From 99d4821769cb952a3954dfe702e9f48776dd4b95 Mon Sep 17 00:00:00 2001
From: Lukas Korba <lukas.korba@seznam.cz>
Date: Tue, 6 Feb 2024 10:10:02 +0100
Subject: [PATCH] [#1368] Handle any lightwalletd error with retry logic

- The retry logic was implemented for blockStream errors only but this PR generalize it for any lightwalletd error
---
 .../Block/CompactBlockProcessor.swift         | 30 ++++++++++++-------
 .../Constants/ZcashSDK.swift                  |  7 ++---
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift b/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
index 39ce519c..72a0f729 100644
--- a/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
+++ b/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
@@ -40,7 +40,7 @@ actor CompactBlockProcessor {
     private let fileManager: ZcashFileManager
 
     private var retryAttempts: Int = 0
-    private var blockStreamRetryAttempts: Int = 0
+    private var serviceFailureRetryAttempts: Int = 0
     private var backoffTimer: Timer?
     private var consecutiveChainValidationErrors: Int = 0
     
@@ -264,7 +264,7 @@ extension CompactBlockProcessor {
     func start(retry: Bool = false) async {
         if retry {
             self.retryAttempts = 0
-            self.blockStreamRetryAttempts = 0
+            self.serviceFailureRetryAttempts = 0
             self.backoffTimer?.invalidate()
             self.backoffTimer = nil
         }
@@ -291,7 +291,7 @@ extension CompactBlockProcessor {
         self.backoffTimer = nil
         await stopAllActions()
         retryAttempts = 0
-        blockStreamRetryAttempts = 0
+        serviceFailureRetryAttempts = 0
     }
 
     func latestHeight() async throws -> BlockHeight {
@@ -579,13 +579,23 @@ extension CompactBlockProcessor {
                 await stopAllActions()
                 logger.error("Sync failed with error: \(error)")
 
-                // catching the block stream error
-                if case ZcashError.serviceBlockStreamFailed = error, self.blockStreamRetryAttempts < ZcashSDK.blockStreamRetries {
-                    // This may be false positive communication error that is usually resolved by retry.
-                    // We will try to reset the sync and continue but this will we done at most `ZcashSDK.blockStreamRetries` times.
-                    logger.error("ZcashError.serviceBlockStreamFailed, retry is available, starting the sync all over again.")
+                // catching the service errors
+                let serviceError: Bool
+                switch error {
+                case ZcashError.serviceGetInfoFailed, ZcashError.serviceLatestBlockFailed,
+                    ZcashError.serviceLatestBlockHeightFailed, ZcashError.serviceBlockRangeFailed,
+                    ZcashError.serviceSubmitFailed, ZcashError.serviceFetchTransactionFailed,
+                    ZcashError.serviceFetchUTXOsFailed, ZcashError.serviceBlockStreamFailed,
+                    ZcashError.serviceSubtreeRootsStreamFailed: serviceError = true
+                default: serviceError = false
+                }
 
-                    self.blockStreamRetryAttempts += 1
+                if serviceError && self.serviceFailureRetryAttempts < ZcashSDK.serviceFailureRetries {
+                    // This may be false positive communication error that is usually resolved by retry.
+                    // We will try to reset the sync and continue but this will we done at most `ZcashSDK.serviceFailureRetries` times.
+                    logger.error("ServiceError: \(error), retry is available, starting the sync all over again.")
+
+                    self.serviceFailureRetryAttempts += 1
                     
                     // Start sync all over again
                     await resetContext()
@@ -694,7 +704,7 @@ extension CompactBlockProcessor {
             latestBlockHeightWhenSyncing > 0 && latestBlockHeightWhenSyncing < latestBlockHeight
 
         retryAttempts = 0
-        blockStreamRetryAttempts = 0
+        serviceFailureRetryAttempts = 0
         consecutiveChainValidationErrors = 0
 
         let lastScannedHeight = await latestBlocksDataProvider.maxScannedHeight
diff --git a/Sources/ZcashLightClientKit/Constants/ZcashSDK.swift b/Sources/ZcashLightClientKit/Constants/ZcashSDK.swift
index ff89768a..22770e88 100644
--- a/Sources/ZcashLightClientKit/Constants/ZcashSDK.swift
+++ b/Sources/ZcashLightClientKit/Constants/ZcashSDK.swift
@@ -105,10 +105,9 @@ public enum ZcashSDK {
     // TODO: [#1304] smart retry logic, https://github.com/zcash/ZcashLightClientKit/issues/1304
     public static let defaultRetries = Int.max
 
-    /// The communication errors are represented as serviceBlockStreamFailed : LightWalletServiceError, unavailable 14
-    /// These cases are usually false positive and another try will continue the work, in case the service is trully down we
-    /// cap the amount of retries by this value.
-    public static let blockStreamRetries = 3
+    /// The communication errors are usually false positive and another try will continue the work, 
+    /// in case the service is trully down we cap the amount of retries by this value.
+    public static let serviceFailureRetries = 3
 
     /// The default maximum amount of time to wait during retry backoff intervals. Failed loops will never wait longer than
     /// this before retrying.