feat: transaction polling task

Sources/web3swift/Transaction/TransactionPollingTask.swift

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+//
+//  TransactionPollingTask.swift
+//
+//  Created by JeneaVranceanu on 10.03.2023.
+//
+
+import Foundation
+import Web3Core
+
+/// Monitors a transaction's state on blockchain until transaction is completed successfully or not.
+final public class TransactionPollingTask {
+
+    private enum DelayUnit: UInt64 {
+        case shortest = 1
+        case medium = 5
+        case longest = 60
+
+        func shouldIncreaseDelay(_ startTime: Date) -> Bool {
+            let timePassed = Date().timeIntervalSince1970 - startTime.timeIntervalSince1970
+            switch self {
+            case .shortest:
+                return timePassed > 10
+            case .medium:
+                return timePassed > 120
+            case .longest:
+                return false
+            }
+        }
+
+        var nextDelayUnit: DelayUnit {
+            switch self {
+            case .shortest:
+                return .medium
+            case .medium, .longest:
+                return .longest
+            }
+        }
+    }
+
+    public let transactionHash: Data
+
+    private let web3Instance: Web3
+    private var delayUnit: DelayUnit = .shortest
+
+    public init(transactionHash: Data, web3Instance: Web3) {
+        self.transactionHash = transactionHash
+        self.web3Instance = web3Instance
+    }
+
+    public func wait() async throws -> TransactionReceipt {
+        let startTime = Date()
+        while true {
+            let transactionReceipt = try await web3Instance.eth.transactionReceipt(transactionHash)
+
+            if transactionReceipt.status != .notYetProcessed {
+                return transactionReceipt
+            }
+
+            if delayUnit.shouldIncreaseDelay(startTime) {
+                delayUnit = delayUnit.nextDelayUnit
+            }
+
+            try await Task.sleep(nanoseconds: delayUnit.rawValue)
+        }
+    }
+}

Tests/web3swiftTests/localTests/TransactionPollingTaskTest.swift

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+//
+//  TransactionPollingTaskTest.swift
+//
+//  Created by JeneaVranceanu on 10.03.2023.
+//
+
+import XCTest
+import Foundation
+@testable import web3swift
+@testable import Web3Core
+
+class TransactionPollingTaskTest: LocalTestCase {
+
+    func testTransactionPolling() async throws {
+        let web3 = try await Web3.new(LocalTestCase.url)
+        let sendToAddress = EthereumAddress("0xe22b8979739D724343bd002F9f432F5990879901")!
+        let allAddresses = try await web3.eth.ownedAccounts()
+        let contract = web3.contract(Web3.Utils.coldWalletABI, at: sendToAddress)
+        let writeTX = contract!.createWriteOperation("fallback")!
+        writeTX.transaction.from = allAddresses[0]
+        writeTX.transaction.value = 1
+
+        let policies = Policies(gasLimitPolicy: .automatic)
+        let result = try await writeTX.writeToChain(password: "", policies: policies, sendRaw: false)
+
+        let txHash = Data.fromHex(result.hash.stripHexPrefix())!
+
+        let transactionReceipt = try await TransactionPollingTask(transactionHash: txHash, web3Instance: web3).wait()
+
+        XCTAssertEqual(transactionReceipt.status, .ok)
+    }
+
+}