change(mining): Restores parts of the internal-miner feature for use on Regtest (#8506)

* Allow configurable Nu5 activation height on Regtest

* Fixes test

* removes outdated TODO

* Adds `current_with_activation_height()` method and uses it in `Commitment::from_bytes()`

* Enables parts of the internal miner for use on Regtest when the solution isn't checked

* Update internal miner config field docs

zebra-chain/src/work/equihash.rs

@@ -132,7 +132,7 @@ impl Solution {
     #[cfg(feature = "internal-miner")]
     #[allow(clippy::unwrap_in_result)]
     pub fn solve<F>(
-        mut _header: Header,
+        mut header: Header,
         mut _cancel_fn: F,
     ) -> Result<AtLeastOne<Header>, SolverCancelled>
     where
@@ -141,8 +141,8 @@ impl Solution {
         // TODO: Function code was removed as part of https://github.com/ZcashFoundation/zebra/issues/8180
         // Find the removed code at https://github.com/ZcashFoundation/zebra/blob/v1.5.1/zebra-chain/src/work/equihash.rs#L115-L166
         // Restore the code when conditions are met. https://github.com/ZcashFoundation/zebra/issues/8183
-
-        Err(SolverCancelled)
+        header.solution = Solution::for_proposal();
+        Ok(AtLeastOne::from_one(header))
     }
 
     // TODO: Some methods were removed as part of https://github.com/ZcashFoundation/zebra/issues/8180

zebra-rpc/src/config/mining.rs

@@ -29,6 +29,17 @@ pub struct Config {
     ///
     /// This developer-only config is not supported for general use.
     pub debug_like_zcashd: bool,
+
+    /// Mine blocks using Zebra's internal miner, without an external mining pool or equihash solver.
+    ///
+    /// This experimental feature is only supported on regtest as it uses null solutions and skips checking
+    /// for a valid Proof of Work.
+    ///
+    /// The internal miner is off by default.
+    // TODO: Restore equihash solver and recommend that Mainnet miners should use a mining pool with
+    //       GPUs or ASICs designed for efficient mining.
+    #[cfg(feature = "internal-miner")]
+    pub internal_miner: bool,
 }
 
 impl Default for Config {
@@ -42,6 +53,8 @@ impl Default for Config {
             // TODO: Internal miner config code was removed as part of https://github.com/ZcashFoundation/zebra/issues/8180
             // Find the removed code at https://github.com/ZcashFoundation/zebra/blob/v1.5.1/zebra-rpc/src/config/mining.rs#L61-L66
             // Restore the code when conditions are met. https://github.com/ZcashFoundation/zebra/issues/8183
+            #[cfg(feature = "internal-miner")]
+            internal_miner: false,
         }
     }
 }
@@ -61,6 +74,6 @@ impl Config {
         // TODO: Changed to return always false so internal miner is never started. Part of https://github.com/ZcashFoundation/zebra/issues/8180
         // Find the removed code at https://github.com/ZcashFoundation/zebra/blob/v1.5.1/zebra-rpc/src/config/mining.rs#L83
         // Restore the code when conditions are met. https://github.com/ZcashFoundation/zebra/issues/8183
-        false
+        self.internal_miner
     }
 }

zebra-rpc/src/methods/tests/snapshot/get_block_template_rpcs.rs

@@ -101,7 +101,7 @@ pub async fn test_responses<State, ReadState>(
         extra_coinbase_data: None,
         debug_like_zcashd: true,
         // TODO: Use default field values when optional features are enabled in tests #8183
-        //..Default::default()
+        ..Default::default()
     };
 
     // nu5 block height

zebra-rpc/src/methods/tests/vectors.rs

@@ -1286,7 +1286,7 @@ async fn rpc_getblocktemplate_mining_address(use_p2pkh: bool) {
         extra_coinbase_data: None,
         debug_like_zcashd: true,
         // TODO: Use default field values when optional features are enabled in tests #8183
-        //..Default::default()
+        ..Default::default()
     };
 
     // nu5 block height
@@ -1735,7 +1735,7 @@ async fn rpc_getdifficulty() {
         extra_coinbase_data: None,
         debug_like_zcashd: true,
         // TODO: Use default field values when optional features are enabled in tests #8183
-        //..Default::default()
+        ..Default::default()
     };
 
     // nu5 block height

zebrad/src/commands/start.rs

@@ -359,7 +359,7 @@ impl StartCmd {
                 address_book,
             );
 
-            crate::components::miner::spawn_init(&config.mining, rpc)
+            crate::components::miner::spawn_init(&config.network.network, &config.mining, rpc)
         } else {
             tokio::spawn(std::future::pending().in_current_span())
         };

zebrad/src/components/miner.rs

@@ -16,11 +16,11 @@ use tower::Service;
 use tracing::{Instrument, Span};
 
 use zebra_chain::{
-    block::{self, Block},
+    block::{self, Block, Height},
     chain_sync_status::ChainSyncStatus,
     chain_tip::ChainTip,
     diagnostic::task::WaitForPanics,
-    parameters::NetworkUpgrade,
+    parameters::{Network, NetworkUpgrade},
     serialization::{AtLeastOne, ZcashSerialize},
     shutdown::is_shutting_down,
     work::equihash::{Solution, SolverCancelled},
@@ -61,6 +61,7 @@ pub const BLOCK_MINING_WAIT_TIME: Duration = Duration::from_secs(3);
 ///
 /// See [`run_mining_solver()`] for more details.
 pub fn spawn_init<Mempool, State, Tip, BlockVerifierRouter, SyncStatus, AddressBook>(
+    network: &Network,
     config: &Config,
     rpc: GetBlockTemplateRpcImpl<Mempool, State, Tip, BlockVerifierRouter, SyncStatus, AddressBook>,
 ) -> JoinHandle<Result<(), Report>>
@@ -94,10 +95,11 @@ where
     SyncStatus: ChainSyncStatus + Clone + Send + Sync + 'static,
     AddressBook: AddressBookPeers + Clone + Send + Sync + 'static,
 {
+    let network = network.clone();
     let config = config.clone();
 
     // TODO: spawn an entirely new executor here, so mining is isolated from higher priority tasks.
-    tokio::spawn(init(config, rpc).in_current_span())
+    tokio::spawn(init(network, config, rpc).in_current_span())
 }
 
 /// Initialize the miner based on its config.
@@ -107,6 +109,7 @@ where
 ///
 /// See [`run_mining_solver()`] for more details.
 pub async fn init<Mempool, State, Tip, BlockVerifierRouter, SyncStatus, AddressBook>(
+    network: Network,
     _config: Config,
     rpc: GetBlockTemplateRpcImpl<Mempool, State, Tip, BlockVerifierRouter, SyncStatus, AddressBook>,
 ) -> Result<(), Report>
@@ -163,7 +166,7 @@ where
     let mut abort_handles = Vec::new();
 
     let template_generator = tokio::task::spawn(
-        generate_block_templates(rpc.clone(), template_sender).in_current_span(),
+        generate_block_templates(network, rpc.clone(), template_sender).in_current_span(),
     );
     abort_handles.push(template_generator.abort_handle());
     let template_generator = template_generator.wait_for_panics();
@@ -217,6 +220,7 @@ pub async fn generate_block_templates<
     SyncStatus,
     AddressBook,
 >(
+    network: Network,
     rpc: GetBlockTemplateRpcImpl<Mempool, State, Tip, BlockVerifierRouter, SyncStatus, AddressBook>,
     template_sender: watch::Sender<Option<Arc<Block>>>,
 ) -> Result<(), Report>
@@ -260,11 +264,11 @@ where
 
     // Shut down the task when all the template receivers are dropped, or Zebra shuts down.
     while !template_sender.is_closed() && !is_shutting_down() {
-        let template = rpc.get_block_template(Some(parameters.clone())).await;
+        let template: Result<_, _> = rpc.get_block_template(Some(parameters.clone())).await;
 
         // Wait for the chain to sync so we get a valid template.
         let Ok(template) = template else {
-            debug!(
+            info!(
                 ?BLOCK_TEMPLATE_WAIT_TIME,
                 "waiting for a valid block template",
             );
@@ -291,9 +295,12 @@ where
         // Tell the next get_block_template() call to wait until the template has changed.
         parameters.long_poll_id = Some(template.long_poll_id);
 
-        let block =
-            proposal_block_from_template(&template, TimeSource::CurTime, NetworkUpgrade::Nu5)
-                .expect("unexpected invalid block template");
+        let block = proposal_block_from_template(
+            &template,
+            TimeSource::CurTime,
+            NetworkUpgrade::current(&network, Height(template.height)),
+        )
+        .expect("unexpected invalid block template");
 
         // If the template has actually changed, send an updated template.
         template_sender.send_if_modified(|old_block| {