Struct diem_sdk::types::contract_event::EventByVersionWithProof
pub struct EventByVersionWithProof {
pub lower_bound_incl: Option<EventWithProof>,
pub upper_bound_excl: Option<EventWithProof>,
}
Expand description
The response type for get_event_by_version_with_proof
, which contains lower
and upper bound events surrounding the requested version along with proofs
for each event.
Why do we need two events?
If we could always get the event count at the requested event_version, we
could return only the lower bound event. With the event count we could verify
that the returned event is actually the latest event at the historical ledger
view just by checking that event.sequence_number == event_count
.
Unfortunately, the event count is only (verifiably) accessible via the on-chain state. While we can easily acquire the event count near the chain HEAD, historical event counts (at versions below HEAD for more than the prune window) may be inaccessible after most non-archival fullnodes have pruned past that version.
Including the Upper Bound Event
In contrast, if we also return the upper bound event, then we can always verify the request even if the version is past the prune window and we don’t know the event_count (at event_version). The upper bound event lets us prove that there is no untransmitted event that is actually closer to the requested event_version than the lower bound.
For example, consider the case where there are three events at versions 10, 20, and 30. A client asks for the latest event at or below version 25. If we just returned the lower bound event, then a malicious server could return the event at version 10; the client would not be able to distinguish this response from the correct response without the event count (2) at version 25.
If we also return the upper bound event (the event at version 30), the client can verify that the upper bound is the next event after the lower bound and that the upper bound comes after their requested version. This proves that the lower bound is actually the latest event at or below their requested version.
Fields§
§lower_bound_incl: Option<EventWithProof>
§upper_bound_excl: Option<EventWithProof>
Implementations§
§impl EventByVersionWithProof
impl EventByVersionWithProof
pub fn new( lower_bound_incl: Option<EventWithProof>, upper_bound_excl: Option<EventWithProof> ) -> EventByVersionWithProof
pub fn verify(
&self,
ledger_info: &LedgerInfo,
event_key: &EventKey,
latest_event_count: Option<u64>,
event_version: u64
) -> Result<(), Error>
pub fn verify( &self, ledger_info: &LedgerInfo, event_key: &EventKey, latest_event_count: Option<u64>, event_version: u64 ) -> Result<(), Error>
Verify that the lower_bound_incl
EventWithProof
is the latest event
at or below the requested event_version
.
The ledger_info
is the client’s latest know ledger info (will be near
chain HEAD if the client is synced).
The latest_event_count
is the event count at the ledger_info
version
(not the event_version
) and is needed to verify the empty event stream
and version after last event cases. In some select instances
(e.g. NewBlockEvent
s) we can determine these cases more efficiently
and so this parameter is left optional.
Trait Implementations§
§impl Arbitrary for EventByVersionWithProof
impl Arbitrary for EventByVersionWithProof
§type Parameters = (<Option<EventWithProof> as Arbitrary>::Parameters, <Option<EventWithProof> as Arbitrary>::Parameters)
type Parameters = (<Option<EventWithProof> as Arbitrary>::Parameters, <Option<EventWithProof> as Arbitrary>::Parameters)
arbitrary_with
accepts for configuration
of the generated Strategy
. Parameters must implement Default
.§type Strategy = Map<(<Option<EventWithProof> as Arbitrary>::Strategy, <Option<EventWithProof> as Arbitrary>::Strategy), fn(_: (Option<EventWithProof>, Option<EventWithProof>)) -> EventByVersionWithProof>
type Strategy = Map<(<Option<EventWithProof> as Arbitrary>::Strategy, <Option<EventWithProof> as Arbitrary>::Strategy), fn(_: (Option<EventWithProof>, Option<EventWithProof>)) -> EventByVersionWithProof>
Strategy
used to generate values of type Self
.§fn arbitrary_with(
_top: <EventByVersionWithProof as Arbitrary>::Parameters
) -> <EventByVersionWithProof as Arbitrary>::Strategy
fn arbitrary_with( _top: <EventByVersionWithProof as Arbitrary>::Parameters ) -> <EventByVersionWithProof as Arbitrary>::Strategy
§impl Clone for EventByVersionWithProof
impl Clone for EventByVersionWithProof
§fn clone(&self) -> EventByVersionWithProof
fn clone(&self) -> EventByVersionWithProof
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read more§impl Debug for EventByVersionWithProof
impl Debug for EventByVersionWithProof
§impl<'de> Deserialize<'de> for EventByVersionWithProof
impl<'de> Deserialize<'de> for EventByVersionWithProof
§fn deserialize<__D>(
__deserializer: __D
) -> Result<EventByVersionWithProof, <__D as Deserializer<'de>>::Error>where
__D: Deserializer<'de>,
fn deserialize<__D>( __deserializer: __D ) -> Result<EventByVersionWithProof, <__D as Deserializer<'de>>::Error>where __D: Deserializer<'de>,
§impl PartialEq<EventByVersionWithProof> for EventByVersionWithProof
impl PartialEq<EventByVersionWithProof> for EventByVersionWithProof
§fn eq(&self, other: &EventByVersionWithProof) -> bool
fn eq(&self, other: &EventByVersionWithProof) -> bool
self
and other
values to be equal, and is used
by ==
.§impl Serialize for EventByVersionWithProof
impl Serialize for EventByVersionWithProof
§fn serialize<__S>(
&self,
__serializer: __S
) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>where
__S: Serializer,
fn serialize<__S>( &self, __serializer: __S ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>where __S: Serializer,
§impl TryFrom<&EventByVersionWithProof> for EventByVersionWithProofView
impl TryFrom<&EventByVersionWithProof> for EventByVersionWithProofView
§fn try_from(
proof: &EventByVersionWithProof
) -> Result<EventByVersionWithProofView, <EventByVersionWithProofView as TryFrom<&EventByVersionWithProof>>::Error>
fn try_from( proof: &EventByVersionWithProof ) -> Result<EventByVersionWithProofView, <EventByVersionWithProofView as TryFrom<&EventByVersionWithProof>>::Error>
§impl TryFrom<&EventByVersionWithProofView> for EventByVersionWithProof
impl TryFrom<&EventByVersionWithProofView> for EventByVersionWithProof
§fn try_from(
view: &EventByVersionWithProofView
) -> Result<EventByVersionWithProof, <EventByVersionWithProof as TryFrom<&EventByVersionWithProofView>>::Error>
fn try_from( view: &EventByVersionWithProofView ) -> Result<EventByVersionWithProof, <EventByVersionWithProof as TryFrom<&EventByVersionWithProofView>>::Error>
impl Eq for EventByVersionWithProof
impl StructuralEq for EventByVersionWithProof
impl StructuralPartialEq for EventByVersionWithProof
Auto Trait Implementations§
impl RefUnwindSafe for EventByVersionWithProof
impl Send for EventByVersionWithProof
impl Sync for EventByVersionWithProof
impl Unpin for EventByVersionWithProof
impl UnwindSafe for EventByVersionWithProof
Blanket Implementations§
source§impl<Q, K> Equivalent<K> for Qwhere
Q: Eq + ?Sized,
K: Borrow<Q> + ?Sized,
impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,
source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key
and return true
if they are equal.