feat(COP): only in testnet: reduce the number of block producers (#9563)

In chains that are not `mainnet`:
* Decrease the number of block producers to 20
* Decrease the number of chunk only producers to 100

This change lets testnet in its current state perform testing of
chunk-only producers.

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: Anton Puhach <anton@near.org>
Co-authored-by: Jakob Meier <mail@jakobmeier.ch>
Co-authored-by: Simonas Kazlauskas <git@kazlauskas.me>
Co-authored-by: Saketh Are <saketh.are@gmail.com>
Co-authored-by: Shreyan Gupta <shreyan@near.org>
Co-authored-by: Ekleog-NEAR <96595974+Ekleog-NEAR@users.noreply.github.com>
Co-authored-by: Marcelo Diop-Gonzalez <marcelo827@gmail.com>
Co-authored-by: Bowen Wang <bowenwang1996@users.noreply.github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: wacban <wacban@users.noreply.github.com>
Co-authored-by: Adam Chudaś <18039094+staffik@users.noreply.github.com>
Co-authored-by: robin-near <111538878+robin-near@users.noreply.github.com>
Co-authored-by: Olga Telezhnaya <olyatelezhnaya@gmail.com>
Co-authored-by: i-fix-typos <146758284+i-fix-typos@users.noreply.github.com>
Co-authored-by: Aleksandr Logunov <alex.logunov@near.org>
Co-authored-by: Jure Bajic <jure@near.org>
Co-authored-by: dj8yf0μl <26653921+dj8yfo@users.noreply.github.com>

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Protocol Changes
 * The support for fixed shards in shard layout was removed. [#9219](/~https://github.com/near/nearcore/pull/9219)
 * Restrict the creation of non-implicit top-level account that are longer than 32 bytes. Only the registrar account can create them. [#9589](/~https://github.com/near/nearcore/pull/9589)
+* Adjust the number of block producers and chunk producers on testnet to facilitate testing of chunk-only producers [#9563](/~https://github.com/near/nearcore/pull/9563)
 
 
 ### Non-protocol Changes

chain/epoch-manager/src/shard_tracker.rs

@@ -237,7 +237,7 @@ mod tests {
         };
         EpochManager::new(
             store,
-            AllEpochConfig::new(use_production_config, initial_epoch_config),
+            AllEpochConfig::new(use_production_config, initial_epoch_config, "test-chain"),
             genesis_protocol_version,
             reward_calculator,
             vec![ValidatorStake::new(

chain/epoch-manager/src/test_utils.rs

@@ -154,7 +154,7 @@ pub fn epoch_config_with_production_config(
         shard_layout: ShardLayout::v0(num_shards, 0),
         validator_max_kickout_stake_perc: 100,
     };
-    AllEpochConfig::new(use_production_config, epoch_config)
+    AllEpochConfig::new(use_production_config, epoch_config, "test-chain")
 }
 
 pub fn epoch_config(

chain/epoch-manager/src/tests/mod.rs

@@ -2207,7 +2207,7 @@ fn test_protocol_version_switch_with_many_seats() {
         validator_selection_config: Default::default(),
         validator_max_kickout_stake_perc: 100,
     };
-    let config = AllEpochConfig::new(false, epoch_config);
+    let config = AllEpochConfig::new(false, epoch_config, "test-chain");
     let amount_staked = 1_000_000;
     let validators = vec![
         stake("test1".parse().unwrap(), amount_staked),

core/chain-configs/src/genesis_config.rs

@@ -219,7 +219,11 @@ impl From<&GenesisConfig> for EpochConfig {
 impl From<&GenesisConfig> for AllEpochConfig {
     fn from(genesis_config: &GenesisConfig) -> Self {
         let initial_epoch_config = EpochConfig::from(genesis_config);
-        let epoch_config = Self::new(genesis_config.use_production_config(), initial_epoch_config);
+        let epoch_config = Self::new(
+            genesis_config.use_production_config(),
+            initial_epoch_config,
+            &genesis_config.chain_id,
+        );
         epoch_config
     }
 }

core/primitives-core/src/version.rs

@@ -126,6 +126,8 @@ pub enum ProtocolFeature {
     /// Enables block production with post-state-root.
     /// NEP: /~https://github.com/near/NEPs/pull/507
     PostStateRoot,
+    /// Increases the number of chunk producers.
+    TestnetFewerBlockProducers,
 }
 
 impl ProtocolFeature {
@@ -181,6 +183,7 @@ impl ProtocolFeature {
             #[cfg(feature = "protocol_feature_simple_nightshade_v2")]
             ProtocolFeature::SimpleNightshadeV2 => 135,
             ProtocolFeature::PostStateRoot => 136,
+            ProtocolFeature::TestnetFewerBlockProducers => 140,
         }
     }
 }

core/primitives/src/epoch_manager.rs

@@ -83,11 +83,17 @@ pub struct AllEpochConfig {
     use_production_config: bool,
     /// EpochConfig from genesis
     genesis_epoch_config: EpochConfig,
+    /// Chain Id. Some parameters are specific to certain chains.
+    chain_id: String,
 }
 
 impl AllEpochConfig {
-    pub fn new(use_production_config: bool, genesis_epoch_config: EpochConfig) -> Self {
-        Self { use_production_config, genesis_epoch_config }
+    pub fn new(
+        use_production_config: bool,
+        genesis_epoch_config: EpochConfig,
+        chain_id: &str,
+    ) -> Self {
+        Self { use_production_config, genesis_epoch_config, chain_id: chain_id.to_string() }
     }
 
     pub fn for_protocol_version(&self, protocol_version: ProtocolVersion) -> EpochConfig {
@@ -98,7 +104,7 @@ impl AllEpochConfig {
 
         Self::config_nightshade(&mut config, protocol_version);
 
-        Self::config_chunk_only_producers(&mut config, protocol_version);
+        Self::config_chunk_only_producers(&mut config, &self.chain_id, protocol_version);
 
         Self::config_max_kickout_stake(&mut config, protocol_version);
 
@@ -126,7 +132,11 @@ impl AllEpochConfig {
         config.avg_hidden_validator_seats_per_shard = vec![0; num_shards];
     }
 
-    fn config_chunk_only_producers(config: &mut EpochConfig, protocol_version: u32) {
+    fn config_chunk_only_producers(
+        config: &mut EpochConfig,
+        chain_id: &str,
+        protocol_version: u32,
+    ) {
         if checked_feature!("stable", ChunkOnlyProducers, protocol_version) {
             let num_shards = config.shard_layout.num_shards() as usize;
             // On testnet, genesis config set num_block_producer_seats to 200
@@ -139,6 +149,20 @@ impl AllEpochConfig {
             config.chunk_producer_kickout_threshold = 80;
             config.validator_selection_config.num_chunk_only_producer_seats = 200;
         }
+
+        // Adjust the number of block and chunk producers for all chains except
+        // mainnet, to make it easier to test the change.
+        if chain_id != crate::chains::MAINNET
+            && checked_feature!("stable", TestnetFewerBlockProducers, protocol_version)
+        {
+            let num_shards = config.shard_layout.num_shards() as usize;
+            // Decrease the number of block producers from 100 to 20.
+            config.num_block_producer_seats = 20;
+            config.num_block_producer_seats_per_shard =
+                vec![config.num_block_producer_seats; num_shards];
+            // Decrease the number of chunk producers.
+            config.validator_selection_config.num_chunk_only_producer_seats = 100;
+        }
     }
 
     fn config_max_kickout_stake(config: &mut EpochConfig, protocol_version: u32) {

integration-tests/src/tests/client/resharding.rs

@@ -742,7 +742,7 @@ fn setup_genesis(
     genesis.config.protocol_upgrade_stake_threshold = Rational32::new(7, 10);
 
     let default_epoch_config = EpochConfig::from(&genesis.config);
-    let all_epoch_config = AllEpochConfig::new(true, default_epoch_config);
+    let all_epoch_config = AllEpochConfig::new(true, default_epoch_config, "test-chain");
     let epoch_config = all_epoch_config.for_protocol_version(genesis_protocol_version);
 
     genesis.config.shard_layout = epoch_config.shard_layout;