
 
     def _Rebase(self, upstream, onto=None):
         cmd = ["rebase"]