Safe Haskell	Safe-Inferred
Language	GHC2021

Database.LSMTree.Internal.RunReaders

Contents

Internals

Synopsis

data Readers m h = Readers {
- readersHeap :: !(MutableHeap (PrimState m) (ReadCtx m h))
- readersNext :: !(MutVar (PrimState m) (ReadCtx m h))
}
data OffsetKey
- = NoOffsetKey
- | OffsetKey !SerialisedKey
new :: forall m h. (MonadMask m, MonadST m, MonadSTM m) => OffsetKey -> Maybe (WriteBuffer, Ref (WriteBufferBlobs m h)) -> Vector (Ref (Run m h)) -> m (Maybe (Readers m h))
close :: (MonadMask m, MonadSTM m, PrimMonad m) => Readers m h -> m ()
peekKey :: PrimMonad m => Readers m h -> m SerialisedKey
data HasMore
- = HasMore
- | Drained
pop :: (MonadMask m, MonadSTM m, MonadST m) => Readers m h -> m (SerialisedKey, Entry m h, HasMore)
dropWhileKey :: (MonadMask m, MonadSTM m, MonadST m) => Readers m h -> SerialisedKey -> m (Int, HasMore)
data Reader m h
- = ReadRun !(RunReader m h)
- | ReadBuffer !(MutVar (PrimState m) [KOp m h])
newtype ReaderNumber = ReaderNumber Int
data ReadCtx m h = ReadCtx {
- readCtxHeadKey :: !SerialisedKey
- readCtxHeadEntry :: !(Entry m h)
- readCtxNumber :: !ReaderNumber
- readCtxReader :: !(Reader m h)
}

Documentation

data Readers m h Source #

A collection of runs and write buffers being read from, yielding elements in order. More precisely, that means first ordered by their key, then by the input run they came from. This is important for resolving multiple entries with the same key into one.

Construct with new, then keep calling pop. If aborting early, remember to call close!

Creating a Readers does not retain a reference to the input Runs or the WriteBufferBlobs, but does retain an independent reference on their blob files. It is not necessary to separately retain the Runs or the WriteBufferBlobs for correct use of the Readers. There is one important caveat however: to preserve the validity of BlobRefs then it is necessary to separately retain a reference to the Run or its BlobFile to preserve the validity of BlobRefs.

TODO: do this more nicely by changing Reader to preserve the BlobFile ref until it is explicitly closed, and also retain the BlobFile from the WBB and release all of these BlobFiles once the Readers is itself closed.

Constructors

Readers
Fields readersHeap :: !(MutableHeap (PrimState m) (ReadCtx m h)) readersNext :: !(MutVar (PrimState m) (ReadCtx m h)) Since there is always one reader outside of the heap, we need to store it separately. This also contains the next k/op to yield, unless all readers are drained, i.e. both: 1. the reader inside the `ReadCtx` is empty 2. the heap is empty

data OffsetKey Source #

Constructors

NoOffsetKey
OffsetKey !SerialisedKey

new :: forall m h. (MonadMask m, MonadST m, MonadSTM m) => OffsetKey -> Maybe (WriteBuffer, Ref (WriteBufferBlobs m h)) -> Vector (Ref (Run m h)) -> m (Maybe (Readers m h)) Source #

close :: (MonadMask m, MonadSTM m, PrimMonad m) => Readers m h -> m () Source #

Only call when aborting before all readers have been drained.

peekKey :: PrimMonad m => Readers m h -> m SerialisedKey Source #

data HasMore Source #

Once a function returned Drained, do not use the Readers any more!

Constructors

HasMore
Drained

Instances

Instances details

Show HasMore Source #
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods showsPrec :: Int -> HasMore -> ShowS # show :: HasMore -> String # showList :: [HasMore] -> ShowS #
Eq HasMore Source #
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods (==) :: HasMore -> HasMore -> Bool # (/=) :: HasMore -> HasMore -> Bool #

pop :: (MonadMask m, MonadSTM m, MonadST m) => Readers m h -> m (SerialisedKey, Entry m h, HasMore) Source #

dropWhileKey Source #

Arguments

:: (MonadMask m, MonadSTM m, MonadST m)
=> Readers m h
-> SerialisedKey
-> m (Int, HasMore)	How many were dropped?

Internals

data Reader m h Source #

Constructors

ReadRun !(RunReader m h)
ReadBuffer !(MutVar (PrimState m) [KOp m h])

newtype ReaderNumber Source #

Constructors

ReaderNumber Int

Instances

Instances details

Eq ReaderNumber Source #
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods (==) :: ReaderNumber -> ReaderNumber -> Bool # (/=) :: ReaderNumber -> ReaderNumber -> Bool #
Ord ReaderNumber Source #
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods compare :: ReaderNumber -> ReaderNumber -> Ordering # (<) :: ReaderNumber -> ReaderNumber -> Bool # (<=) :: ReaderNumber -> ReaderNumber -> Bool # (>) :: ReaderNumber -> ReaderNumber -> Bool # (>=) :: ReaderNumber -> ReaderNumber -> Bool # max :: ReaderNumber -> ReaderNumber -> ReaderNumber # min :: ReaderNumber -> ReaderNumber -> ReaderNumber #

data ReadCtx m h Source #

Each heap element needs some more context than just the reader. E.g. the Eq instance we need to be able to access the first key to be read in a pure way.

TODO(optimisation): We allocate this record for each k/op. This might be avoidable, see ideas below.

Constructors

ReadCtx
Fields readCtxHeadKey :: !SerialisedKey readCtxHeadEntry :: !(Entry m h) readCtxNumber :: !ReaderNumber readCtxReader :: !(Reader m h)

Instances

Instances details

Eq (ReadCtx m h) Source #
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods (==) :: ReadCtx m h -> ReadCtx m h -> Bool # (/=) :: ReadCtx m h -> ReadCtx m h -> Bool #
Ord (ReadCtx m h) Source #	Makes sure we resolve entries in the right order.
Instance details Defined in Database.LSMTree.Internal.RunReaders Methods compare :: ReadCtx m h -> ReadCtx m h -> Ordering # (<) :: ReadCtx m h -> ReadCtx m h -> Bool # (<=) :: ReadCtx m h -> ReadCtx m h -> Bool # (>) :: ReadCtx m h -> ReadCtx m h -> Bool # (>=) :: ReadCtx m h -> ReadCtx m h -> Bool # max :: ReadCtx m h -> ReadCtx m h -> ReadCtx m h # min :: ReadCtx m h -> ReadCtx m h -> ReadCtx m h #