|
1 | | -// |
2 | | -// Web3+GasOracle.swift |
3 | | -// web3swift |
4 | | -// |
5 | | -// Created by Yaroslav on 31.03.2022. |
6 | | -// Copyright © 2022 web3swift. All rights reserved. |
7 | | -// |
8 | | - |
9 | | -import Foundation |
10 | | -import BigInt |
11 | | - |
12 | | -extension Web3 { |
13 | | - /// Oracle is the class to of a transaction fee suggestion |
14 | | - /// |
15 | | - /// It designed for EIP-1559 transactions only. |
16 | | - final public class Oracle { |
17 | | - private var latestBlock: Block? |
18 | | - |
19 | | - /// Web3 provider by wich accessing to the blockchain |
20 | | - private let web3Provider: web3 |
21 | | - |
22 | | - /// Ethereum scope shortcut |
23 | | - private var eth: web3.Eth { web3Provider.eth } |
24 | | - |
25 | | - /// Number of block to caltulate statistics |
26 | | - public private(set) var blocksNumber: BigUInt |
27 | | - |
28 | | - /// Number of transacrtions to filter block for tip calculation |
29 | | - public private(set) var transactionsNumber: BigUInt |
30 | | - |
31 | | - /// Oracle initializer |
32 | | - /// - Parameters: |
33 | | - /// - provider: Web3 Ethereum provider |
34 | | - /// - blocksNumber: Number of block to caltulate statistics |
35 | | - /// - transactionsNumber: Number of transacrtions to filter block for tip calculation |
36 | | - public init(_ provider: web3, blocksNumber: BigUInt = 20, transactionsNumber: BigUInt = 50) { |
37 | | - self.web3Provider = provider |
38 | | - self.blocksNumber = blocksNumber |
39 | | - self.transactionsNumber = transactionsNumber |
40 | | - } |
41 | | - |
42 | | - private func calcBaseFee(for block: Block?) -> BigUInt { |
43 | | - guard let block = block else { return 0 } |
44 | | - return Web3.calcBaseFee(block) |
45 | | - } |
46 | | - |
47 | | - private func calculateStatistic(_ data: [BigUInt], _ statistic: Statistic) throws -> BigUInt { |
48 | | - let sortedData = data.sorted() |
49 | | - let noAnomalyArray = sortedData.cropAnomalyValues() |
50 | | - |
51 | | - guard !noAnomalyArray.isEmpty else { throw Web3Error.unknownError } |
52 | | - |
53 | | - switch statistic { |
54 | | - // Force unwrapping is ok, since array checked for epmtiness above |
55 | | - case .minimum: return noAnomalyArray.min()! |
56 | | - case .mean: return noAnomalyArray.mean()! |
57 | | - case .median: return noAnomalyArray.median()! |
58 | | - case .maximum: |
59 | | - // Checking that suggestedBaseFee are not lower than will be in the next block |
60 | | - // because in tne maximum statistic we should guarantee that transaction would be included in it. |
61 | | - return max(calcBaseFee(for: latestBlock), noAnomalyArray.max()!) |
62 | | - } |
63 | | - } |
64 | | - |
65 | | - private func suggestTipValue(_ statistic: Statistic) throws -> BigUInt { |
66 | | - let latestBlockNumber = try eth.getBlockNumber() |
67 | | - |
68 | | - var block: Block |
69 | | - |
70 | | - // TODO: Make me work with cache |
71 | | - repeat { |
72 | | - block = try eth.getBlockByNumber(latestBlockNumber, fullTransactions: true) |
73 | | - } while block.transactions.count < transactionsNumber |
74 | | - |
75 | | - // Storing last block to calculate baseFee of the next block |
76 | | - latestBlock = block |
77 | | - |
78 | | - let transactionsTips = block.transactions |
79 | | - .compactMap { t -> EthereumTransaction? in |
80 | | - guard case let .transaction(transaction) = t else { return nil } |
81 | | - return transaction |
82 | | - } |
83 | | - // TODO: Add filter for transaction types |
84 | | - .map { $0.maxPriorityFeePerGas } |
85 | | - |
86 | | - return try calculateStatistic(transactionsTips, statistic) |
87 | | - } |
88 | | - |
89 | | - private func suggestBaseFee(_ statistic: Statistic) throws -> BigUInt { |
90 | | - let latestBlockNumber = try eth.getBlockNumber() |
91 | | - |
92 | | - // Assigning last block to object var to predict baseFee of the next block |
93 | | - latestBlock = try eth.getBlockByNumber(latestBlockNumber) |
94 | | - // TODO: Make me work with cache |
95 | | - let lastNthBlocksBaseFees = try (latestBlockNumber - blocksNumber ... latestBlockNumber) |
96 | | - .map { try eth.getBlockByNumber($0) } |
97 | | - .filter { !$0.transactions.isEmpty } |
98 | | - .map { $0.baseFeePerGas } |
99 | | - |
100 | | - return try calculateStatistic(lastNthBlocksBaseFees, statistic) |
101 | | - } |
102 | | - } |
103 | | -} |
104 | | - |
105 | | -public extension Web3.Oracle { |
106 | | - // MARK: - Base Fee |
107 | | - /// Base fee amount based on last Nth blocks |
108 | | - /// |
109 | | - /// Normalized means that most high and most low value were droped from calculation. |
110 | | - /// |
111 | | - /// Nth block may include empty ones. |
112 | | - /// |
113 | | - /// - Parameter statistic: Statistic to apply for base fee calculation |
114 | | - /// - Returns: Suggested base fee amount according to statistic, nil if failed to perdict |
115 | | - func predictBaseFee(_ statistic: Statistic) -> BigUInt? { |
116 | | - guard let value = try? suggestBaseFee(statistic) else { return nil } |
117 | | - return value |
118 | | - } |
119 | | - |
120 | | - // MARK: - Tip |
121 | | - /// Maximum tip amount based on last block tips |
122 | | - /// |
123 | | - /// Normalized means that most high and most low value were droped from calculation. |
124 | | - /// |
125 | | - /// Account first of the latest block that have more than `transactionsNumber` value. |
126 | | - /// |
127 | | - /// - Parameter statistic: Statistic to apply for tip calculation |
128 | | - /// - Returns: Suggested tip amount according to statistic, nil if failed to perdict |
129 | | - func predictTip(_ statistic: Statistic) -> BigUInt? { |
130 | | - guard let value = try? suggestTipValue(statistic) else { return nil } |
131 | | - return value |
132 | | - } |
133 | | - |
134 | | - // MARK: - Summary fees |
135 | | - /// Method to get summary fees |
136 | | - /// - Parameters: |
137 | | - /// - baseFee: Statistic to apply for baseFee |
138 | | - /// - tip: Statistic to apply for tip |
139 | | - /// - Returns: Touple where [0] — base fee, [1] — tip, nil if failed to predict |
140 | | - func predictBothFees(baseFee: Statistic, tip: Statistic) -> (BigUInt, BigUInt)? { |
141 | | - guard let baseFee = try? suggestBaseFee(baseFee) else { return nil } |
142 | | - guard let tip = try? suggestTipValue(tip) else { return nil } |
143 | | - |
144 | | - return (baseFee, tip) |
145 | | - } |
146 | | -} |
147 | | - |
148 | | -public extension Web3.Oracle { |
149 | | - // TODO: Make me struct and incapsulate math within to make me extendable |
150 | | - enum Statistic { |
151 | | - /// Mininum statistic |
152 | | - case minimum |
153 | | - /// Mean statistic |
154 | | - case mean |
155 | | - /// Median statistic |
156 | | - case median |
157 | | - /// Maximum statistic |
158 | | - case maximum |
159 | | - } |
160 | | -} |
161 | | - |
162 | | -extension Array { |
163 | | - func cropAnomalyValues() -> Self { |
164 | | - var tmpArr = self.dropFirst() |
165 | | - tmpArr = self.dropLast() |
166 | | - return Array(tmpArr) |
167 | | - } |
168 | | -} |
169 | | - |
170 | | -extension Array where Element: BinaryInteger { |
171 | | - func mean() -> BigUInt? { |
172 | | - guard !self.isEmpty else { return nil } |
173 | | - return BigUInt(self.reduce(0, +)) / BigUInt(self.count) |
174 | | - } |
175 | | - |
176 | | - func median() -> BigUInt? { |
177 | | - guard !self.isEmpty else { return nil } |
178 | | - |
179 | | - let sorted_data = self.sorted() |
180 | | - if self.count % 2 == 1 { |
181 | | - return BigUInt(sorted_data[Int(floor(Double(self.count) / 2))]) |
182 | | - } else { |
183 | | - return BigUInt(sorted_data[self.count / 2] + sorted_data[(self.count / 2) - 1] / 2) |
184 | | - } |
185 | | - } |
186 | | -} |
0 commit comments