feeHistory implementation (#484)

* feeHistory implementation

* code review fix

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

@@ -59,8 +59,8 @@ use v1::{
     traits::Eth,
     types::{
         block_number_to_id, Block, BlockNumber, BlockTransactions, Bytes, CallRequest, EthAccount,
-        Filter, Index, Log, Receipt, RichBlock, StorageProof, SyncInfo, SyncStatus, Transaction,
-        Work,
+        EthFeeHistory, Filter, Index, Log, Receipt, RichBlock, StorageProof, SyncInfo, SyncStatus,
+        Transaction, Work,
     },
 };
 
@@ -696,6 +696,205 @@ where
         )))
     }
 
+    fn fee_history(
+        &self,
+        mut block_count: U256,
+        newest_block: BlockNumber,
+        reward_percentiles: Option<Vec<f64>>,
+    ) -> BoxFuture<EthFeeHistory> {
+        let mut result = EthFeeHistory::default();
+
+        if block_count < 1.into() {
+            return Box::new(future::done(Ok(result)));
+        }
+
+        if block_count > 1024.into() {
+            block_count = 1024.into();
+        }
+
+        let latest_block = self.client.chain_info().best_block_number;
+        let pending_block = self.client.chain_info().best_block_number + 1;
+
+        let last_block = match newest_block {
+            BlockNumber::Hash {
+                hash: _,
+                require_canonical: _,
+            } => 0,
+            BlockNumber::Num(number) => {
+                if number <= pending_block {
+                    number
+                } else {
+                    0
+                }
+            }
+            BlockNumber::Latest => latest_block,
+            BlockNumber::Earliest => 0,
+            BlockNumber::Pending => pending_block,
+        };
+
+        let first_block = if last_block >= block_count.as_u64() - 1 {
+            last_block - (block_count.as_u64() - 1)
+        } else {
+            0
+        };
+
+        result.oldest_block = BlockNumber::Num(first_block);
+
+        let get_block_header = |i| {
+            self.client
+                .block_header(BlockId::Number(i))
+                .ok_or_else(errors::state_pruned)
+                .and_then(|h| {
+                    h.decode(self.client.engine().params().eip1559_transition)
+                        .map_err(errors::decode)
+                })
+        };
+
+        let calculate_base_fee = |h| {
+            self.client
+                .engine()
+                .calculate_base_fee(&h)
+                .unwrap_or_default()
+        };
+
+        let calculate_gas_used_ratio = |h: &Header| {
+            let gas_used = match self.client.block_receipts(&h.hash()) {
+                Some(receipts) => receipts
+                    .receipts
+                    .last()
+                    .map_or(U256::zero(), |r| r.gas_used),
+                None => 0.into(),
+            };
+
+            (gas_used.as_u64() as f64) / (h.gas_limit().as_u64() as f64)
+        };
+
+        let get_block_transactions = |i| match self.client.block_body(BlockId::Number(i)) {
+            Some(body) => Some(body.transactions()),
+            None => None,
+        };
+
+        let reward_percentiles = reward_percentiles.unwrap_or_default();
+        let mut reward_final = vec![];
+
+        for i in first_block..=last_block + 1 {
+            let is_last = i == last_block + 1;
+
+            if i < pending_block {
+                match get_block_header(i) {
+                    Ok(h) => {
+                        let base_fee = h.base_fee();
+
+                        result.base_fee_per_gas.push(base_fee.unwrap_or_default());
+
+                        if !is_last {
+                            result.gas_used_ratio.push(calculate_gas_used_ratio(&h));
+
+                            if reward_percentiles.len() > 0 {
+                                let mut gas_and_reward: Vec<(U256, U256)> = vec![];
+                                if let Some(txs) = get_block_transactions(i) {
+                                    if let Some(receipt) = self.client.block_receipts(&h.hash()) {
+                                        if txs.len() == receipt.receipts.len() {
+                                            for i in 0..txs.len() {
+                                                let gas_used = if i == 0 {
+                                                    receipt.receipts[i].gas_used
+                                                } else {
+                                                    receipt.receipts[i].gas_used
+                                                        - receipt.receipts[i - 1].gas_used
+                                                };
+
+                                                gas_and_reward.push((
+                                                    gas_used,
+                                                    txs[i].effective_gas_price(base_fee)
+                                                        - base_fee.unwrap_or_default(),
+                                                ));
+                                            }
+                                        }
+                                    }
+                                }
+
+                                gas_and_reward.sort_by(|a, b| a.1.cmp(&b.1));
+
+                                reward_final.push(
+                                    reward_percentiles
+                                        .iter()
+                                        .map(|p| {
+                                            let target_gas = U256::from(
+                                                ((h.gas_used().as_u64() as f64) * p / 100.0) as u64,
+                                            );
+                                            let mut sum_gas = U256::default();
+                                            for pair in &gas_and_reward {
+                                                sum_gas += pair.0;
+                                                if target_gas <= sum_gas {
+                                                    return pair.1;
+                                                }
+                                            }
+                                            0.into()
+                                        })
+                                        .collect(),
+                                );
+                            }
+                        }
+                    }
+                    Err(_) => break, //reorg happened, skip rest of the blocks
+                }
+            } else if i == pending_block {
+                match self.miner.pending_block_header(i - 1) {
+                    Some(h) => {
+                        result
+                            .base_fee_per_gas
+                            .push(h.base_fee().unwrap_or_default());
+
+                        if !is_last {
+                            result.gas_used_ratio.push(calculate_gas_used_ratio(&h));
+
+                            if reward_percentiles.len() > 0 {
+                                //zero values since can't be calculated for pending block
+                                reward_final.push(vec![0.into(); reward_percentiles.len()]);
+                            }
+                        }
+                    }
+                    None => {
+                        //calculate base fee based on the latest block
+                        match get_block_header(i - 1) {
+                            Ok(h) => {
+                                result.base_fee_per_gas.push(calculate_base_fee(h));
+
+                                if !is_last {
+                                    result.gas_used_ratio.push(0.into());
+
+                                    if reward_percentiles.len() > 0 {
+                                        //zero values since can't be calculated for pending block
+                                        reward_final.push(vec![0.into(); reward_percentiles.len()]);
+                                    }
+                                }
+                            }
+                            Err(_) => break, //reorg happened, skip rest of the blocks
+                        }
+                    }
+                }
+            } else if i == pending_block + 1 {
+                //calculate base fee based on the pending block, if exist
+                match self.miner.pending_block_header(i - 1) {
+                    Some(h) => {
+                        result.base_fee_per_gas.push(calculate_base_fee(h));
+                    }
+                    None => {
+                        result.base_fee_per_gas.push(0.into());
+                    }
+                }
+            } else {
+                unreachable!();
+            };
+        }
+
+        if !reward_final.is_empty() {
+            result.reward = Some(reward_final);
+        }
+
+        Box::new(future::done(Ok(result)))
+    }
+
     fn accounts(&self) -> Result<Vec<H160>> {
         self.deprecation_notice
             .print("eth_accounts", deprecated::msgs::ACCOUNTS);

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

@@ -20,8 +20,8 @@ use jsonrpc_core::{BoxFuture, Result};
 use jsonrpc_derive::rpc;
 
 use v1::types::{
-    BlockNumber, Bytes, CallRequest, EthAccount, Filter, FilterChanges, Index, Log, Receipt,
-    RichBlock, SyncStatus, Transaction, Work,
+    BlockNumber, Bytes, CallRequest, EthAccount, EthFeeHistory, Filter, FilterChanges, Index, Log,
+    Receipt, RichBlock, SyncStatus, Transaction, Work,
 };
 
 /// Eth rpc interface.
@@ -60,6 +60,11 @@ pub trait Eth {
     #[rpc(name = "eth_gasPrice")]
     fn gas_price(&self) -> BoxFuture<U256>;
 
+    /// Returns transaction fee history.
+    #[rpc(name = "eth_feeHistory")]
+    fn fee_history(&self, _: U256, _: BlockNumber, _: Option<Vec<f64>>)
+        -> BoxFuture<EthFeeHistory>;
+
     /// Returns accounts list.
     #[rpc(name = "eth_accounts")]
     fn accounts(&self) -> Result<Vec<H160>>;

crates/rpc/src/v1/types/fee_history.rs

@@ -0,0 +1,30 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// OpenEthereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Return types for RPC calls
+
+use ethereum_types::U256;
+use v1::types::BlockNumber;
+
+/// Account information.
+#[derive(Debug, Default, Clone, PartialEq, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct EthFeeHistory {
+    pub oldest_block: BlockNumber,
+    pub base_fee_per_gas: Vec<U256>,
+    pub gas_used_ratio: Vec<f64>,
+    pub reward: Option<Vec<Vec<U256>>>,
+}

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

@@ -29,6 +29,7 @@ pub use self::{
     },
     derivation::{Derive, DeriveHash, DeriveHierarchical},
     eip191::{EIP191Version, PresignedTransaction},
+    fee_history::EthFeeHistory,
     filter::{Filter, FilterChanges},
     histogram::Histogram,
     index::Index,
@@ -62,6 +63,7 @@ mod call_request;
 mod confirmations;
 mod derivation;
 mod eip191;
+mod fee_history;
 mod filter;
 mod histogram;
 mod index;