ct/l1/lsm: some iobuf shares #29248
Merged
ct/l1/lsm: some iobuf shares #29248
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The underlying iobufs aren't mutated, and don't have a hard requirement to be called from a const context. As such, swaps over to sharing instead of copying.
Contributor
There was a problem hiding this comment.
Pull request overview
This PR optimizes memory usage by replacing copy() operations with share() operations for iobuf instances in the LSM (Log-Structured Merge-tree) implementation. Since the underlying iobufs are not mutated and don't require const contexts, sharing is more efficient than copying.
Changes:
- Renamed methods from
copy()toshare()across multiple structs (lsm_state,serialized_manifest,apply_write_batch_update) - Removed
constqualifiers from methods and parameters that previously enforced const semantics but are no longer needed - Added
mutable_state()accessor to the STM class to support non-const access
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
| src/v/cloud_topics/level_one/metastore/lsm/stm.h | Added mutable_state() accessor and removed const from make_snapshot() |
| src/v/cloud_topics/level_one/metastore/lsm/stm.cc | Changed snapshot creation to use share() instead of copy() |
| src/v/cloud_topics/level_one/metastore/lsm/state.h | Renamed copy() methods to share() in lsm_state and serialized_manifest |
| src/v/cloud_topics/level_one/metastore/lsm/state.cc | Updated implementations to use share() and removed const qualifiers |
| src/v/cloud_topics/level_one/metastore/lsm/replicated_persistence.cc | Updated to use mutable_state() and share() for accessing persisted manifest |
| src/v/cloud_topics/level_one/metastore/lsm/replicated_db.cc | Changed write batch serialization to use share() |
| src/v/cloud_topics/level_one/metastore/lsm/lsm_update.h | Renamed copy() to share() in apply_write_batch_update |
| src/v/cloud_topics/level_one/metastore/lsm/lsm_update.cc | Updated implementation to use share() and removed const qualifiers |
rockwotj
approved these changes
Jan 14, 2026
Collaborator
CI test resultstest results on build#78995 |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The underlying iobufs aren't mutated, and don't have a hard requirement to be called from a const context. As such, swaps over to sharing instead of copying.
Follow up from #29161 and #29160
Backports Required
Release Notes