feat(regtest): Add regtest halving interval and port test

zebra-chain/src/parameters/network/subsidy.rs

@@ -40,6 +40,10 @@ pub const BLOSSOM_POW_TARGET_SPACING_RATIO: u32 = 2;
 /// `(60 * 60 * 24 * 365 * 4) / 150 = 840960`
 pub const PRE_BLOSSOM_HALVING_INTERVAL: HeightDiff = 840_000;
 
+/// The halving height interval in the regtest is 6 hours.
+/// [zcashd regtest halving interval](https://github.com/zcash/zcash/blob/v5.10.0/src/consensus/params.h#L252)
+pub(crate) const PRE_BLOSSOM_REGTEST_HALVING_INTERVAL: HeightDiff = 144;
+
 /// After Blossom the block time is reduced to 75 seconds but halving period should remain around 4 years.
 pub const POST_BLOSSOM_HALVING_INTERVAL: HeightDiff =
     PRE_BLOSSOM_HALVING_INTERVAL * (BLOSSOM_POW_TARGET_SPACING_RATIO as HeightDiff);
@@ -48,7 +52,10 @@ pub const POST_BLOSSOM_HALVING_INTERVAL: HeightDiff =
 /// as specified in [protocol specification §7.10.1][7.10.1]
 ///
 /// [7.10.1]: https://zips.z.cash/protocol/protocol.pdf#zip214fundingstreams
-pub const FIRST_HALVING_TESTNET: Height = Height(1_116_000);
+pub(crate) const FIRST_HALVING_TESTNET: Height = Height(1_116_000);
+
+/// The first halving height in the regtest is at block height `287`.
+const FIRST_HALVING_REGTEST: Height = Height(287);
 
 /// The funding stream receiver categories.
 #[derive(Deserialize, Clone, Copy, Debug, Eq, Hash, PartialEq)]
@@ -379,6 +386,15 @@ pub trait ParameterSubsidy {
     ///
     /// [7.10]: <https://zips.z.cash/protocol/protocol.pdf#fundingstreams>
     fn height_for_first_halving(&self) -> Height;
+
+    /// Returns the halving interval after Blossom
+    fn post_blossom_halving_interval(&self) -> HeightDiff;
+
+    /// Returns the halving interval before Blossom
+    fn pre_blossom_halving_interval(&self) -> HeightDiff;
+
+    /// Returns the address change interval for funding streams
+    fn funding_stream_address_change_interval(&self) -> HeightDiff;
 }
 
 /// Network methods related to Block Subsidy and Funding Streams
@@ -391,10 +407,36 @@ impl ParameterSubsidy for Network {
             Network::Mainnet => NetworkUpgrade::Canopy
                 .activation_height(self)
                 .expect("canopy activation height should be available"),
-            // TODO: Check what zcashd does here, consider adding a field to `testnet::Parameters` to make this configurable.
-            Network::Testnet(_params) => FIRST_HALVING_TESTNET,
+            Network::Testnet(params) => {
+                if params.is_regtest() {
+                    FIRST_HALVING_REGTEST
+                } else if params.is_default_testnet() {
+                    FIRST_HALVING_TESTNET
+                } else {
+                    height_for_halving_index(1, self)
+                        .expect("first halving height should be available")
+                }
+            }
         }
     }
+
+    fn post_blossom_halving_interval(&self) -> HeightDiff {
+        match self {
+            Network::Mainnet => POST_BLOSSOM_HALVING_INTERVAL,
+            Network::Testnet(params) => params.post_blossom_halving_interval(),
+        }
+    }
+
+    fn pre_blossom_halving_interval(&self) -> HeightDiff {
+        match self {
+            Network::Mainnet => PRE_BLOSSOM_HALVING_INTERVAL,
+            Network::Testnet(params) => params.pre_blossom_halving_interval(),
+        }
+    }
+
+    fn funding_stream_address_change_interval(&self) -> HeightDiff {
+        self.post_blossom_halving_interval() / 48
+    }
 }
 
 /// List of addresses for the Zcash Foundation funding stream in the Mainnet.
@@ -503,10 +545,54 @@ pub fn funding_stream_address_period<N: ParameterSubsidy>(height: Height, networ
 
     let height_after_first_halving = height - network.height_for_first_halving();
 
-    let address_period = (height_after_first_halving + POST_BLOSSOM_HALVING_INTERVAL)
-        / FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL;
+    let address_period = (height_after_first_halving + network.post_blossom_halving_interval())
+        / network.funding_stream_address_change_interval();
 
     address_period
         .try_into()
         .expect("all values are positive and smaller than the input height")
 }
+
+/// The first block height of the halving at the provided halving index for a network.
+///
+/// See `Halving(height)`, as described in [protocol specification §7.8][7.8]
+///
+/// [7.8]: https://zips.z.cash/protocol/protocol.pdf#subsidies
+pub fn height_for_halving_index(halving_index: u32, network: &Network) -> Option<Height> {
+    if halving_index == 0 {
+        return Some(Height(0));
+    }
+
+    let slow_start_shift = i64::from(network.slow_start_shift().0);
+    let blossom_height = i64::from(
+        NetworkUpgrade::Blossom
+            .activation_height(network)
+            .expect("blossom activation height should be available")
+            .0,
+    );
+    let pre_blossom_halving_interval = network.pre_blossom_halving_interval();
+    let halving_index = i64::from(halving_index);
+
+    let unscaled_height = halving_index
+        .checked_mul(pre_blossom_halving_interval)
+        .expect("Multiplication overflow: consider reducing the halving interval");
+
+    let pre_blossom_height = unscaled_height
+        .min(blossom_height)
+        .checked_add(slow_start_shift)
+        .expect("Addition overflow: consider reducing the halving interval");
+
+    let post_blossom_height = 0
+        .max(unscaled_height - blossom_height)
+        .checked_mul(i64::from(BLOSSOM_POW_TARGET_SPACING_RATIO))
+        .expect("Multiplication overflow: consider reducing the halving interval")
+        .checked_add(slow_start_shift)
+        .expect("Addition overflow: consider reducing the halving interval");
+
+    let height = pre_blossom_height
+        .checked_add(post_blossom_height)
+        .expect("Addition overflow: consider reducing the halving interval");
+
+    let height = u32::try_from(height).ok()?;
+    height.try_into().ok()
+}

zebra-chain/src/parameters/network/testnet.rs

@@ -2,7 +2,7 @@
 use std::{collections::BTreeMap, fmt};
 
 use crate::{
-    block::{self, Height},
+    block::{self, Height, HeightDiff},
     parameters::{
         constants::{magics, SLOW_START_INTERVAL, SLOW_START_SHIFT},
         network_upgrade::TESTNET_ACTIVATION_HEIGHTS,
@@ -16,7 +16,10 @@ use super::{
     magic::Magic,
     subsidy::{
         FundingStreamReceiver, FundingStreamRecipient, FundingStreams, ParameterSubsidy,
-        FIRST_HALVING_TESTNET, POST_NU6_FUNDING_STREAMS_MAINNET, POST_NU6_FUNDING_STREAMS_TESTNET,
+        BLOSSOM_POW_TARGET_SPACING_RATIO, FIRST_HALVING_TESTNET,
+        FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL, POST_BLOSSOM_HALVING_INTERVAL,
+        POST_NU6_FUNDING_STREAMS_MAINNET, POST_NU6_FUNDING_STREAMS_TESTNET,
+        PRE_BLOSSOM_HALVING_INTERVAL, PRE_BLOSSOM_REGTEST_HALVING_INTERVAL,
         PRE_NU6_FUNDING_STREAMS_MAINNET, PRE_NU6_FUNDING_STREAMS_TESTNET,
     },
 };
@@ -57,6 +60,17 @@ impl ParameterSubsidy for TestnetParameterSubsidyImpl {
     fn height_for_first_halving(&self) -> Height {
         FIRST_HALVING_TESTNET
     }
+    fn post_blossom_halving_interval(&self) -> block::HeightDiff {
+        POST_BLOSSOM_HALVING_INTERVAL
+    }
+
+    fn pre_blossom_halving_interval(&self) -> block::HeightDiff {
+        PRE_BLOSSOM_HALVING_INTERVAL
+    }
+
+    fn funding_stream_address_change_interval(&self) -> HeightDiff {
+        FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL
+    }
 }
 
 /// Configurable funding stream recipient for configured Testnets.
@@ -217,6 +231,10 @@ pub struct ParametersBuilder {
     target_difficulty_limit: ExpandedDifficulty,
     /// A flag for disabling proof-of-work checks when Zebra is validating blocks
     disable_pow: bool,
+    /// The pre-Blossom halving interval for this network
+    pre_blossom_halving_interval: HeightDiff,
+    /// The post-Blossom halving interval for this network
+    post_blossom_halving_interval: HeightDiff,
 }
 
 impl Default for ParametersBuilder {
@@ -249,6 +267,8 @@ impl Default for ParametersBuilder {
             disable_pow: false,
             pre_nu6_funding_streams: PRE_NU6_FUNDING_STREAMS_TESTNET.clone(),
             post_nu6_funding_streams: POST_NU6_FUNDING_STREAMS_TESTNET.clone(),
+            pre_blossom_halving_interval: PRE_BLOSSOM_HALVING_INTERVAL,
+            post_blossom_halving_interval: POST_BLOSSOM_HALVING_INTERVAL,
         }
     }
 }
@@ -411,6 +431,14 @@ impl ParametersBuilder {
         self
     }
 
+    /// Sets the pre and post Blosssom halving intervals to be used in the [`Parameters`] being built.
+    pub fn with_halving_interval(mut self, pre_blossom_halving_interval: HeightDiff) -> Self {
+        self.pre_blossom_halving_interval = pre_blossom_halving_interval;
+        self.post_blossom_halving_interval =
+            self.pre_blossom_halving_interval * (BLOSSOM_POW_TARGET_SPACING_RATIO as HeightDiff);
+        self
+    }
+
     /// Converts the builder to a [`Parameters`] struct
     pub fn finish(self) -> Parameters {
         let Self {
@@ -423,6 +451,8 @@ impl ParametersBuilder {
             post_nu6_funding_streams,
             target_difficulty_limit,
             disable_pow,
+            pre_blossom_halving_interval,
+            post_blossom_halving_interval,
         } = self;
         Parameters {
             network_name,
@@ -435,6 +465,8 @@ impl ParametersBuilder {
             post_nu6_funding_streams,
             target_difficulty_limit,
             disable_pow,
+            pre_blossom_halving_interval,
+            post_blossom_halving_interval,
         }
     }
 
@@ -455,6 +487,8 @@ impl ParametersBuilder {
             post_nu6_funding_streams,
             target_difficulty_limit,
             disable_pow,
+            pre_blossom_halving_interval,
+            post_blossom_halving_interval,
         } = Self::default();
 
         self.activation_heights == activation_heights
@@ -465,6 +499,8 @@ impl ParametersBuilder {
             && self.post_nu6_funding_streams == post_nu6_funding_streams
             && self.target_difficulty_limit == target_difficulty_limit
             && self.disable_pow == disable_pow
+            && self.pre_blossom_halving_interval == pre_blossom_halving_interval
+            && self.post_blossom_halving_interval == post_blossom_halving_interval
     }
 }
 
@@ -495,6 +531,10 @@ pub struct Parameters {
     target_difficulty_limit: ExpandedDifficulty,
     /// A flag for disabling proof-of-work checks when Zebra is validating blocks
     disable_pow: bool,
+    /// Pre-Blossom halving interval for this network
+    pre_blossom_halving_interval: HeightDiff,
+    /// Post-Blossom halving interval for this network
+    post_blossom_halving_interval: HeightDiff,
 }
 
 impl Default for Parameters {
@@ -540,6 +580,7 @@ impl Parameters {
                     nu6: nu6_activation_height,
                     ..Default::default()
                 })
+                .with_halving_interval(PRE_BLOSSOM_REGTEST_HALVING_INTERVAL)
                 .finish()
         }
     }
@@ -568,6 +609,8 @@ impl Parameters {
             post_nu6_funding_streams,
             target_difficulty_limit,
             disable_pow,
+            pre_blossom_halving_interval,
+            post_blossom_halving_interval,
         } = Self::new_regtest(None, None);
 
         self.network_name == network_name
@@ -578,6 +621,8 @@ impl Parameters {
             && self.post_nu6_funding_streams == post_nu6_funding_streams
             && self.target_difficulty_limit == target_difficulty_limit
             && self.disable_pow == disable_pow
+            && self.pre_blossom_halving_interval == pre_blossom_halving_interval
+            && self.post_blossom_halving_interval == post_blossom_halving_interval
     }
 
     /// Returns the network name
@@ -629,6 +674,16 @@ impl Parameters {
     pub fn disable_pow(&self) -> bool {
         self.disable_pow
     }
+
+    /// Returns the pre-Blossom halving interval for this network
+    pub fn pre_blossom_halving_interval(&self) -> HeightDiff {
+        self.pre_blossom_halving_interval
+    }
+
+    /// Returns the post-Blossom halving interval for this network
+    pub fn post_blossom_halving_interval(&self) -> HeightDiff {
+        self.post_blossom_halving_interval
+    }
 }
 
 impl Network {

zebra-chain/src/parameters/network_upgrade.rs

@@ -59,6 +59,7 @@ pub enum NetworkUpgrade {
     #[serde(rename = "NU5")]
     Nu5,
     /// The Zcash protocol after the NU6 upgrade.
+    #[serde(rename = "NU6")]
     Nu6,
 }