Improve code coverage of the main library

[jeltsch]

This issue calls for improving code coverage of the main library.

A code coverage report was created by executing cabal test --enable-coverage lsm-tree:lsm-tree-test on the jeltsch/unsliced-keys-in-ordinary-indexes branch as of 28 March 2025, that is, on commit dd6b71c.

The individual coverage deficits of all modules in the main library where examined. All non-trivial cases of missing coverage are listed below. Each case is described by either of the following:

• A situation that never occurred, which led to code not being executed
• A value that was never used (in which case the description contains the phrase “never used”)

Coverage deficits of the following kinds were considered trivial and are therefore not mentioned here:

• Derived class instantiations
• Instantiations of NFData
• Field selectors
• Error message strings or parts thereof
• Deliberately unused values¹ (where it was clear that they are deliberately unused)
• Explicit ()

Data.Arena

• scrambleArena
  • Non-empty free list
• newBlockWithFree
  • Non-empty free list

Data.Map.Range

• rangeLookup
  • Unbounded in at least one direction
• evalLowerBound
  • Exclusive lower bound

Database.LSMTree

• Bifunctor LookupResult
  • Never used
• Bifunctor (QueryResult k)
  • Never used
• rangeLookup
  • Resolver never used
• withCursor
  • Never used
• withCursorAtOffset
  • Never used
• readCursor
  • Resolver never used
• retrieveBlobs
  • Invalid blob reference
• unions
  • Table type mismatch

Database.LSMTree.Common

Nothing

Database.LSMTree.Internal

• All trace messages never used
• withOpenSession
  • Session is closed
• openSession
  • Unexected error when acquiring session file lock
  • Session directory locked with tryLockFile returning Nothing
  • Registry never used for restoring session
  • Active directory never used when removing it in session creation
  • Snapshots directory never used when removing it in session creation
  • Corrupted snapshots directory when restoring session
  • Non-empty active directory when restoring session
  • Session already closed when closing session
  • Rollback for cursor list acquisition when closing session
  • Non-empty list of cursors when closing session
  • Rollback for table list acquisition when closing session
• newEmptyTableContent
  • Registry never used for creating levels cache
• rangeLookup
  • Resolver never used
  • Multiple chunks
• readCursor
  • Resolver never used
• readCursorWhile
  • Resolver never used
• createSnapshot
  • Named snapshot directory never used when rolling back snapshot directory creation
• openSnapshot
  • Wrong table type
  • Resolver never used when opening write buffer
• wrapFileCorruptedErrorAsSnapshotCorruptedError
  • Ordinary action registry abort (ExitCaseAbort)
  • Commit action registry error
  • Unmentioned exception
• doesSnapshotExist
  • Never used
• listSnapshots
  • Alleged snapshot directory not being a directory
• unions
  • Table session mismatch
  • Session closed
  • Unmodified session state after creation of unions table never used
• writeBufferToNewRun
  • Level number 1 never used
• matchSessions
  • Session root mismatch
• supplyUnionCredits
  • Union level denotation never used

Database.LSMTree.Internal.Assertions

• fromIntegralChecked
  • Conversion error found

Database.LSMTree.Internal.BitMath

• mod2
  • Never used
• ceilDiv2
  • Never used
• mod4
  • Never used
• div16
  • Never used
• mod16
  • Never used
• mul16
  • Never used
• divPageSize
  • Never used
• modPageSize
  • Never used

Database.LSMTree.Internal.BlobFile

• openBlobFile
  • Error when opening the file

Database.LSMTree.Internal.BlobRef

• deRefWeakBlobRef
  • Invalid reference

Database.LSMTree.Internal.BloomFilter

• bloomFilterFromSBS
  • Wrong endianness
  • Bloom filter too large
  • Byte array too large for components

Database.LSMTree.Internal.BloomFilterQuery1

• Show RunIxKeyIx
  • Never used

Database.LSMTree.Internal.BloomFilterQuery2

• All assertion properties never used
• alignmentOfType# @CandidateProbe
  • Never used
• indexOffAddr# @CandidateProbe
  • Never used
• Show CandidateProbe
  • Never used

Database.LSMTree.Internal.ByteString

• tryCheapToShort
  • Never used
• tryGetByteArray
  • Non-zero offset into byte array
  • Contents referenced by a MallocPtr
  • Contents referenced by a PlainForeignPtr
  • Contents referenced by a FinalPtr
• unsafePinnedByteArrayToByteString
  • Byte array not pinned
  • Contents pointer never used

Database.LSMTree.Internal.CRC32C

• hGetExactlyCRC32C_SBS
  • Contents pointer never used
• hGetAllCRC32C'
  • Non-positive chunk size
  • Contents pointer of internally used byte string never used

Database.LSMTree.Internal.ChecksumHandle

Nothing

Database.LSMTree.Internal.Chunk

Nothing

Database.LSMTree.Internal.Config

• runParamsForLevel
  • Level number never used
• Semigroup TableConfigOverride
  • Never used
• Monoid TableConfigOverride
  • Never used
• configOverrideDiskCachePolicy
  • Never used
• bloomFilterAllocForLevel
  • FPR request
• diskCachePolicyForLevel
  • Caching from a given level downwards

Database.LSMTree.Internal.Cursor

• readEntriesWhile
  • Mupsert with a key that has other entries

Database.LSMTree.Internal.Entry

• hasBlob
  • Never used
• onBlobRef
  • Never used
• bifoldMap @Entry
  • Blob reference not used when inserting with blob
• combineMaybe
  • Never used

Database.LSMTree.Internal.IncomingRun

• nominalDebtAsCredits
  • Never used
• supplyCreditsIncomingRun
  • Level number never used when computing threshold
• depositNominalCredits
  • Previous nominal credits never used
• immediatelyCompleteIncomingRun
  • Level number never used when supplying credits

Database.LSMTree.Internal.Index

Nothing

Database.LSMTree.Internal.Index.Compact

• search
  • Empty index
  • Sequence of large-entry pages and pages with clashes without preceding pages found
  • Search key belongs to the second or later page in a series of clashing pages²
• hasClashes
  • Never used
• toLBS
  • Never used
• putBitVec
  • Bit vector not byte-aligned
• fromSBS
  • Wrong endianness
  • Number of pages not representable as Int value
  • Number of entries not representable as Int value
  • Byte array too large for components
• checkedPrimVec
  • Negative offset
• checkedBitVec
  • Negative offset
• bitIndexFromToRev
  • No upper bound
• vectorLowerBound
  • No lower bound
• vectorUpperBound
  • Exclusive upper bound

Database.LSMTree.Internal.Index.CompactAcc

Nothing

Database.LSMTree.Internal.Index.Ordinary

• fromSBS
  • Wrong endianness
  • Number of entries not representable as Int value

Database.LSMTree.Internal.Index.OrdinaryAcc

Nothing

Database.LSMTree.Internal.Lookup

• intraPageLookupsOn
  • Combining of entries never used (two occurrences)
  • Byte count discrepancy

Database.LSMTree.Internal.Merge

• abort
  • Implicitly closed merge
  • Explicitly closed merge
• complete
  • Ongoing merge
  • Implicitly closed merge
  • Explicitly closed merge
• stepsToCompletion
  • Never used
• steps
  • Completed merge
  • Implicitly closed merge
  • Explicitly closed merge
• doStepsLevel
  • Readers drained when handling mupdate
  • Readers drained when dropping remaining entries of the same key

Database.LSMTree.Internal.MergeSchedule

• All trace messages never used
• mkLevelsCache
  • Reference release operation never used in rollback for duplicating runs
• iforLevelM_
  • Level number never used by consumer
• flushWriteBuffer
  • Empty table write buffer
  • Level number 1 never used
• addRunToLevels
  • Level number never used when immediately completing incoming run
• mergingRunParamsForLevel
  • Regular level specification never used
• maxRunSize
  • Negative level number
• mergeTypeForLevel
  • Last-level denotation never used
• supplyCredits
  • Level numbers never used

Database.LSMTree.Internal.MergingRun

• new
  • Empty new merge
• newCompleted
  • Error handler never used
• unsafeNew
  • Table too large
• atomicModifyInt
  • CAS looping
• supplyCreditsAbsolute
  • Information on supplied credits never used (two values)
• performMergeSteps
  • Merge completed
• completeMerge
  • Merge completed
• expectCompleted
  • Merge maybe completed
  • Merge ongoing

Database.LSMTree.Internal.MergingTree

• expectCompleted
  • Ongoing tree merge
  • Pending tree merge

Database.LSMTree.Internal.MergingTree.Lookup

• mkLookupNode
  • One lookup tree
• mergeLookupAcc
  • Resolver never used when merging levels
• buildLookupTree
  • Reference release operation never used in rollback for duplicating runs (two occurrences)
  • Pending level merge with no merging runs but a union merge

Database.LSMTree.Internal.Page

Nothing

Database.LSMTree.Internal.PageAcc

Nothing

Database.LSMTree.Internal.PageAcc1

• singletonPage
  • Deletion

Database.LSMTree.Internal.Paths

• isValidSnapshotName
  • String contains a character that is neither a lowercase Latin letter nor a digit
• toSnapshotName
  • String is not a valid snapshot name
• pure @ForRunFiles
  • Never used

Database.LSMTree.Internal.Primitive

Nothing

Database.LSMTree.Internal.Range

Nothing

Database.LSMTree.Internal.RawBytes

• IsList RawBytes
  • Never used
• unpack
  • Never used
• unsafeFromByteString
  • Byte array fetching unsuccessful

Database.LSMTree.Internal.RawOverflowPage

Nothing

Database.LSMTree.Internal.RawPage

• getRawPageIndexKey
  • No index

Database.LSMTree.Internal.Run

• Show (Run m h)
  • Never used
• runFsPathsNumber
  • Never used
• mkRawBlobRef
  • Never used
• openFromDisk
  • Invalid file (three occurrences)
  • Unexpected checksum

Database.LSMTree.Internal.RunAcc

• addKeyOp
  • Chunks emmitted by small key/op addition with page emission never used

Database.LSMTree.Internal.RunBuilder

Nothing

Database.LSMTree.Internal.RunNumber

Nothing

Database.LSMTree.Internal.RunReader

Nothing

Database.LSMTree.Internal.RunReaders

• Eq (ReadCtx m h)
  • Never used
• nextReadCtx
  • Reinstantiated empty key/op buffer never used

Database.LSMTree.Internal.Serialise

• sizeofKey64
  • Never used
• sizeofValue16
  • Never used
• sizeofValue64
  • Never used
• serialisedValue
  • Never used
• SerialisedBlob
  • Never used (at least not in expressions)
• serialisedBlob
  • Never used

Database.LSMTree.Internal.Serialise.Class

• serialiseKeyMinimalSize
  • Never used
• requireBytesExactly
  • Unexpected number of bytes
• deserialiseKey @Word64
  • Unexpected number of bytes
• deserialiseValue @Word64
  • Unexpected number of bytes
• serialiseValue @Void
  • Never used
• deserialiseValue @Void
  • Never used

Database.LSMTree.Internal.Snapshot

• fromSnapMergingTree
  • Completed tree merge
  • Pending level merge
• snapshotWriteBuffer
  • Rollback for write buffer writing
• openWriteBuffer
  • Resolver never used
• fromSnapLevels
  • Level number never used
• fromSnapMergingRun
  • Error handler never used

Database.LSMTree.Internal.Snapshot.Codec

• prettySnapshotVersion
  • Never used
• readFileSnapshotMetaData
  • Invalid file
• decodeSnapshotMetaData
  • Exception
• decode @(Versioned a)
  • Incompatible snapshot format version
• decode @SnapshotVersion
  • Unknown snapshot format version
• decodeVersioned @SnapshotTableType
  • Unexpected tag
• decodeVersioned @SnapshotRun
  • Unexpected combination of list length and tag
• decodeVersioned @MergePolicy
  • Unexpected tag
• decodeVersioned @SizeRation
  • Not 4
• decodeVersioned @WriteBufferAlloc
  • Unexpected tag
• decodeVersioned @RunParams
  • Unexpected combination of list length and tag
• decodedVersion @RunDataCaching
  • Unexpected tag
• decodedVersion @IndexType
  • Unexpected tag
• decodedVersion @RunBloomFilterAlloc
  • Unexpected combination of list length and tag
• decodedVersion @BloomFilterAlloc
  • Unexpected combination of list length and tag
• decodedVersion @FencePointerIndex
  • Unexpected tag
• decodedVersion @DiskCachePolicy
  • Unexpected combination of list length and tag
• decodedVersion @MergeSchedule
  • Unexpected tag
• decodedVersion @SnapIncomingRun
  • Unexpected combination of list length and tag
• decodedVersion @MergePolicyForLevel
  • Unexpected tag
• decodedVersion @SnapMergingRun
  • Unexpected combination of list length and tag
• decodedVersion @LevelMergeType
  • Unexpected tag
• decodedVersion @TreeMergeType
  • Unexpected tag
• decodedVersion @SnapMergingTreeState
  • Unexpected combination of list length and tag
• decodedVersion @SnapPendingMerge
  • Unexpected combination of list length and tag
• decodedVersion @SnapPreExistingRun
  • Unexpected combination of list length and tag

Database.LSMTree.Internal.StrictArray

Nothing

Database.LSMTree.Internal.UniqCounter

Nothing

Database.LSMTree.Internal.Unsliced

• unsafeMakeUnsliced
  • Never used
• unsafeMakeUnslicedKey
  • Never used
• Show (Unsliced SerialisedKey)
  • Never used

Database.LSMTree.Internal.Vector

• mapMStrict
  • Never used
• imapMStrict
  • Never used
• zipWithStrict
  • Never used

Database.LSMTree.Internal.Vector.Growing

• new
  • Non-positive buffer size
• append
  • Length overflow
  • Only one possible new buffer size
  • No possible new buffer size

Database.LSMTree.Internal.WriteBuffer

• fromList
  • Never used
• lookups
  • Never used
• rangeLookups
  • Never used
• convertRange
  • Never used

Database.LSMTree.Internal.WriteBufferBlobs

Nothing

Database.LSMTree.Internal.WriteBufferReader

• readWriteBuffer
  • Resolver never used
• new
  • Error handler never used (two occurrences)

Database.LSMTree.Internal.WriteBufferWriter

• unsafeFinalise
  • Result never used

Database.LSMTree.Monoidal

• withTable
  • Never used
• new
  • Never used
• close
  • Never used
• lookups
  • Never used
• rangeLookup
  • Never used
• withCursor
  • Never used
• withCursorAtOffset
  • Never used
• newCursor
  • Never used
• newCursorAtOffset
  • Never used
• closeCursor
  • Never used
• readCursor
  • Never used
• updates
  • Never used
• inserts
  • Never used
• deletes
  • Never used
• mupserts
  • Never used
• createSnapshot
  • Never used
• openSnapshot
  • Never used
• duplicate
  • Never used
• union
  • Never used
• unions
  • Never used
• remainingUnionDebt
  • Never used
• supplyUnionCredits
  • Never used
• resolve
  • Never used

Database.LSMTree.Normal

• withTable
  • Never used
• new
  • Never used
• close
  • Never used
• Bifunctor LookupResult
  • Never used
• lookups
  • Never used
• Bifunctor (QueryResult k)
  • Never used
• rangeLookup
  • Never used
• withCursor
  • Never used
• withCursorAtOffset
  • Never used
• newCursor
  • Never used
• newCursorAtOffset
  • Never used
• closeCursor
  • Never used
• readCursor
  • Never used
• toNormalQueryResult
  • Never used
• updates
  • Never used
• inserts
  • Never used
• deletes
  • Never used
• retrieveBlobs
  • Never used
• createSnapshot
  • Never used
• openSnapshot
  • Never used
• duplicate
  • Never used
• union
  • Never used
• unions
  • Never used
• remainingUnionDebt
  • Never used
• supplyUnionCredits
  • Never used

Footnotes

1. An example is the index argument in the second alternative of Database.LSMTree.Internal.Index.finalLBS, which is not used by the underlying function Database.LSMTree.Internal.Index.Ordinary.finalLBS. ↩

2. The existence of this case in connection with the previous one suggests that there might be no clashes at all. ↩

[jeltsch]

For further details see the machine-generated report.