128 lines
4.5 KiB
Rust
128 lines
4.5 KiB
Rust
//! Supporting types for checkpoint-based block verification
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use std::cmp::Ordering;
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use zebra_chain::block;
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use Progress::*;
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use TargetHeight::*;
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/// A `CheckpointVerifier`'s current progress verifying the chain.
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub enum Progress<HeightOrHash> {
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/// We have not verified any blocks yet.
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BeforeGenesis,
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/// We have verified up to and including this initial tip.
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///
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/// Initial tips might not be one of our hard-coded checkpoints, because we
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/// might have:
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/// - changed the checkpoint spacing, or
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/// - added new checkpoints above the initial tip.
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InitialTip(HeightOrHash),
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/// We have verified up to and including this checkpoint.
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PreviousCheckpoint(HeightOrHash),
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/// We have finished verifying.
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///
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/// The final checkpoint is not included in this variant. The verifier has
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/// finished, so the checkpoints aren't particularly useful.
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/// To get the value of the final checkpoint, use `checkpoint_list.max_height()`.
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FinalCheckpoint,
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}
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/// Block height progress, in chain order.
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impl Ord for Progress<block::Height> {
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fn cmp(&self, other: &Self) -> Ordering {
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if self == other {
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return Ordering::Equal;
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}
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match (self, other) {
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(BeforeGenesis, _) => Ordering::Less,
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(_, BeforeGenesis) => Ordering::Greater,
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(FinalCheckpoint, _) => Ordering::Greater,
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(_, FinalCheckpoint) => Ordering::Less,
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(InitialTip(self_height), InitialTip(other_height))
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| (InitialTip(self_height), PreviousCheckpoint(other_height))
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| (PreviousCheckpoint(self_height), InitialTip(other_height))
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| (PreviousCheckpoint(self_height), PreviousCheckpoint(other_height)) => {
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self_height.cmp(other_height)
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}
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}
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}
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}
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/// Partial order for block height progress.
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///
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/// The partial order must match the total order.
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impl PartialOrd for Progress<block::Height> {
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fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
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Some(self.cmp(other))
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}
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}
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impl Progress<block::Height> {
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/// Returns the contained height, or `None` if the progress has finished, or has not started.
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pub fn height(&self) -> Option<block::Height> {
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match self {
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BeforeGenesis => None,
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InitialTip(height) => Some(*height),
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PreviousCheckpoint(height) => Some(*height),
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FinalCheckpoint => None,
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}
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}
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}
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impl<HeightOrHash> Progress<HeightOrHash> {
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/// Returns `true` if the progress is before the genesis block.
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#[allow(dead_code)]
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pub fn is_before_genesis(&self) -> bool {
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matches!(self, BeforeGenesis)
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}
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/// Returns `true` if the progress is at or after the final checkpoint block.
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pub fn is_final_checkpoint(&self) -> bool {
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matches!(self, FinalCheckpoint)
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}
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}
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/// A `CheckpointVerifier`'s target checkpoint height, based on the current
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/// queue.
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub enum TargetHeight {
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/// We need more blocks before we can choose a target checkpoint.
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WaitingForBlocks,
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/// We want to verify this checkpoint.
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///
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/// The target checkpoint can be multiple checkpoints ahead of the previous
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/// checkpoint.
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Checkpoint(block::Height),
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/// We have finished verifying, there will be no more targets.
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FinishedVerifying,
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}
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/// Block height target, in chain order.
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///
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/// `WaitingForBlocks` is incomparable with itself and `Checkpoint(_)`.
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impl PartialOrd for TargetHeight {
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fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
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match (self, other) {
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// FinishedVerifying is the final state
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(FinishedVerifying, FinishedVerifying) => Some(Ordering::Equal),
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(FinishedVerifying, _) => Some(Ordering::Greater),
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(_, FinishedVerifying) => Some(Ordering::Less),
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// Checkpoints are comparable with each other by height
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(Checkpoint(self_height), Checkpoint(other_height)) => {
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self_height.partial_cmp(other_height)
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}
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// We can wait for blocks before or after any target checkpoint,
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// so there is no ordering between checkpoint and waiting.
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(WaitingForBlocks, Checkpoint(_)) => None,
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(Checkpoint(_), WaitingForBlocks) => None,
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// However, we consider waiting equal to itself.
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(WaitingForBlocks, WaitingForBlocks) => Some(Ordering::Equal),
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}
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}
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}
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