Enum polkadot_service::generic::DigestItem

pub enum DigestItem {
    PreRuntime([u8; 4], Vec<u8>),
    Consensus([u8; 4], Vec<u8>),
    Seal([u8; 4], Vec<u8>),
    Other(Vec<u8>),
    RuntimeEnvironmentUpdated,
}

Digest item that is able to encode/decode ‘system’ digest items and provide opaque access to other items.

Variants

PreRuntime([u8; 4], Vec<u8>)

A pre-runtime digest.

These are messages from the consensus engine to the runtime, although the consensus engine can (and should) read them itself to avoid code and state duplication. It is erroneous for a runtime to produce these, but this is not (yet) checked.

NOTE: the runtime is not allowed to panic or fail in an on_initialize call if an expected PreRuntime digest is not present. It is the responsibility of a external block verifier to check this. Runtime API calls will initialize the block without pre-runtime digests, so initialization cannot fail when they are missing.

Consensus([u8; 4], Vec<u8>)

A message from the runtime to the consensus engine. This should never be generated by the native code of any consensus engine, but this is not checked (yet).

Seal([u8; 4], Vec<u8>)

Put a Seal on it. This is only used by native code, and is never seen by runtimes.

Other(Vec<u8>)

Some other thing. Unsupported and experimental.

RuntimeEnvironmentUpdated

An indication for the light clients that the runtime execution environment is updated.

Currently this is triggered when:

1. Runtime code blob is changed or
2. heap_pages value is changed.

Implementations

impl DigestItem

pub fn dref(&self) -> DigestItemRef<'_>

Returns a ‘referencing view’ for this digest item.

pub fn as_pre_runtime(&self) -> Option<([u8; 4], &[u8])>

Returns Some if this entry is the PreRuntime entry.

pub fn as_consensus(&self) -> Option<([u8; 4], &[u8])>

Returns Some if this entry is the Consensus entry.

pub fn as_seal(&self) -> Option<([u8; 4], &[u8])>

Returns Some if this entry is the Seal entry.

pub fn as_other(&self) -> Option<&[u8]>

Returns Some if self is a DigestItem::Other.

pub fn try_as_raw(&self, id: OpaqueDigestItemId<'_>) -> Option<&[u8]>

Returns the opaque data contained in the item if Some if this entry has the id given.

pub fn try_to<T>(&self, id: OpaqueDigestItemId<'_>) -> Option<T>

where T: Decode,

Returns the data contained in the item if Some if this entry has the id given, decoded to the type provided T.

pub fn seal_try_to<T>(&self, id: &[u8; 4]) -> Option<T>

where T: Decode,

Try to match this to a Self::Seal, check id matches and decode it.

Returns None if this isn’t a seal item, the id doesn’t match or when the decoding fails.

pub fn consensus_try_to<T>(&self, id: &[u8; 4]) -> Option<T>

where T: Decode,

Try to match this to a Self::Consensus, check id matches and decode it.

Returns None if this isn’t a consensus item, the id doesn’t match or when the decoding fails.

pub fn pre_runtime_try_to<T>(&self, id: &[u8; 4]) -> Option<T>

where T: Decode,

Try to match this to a Self::PreRuntime, check id matches and decode it.

Returns None if this isn’t a pre-runtime item, the id doesn’t match or when the decoding fails.

Trait Implementations

impl CheckEqual for DigestItem

fn check_equal(&self, other: &DigestItem)

Perform the equality check.

impl Clone for DigestItem

fn clone(&self) -> DigestItem

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Signature> CompatibleDigestItem<Signature> for DigestItem

where Signature: Codec,

fn aura_seal(signature: Signature) -> DigestItem

Construct a digest item which contains a signature on the hash.

fn as_aura_seal(&self) -> Option<Signature>

If this item is an Aura seal, return the signature.

fn aura_pre_digest(slot: Slot) -> DigestItem

Construct a digest item which contains the slot number

fn as_aura_pre_digest(&self) -> Option<Slot>

If this item is an AuRa pre-digest, return the slot number

impl CompatibleDigestItem for DigestItem

fn babe_pre_digest(digest: PreDigest) -> DigestItem

Construct a digest item which contains a BABE pre-digest.

fn as_babe_pre_digest(&self) -> Option<PreDigest>

If this item is an BABE pre-digest, return it.

fn babe_seal(signature: Signature) -> DigestItem

Construct a digest item which contains a BABE seal.

fn as_babe_seal(&self) -> Option<Signature>

If this item is a BABE signature, return the signature.

fn as_next_epoch_descriptor(&self) -> Option<NextEpochDescriptor>

If this item is a BABE epoch descriptor, return it.

fn as_next_config_descriptor(&self) -> Option<NextConfigDescriptor>

If this item is a BABE config descriptor, return it.

impl Debug for DigestItem

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Decode for DigestItem

fn decode<I>(input: &mut I) -> Result<DigestItem, Error>

where I: Input,

Attempt to deserialise the value from input.

fn decode_into<I>( input: &mut I, dst: &mut MaybeUninit<Self>, ) -> Result<DecodeFinished, Error>

where I: Input,

Attempt to deserialize the value from input into a pre-allocated piece of memory.

fn skip<I>(input: &mut I) -> Result<(), Error>

where I: Input,

Attempt to skip the encoded value from input.

fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<'a> Deserialize<'a> for DigestItem

fn deserialize<D>(de: D) -> Result<DigestItem, <D as Deserializer<'a>>::Error>

where D: Deserializer<'a>,

Deserialize this value from the given Serde deserializer.

impl Encode for DigestItem

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode_to<T>(&self, dest: &mut T)

where T: Output + ?Sized,

Convert self to a slice and append it to the destination.

fn using_encoded<R, F>(&self, f: F) -> R

where F: FnOnce(&[u8]) -> R,

Convert self to a slice and then invoke the given closure with it.

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl From<ConsensusLog> for DigestItem

fn from(c: ConsensusLog) -> DigestItem

Converts to this type from the input type.

impl PartialEq for DigestItem

fn eq(&self, other: &DigestItem) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for DigestItem

fn serialize<S>( &self, seq: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl TypeInfo for DigestItem

type Identity = DigestItem

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl EncodeLike for DigestItem

impl Eq for DigestItem

impl StorageAppend<DigestItem> for Digest

We abuse the fact that SCALE does not put any marker into the encoding, i.e. we only encode the internal vec and we can append to this vec. We have a test that ensures that if the Digest format ever changes, we need to remove this here.

impl StructuralPartialEq for DigestItem