ouroboros-consensus-0.1.0.0: Consensus layer for the Ouroboros blockchain protocol
Safe HaskellNone
LanguageHaskell2010

Ouroboros.Consensus.Storage.VolatileDB.API

Synopsis

API

data VolatileDB m blk Source #

Constructors

VolatileDB 

Fields

  • closeDBHasCallStack ⇒ m ()

    Close the VolatileDB.

    NOTE: idempotent after a manual closure, but not after an automatic closure in case of an UnexpectedFailure. In that case, closing it again will cause a ClosedDBError wrapping the original UnexpectedFailure to be thrown.

  • getBlockComponent ∷ ∀ b. HasCallStackBlockComponent blk b → HeaderHash blk → m (Maybe b)

    Return the request block component for the block with the given hash. When not in the VolatileDB, Nothing is returned.

  • putBlockHasCallStack ⇒ blk → m ()

    Store the given block in the VolatileDB.

    Returns after the block has been written to disk.

  • filterByPredecessorHasCallStackSTM m (ChainHash blk → Set (HeaderHash blk))

    Return a function that returns the successors of the block with the given hash.

    This function will return a non-empty set for any block of which a predecessor has been added to the VolatileDB and will return an empty set if no successors for the given block have been added to the VolatileDB (yet).

    Note that it is not required that the given block has been added to the VolatileDB.

  • getBlockInfoHasCallStackSTM m (HeaderHash blk → Maybe (BlockInfo blk))

    Return a function that returns the BlockInfo of the block with the given hash or Nothing if the block is not found in the VolatileDB.

  • garbageCollectHasCallStackSlotNo → m ()

    Try to remove all blocks with a slot number less than the given one.

    Context

    When the current chain changes, blocks older than k, i.e., blocks that are followed by k blocks or more, become immutable. Whenever this happens, we schedule a garbage collection on the VolatileDB that will try to remove blocks older than the most recent immutable block, as such blocks will never be adopted. There's no point in storing them anymore.

    Block number vs slot number

    While we typically talk in terms of block numbers when discussing immutability, i.e., k blocks, we use slot number for garbage collection. We schedule a garbage collection for blocks with a /slot number/ less than the slot number of the immutable block, as opposed to the block number. The reason for this is that the VolatileDB is not aware of block numbers, only of slot numbers.

    By using slot numbers for garbage collection, we might not yet have garbage collected some blocks that could never be adopted again and that we would have garbage collected when using block numbers. This is harmless. The opposite direction is more important and problematic: garbage collecting a block that we might want to adopt after all. Say we have mistakenly garbage collected such a block, in that case the following would be true:

    1. The block has a slot number older than the immutable block's slot number: otherwise we wouldn't have mistakenly garbage collected it.
    2. The block has a block number greater than the immutable block's block number: otherwise we wouldn't want to adopt it, as it would have been older than k.
    3. The block is a part of a fork fitting on the immutable block. As we cannot roll back this block, all forks we could ever adopt would have to go through this block.

    As slot numbers grow monotonically within a chain, all forks starting after the immutable block will only contain blocks with slot numbers greater (or equal to in case of EBBs) than the immutable block's slot number. This directly contradicts (1), so we will never garbage collect a block that we might still want to adopt.

    Less than vs. less than or equal to

    Note that we remove blocks with a slot number less than the given slot number, but not equal to it. In practice, this off-by-one difference will not matter in terms of disk space usage, because as soon as the chain grows again by at least one block, those blocks will be removed anyway. The reason for < opposed to <= is to avoid issues with EBBs, which have the same slot number as the block after it.

  • getMaxSlotNoHasCallStackSTM m MaxSlotNo

    Return the highest slot number ever stored by the VolatileDB.

Instances

Instances details
NoThunks (VolatileDB m blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

Methods

noThunks ∷ Context → VolatileDB m blk → IO (Maybe ThunkInfo) #

wNoThunks ∷ Context → VolatileDB m blk → IO (Maybe ThunkInfo) #

showTypeOfProxy (VolatileDB m blk) → String #

Types

data BlockInfo blk Source #

The information that the user has to provide for each new block.

Constructors

BlockInfo 

Instances

Instances details
StandardHash blk ⇒ Eq (BlockInfo blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

Methods

(==)BlockInfo blk → BlockInfo blk → Bool Source #

(/=)BlockInfo blk → BlockInfo blk → Bool Source #

StandardHash blk ⇒ Show (BlockInfo blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

Methods

showsPrecIntBlockInfo blk → ShowS Source #

showBlockInfo blk → String Source #

showList ∷ [BlockInfo blk] → ShowS Source #

Generic (BlockInfo blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

Associated Types

type Rep (BlockInfo blk) ∷ TypeType Source #

Methods

fromBlockInfo blk → Rep (BlockInfo blk) x Source #

toRep (BlockInfo blk) x → BlockInfo blk Source #

(StandardHash blk, Typeable blk) ⇒ NoThunks (BlockInfo blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

Methods

noThunks ∷ Context → BlockInfo blk → IO (Maybe ThunkInfo) #

wNoThunks ∷ Context → BlockInfo blk → IO (Maybe ThunkInfo) #

showTypeOfProxy (BlockInfo blk) → String #

type Rep (BlockInfo blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

type Rep (BlockInfo blk) = D1 ('MetaData "BlockInfo" "Ouroboros.Consensus.Storage.VolatileDB.API" "ouroboros-consensus-0.1.0.0-inplace" 'False) (C1 ('MetaCons "BlockInfo" 'PrefixI 'True) ((S1 ('MetaSel ('Just "biHash") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 (HeaderHash blk)) :*: (S1 ('MetaSel ('Just "biSlotNo") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 SlotNo) :*: S1 ('MetaSel ('Just "biBlockNo") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 BlockNo))) :*: ((S1 ('MetaSel ('Just "biPrevHash") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 (ChainHash blk)) :*: S1 ('MetaSel ('Just "biIsEBB") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 IsEBB)) :*: (S1 ('MetaSel ('Just "biHeaderOffset") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Word16) :*: S1 ('MetaSel ('Just "biHeaderSize") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Word16)))))

Errors

newtype ApiMisuse Source #

Constructors

ClosedDBError (Maybe SomeException)

The VolatileDB was closed. In case it was automatically closed because an unexpected error was thrown during a read operation or any exception was thrown during a write operation, that exception is embedded.

Instances

Instances details
Show ApiMisuse Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

data UnexpectedFailure blk Source #

Constructors

FileSystemError FsError 
ParseError FsPath (RealPoint blk) DeserialiseFailure

A block failed to parse

TrailingDataError FsPath (RealPoint blk) ByteString

When parsing a block we got some trailing data

MissingBlockError (HeaderHash blk)

Block missing

This exception gets thrown when a block that we know it should be in the VolatileDB, nonetheless was not found.

This exception will be thrown by getKnownBlockComponent.

CorruptBlockError (HeaderHash blk)

A (parsed) block did not pass the integrity check.

This exception gets thrown when a block doesn't pass the integrity check done for GetVerifiedBlock.

NOTE: we do not check the integrity of a block when it is added to the VolatileDB. While this exception typically means the block has been corrupted, it could also mean the block didn't pass the check at the time it was added.

Instances

Instances details
(Typeable blk, StandardHash blk) ⇒ Show (UnexpectedFailure blk) Source # 
Instance details

Defined in Ouroboros.Consensus.Storage.VolatileDB.API

data VolatileDBError blk Source #

Errors which might arise when working with this database.

Constructors

ApiMisuse ApiMisuse

An error thrown because of incorrect usage of the VolatileDB by the user.

UnexpectedFailure (UnexpectedFailure blk)

An unexpected failure thrown because something went wrong.

Derived functionality

getIsMemberFunctor (STM m) ⇒ VolatileDB m blk → STM m (HeaderHash blk → Bool) Source #

getKnownBlockComponent ∷ (MonadThrow m, HasHeader blk) ⇒ VolatileDB m blk → BlockComponent blk b → HeaderHash blk → m b Source #

getPredecessorFunctor (STM m) ⇒ VolatileDB m blk → STM m (HeaderHash blk → Maybe (ChainHash blk)) Source #

withDB Source #

Arguments

∷ (HasCallStack, MonadThrow m) 
⇒ m (VolatileDB m blk)

How to open the database

→ (VolatileDB m blk → m a)

Action to perform using the database

→ m a 

Open the database using the given function, perform the given action using the database, and closes the database using its closeDB function, in case of success or when an exception was raised.