hyperledger / fabric-x-committer / 36715313134

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main: 91%

Pull #826

github

[cmd, statedb] Add committer delete-clone to drop a snapshot database clone

#### Type of change

- New feature
- Dependency update
- Documentation update

#### Description

- Adds `committer delete-clone --config <vc-config> --tx-id <snapshot-tx-id>`, which,
  like `init-db`, reads the VC config and works on the state database directly, so it
  can run while the committer is running. It drops the database named by the
  `_snapshot` record's `clone_database` field and clears that field, keeping the
  record so the snapshot's status and hash stay queryable.
- Deletion is refused unless the snapshot is `CHECKPOINTED` or `ABORTED`
  (`statedb.ErrSnapshotCloneInUse`), because only then will the clone never be hashed
  again. An empty or unknown `--tx-id` fails; a record whose `clone_database` is
  already empty succeeds for any status, so running the command again is a no-op.
- The logic lives in `statedb.DeleteSnapshotClone`. `adminExec` moves from
  `service/vc` to `statedb.AdminExec`, so snapshot creation and deletion share the
  maintenance-database connection.
- Adds `ClearCloneDatabase` to `statedb.SnapshotUpdate`. The clear keeps the locked
  row's error text and requires the locked row to still have the status the command
  checked, so a concurrent writer is neither overwritten nor bypassed.
- Adds `statedb.SnapshotStateManager.Read(tx_id)` and the `statedb.ErrSnapshotNotFound`
  sentinel, sharing `ReadLatest`'s read-and-decode step.
- Bumps fabric-x-common to `38584e4` for the `ABORTED` snapshot status.

#### Additional details (Optional)

The drop and the record update cannot be one atomic transaction, because PostgreSQL
does not allow `DROP DATABASE` inside a transaction. They are ordered drop-then-clear:
a stop between them leaves the record naming a missing database, and running the
command again finishes (`DROP DATABASE IF EXISTS` is a no-op, then the clear runs). The
reverse order could leave an orphan database that no record names.

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