fix(testnet): look back up to 10,000 blocks on testnet for a legacy chain (#5133)

* Look back 10,000 blocks on testnet for a legacy chain

* Use a smaller number of legacy chain blocks in the tests

* Fix test assertion error message

* Clarify legacy chain check comment

* cargo fmt --all

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

zebra-state/src/constants.rs

@@ -22,7 +22,9 @@ pub const DATABASE_FORMAT_VERSION: u32 = 25;
 
 /// The maximum number of blocks to check for NU5 transactions,
 /// before we assume we are on a pre-NU5 legacy chain.
-pub const MAX_LEGACY_CHAIN_BLOCKS: usize = 1000;
+///
+/// Zebra usually only has to check back a few blocks, but on testnet it can be a long time between v5 transactions.
+pub const MAX_LEGACY_CHAIN_BLOCKS: usize = 10_000;
 
 /// The maximum number of block hashes allowed in `getblocks` responses in the Zcash network protocol.
 pub const MAX_FIND_BLOCK_HASHES_RESULTS: u32 = 500;

zebra-state/src/service.rs

@@ -38,7 +38,10 @@ use zebra_chain::{
 };
 
 use crate::{
-    constants::{MAX_FIND_BLOCK_HASHES_RESULTS, MAX_FIND_BLOCK_HEADERS_RESULTS_FOR_ZEBRA},
+    constants::{
+        MAX_FIND_BLOCK_HASHES_RESULTS, MAX_FIND_BLOCK_HEADERS_RESULTS_FOR_ZEBRA,
+        MAX_LEGACY_CHAIN_BLOCKS,
+    },
     service::{
         chain_tip::{ChainTipBlock, ChainTipChange, ChainTipSender, LatestChainTip},
         finalized_state::{FinalizedState, ZebraDb},
@@ -251,6 +254,7 @@ impl StateService {
                 nu5_activation_height,
                 state.any_ancestor_blocks(tip.1),
                 state.network,
+                MAX_LEGACY_CHAIN_BLOCKS,
             ) {
                 let legacy_db_path = state.disk.path().to_path_buf();
                 panic!(

zebra-state/src/service/check.rs

@@ -12,7 +12,7 @@ use zebra_chain::{
     work::difficulty::CompactDifficulty,
 };
 
-use crate::{constants, BoxError, PreparedBlock, ValidateContextError};
+use crate::{BoxError, PreparedBlock, ValidateContextError};
 
 // use self as check
 use super::check;
@@ -289,10 +289,15 @@ fn difficulty_threshold_is_valid(
 }
 
 /// Check if zebra is following a legacy chain and return an error if so.
+///
+/// `nu5_activation_height` should be `NetworkUpgrade::Nu5.activation_height(network)`, and
+/// `max_legacy_chain_blocks` should be [`MAX_LEGACY_CHAIN_BLOCKS`](crate::constants::MAX_LEGACY_CHAIN_BLOCKS).
+/// They are only changed from the defaults for testing.
 pub(crate) fn legacy_chain<I>(
     nu5_activation_height: block::Height,
     ancestors: I,
     network: Network,
+    max_legacy_chain_blocks: usize,
 ) -> Result<(), BoxError>
 where
     I: Iterator<Item = Arc<Block>>,
@@ -315,8 +320,8 @@ where
         }
 
         // If we are past our NU5 activation height, but there are no V5 transactions in recent blocks,
-        // the Zebra instance that verified those blocks had no NU5 activation height.
-        if index >= constants::MAX_LEGACY_CHAIN_BLOCKS {
+        // the last Zebra instance that updated this cached state had no NU5 activation height.
+        if index >= max_legacy_chain_blocks {
             return Err(format!(
                 "could not find any transactions in recent blocks: \
                  checked {index} blocks back from {:?}",

zebra-state/src/service/tests.rs

@@ -20,7 +20,6 @@ use zebra_test::{prelude::*, transcript::Transcript};
 
 use crate::{
     arbitrary::Prepare,
-    constants::{self, MAX_LEGACY_CHAIN_BLOCKS},
     init_test,
     service::{arbitrary::populated_state, chain_tip::TipAction, StateService},
     tests::setup::{partial_nu5_chain_strategy, transaction_v4_from_coinbase},
@@ -277,11 +276,14 @@ fn state_behaves_when_blocks_are_committed_in_order() -> Result<()> {
 
 const DEFAULT_PARTIAL_CHAIN_PROPTEST_CASES: u32 = 2;
 
+/// The legacy chain limit for tests.
+const TEST_LEGACY_CHAIN_LIMIT: usize = 100;
+
 /// Check more blocks than the legacy chain limit.
-const OVER_LEGACY_CHAIN_LIMIT: u32 = constants::MAX_LEGACY_CHAIN_BLOCKS as u32 + 10;
+const OVER_LEGACY_CHAIN_LIMIT: u32 = TEST_LEGACY_CHAIN_LIMIT as u32 + 10;
 
 /// Check fewer blocks than the legacy chain limit.
-const UNDER_LEGACY_CHAIN_LIMIT: u32 = constants::MAX_LEGACY_CHAIN_BLOCKS as u32 - 10;
+const UNDER_LEGACY_CHAIN_LIMIT: u32 = TEST_LEGACY_CHAIN_LIMIT as u32 - 10;
 
 proptest! {
     #![proptest_config(
@@ -304,7 +306,7 @@ proptest! {
     fn some_block_less_than_network_upgrade(
         (network, nu_activation_height, chain) in partial_nu5_chain_strategy(4, true, UNDER_LEGACY_CHAIN_LIMIT, NetworkUpgrade::Canopy)
     ) {
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network)
+        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(response, Ok(()));
@@ -321,13 +323,13 @@ proptest! {
             .coinbase_height()
             .expect("chain contains valid blocks");
 
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network)
+        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(
             response,
             Err(format!(
-                "could not find any transactions in recent blocks: checked {MAX_LEGACY_CHAIN_BLOCKS} blocks back from {tip_height:?}",
+                "could not find any transactions in recent blocks: checked {TEST_LEGACY_CHAIN_LIMIT} blocks back from {tip_height:?}",
             ))
         );
     }
@@ -360,7 +362,8 @@ proptest! {
         let response = crate::service::check::legacy_chain(
             nu_activation_height,
             chain.clone().into_iter().rev(),
-            network
+            network,
+            TEST_LEGACY_CHAIN_LIMIT,
         ).map_err(|error| error.to_string());
 
         prop_assert_eq!(
@@ -377,7 +380,7 @@ proptest! {
     fn at_least_one_transaction_with_valid_network_upgrade(
         (network, nu_activation_height, chain) in partial_nu5_chain_strategy(5, true, UNDER_LEGACY_CHAIN_LIMIT, NetworkUpgrade::Canopy)
     ) {
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network)
+        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(response, Ok(()));