[#1043] Implement DownloadAction

Closes #1043

Sources/ZcashLightClientKit/Block/Actions/DownloadAction.swift

@@ -8,28 +8,41 @@
 import Foundation
 
 class DownloadAction {
-    init(container: DIContainer) { }
+    let config: CompactBlockProcessorNG.Configuration
+    let downloader: BlockDownloader
+    let transactionRepository: TransactionRepository
+    init(container: DIContainer, config: CompactBlockProcessorNG.Configuration) {
+        self.config = config
+        downloader = container.resolve(BlockDownloader.self)
+        transactionRepository = container.resolve(TransactionRepository.self)
+    }
+
+    private func update(context: ActionContext) async -> ActionContext {
+        await context.update(state: .validate)
+        return context
+    }
 }
 
 extension DownloadAction: Action {
     func run(with context: ActionContext, didUpdate: @escaping (ActionProgress) async -> Void) async throws -> ActionContext {
-        // Use `BlockDownloader` to set download limit to latestScannedHeight + (2*batchSize) (after parallel is merged).
-        // And start download.
-        // Compute batch sync range (range used by one loop in `downloadAndScanBlocks` method) and wait until blocks in this range are downloaded.
+        guard let downloadRange = await context.syncRanges.downloadAndScanRange else {
+            return await update(context: context)
+        }
 
-//        do {
-//            await blockDownloader.setDownloadLimit(processingRange.upperBound + (2 * batchSize))
-//            await blockDownloader.startDownload(maxBlockBufferSize: config.downloadBufferSize)
-//
-//            try await blockDownloader.waitUntilRequestedBlocksAreDownloaded(in: processingRange)
-//        } catch {
-//            await ifTaskIsNotCanceledClearCompactBlockCache(lastScannedHeight: lastScannedHeight)
-//            throw error
-//        }
+        let lastScannedHeight = try await transactionRepository.lastScannedHeight()
+        let downloadLimit = lastScannedHeight + (2 * config.batchSize)
+        let batchRange = lastScannedHeight...lastScannedHeight + config.batchSize
+
+        try await downloader.setSyncRange(downloadRange)
+        await downloader.setDownloadLimit(downloadLimit)
+
+        try await downloader.waitUntilRequestedBlocksAreDownloaded(in: batchRange)
 
         await context.update(state: .validate)
         return context
     }
 
-    func stop() async { }
+    func stop() async {
+        await downloader.stopDownload()
+    }
 }

Sources/ZcashLightClientKit/Block/CompactBlockProcessorNG.swift

@@ -35,8 +35,7 @@ class CompactBlockProcessorNG {
         let dataDb: URL
         let spendParamsURL: URL
         let outputParamsURL: URL
-        let downloadBatchSize: Int
-        let scanningBatchSize: Int
+        let batchSize: Int
         let retries: Int
         let maxBackoffInterval: TimeInterval
         let maxReorgSize = ZcashSDK.maxReorgSize
@@ -59,11 +58,10 @@ class CompactBlockProcessorNG {
             spendParamsURL: URL,
             outputParamsURL: URL,
             saplingParamsSourceURL: SaplingParamsSourceURL,
-            downloadBatchSize: Int = ZcashSDK.DefaultDownloadBatch,
+            batchSize: Int = ZcashSDK.DefaultSyncBatch,
             retries: Int = ZcashSDK.defaultRetries,
             maxBackoffInterval: TimeInterval = ZcashSDK.defaultMaxBackOffInterval,
             rewindDistance: Int = ZcashSDK.defaultRewindDistance,
-            scanningBatchSize: Int = ZcashSDK.DefaultScanningBatch,
             walletBirthdayProvider: @escaping () -> BlockHeight,
             saplingActivation: BlockHeight,
             network: ZcashNetwork
@@ -75,15 +73,13 @@ class CompactBlockProcessorNG {
             self.outputParamsURL = outputParamsURL
             self.saplingParamsSourceURL = saplingParamsSourceURL
             self.network = network
-            self.downloadBatchSize = downloadBatchSize
+            self.batchSize = batchSize
             self.retries = retries
             self.maxBackoffInterval = maxBackoffInterval
             self.rewindDistance = rewindDistance
-            self.scanningBatchSize = scanningBatchSize
             self.walletBirthdayProvider = walletBirthdayProvider
             self.saplingActivation = saplingActivation
             self.cacheDbURL = cacheDbURL
-            assert(downloadBatchSize >= scanningBatchSize)
         }
 
         init(
@@ -93,11 +89,10 @@ class CompactBlockProcessorNG {
             spendParamsURL: URL,
             outputParamsURL: URL,
             saplingParamsSourceURL: SaplingParamsSourceURL,
-            downloadBatchSize: Int = ZcashSDK.DefaultDownloadBatch,
+            batchSize: Int = ZcashSDK.DefaultSyncBatch,
             retries: Int = ZcashSDK.defaultRetries,
             maxBackoffInterval: TimeInterval = ZcashSDK.defaultMaxBackOffInterval,
             rewindDistance: Int = ZcashSDK.defaultRewindDistance,
-            scanningBatchSize: Int = ZcashSDK.DefaultScanningBatch,
             walletBirthdayProvider: @escaping () -> BlockHeight,
             network: ZcashNetwork
         ) {
@@ -111,25 +106,22 @@ class CompactBlockProcessorNG {
             self.saplingActivation = network.constants.saplingActivationHeight
             self.network = network
             self.cacheDbURL = nil
-            self.downloadBatchSize = downloadBatchSize
+            self.batchSize = batchSize
             self.retries = retries
             self.maxBackoffInterval = maxBackoffInterval
             self.rewindDistance = rewindDistance
-            self.scanningBatchSize = scanningBatchSize
-
-            assert(downloadBatchSize >= scanningBatchSize)
         }
     }
 
     init(container: DIContainer, config: Configuration) {
         context = ActionContext(state: .validateServer)
-        actions = Self.makeActions(container: container)
+        actions = Self.makeActions(container: container, config: config)
         self.logger = container.resolve(Logger.self)
         self.config = config
     }
 
     // swiftlint:disable:next cyclomatic_complexity
-    static func makeActions(container: DIContainer) -> [CBPState: Action] {
+    static func makeActions(container: DIContainer, config: Configuration) -> [CBPState: Action] {
         let actionsDefinition = CBPState.allCases.compactMap { state -> (CBPState, Action)? in
             let action: Action
             switch state {
@@ -142,7 +134,7 @@ class CompactBlockProcessorNG {
             case .scanDownloaded:
                 action = ScanDownloadedButUnscannedAction(container: container)
             case .download:
-                action = DownloadAction(container: container)
+                action = DownloadAction(container: container, config: config)
             case .validate:
                 action = ValidateAction(container: container)
             case .scan:

Sources/ZcashLightClientKit/Block/Download/BlockDownloader.swift

@@ -224,6 +224,7 @@ extension BlockDownloaderImpl: BlockDownloader {
     }
 
     func setSyncRange(_ range: CompactBlockRange) async throws {
+        guard range != syncRange else { return }
         downloadStream = try await compactBlocksDownloadStream(startHeight: range.lowerBound, targetHeight: range.upperBound)
         syncRange = range
     }

Sources/ZcashLightClientKit/Constants/ZcashSDK.swift

@@ -100,6 +100,10 @@ public enum ZcashSDK {
     /// Default batch size for scanning blocks for the compact block processor
     public static let DefaultScanningBatch = 100
 
+    /// Default batch size for downloading and scanning blocks for the compact block processor. Be careful with this number. This amount of blocks
+    /// times three is held in memory at some point of the sync process.
+    public static let DefaultSyncBatch = 100
+
     /// Default amount of time, in in seconds, to poll for new blocks. Typically, this should be about half the average
     /// block time.
     public static let defaultPollInterval: TimeInterval = 20