Adds eth_maxPriorityFeePerGas implementaiton (#570)

* added eth_maxPriorityFeePerGas rpc call

* cargo fmt

* moved block_base_fee implementation into the trait

* added basic test for eth_maxPriorityFeePerGas

* added test for eth_maxPriorityFeePerGas calculation

* Added support for zero-cost transactions

* Added 'eip1559_not_activated' error

* Fixes 'chain::supplier::test::return_nodes' test

* cargo fmt

* cargo fmt

* made calculation of fallback priority fee to ignore zero-cost transactions

* cargo fmt

* made use of 'saturating_sub' instead of minus

crates/concensus/miner/src/pool/queue.rs

@@ -666,6 +666,20 @@ impl TransactionQueue {
         }
     }
 
+    /// Returns effective priority fee gas price of currently the worst transaction in the pool.
+    /// If the worst transaction has zero gas price, the minimal gas price is returned.
+    pub fn current_worst_effective_priority_fee(&self) -> U256 {
+        self.pool
+            .read()
+            .worst_transaction()
+            .filter(|tx| !tx.signed().has_zero_gas_price())
+            .map(|tx| {
+                tx.signed()
+                    .effective_priority_fee(self.options.read().block_base_fee)
+            })
+            .unwrap_or(self.options.read().minimal_gas_price)
+    }
+
     /// Returns a status of the queue.
     pub fn status(&self) -> Status {
         let pool = self.pool.read();

crates/ethcore/src/client/test_client.rs

@@ -1090,6 +1090,10 @@ impl BlockChainClient for TestBlockChainClient {
         }
         None
     }
+
+    fn is_aura(&self) -> bool {
+        self.engine().name() == "AuthorityRound"
+    }
 }
 
 impl IoClient for TestBlockChainClient {

crates/ethcore/src/client/traits.rs

@@ -416,6 +416,40 @@ pub trait BlockChainClient:
         corpus.into()
     }
 
+    /// Sorted list of transaction priority gas prices from at least last sample_size blocks.
+    fn priority_gas_price_corpus(
+        &self,
+        sample_size: usize,
+        eip1559_transition: BlockNumber,
+    ) -> ::stats::Corpus<U256> {
+        let mut h = self.chain_info().best_block_hash;
+        let mut corpus = Vec::new();
+        while corpus.is_empty() {
+            for _ in 0..sample_size {
+                let block = match self.block(BlockId::Hash(h)) {
+                    Some(block) => block,
+                    None => return corpus.into(),
+                };
+
+                if block.number() == 0 || block.number() < eip1559_transition {
+                    return corpus.into();
+                }
+                block
+                    .transaction_views()
+                    .iter()
+                    .filter(
+                        |t| t.gas_price() > 0.into(), /* filter zero cost transactions */
+                    )
+                    .foreach(|t| {
+                        // As block.number() >= eip_1559_transition, the base_fee should exist
+                        corpus.push(t.effective_priority_gas_price(Some(block.header().base_fee())))
+                    });
+                h = block.parent_hash().clone();
+            }
+        }
+        corpus.into()
+    }
+
     /// Get the preferred chain ID to sign on
     fn signing_chain_id(&self) -> Option<u64>;
 

crates/ethcore/src/miner/miner.rs

@@ -1006,6 +1006,14 @@ impl miner::MinerService for Miner {
         self.transaction_queue.current_worst_gas_price() * 110u32 / 100
     }
 
+    fn sensible_max_priority_fee(&self) -> U256 {
+        // 10% above our minimum.
+        self.transaction_queue
+            .current_worst_effective_priority_fee()
+            * 110u32
+            / 100
+    }
+
     fn sensible_gas_limit(&self) -> U256 {
         self.params.read().gas_range_target.0 / 5
     }

crates/ethcore/src/miner/mod.rs

@@ -260,6 +260,9 @@ pub trait MinerService: Send + Sync {
     /// Suggested gas price.
     fn sensible_gas_price(&self) -> U256;
 
+    /// Suggested max priority fee gas price
+    fn sensible_max_priority_fee(&self) -> U256;
+
     /// Suggested gas limit.
     fn sensible_gas_limit(&self) -> U256;
 

crates/ethcore/sync/src/chain/supplier.rs

@@ -504,7 +504,10 @@ mod test {
     use super::{super::tests::*, *};
     use blocks::SyncHeader;
     use bytes::Bytes;
-    use ethcore::client::{BlockChainClient, EachBlockWith, TestBlockChainClient};
+    use ethcore::{
+        client::{BlockChainClient, EachBlockWith, TestBlockChainClient},
+        spec::Spec,
+    };
     use ethereum_types::H256;
     use parking_lot::RwLock;
     use rlp::{Rlp, RlpStream};
@@ -769,7 +772,7 @@ mod test {
 
     #[test]
     fn return_nodes() {
-        let mut client = TestBlockChainClient::new();
+        let mut client = TestBlockChainClient::new_with_spec(Spec::new_test_round());
         let queue = RwLock::new(VecDeque::new());
         let sync = dummy_sync_with_peer(H256::zero(), &client);
         let ss = TestSnapshotService::new();

crates/ethcore/types/src/views/typed_transaction.rs

@@ -137,6 +137,29 @@ impl<'a> TypedTransactionView<'a> {
         }
     }
 
+    /// Get the actual priority gas price paid to the miner
+    pub fn effective_priority_gas_price(&self, block_base_fee: Option<U256>) -> U256 {
+        match self.transaction_type {
+            TypedTxId::Legacy => self
+                .gas_price()
+                .saturating_sub(block_base_fee.unwrap_or_default()),
+            TypedTxId::AccessList => self
+                .gas_price()
+                .saturating_sub(block_base_fee.unwrap_or_default()),
+            TypedTxId::EIP1559Transaction => {
+                let max_priority_fee_per_gas: U256 =
+                    view!(Self, &self.rlp.rlp.data().unwrap()[1..])
+                        .rlp
+                        .val_at(2);
+                min(
+                    max_priority_fee_per_gas,
+                    self.gas_price()
+                        .saturating_sub(block_base_fee.unwrap_or_default()),
+                )
+            }
+        }
+    }
+
     /// Get the gas field of the transaction.
     pub fn gas(&self) -> U256 {
         match self.transaction_type {
@@ -260,6 +283,7 @@ mod tests {
         assert_eq!(view.nonce(), 0.into());
         assert_eq!(view.gas_price(), 1.into());
         assert_eq!(view.effective_gas_price(None), 1.into());
+        assert_eq!(view.effective_priority_gas_price(None), 1.into());
         assert_eq!(view.gas(), 0x61a8.into());
         assert_eq!(view.value(), 0xa.into());
         assert_eq!(
@@ -285,6 +309,7 @@ mod tests {
         let view = view!(TypedTransactionView, &rlp);
         assert_eq!(view.nonce(), 0x1.into());
         assert_eq!(view.gas_price(), 0xa.into());
+        assert_eq!(view.effective_priority_gas_price(None), 0xa.into());
         assert_eq!(view.gas(), 0x1e241.into());
         assert_eq!(view.value(), 0x0.into());
         assert_eq!(view.data(), "".from_hex().unwrap());
@@ -306,6 +331,10 @@ mod tests {
         assert_eq!(view.nonce(), 0x1.into());
         assert_eq!(view.gas_price(), 0xa.into());
         assert_eq!(view.effective_gas_price(Some(0x07.into())), 0x08.into());
+        assert_eq!(
+            view.effective_priority_gas_price(Some(0x07.into())),
+            0x01.into()
+        );
         assert_eq!(view.gas(), 0x1e241.into());
         assert_eq!(view.value(), 0x0.into());
         assert_eq!(view.data(), "".from_hex().unwrap());

crates/rpc/src/v1/helpers/dispatch/mod.rs

@@ -91,7 +91,10 @@ use ethcore::{client::BlockChainClient, miner::MinerService};
 use ethereum_types::{Address, H256, H520, U256};
 use ethkey::Password;
 use hash::keccak;
-use types::transaction::{PendingTransaction, SignedTransaction};
+use types::{
+    transaction::{PendingTransaction, SignedTransaction},
+    BlockNumber,
+};
 
 use jsonrpc_core::{
     futures::{future, Future, IntoFuture},
@@ -397,6 +400,24 @@ where
         .unwrap_or_else(|| miner.sensible_gas_price())
 }
 
+/// Extract the default priority gas price from a client and miner.
+pub fn default_max_priority_fee_per_gas<C, M>(
+    client: &C,
+    miner: &M,
+    percentile: usize,
+    eip1559_transition: BlockNumber,
+) -> U256
+where
+    C: BlockChainClient,
+    M: MinerService,
+{
+    client
+        .priority_gas_price_corpus(100, eip1559_transition)
+        .percentile(percentile)
+        .cloned()
+        .unwrap_or_else(|| miner.sensible_max_priority_fee())
+}
+
 /// Convert RPC confirmation payload to signer confirmation payload.
 /// May need to resolve in the future to fetch things like gas price.
 pub fn from_rpc<D>(

crates/rpc/src/v1/helpers/errors.rs

@@ -273,6 +273,10 @@ where
     }
 }
 
+pub fn eip1559_not_activated() -> Error {
+    unsupported("EIP-1559 is not activated", None)
+}
+
 pub fn not_enough_data() -> Error {
     Error {
         code: ErrorCode::ServerError(codes::UNSUPPORTED_REQUEST),

crates/rpc/src/v1/impls/eth.rs

@@ -52,7 +52,7 @@ use v1::{
         self,
         block_import::is_major_importing,
         deprecated::{self, DeprecationNotice},
-        dispatch::{default_gas_price, FullDispatcher},
+        dispatch::{default_gas_price, default_max_priority_fee_per_gas, FullDispatcher},
         errors, fake_sign, limit_logs,
     },
     metadata::Metadata,
@@ -696,6 +696,22 @@ where
         )))
     }
 
+    fn max_priority_fee_per_gas(&self) -> BoxFuture<U256> {
+        let latest_block = self.client.chain_info().best_block_number;
+        let eip1559_transition = self.client.engine().params().eip1559_transition;
+
+        if latest_block + 1 >= eip1559_transition {
+            Box::new(future::ok(default_max_priority_fee_per_gas(
+                &*self.client,
+                &*self.miner,
+                self.options.gas_price_percentile,
+                eip1559_transition,
+            )))
+        } else {
+            Box::new(future::done(Err(errors::eip1559_not_activated())))
+        }
+    }
+
     fn fee_history(
         &self,
         mut block_count: U256,
@@ -805,8 +821,11 @@ where
 
                                                 gas_and_reward.push((
                                                     gas_used,
-                                                    txs[i].effective_gas_price(base_fee)
-                                                        - base_fee.unwrap_or_default(),
+                                                    txs[i]
+                                                        .effective_gas_price(base_fee)
+                                                        .saturating_sub(
+                                                            base_fee.unwrap_or_default(),
+                                                        ),
                                                 ));
                                             }
                                         }

crates/rpc/src/v1/tests/eth.rs

@@ -19,7 +19,7 @@ use std::{env, sync::Arc};
 
 use accounts::AccountProvider;
 use ethcore::{
-    client::{BlockChainClient, ChainInfo, Client, ClientConfig, ImportBlock},
+    client::{BlockChainClient, ChainInfo, Client, ClientConfig, EvmTestClient, ImportBlock},
     ethereum,
     miner::Miner,
     spec::{Genesis, Spec},
@@ -67,7 +67,7 @@ fn snapshot_service() -> Arc<TestSnapshotService> {
 
 fn make_spec(chain: &BlockChain) -> Spec {
     let genesis = Genesis::from(chain.genesis());
-    let mut spec = ethereum::new_frontier_test();
+    let mut spec = EvmTestClient::spec_from_json(&chain.network).unwrap();
     let state = chain.pre_state.clone().into();
     spec.set_genesis_state(state)
         .expect("unable to set genesis state");
@@ -281,6 +281,26 @@ fn eth_get_block() {
     );
 }
 
+#[test]
+fn eth_get_max_priority_fee_per_gas() {
+    let chain = extract_non_legacy_chain!(
+        "BlockchainTests/ValidBlocks/bcEIP1559/transType",
+        ForkSpec::London
+    );
+    let tester = EthTester::from_chain(&chain);
+    let request = r#"{"method":"eth_maxPriorityFeePerGas","params":[],"id":1,"jsonrpc":"2.0"}"#;
+
+    // We are expecting for 50-th percentile of the previous 100 blocks transactions priority fees.
+    //
+    // Sorted priority fees: 0x64 0x64 0x64 0x7d 0x7d 0xea 0x149.
+    // Currently, the way 50-th percentile is calculated, the 3rd fee would be the result.
+    let response = r#"{"jsonrpc":"2.0","result":"0x64","id":1}"#;
+    assert_eq!(
+        tester.handler.handle_request_sync(request).unwrap(),
+        response
+    )
+}
+
 #[test]
 fn eth_get_block_by_hash() {
     let chain = extract_chain!("BlockchainTests/ValidBlocks/bcGasPricerTest/RPC_API_Test");

crates/rpc/src/v1/tests/helpers/miner_service.rs

@@ -359,6 +359,10 @@ impl MinerService for TestMinerService {
         20_000_000_000u64.into()
     }
 
+    fn sensible_max_priority_fee(&self) -> U256 {
+        2_000_000_000u64.into()
+    }
+
     fn sensible_gas_limit(&self) -> U256 {
         0x5208.into()
     }

crates/rpc/src/v1/tests/mocked/eth.rs

@@ -23,7 +23,7 @@ use std::{
 
 use accounts::AccountProvider;
 use ethcore::{
-    client::{BlockChainClient, EachBlockWith, Executed, TestBlockChainClient},
+    client::{BlockChainClient, EachBlockWith, EvmTestClient, Executed, TestBlockChainClient},
     miner::{self, MinerService},
 };
 use ethereum_types::{Address, Bloom, H160, H256, U256};
@@ -51,6 +51,12 @@ fn blockchain_client() -> Arc<TestBlockChainClient> {
     Arc::new(client)
 }
 
+fn eip1559_blockchain_client() -> Arc<TestBlockChainClient> {
+    let spec = EvmTestClient::spec_from_json(&ethjson::spec::ForkSpec::London).unwrap();
+    let client = TestBlockChainClient::new_with_spec(spec);
+    Arc::new(client)
+}
+
 fn accounts_provider() -> Arc<AccountProvider> {
     Arc::new(AccountProvider::transient_provider())
 }
@@ -89,8 +95,25 @@ impl Default for EthTester {
 
 impl EthTester {
     pub fn new_with_options(options: EthClientOptions) -> Self {
-        let runtime = Runtime::with_thread_count(1);
         let client = blockchain_client();
+        EthTester::new_with_client_and_options(client, options)
+    }
+
+    fn new_eip1559_with_options(options: EthClientOptions) -> Self {
+        let client = eip1559_blockchain_client();
+        EthTester::new_with_client_and_options(client, options)
+    }
+
+    pub fn add_blocks(&self, count: usize, with: EachBlockWith) {
+        self.client.add_blocks(count, with);
+        self.sync.increase_imported_block_number(count as u64);
+    }
+
+    fn new_with_client_and_options(
+        client: Arc<TestBlockChainClient>,
+        options: EthClientOptions,
+    ) -> Self {
+        let runtime = Runtime::with_thread_count(1);
         let sync = sync_provider();
         let ap = accounts_provider();
         let ap2 = ap.clone();
@@ -126,11 +149,6 @@ impl EthTester {
             hashrates,
         }
     }
-
-    pub fn add_blocks(&self, count: usize, with: EachBlockWith) {
-        self.client.add_blocks(count, with);
-        self.sync.increase_imported_block_number(count as u64);
-    }
 }
 
 #[test]
@@ -537,6 +555,33 @@ fn rpc_eth_gas_price() {
     );
 }
 
+#[test]
+fn rpc_eth_get_max_priority_fee_per_gas() {
+    let tester = EthTester::new_eip1559_with_options(Default::default());
+
+    let request = r#"{"method":"eth_maxPriorityFeePerGas","params":[],"id":1,"jsonrpc":"2.0"}"#;
+    let response = r#"{"jsonrpc":"2.0","result":"0x77359400","id":1}"#; // 2 GWei
+
+    assert_eq!(
+        tester.io.handle_request_sync(request),
+        Some(response.to_owned())
+    );
+}
+
+#[test]
+fn rpc_eth_get_max_priority_fee_per_gas_error() {
+    let tester = EthTester::default();
+
+    let request = r#"{"method":"eth_maxPriorityFeePerGas","params":[],"id":1,"jsonrpc":"2.0"}"#;
+    let response =
+        r#"{"jsonrpc":"2.0","error":{"code":-32000,"message":"EIP-1559 is not activated"},"id":1}"#;
+
+    assert_eq!(
+        tester.io.handle_request_sync(request),
+        Some(response.to_owned())
+    );
+}
+
 #[test]
 fn rpc_eth_accounts() {
     let tester = EthTester::default();

crates/rpc/src/v1/tests/mod.rs

@@ -51,6 +51,23 @@ macro_rules! register_test {
 	};
 }
 
+macro_rules! extract_non_legacy_chain {
+    ($file: expr, $network: expr) => {{
+        const RAW_DATA: &'static [u8] = include_bytes!(concat!(
+            "../../../../ethcore/res/json_tests/",
+            $file,
+            ".json"
+        ));
+        ::ethjson::blockchain::Test::load(RAW_DATA)
+            .unwrap()
+            .into_iter()
+            .filter(|&(_, ref t)| t.network == $network)
+            .next()
+            .unwrap()
+            .1
+    }};
+}
+
 #[cfg(test)]
 mod eth;
 #[cfg(test)]

crates/rpc/src/v1/traits/eth.rs

@@ -60,6 +60,10 @@ pub trait Eth {
     #[rpc(name = "eth_gasPrice")]
     fn gas_price(&self) -> BoxFuture<U256>;
 
+    /// Returns current max_priority_fee
+    #[rpc(name = "eth_maxPriorityFeePerGas")]
+    fn max_priority_fee_per_gas(&self) -> BoxFuture<U256>;
+
     /// Returns transaction fee history.
     #[rpc(name = "eth_feeHistory")]
     fn fee_history(&self, _: U256, _: BlockNumber, _: Option<Vec<f64>>)