lib: multiple fixes of async functions

lib/android/src/main/aidl/im/molly/monero/IWallet.aidl

@@ -9,7 +9,7 @@ interface IWallet {
     void removeBalanceListener(in IBalanceListener listener);
     oneway void save(in ParcelFileDescriptor destination);
     oneway void resumeRefresh(boolean skipCoinbaseOutputs, in IRefreshCallback callback);
-    void cancelRefresh();
-    void setRefreshSince(long heightOrTimestamp);
+    oneway void cancelRefresh();
+    oneway void setRefreshSince(long heightOrTimestamp);
     void close();
 }

lib/android/src/main/kotlin/im/molly/monero/MoneroWallet.kt

@@ -2,6 +2,7 @@ package im.molly.monero
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.channels.onFailure
 import kotlinx.coroutines.channels.trySendBlocking
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
@@ -12,6 +13,8 @@ class MoneroWallet internal constructor(
     val remoteNodeClient: RemoteNodeClient?,
 ) : IWallet by wallet, AutoCloseable {
 
+    private val logger = loggerFor<MoneroWallet>()
+
     val publicAddress: String = wallet.primaryAccountAddress
 
     /**
@@ -23,11 +26,18 @@ class MoneroWallet internal constructor(
 
             override fun onBalanceChanged(txOuts: List<OwnedTxOut>?, checkedAtBlockHeight: Long) {
                 lastKnownLedger = Ledger(publicAddress, txOuts!!, checkedAtBlockHeight)
-                trySendBlocking(lastKnownLedger)
+                sendLedger(lastKnownLedger)
             }
 
             override fun onRefresh(blockchainHeight: Long) {
-                trySendBlocking(lastKnownLedger.copy(checkedAtBlockHeight = blockchainHeight))
+                sendLedger(lastKnownLedger.copy(checkedAtBlockHeight = blockchainHeight))
+            }
+
+            private fun sendLedger(ledger: Ledger) {
+                trySend(ledger)
+                    .onFailure {
+                        logger.e("Too many ledger updates, channel capacity exceeded")
+                    }
             }
         }
 

lib/android/src/main/kotlin/im/molly/monero/WalletNative.kt

@@ -93,11 +93,17 @@ class WalletNative private constructor(
         }
     }
 
-    override fun cancelRefresh() = nativeCancelRefresh(handle)
+    override fun cancelRefresh() {
+        scope.launch(ioDispatcher) {
+            nativeCancelRefresh(handle)
+        }
+    }
 
     override fun setRefreshSince(blockHeightOrTimestamp: Long) {
+        scope.launch(ioDispatcher) {
             nativeSetRefreshSince(handle, blockHeightOrTimestamp)
         }
+    }
 
     /**
      * Also replays the last known balance whenever a new listener registers.
@@ -158,7 +164,12 @@ class WalletNative private constructor(
 
     private val pendingRequestLock = ReentrantLock()
 
-    @CalledByNative("wallet.cc")
+    /**
+     * Invoked by native code to make a cancellable remote call to a remote node.
+     *
+     * Caller must close [HttpResponse.body] upon completion of processing the response.
+     */
+    @CalledByNative("http_client.cc")
     private fun callRemoteNode(
         method: String?,
         path: String?,
@@ -166,19 +177,26 @@ class WalletNative private constructor(
         body: ByteArray?,
     ): HttpResponse? = runBlocking {
         pendingRequestLock.withLock {
-            pendingRequest = if (requestsAllowed) {
-                async {
+            if (!requestsAllowed) {
+                return@runBlocking null
+            }
+            pendingRequest = async {
                 remoteNodeClient?.request(HttpRequest(method, path, header, body))
             }
-            } else null
         }
+        try {
             runCatching {
                 pendingRequest?.await()
             }.onFailure { throwable ->
-            if (throwable !is CancellationException) {
-                throw throwable
+                if (throwable is CancellationException) {
+                    return@onFailure
                 }
+                logger.e("Error waiting for HTTP response", throwable)
+                throw throwable
             }.getOrNull()
+        } finally {
+            pendingRequest = null
+        }
     }
 
     override fun close() {