bzr source plugins: Remove all of the atomic backup directory business logic

Follow up of last commit which uses exclusive locking to
protect bzr operations instead.

1 files changed, 18 insertions, 74 deletions

diff --git a/buildstream/plugins/sources/bzr.py b/buildstream/plugins/sources/bzr.py
index 39cee2bf9..5b993c043 100644
--- a/buildstream/plugins/sources/bzr.py
+++ b/buildstream/plugins/sources/bzr.py
@@ -180,83 +180,27 @@ class BzrSource(Source):
         return os.path.join(self.get_mirror_directory(),
                             utils.url_directory_name(self.original_url))
 
-    def _atomic_replace_mirrordir(self, srcdir):
-        """Helper function to safely replace the mirror dir"""
+    def _ensure_mirror(self, skip_ref_check=False):
+        mirror_dir = self._get_mirror_dir()
+        bzr_metadata_dir = os.path.join(mirror_dir, ".bzr")
+        if not os.path.exists(bzr_metadata_dir):
+            self.call([self.host_bzr, "init-repo", "--no-trees", mirror_dir],
+                      fail="Failed to initialize bzr repository")
+
+        branch_dir = os.path.join(mirror_dir, self.tracking)
+        branch_url = self.url + "/" + self.tracking
+        if not os.path.exists(branch_dir):
+            # `bzr branch` the branch if it doesn't exist
+            # to get the upstream code
+            self.call([self.host_bzr, "branch", branch_url, branch_dir],
+                      fail="Failed to branch from {} to {}".format(branch_url, branch_dir))
 
-        if not os.path.exists(self._get_mirror_dir()):
-            # Just move the srcdir to the mirror dir
-            try:
-                os.rename(srcdir, self._get_mirror_dir())
-            except OSError as e:
-                raise SourceError("{}: Failed to move srcdir '{}' to mirror dir '{}'"
-                                  .format(str(self), srcdir, self._get_mirror_dir())) from e
         else:
-            # Atomically swap the backup dir.
-            backupdir = self._get_mirror_dir() + ".bak"
-            try:
-                os.rename(self._get_mirror_dir(), backupdir)
-            except OSError as e:
-                raise SourceError("{}: Failed to move mirrordir '{}' to backup dir '{}'"
-                                  .format(str(self), self._get_mirror_dir(), backupdir)) from e
-
-            try:
-                os.rename(srcdir, self._get_mirror_dir())
-            except OSError as e:
-                # Attempt to put the backup back!
-                os.rename(backupdir, self._get_mirror_dir())
-                raise SourceError("{}: Failed to replace bzr repo '{}' with '{}"
-                                  .format(str(self), srcdir, self._get_mirror_dir())) from e
-            finally:
-                if os.path.exists(backupdir):
-                    shutil.rmtree(backupdir)
+            # `bzr pull` the branch if it does exist
+            # to get any changes to the upstream code
+            self.call([self.host_bzr, "pull", "--directory={}".format(branch_dir), branch_url],
+                      fail="Failed to pull new changes for {}".format(branch_dir))
 
-    @contextmanager
-    def _atomic_repodir(self):
-        """Context manager for working in a copy of the bzr repository
-
-        Yields:
-           (str): A path to the copy of the bzr repo
-
-        This should be used because bzr does not give any guarantees of
-        atomicity, and aborting an operation at the wrong time (or
-        accidentally running multiple concurrent operations) can leave the
-        repo in an inconsistent state.
-        """
-        with self.tempdir() as repodir:
-            mirror_dir = self._get_mirror_dir()
-            if os.path.exists(mirror_dir):
-                try:
-                    # shutil.copytree doesn't like it if destination exists
-                    shutil.rmtree(repodir)
-                    shutil.copytree(mirror_dir, repodir)
-                except (shutil.Error, OSError) as e:
-                    raise SourceError("{}: Failed to copy bzr repo from '{}' to '{}'"
-                                      .format(str(self), mirror_dir, repodir)) from e
-
-            yield repodir
-            self._atomic_replace_mirrordir(repodir)
-
-    def _ensure_mirror(self, skip_ref_check=False):
-        with self._atomic_repodir() as repodir:
-            # Initialize repo if no metadata
-            bzr_metadata_dir = os.path.join(repodir, ".bzr")
-            if not os.path.exists(bzr_metadata_dir):
-                self.call([self.host_bzr, "init-repo", "--no-trees", repodir],
-                          fail="Failed to initialize bzr repository")
-
-            branch_dir = os.path.join(repodir, self.tracking)
-            branch_url = self.url + "/" + self.tracking
-            if not os.path.exists(branch_dir):
-                # `bzr branch` the branch if it doesn't exist
-                # to get the upstream code
-                self.call([self.host_bzr, "branch", branch_url, branch_dir],
-                          fail="Failed to branch from {} to {}".format(branch_url, branch_dir))
-
-            else:
-                # `bzr pull` the branch if it does exist
-                # to get any changes to the upstream code
-                self.call([self.host_bzr, "pull", "--directory={}".format(branch_dir), branch_url],
-                          fail="Failed to pull new changes for {}".format(branch_dir))
         if not skip_ref_check and not self._check_ref():
             raise SourceError("Failed to ensure ref '{}' was mirrored".format(self.ref),
                               reason="ref-not-mirrored")