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shadow index updates: simplify and more comments 

no functional change here.
This commit is contained in:
Thomas Waldmann 2023-10-28 17:36:10 +02:00
parent 6d9513f507
commit 3ba533ac50
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GPG Key ID: 243ACFA951F78E01
1 changed files with 12 additions and 10 deletions
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22
src/borg/repository.py
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@ -1299,8 +1299,11 @@ class Repository:
except KeyError:
pass
else:
# note: doing a delete first will do some bookkeeping.
self._delete(id, in_index.segment, in_index.offset, in_index.size, update_shadow_index=True)
# this put call supersedes a previous put to same id.
# it is essential to do a delete first to get correct quota bookkeeping
# and also a correctly updated shadow_index, so that the compaction code
# does not wrongly resurrect an old PUT by dropping a DEL that is still needed.
self._delete(id, in_index.segment, in_index.offset, in_index.size)
segment, offset = self.io.write_put(id, data)
self.storage_quota_use += header_size(TAG_PUT2) + len(data)
self.segments.setdefault(segment, 0)
@ -1324,16 +1327,15 @@ class Repository:
in_index = self.index.pop(id)
except KeyError:
raise self.ObjectNotFound(id, self.path) from None
# if we get here, there is an object with this id in the repo,
# we write a DEL here that shadows the respective PUT.
# after the delete, the object is not in the repo index any more,
# for the compaction code, we need to update the shadow_index in this case.
self._delete(id, in_index.segment, in_index.offset, in_index.size, update_shadow_index=True)
self._delete(id, in_index.segment, in_index.offset, in_index.size)
def _delete(self, id, segment, offset, size, *, update_shadow_index):
def _delete(self, id, segment, offset, size):
# common code used by put and delete
if update_shadow_index:
self.shadow_index.setdefault(id, []).append(segment)
# because we'll write a DEL tag to the repository, we must update the shadow index.
# this is always true, no matter whether we are called from put() or delete().
# the compaction code needs this to not drop DEL tags if they are still required
# to keep a PUT in an earlier segment in the "effectively deleted" state.
self.shadow_index.setdefault(id, []).append(segment)
self.segments[segment] -= 1
self.compact[segment] += header_size(TAG_PUT2) + size
segment, size = self.io.write_delete(id)