Safe Haskell	None
Language	Haskell2010

Ouroboros.Consensus.Storage.LedgerDB.V1.Lock

Contents

LedgerDB lock

Synopsis

data LedgerDBLock (m ∷ Type → Type)
newtype ReadLocked (m ∷ Type → Type) a = ReadLocked {
- unsafeRunReadLocked ∷ m a
}
data WriteLocked (m ∷ Type → Type) a
mkLedgerDBLock ∷ IOLike m ⇒ m (LedgerDBLock m)
readLocked ∷ m a → ReadLocked m a
unsafeIgnoreWriteLock ∷ WriteLocked m a → m a
withReadLock ∷ IOLike m ⇒ LedgerDBLock m → ReadLocked m a → m a
withWriteLock ∷ IOLike m ⇒ LedgerDBLock m → WriteLocked m a → m a
writeLocked ∷ m a → WriteLocked m a
unsafeAcquireReadAccess ∷ ∀ (m ∷ Type → Type). IOLike m ⇒ LedgerDBLock m → STM m ()
unsafeReleaseReadAccess ∷ ∀ (m ∷ Type → Type). IOLike m ⇒ LedgerDBLock m → STM m ()

LedgerDB lock

data LedgerDBLock (m ∷ Type → Type) Source #

A lock to prevent the LedgerDB (i.e. a DbChangelog) from getting out of sync with the BackingStore.

We rely on the capability of the BackingStores of providing BackingStoreValueHandles that can be used to hold a persistent view of the database as long as the handle is open. Assuming this functionality, the lock is used in three ways:

Read lock to acquire a value handle: we do this when acquiring a view of the LedgerDB (which lives in a StrictTVar at the ChainDB level) and of the BackingStore. We momentarily acquire a read lock, consult the transactional variable and also open a BackingStoreValueHandle. This is the case for ledger state queries and for the forging loop.
Read lock to ensure two operations are in sync: in the above situation, we relied on the BackingStoreValueHandle functionality, but sometimes we won't access the values through a value handle, and instead we might use the LMDB environment (as it is the case for lmdbCopy). In these cases, we acquire a read lock until we ended the copy, so that writers are blocked until this process is completed. This is the case when taking a snapshot.
Write lock when flushing differences.

Instances

Instances details

NoThunks (RAWLock m ()) ⇒ NoThunks (LedgerDBLock m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods noThunks ∷ Context → LedgerDBLock m → IO (Maybe ThunkInfo) Source # wNoThunks ∷ Context → LedgerDBLock m → IO (Maybe ThunkInfo) Source # showTypeOf ∷ Proxy (LedgerDBLock m) → String Source #

newtype ReadLocked (m ∷ Type → Type) a Source #

An action in m that has to hold the read lock. See withReadLock.

Constructors

ReadLocked
Fields unsafeRunReadLocked ∷ m a

Instances

Instances details

Applicative m ⇒ Applicative (ReadLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods pure ∷ a → ReadLocked m a # (<>) ∷ ReadLocked m (a → b) → ReadLocked m a → ReadLocked m b # liftA2 ∷ (a → b → c) → ReadLocked m a → ReadLocked m b → ReadLocked m c # (>) ∷ ReadLocked m a → ReadLocked m b → ReadLocked m b # (<*) ∷ ReadLocked m a → ReadLocked m b → ReadLocked m a #
Functor m ⇒ Functor (ReadLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods fmap ∷ (a → b) → ReadLocked m a → ReadLocked m b # (<$) ∷ a → ReadLocked m b → ReadLocked m a #
Monad m ⇒ Monad (ReadLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods (>>=) ∷ ReadLocked m a → (a → ReadLocked m b) → ReadLocked m b # (>>) ∷ ReadLocked m a → ReadLocked m b → ReadLocked m b # return ∷ a → ReadLocked m a #

data WriteLocked (m ∷ Type → Type) a Source #

An action in m that has to hold the write lock. See withWriteLock.

Instances

Instances details

Applicative m ⇒ Applicative (WriteLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods pure ∷ a → WriteLocked m a # (<>) ∷ WriteLocked m (a → b) → WriteLocked m a → WriteLocked m b # liftA2 ∷ (a → b → c) → WriteLocked m a → WriteLocked m b → WriteLocked m c # (>) ∷ WriteLocked m a → WriteLocked m b → WriteLocked m b # (<*) ∷ WriteLocked m a → WriteLocked m b → WriteLocked m a #
Functor m ⇒ Functor (WriteLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods fmap ∷ (a → b) → WriteLocked m a → WriteLocked m b # (<$) ∷ a → WriteLocked m b → WriteLocked m a #
Monad m ⇒ Monad (WriteLocked m) Source #
Instance details Defined in Ouroboros.Consensus.Storage.LedgerDB.V1.Lock Methods (>>=) ∷ WriteLocked m a → (a → WriteLocked m b) → WriteLocked m b # (>>) ∷ WriteLocked m a → WriteLocked m b → WriteLocked m b # return ∷ a → WriteLocked m a #

mkLedgerDBLock ∷ IOLike m ⇒ m (LedgerDBLock m) Source #

readLocked ∷ m a → ReadLocked m a Source #

Enforce that the action has to be run while holding the read lock.

unsafeIgnoreWriteLock ∷ WriteLocked m a → m a Source #

Used safely, for example, during initialization.

withReadLock ∷ IOLike m ⇒ LedgerDBLock m → ReadLocked m a → m a Source #

Acquire the ledger DB read lock and hold it while performing an action

withWriteLock ∷ IOLike m ⇒ LedgerDBLock m → WriteLocked m a → m a Source #

Acquire the ledger DB write lock and hold it while performing an action

writeLocked ∷ m a → WriteLocked m a Source #

Enforce that the action has to be run while holding the write lock.

unsafeAcquireReadAccess ∷ ∀ (m ∷ Type → Type). IOLike m ⇒ LedgerDBLock m → STM m () Source #

unsafeReleaseReadAccess ∷ ∀ (m ∷ Type → Type). IOLike m ⇒ LedgerDBLock m → STM m () Source #