[#610] Fix block download regression

This includes a few different fixes that prevented the demo app and other SDK consumers from working.

First, initialization of the demo app was fixed to use the sapling activation height rather than the current latest checkpoint.

Second, CompactBlockProcessor wasn’t downloading blocks.

Third, a few potential thread safety issues were resolved by making fields that are accessed by multiple threads volatile.

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/demos/listtransactions/ListTransactionsFragment.kt

@@ -48,12 +48,18 @@ class ListTransactionsFragment : BaseDemoFragment<FragmentListTransactionsBindin
         // have the seed stored
         val seed = Mnemonics.MnemonicCode(seedPhrase).toSeed()
 
-        initializer = runBlocking {
-            Initializer.new(requireApplicationContext()) {
-                runBlocking { it.newWallet(seed, network = ZcashNetwork.fromResources(requireApplicationContext())) }
-                it.setNetwork(ZcashNetwork.fromResources(requireApplicationContext()))
+        initializer = Initializer.newBlocking(
+            requireApplicationContext(),
+            Initializer.Config {
+                runBlocking {
+                    it.importWallet(
+                        seed,
+                        birthday = null,
+                        network = ZcashNetwork.fromResources(requireApplicationContext())
+                    )
+                }
             }
-        }
+        )
         address = runBlocking {
             DerivationTool.deriveShieldedAddress(
                 seed,

sdk-lib/src/androidTest/java/cash/z/ecc/android/sdk/util/DataDbScannerUtil.kt

@@ -72,7 +72,8 @@ class DataDbScannerUtil {
                         BlockHeight.new(
                             ZcashNetwork.Mainnet,
                             birthdayHeight
-                        )
+                        ),
+                        false
                     )
                 }
             }

sdk-lib/src/main/java/cash/z/ecc/android/sdk/Initializer.kt

@@ -87,7 +87,7 @@ class Initializer private constructor(
          * transactions. Again, this value is only considered when [height] is null.
          *
          */
-        fun setBirthdayHeight(height: BlockHeight?, defaultToOldestHeight: Boolean = false): Config =
+        fun setBirthdayHeight(height: BlockHeight?, defaultToOldestHeight: Boolean): Config =
             apply {
                 this.birthdayHeight = height
                 this.defaultToOldestHeight = defaultToOldestHeight
@@ -329,12 +329,23 @@ class Initializer private constructor(
             config: Config
         ): Initializer {
             config.validate()
-            val heightToUse = config.birthdayHeight
-                ?: (if (config.defaultToOldestHeight == true) config.network.saplingActivationHeight else null)
-            val loadedBirthday =
-                CheckpointTool.loadNearest(context, config.network, heightToUse)
 
-            val rustBackend = initRustBackend(context, config.network, config.alias, loadedBirthday.height)
+            val loadedCheckpoint = run {
+                val height = config.birthdayHeight
+                    ?: if (config.defaultToOldestHeight == true) {
+                        config.network.saplingActivationHeight
+                    } else {
+                        null
+                    }
+
+                CheckpointTool.loadNearest(
+                    context,
+                    config.network,
+                    height
+                )
+            }
+
+            val rustBackend = initRustBackend(context, config.network, config.alias, loadedCheckpoint.height)
 
             return Initializer(
                 context.applicationContext,
@@ -345,7 +356,7 @@ class Initializer private constructor(
                 config.port,
                 config.viewingKeys,
                 config.overwriteVks,
-                loadedBirthday
+                loadedCheckpoint
             )
         }
 

sdk-lib/src/main/java/cash/z/ecc/android/sdk/block/CompactBlockProcessor.kt

@@ -147,6 +147,9 @@ class CompactBlockProcessor internal constructor(
      * sequentially, due to the way sqlite works so it is okay for this not to be threadsafe or
      * coroutine safe because processing cannot be concurrent.
      */
+    // This accessed by the Dispatchers.IO thread, which means multiple threads are reading/writing
+    // concurrently.
+    @Volatile
     internal var currentInfo = ProcessorInfo(null, null, null, null, null)
 
     /**
@@ -325,13 +328,14 @@ class CompactBlockProcessor internal constructor(
                     } else {
                         null
                     },
-                    lastDownloadRange = if (initialInfo.lastDownloadedHeight != null && initialInfo.lastScannedHeight != null && initialInfo.networkBlockHeight != null) {
+                    lastDownloadRange = if (initialInfo.networkBlockHeight != null) {
                         BlockHeight.new(
                             network,
-                            max(
-                                initialInfo.lastDownloadedHeight.value,
-                                initialInfo.lastScannedHeight.value
-                            ) + 1
+                            buildList {
+                                add(network.saplingActivationHeight.value)
+                                initialInfo.lastDownloadedHeight?.let { add(it.value + 1) }
+                                initialInfo.lastScannedHeight?.let { add(it.value + 1) }
+                            }.max()
                         )..initialInfo.networkBlockHeight
                     } else {
                         null
@@ -633,7 +637,8 @@ class CompactBlockProcessor internal constructor(
                     metrics.beginBatch()
                     result = rustBackend.scanBlocks(SCAN_BATCH_SIZE)
                     metrics.endBatch()
-                    val lastScannedHeight = BlockHeight.new(network, range.start.value + metrics.cumulativeItems - 1)
+                    val lastScannedHeight =
+                        BlockHeight.new(network, range.start.value + metrics.cumulativeItems - 1)
                     val percentValue =
                         (lastScannedHeight.value - range.start.value) / (range.endInclusive.value - range.start.value + 1).toFloat() * 100.0f
                     val percent = "%.0f".format(percentValue.coerceAtMost(100f).coerceAtLeast(0f))
@@ -674,7 +679,7 @@ class CompactBlockProcessor internal constructor(
         lastDownloadedHeight: BlockHeight? = currentInfo.lastDownloadedHeight,
         lastScanRange: ClosedRange<BlockHeight>? = currentInfo.lastScanRange,
         lastDownloadRange: ClosedRange<BlockHeight>? = currentInfo.lastDownloadRange
-    ): Unit = withContext(IO) {
+    ) {
         currentInfo = currentInfo.copy(
             networkBlockHeight = networkBlockHeight,
             lastScannedHeight = lastScannedHeight,
@@ -682,8 +687,11 @@ class CompactBlockProcessor internal constructor(
             lastScanRange = lastScanRange,
             lastDownloadRange = lastDownloadRange
         )
-        _networkHeight.value = networkBlockHeight
-        _processorInfo.send(currentInfo)
+
+        withContext(IO) {
+            _networkHeight.value = networkBlockHeight
+            _processorInfo.send(currentInfo)
+        }
     }
 
     private suspend fun handleChainError(errorHeight: BlockHeight) {

sdk-lib/src/main/java/cash/z/ecc/android/sdk/internal/Twig.kt

@@ -75,6 +75,7 @@ interface Twig {
  * @see [Twig.clip]
  */
 object Bush {
+    @Volatile
     var trunk: Twig = SilentTwig()
     val leaves: MutableSet<Leaf> = CopyOnWriteArraySet<Leaf>()
 }

sdk-lib/src/main/java/cash/z/ecc/android/sdk/tool/CheckpointTool.kt

@@ -105,7 +105,7 @@ internal object CheckpointTool {
         context: Context,
         network: ZcashNetwork,
         directory: String,
-        birthday: BlockHeight? = null
+        birthday: BlockHeight?
     ): List<String> {
         val unfilteredTreeFiles = listCheckpointDirectoryContents(context, directory)
         if (unfilteredTreeFiles.isNullOrEmpty()) {