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consensus: improve docs 

- remove no longer accurate documentation about transaction verifier;
- add description of the role of the crate.
This commit is contained in:
Henry de Valence 2020-10-16 15:53:22 -07:00 committed by Deirdre Connolly
parent c0aa1b477e
commit d4ce3eb054
2 changed files with 29 additions and 25 deletions
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35
zebra-consensus/src/lib.rs
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@ -1,13 +1,34 @@
//! Consensus handling for Zebra.
//! Implementation of Zcash consensus checks.
//!
//! `verify::BlockVerifier` verifies blocks and their transactions, then adds them to
//! `zebra_state::ZebraState`.
//! More specifically, this crate implements *semantic* validity checks,
//! as defined below.
//!
//! `mempool::MempoolTransactionVerifier` verifies transactions, and adds them to
//! `mempool::ZebraMempoolState`.
//! ## Verification levels.
//!
//! Consensus handling is provided using `tower::Service`s, to support backpressure
//! and batch verification.
//! Zebra's implementation of the Zcash consensus rules is oriented
//! around three telescoping notions of validity:
//!
//! 1. *Structural Validity*, or whether the format and structure of the
//! object are valid. For instance, Sprout-on-BCTV14 proofs are not
//! allowed in version 4 transactions, and a transaction with a spend
//! or output description must include a binding signature.
//!
//! 2. *Semantic Validity*, or whether the object could potentially be
//! valid, depending on the chain state. For instance, a transaction
//! that spends a UTXO must supply a valid unlock script; a shielded
//! transaction must have valid proofs, etc.
//!
//! 3. *Contextual Validity*, or whether a semantically valid
//! transaction is actually valid in the context of a particular
//! chain state. For instance, a transaction that spends a
//! UTXO is only valid if the UTXO remains unspent; a
//! shielded transaction spending some note must reveal a nullifier
//! not already in the nullifier set, etc.
//!
//! *Structural validity* is enforced by the definitions of data
//! structures in `zebra-chain`. *Semantic validity* is enforced by the
//! code in this crate. *Contextual validity* is enforced in
//! `zebra-state` when objects are committed to the chain state.
#![doc(html_favicon_url = "https://www.zfnd.org/images/zebra-favicon-128.png")]
#![doc(html_logo_url = "https://www.zfnd.org/images/zebra-icon.png")]

19
zebra-consensus/src/transaction.rs
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@ -1,17 +1,3 @@
//! Transaction verification for Zebra.
//!
//! Verification occurs in multiple stages:
//! - getting transactions from blocks or the mempool (disk- or network-bound)
//! - context-free verification of signatures, proofs, and scripts (CPU-bound)
//! - context-dependent verification of transactions against the chain state
//! (awaits an up-to-date chain)
//!
//! Verification is provided via a `tower::Service`, to support backpressure and batch
//! verification.
//!
//! This is an internal module. Use `verify::BlockVerifier` for blocks and their
//! transactions, or `mempool::MempoolTransactionVerifier` for mempool transactions.
use std::{
future::Future,
pin::Pin,
@ -37,10 +23,7 @@ use zebra_state as zs;
use crate::{script, BoxError};
/// Internal transaction verification service.
///
/// After verification, the transaction future completes. State changes are
/// handled by `BlockVerifier` or `MempoolTransactionVerifier`.
/// Asynchronous transaction verification.
#[derive(Debug, Clone)]
pub struct Verifier<ZS> {
script_verifier: script::Verifier<ZS>,