change electrum call ordering and add retry handling for better behaviour on electrs

src/main/java/com/sparrowwallet/sparrow/net/BatchedElectrumServerRpc.java

@@ -18,6 +18,8 @@ import java.util.concurrent.atomic.AtomicLong;
 
 public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     private static final Logger log = LoggerFactory.getLogger(BatchedElectrumServerRpc.class);
+    private static final int MAX_RETRIES = 3;
+    private static final int RETRY_DELAY = 0;
 
     private final AtomicLong idCounter = new AtomicLong();
 
@@ -25,8 +27,9 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public void ping(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            client.createRequest().method("server.ping").id(idCounter.incrementAndGet()).executeNullable();
+            new RetryLogic<>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().method("server.ping").id(idCounter.incrementAndGet()).executeNullable());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error pinging server", e);
         }
     }
@@ -35,8 +38,9 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public List<String> getServerVersion(Transport transport, String clientName, String[] supportedVersions) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAsList(String.class).method("server.version").id(idCounter.incrementAndGet()).param("client_name", clientName).param("protocol_version", supportedVersions).execute();
+            return new RetryLogic<List<String>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().returnAsList(String.class).method("server.version").id(idCounter.incrementAndGet()).param("client_name", clientName).param("protocol_version", supportedVersions).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting server version", e);
         }
     }
@@ -45,8 +49,9 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public String getServerBanner(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(String.class).method("server.banner").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().returnAs(String.class).method("server.banner").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting server banner", e);
         }
     }
@@ -55,8 +60,9 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public BlockHeaderTip subscribeBlockHeaders(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(BlockHeaderTip.class).method("blockchain.headers.subscribe").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<BlockHeaderTip>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().returnAs(BlockHeaderTip.class).method("blockchain.headers.subscribe").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error subscribing to block headers", e);
         }
     }
@@ -73,7 +79,7 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<String, ScriptHashTx[]>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch (JsonRpcBatchException e) {
             if(failOnError) {
                 throw new ElectrumServerRpcException("Failed to retrieve references for paths: " + e.getErrors().keySet(), e);
@@ -85,6 +91,8 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
             }
 
             return result;
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to retrieve references for paths: " + pathScriptHashes.keySet(), e);
         }
     }
 
@@ -99,7 +107,7 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<String, ScriptHashTx[]>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             if(failOnError) {
                 throw new ElectrumServerRpcException("Failed to retrieve references for paths: " + e.getErrors().keySet(), e);
@@ -111,6 +119,8 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
             }
 
             return result;
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to retrieve references for paths: " + pathScriptHashes.keySet(), e);
         }
     }
 
@@ -125,10 +135,12 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<String, String>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             //Even if we have some successes, failure to subscribe for all script hashes will result in outdated wallet view. Don't proceed.
             throw new ElectrumServerRpcException("Failed to subscribe for updates for paths: " + e.getErrors().keySet(), e);
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to subscribe for updates for paths: " + pathScriptHashes.keySet(), e);
         }
     }
 
@@ -144,9 +156,11 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<Integer, String>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             return (Map<Integer, String>)e.getSuccesses();
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to block headers for block heights: " + blockHeights, e);
         }
     }
 
@@ -162,7 +176,7 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<String, String>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             Map<String, String> result = (Map<String, String>)e.getSuccesses();
 
@@ -173,6 +187,8 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
             }
 
             return result;
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to retrieve transactions for txids: " + txids, e);
         }
     }
 
@@ -186,10 +202,12 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<String, VerboseTransaction>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             log.warn("Some errors retrieving transactions: " + e.getErrors());
             return (Map<String, VerboseTransaction>)e.getSuccesses();
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Failed to retrieve verbose transactions for txids: " + txids, e);
         }
     }
 
@@ -202,9 +220,11 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
 
         try {
-            return batchRequest.execute();
+            return new RetryLogic<Map<Integer, Double>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(batchRequest::execute);
         } catch(JsonRpcBatchException e) {
             throw new ElectrumServerRpcException("Error getting fee estimates", e);
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Error getting fee estimates for target blocks: " + targetBlocks, e);
         }
     }
 
@@ -212,8 +232,9 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public Double getMinimumRelayFee(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(Double.class).method("blockchain.relayfee").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<Double>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().returnAs(Double.class).method("blockchain.relayfee").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting minimum relay fee", e);
         }
     }
@@ -222,9 +243,12 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     public String broadcastTransaction(Transport transport, String txHex) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(String.class).method("blockchain.transaction.broadcast").id(idCounter.incrementAndGet()).param("raw_tx", txHex).execute();
+            return new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+                    client.createRequest().returnAs(String.class).method("blockchain.transaction.broadcast").id(idCounter.incrementAndGet()).param("raw_tx", txHex).execute());
         } catch(JsonRpcException e) {
             throw new ElectrumServerRpcException(e.getErrorMessage().getMessage(), e);
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Error broadcasting transaction", e);
         }
     }
 }

src/main/java/com/sparrowwallet/sparrow/net/ElectrumServer.java

@@ -138,14 +138,19 @@ public class ElectrumServer {
     public Map<WalletNode, Set<BlockTransactionHash>> getHistory(Wallet wallet, Collection<WalletNode> nodes) throws ServerException {
         Map<WalletNode, Set<BlockTransactionHash>> nodeTransactionMap = new TreeMap<>();
         subscribeWalletNodes(wallet, nodes, nodeTransactionMap, 0);
-        getReferences(wallet, nodes, nodeTransactionMap);
+        getReferences(wallet, nodeTransactionMap.keySet(), nodeTransactionMap, 0);
 
         return nodeTransactionMap;
     }
 
     public void getHistory(Wallet wallet, KeyPurpose keyPurpose, Map<WalletNode, Set<BlockTransactionHash>> nodeTransactionMap) throws ServerException {
         WalletNode purposeNode = wallet.getNode(keyPurpose);
+        //Subscribe to all existing address WalletNodes and add them to nodeTransactionMap as keys to empty sets if they have history
         subscribeWalletNodes(wallet, purposeNode.getChildren(), nodeTransactionMap, 0);
+        //All WalletNode keys in nodeTransactionMap need to have their history fetched (nodes without history will not be keys in the map yet)
+        getReferences(wallet, nodeTransactionMap.keySet(), nodeTransactionMap, 0);
+        //Fetch all referenced transaction to wallet transactions map
+        getReferencedTransactions(wallet, nodeTransactionMap);
 
         //Because node children are added sequentially in WalletNode.fillToIndex, we can simply look at the number of children to determine the highest filled index
         int historySize = purposeNode.getChildren().size();
@@ -154,16 +159,13 @@ public class ElectrumServer {
         while(historySize < gapLimitSize) {
             purposeNode.fillToIndex(gapLimitSize - 1);
             subscribeWalletNodes(wallet, purposeNode.getChildren(), nodeTransactionMap, historySize);
+            getReferences(wallet, nodeTransactionMap.keySet(), nodeTransactionMap, historySize);
+            getReferencedTransactions(wallet, nodeTransactionMap);
             historySize = purposeNode.getChildren().size();
             gapLimitSize = getGapLimitSize(wallet, nodeTransactionMap);
         }
 
-        //All WalletNode keys in nodeTransactionMap need to have their history fetched
+        //Set the remaining WalletNode keys in nodeTransactionMap to empty sets to indicate no history
-        Collection<WalletNode> usedNodes = new ArrayList<>(nodeTransactionMap.keySet());
-        log.debug("Retrieving history for " + usedNodes.stream().map(WalletNode::getDerivationPath).collect(Collectors.joining(", ")));
-        getReferences(wallet, usedNodes, nodeTransactionMap);
-
-        //Set the remaining WalletNode keys to empty sets to indicate no history
         purposeNode.getChildren().stream().filter(node -> !nodeTransactionMap.containsKey(node)).forEach(node -> nodeTransactionMap.put(node, Collections.emptySet()));
     }
 
@@ -172,12 +174,14 @@ public class ElectrumServer {
         return highestIndex + wallet.getGapLimit() + 1;
     }
 
-    public void getReferences(Wallet wallet, Collection<WalletNode> nodes, Map<WalletNode, Set<BlockTransactionHash>> nodeTransactionMap) throws ServerException {
+    public void getReferences(Wallet wallet, Collection<WalletNode> nodes, Map<WalletNode, Set<BlockTransactionHash>> nodeTransactionMap, int startIndex) throws ServerException {
         try {
             Map<String, String> pathScriptHashes = new LinkedHashMap<>(nodes.size());
             for(WalletNode node : nodes) {
+                if(node.getIndex() >= startIndex) {
                     pathScriptHashes.put(node.getDerivationPath(), getScriptHash(wallet, node));
                 }
+            }
 
             if(pathScriptHashes.isEmpty()) {
                 return;
@@ -226,7 +230,11 @@ public class ElectrumServer {
             Set<String> scriptHashes = new HashSet<>();
             Map<String, String> pathScriptHashes = new LinkedHashMap<>();
             for(WalletNode node : nodes) {
-                if(node.getIndex() >= startIndex) {
+                if(node == null) {
+                    log.error("Null node for wallet " + wallet.getName() + " subscribing nodes " + nodes + " startIndex " + startIndex);
+                }
+
+                if(node != null && node.getIndex() >= startIndex) {
                     String scriptHash = getScriptHash(wallet, node);
                     if(getSubscribedScriptHashStatus(scriptHash) != null) {
                         //Already subscribed, but still need to fetch history from a used node
@@ -318,6 +326,14 @@ public class ElectrumServer {
             references.addAll(nodeReferences);
         }
 
+        for(Iterator<BlockTransactionHash> iter = references.iterator(); iter.hasNext(); ) {
+            BlockTransactionHash reference = iter.next();
+            BlockTransaction blockTransaction = wallet.getTransactions().get(reference.getHash());
+            if(blockTransaction != null && reference.getHeight() == blockTransaction.getHeight()) {
+                iter.remove();
+            }
+        }
+
         Map<Sha256Hash, BlockTransaction> transactionMap = new HashMap<>();
         if(!references.isEmpty()) {
             Map<Integer, BlockHeader> blockHeaderMap = getBlockHeaders(references);
@@ -388,7 +404,14 @@ public class ElectrumServer {
                 }
 
                 byte[] rawtx = Utils.hexToBytes(strRawTx);
-                Transaction transaction = new Transaction(rawtx);
+                Transaction transaction;
+
+                try {
+                    transaction = new Transaction(rawtx);
+                } catch(ProtocolException e) {
+                    log.error("Could not parse tx: " + strRawTx);
+                    continue;
+                }
 
                 Optional<BlockTransactionHash> optionalReference = references.stream().filter(reference -> reference.getHash().equals(hash)).findFirst();
                 if(optionalReference.isEmpty()) {
@@ -439,7 +462,9 @@ public class ElectrumServer {
         Set<BlockTransactionHash> history = nodeTransactionMap.get(node);
         for(BlockTransactionHash reference : history) {
             BlockTransaction blockTransaction = wallet.getTransactions().get(reference.getHash());
-            if(blockTransaction == null || blockTransaction.equals(UNFETCHABLE_BLOCK_TRANSACTION)) {
+            if(blockTransaction == null) {
+                throw new IllegalStateException("Did not retrieve transaction for hash " + reference.getHashAsString());
+            } else if(blockTransaction.equals(UNFETCHABLE_BLOCK_TRANSACTION)) {
                 throw new IllegalStateException("Could not retrieve transaction for hash " + reference.getHashAsString());
             }
             Transaction transaction = blockTransaction.getTransaction();
@@ -760,6 +785,7 @@ public class ElectrumServer {
     public static class TransactionHistoryService extends Service<Boolean> {
         private final Wallet wallet;
         private final Set<WalletNode> nodes;
+        private final static Map<Wallet, Object> walletSynchronizeLocks = new HashMap<>();
 
         public TransactionHistoryService(Wallet wallet) {
             this.wallet = wallet;
@@ -775,12 +801,15 @@ public class ElectrumServer {
         protected Task<Boolean> createTask() {
             return new Task<>() {
                 protected Boolean call() throws ServerException {
+                    walletSynchronizeLocks.putIfAbsent(wallet, new Object());
+                    synchronized(walletSynchronizeLocks.get(wallet)) {
                         ElectrumServer electrumServer = new ElectrumServer();
                         Map<WalletNode, Set<BlockTransactionHash>> nodeTransactionMap = (nodes == null ? electrumServer.getHistory(wallet) : electrumServer.getHistory(wallet, nodes));
                         electrumServer.getReferencedTransactions(wallet, nodeTransactionMap);
                         electrumServer.calculateNodeHistory(wallet, nodeTransactionMap);
                         return true;
                     }
+                }
             };
         }
     }

src/main/java/com/sparrowwallet/sparrow/net/RetryLogic.java

@@ -0,0 +1,54 @@
+package com.sparrowwallet.sparrow.net;
+
+import java.util.List;
+
+/**
+ * Generic retry logic. Delegate must throw the specified exception type to trigger the retry logic.
+ */
+public class RetryLogic<T> {
+    public static interface Delegate<T> {
+        T call() throws Exception;
+    }
+
+    private final int maxAttempts;
+    private final int retryWaitSeconds;
+    @SuppressWarnings("rawtypes")
+    private final List<Class> retryExceptionTypes;
+
+    public RetryLogic(int maxAttempts, int retryWaitSeconds, @SuppressWarnings("rawtypes") Class retryExceptionType) {
+        this(maxAttempts, retryWaitSeconds, List.of(retryExceptionType));
+    }
+
+    public RetryLogic(int maxAttempts, int retryWaitSeconds, @SuppressWarnings("rawtypes") List<Class> retryExceptionTypes) {
+        this.maxAttempts = maxAttempts;
+        this.retryWaitSeconds = retryWaitSeconds;
+        this.retryExceptionTypes = retryExceptionTypes;
+    }
+
+    public T getResult(Delegate<T> caller) throws Exception {
+        T result = null;
+        int remainingAttempts = maxAttempts;
+        do {
+            try {
+                return caller.call();
+            } catch(Exception e) {
+                if(retryExceptionTypes.contains(e.getClass())) {
+                    if(--remainingAttempts == 0) {
+                        throw new ServerException("Retries exhausted", e);
+                    } else {
+                        try {
+                            Thread.sleep((1000 * retryWaitSeconds));
+                        } catch(InterruptedException ie) {
+                            //ignore
+                        }
+                    }
+                } else {
+                    throw e;
+                }
+            }
+
+        } while(remainingAttempts > 0);
+
+        throw new IllegalStateException("Should be impossible");
+    }
+}

src/main/java/com/sparrowwallet/sparrow/net/SimpleElectrumServerRpc.java

@@ -18,7 +18,8 @@ import java.util.concurrent.atomic.AtomicLong;
 public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     private static final Logger log = LoggerFactory.getLogger(SimpleElectrumServerRpc.class);
     private static final int MAX_TARGET_BLOCKS = 25;
-    private static final int PER_REQUEST_DELAY_MILLIS = 50;
+    private static final int MAX_RETRIES = 3;
+    private static final int RETRY_DELAY = 0;
 
     private final AtomicLong idCounter = new AtomicLong();
 
@@ -26,8 +27,9 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public void ping(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            client.createRequest().method("server.ping").id(idCounter.incrementAndGet()).executeNullable();
+            new RetryLogic<>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException | IllegalStateException | IllegalArgumentException e) {
+                    client.createRequest().method("server.ping").id(idCounter.incrementAndGet()).executeNullable());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error pinging server", e);
         }
     }
@@ -36,9 +38,10 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public List<String> getServerVersion(Transport transport, String clientName, String[] supportedVersions) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            //Using 1.4 as the version number as EPS tries to parse this number to a float
+            //Using 1.4 as the version number as EPS tries to parse this number to a float :(
-            return client.createRequest().returnAsList(String.class).method("server.version").id(idCounter.incrementAndGet()).params(clientName, "1.4").execute();
+            return new RetryLogic<List<String>>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException | IllegalStateException | IllegalArgumentException e) {
+                    client.createRequest().returnAsList(String.class).method("server.version").id(idCounter.incrementAndGet()).params(clientName, "1.4").execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting server version", e);
         }
     }
@@ -47,8 +50,9 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public String getServerBanner(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(String.class).method("server.banner").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException | IllegalStateException | IllegalArgumentException e) {
+                    client.createRequest().returnAs(String.class).method("server.banner").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting server banner", e);
         }
     }
@@ -57,8 +61,9 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public BlockHeaderTip subscribeBlockHeaders(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(BlockHeaderTip.class).method("blockchain.headers.subscribe").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<BlockHeaderTip>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException | IllegalStateException | IllegalArgumentException e) {
+                    client.createRequest().returnAs(BlockHeaderTip.class).method("blockchain.headers.subscribe").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error subscribing to block headers", e);
         }
     }
@@ -71,10 +76,10 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         for(String path : pathScriptHashes.keySet()) {
             EventManager.get().post(new WalletHistoryStatusEvent(false, "Loading transactions for " + path));
             try {
-                ScriptHashTx[] scriptHashTxes = client.createRequest().returnAs(ScriptHashTx[].class).method("blockchain.scripthash.get_history").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).execute();
+                ScriptHashTx[] scriptHashTxes = new RetryLogic<ScriptHashTx[]>(MAX_RETRIES, RETRY_DELAY, List.of(IllegalStateException.class, IllegalArgumentException.class)).getResult(() ->
+                        client.createRequest().returnAs(ScriptHashTx[].class).method("blockchain.scripthash.get_history").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).execute());
                 result.put(path, scriptHashTxes);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
+            } catch(Exception e) {
-            } catch(JsonRpcException | IllegalStateException | IllegalArgumentException | InterruptedException e) {
                 if(failOnError) {
                     throw new ElectrumServerRpcException("Failed to retrieve reference for path: " + path, e);
                 }
@@ -93,10 +98,10 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         Map<String, ScriptHashTx[]> result = new LinkedHashMap<>();
         for(String path : pathScriptHashes.keySet()) {
             try {
-                ScriptHashTx[] scriptHashTxes = client.createRequest().returnAs(ScriptHashTx[].class).method("blockchain.scripthash.get_mempool").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).execute();
+                ScriptHashTx[] scriptHashTxes = new RetryLogic<ScriptHashTx[]>(MAX_RETRIES, RETRY_DELAY, List.of(IllegalStateException.class, IllegalArgumentException.class)).getResult(() ->
+                        client.createRequest().returnAs(ScriptHashTx[].class).method("blockchain.scripthash.get_mempool").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).execute());
                 result.put(path, scriptHashTxes);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
+            } catch(Exception e) {
-            } catch(JsonRpcException | IllegalStateException | IllegalArgumentException | InterruptedException e) {
                 if(failOnError) {
                     throw new ElectrumServerRpcException("Failed to retrieve reference for path: " + path, e);
                 }
@@ -116,10 +121,10 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         for(String path : pathScriptHashes.keySet()) {
             EventManager.get().post(new WalletHistoryStatusEvent(false, "Finding transactions for " + path));
             try {
-                String scriptHash = client.createRequest().returnAs(String.class).method("blockchain.scripthash.subscribe").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).executeNullable();
+                String scriptHash = new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, List.of(IllegalStateException.class, IllegalArgumentException.class)).getResult(() ->
+                        client.createRequest().returnAs(String.class).method("blockchain.scripthash.subscribe").id(path + "-" + idCounter.incrementAndGet()).params(pathScriptHashes.get(path)).executeNullable());
                 result.put(path, scriptHash);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
+            } catch(Exception e) {
-            } catch(JsonRpcException | IllegalStateException | IllegalArgumentException | InterruptedException e) {
                 //Even if we have some successes, failure to subscribe for all script hashes will result in outdated wallet view. Don't proceed.
                 throw new ElectrumServerRpcException("Failed to retrieve reference for path: " + path, e);
             }
@@ -136,13 +141,13 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         for(Integer blockHeight : blockHeights) {
             EventManager.get().post(new WalletHistoryStatusEvent(false, "Retrieving block at height " + blockHeight));
             try {
-                String blockHeader = client.createRequest().returnAs(String.class).method("blockchain.block.header").id(idCounter.incrementAndGet()).params(blockHeight).execute();
+                String blockHeader = new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, List.of(IllegalStateException.class, IllegalArgumentException.class)).getResult(() ->
+                        client.createRequest().returnAs(String.class).method("blockchain.block.header").id(idCounter.incrementAndGet()).params(blockHeight).execute());
                 result.put(blockHeight, blockHeader);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
-            } catch(IllegalStateException | IllegalArgumentException | InterruptedException e) {
-                log.warn("Failed to retrieve block header for block height: " + blockHeight + " (" + e.getMessage() + ")");
             } catch(JsonRpcException e) {
                 log.warn("Failed to retrieve block header for block height: " + blockHeight + " (" + e.getErrorMessage() + ")");
+            } catch(Exception e) {
+                log.warn("Failed to retrieve block header for block height: " + blockHeight + " (" + e.getMessage() + ")");
             }
         }
 
@@ -157,10 +162,10 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         for(String txid : txids) {
             EventManager.get().post(new WalletHistoryStatusEvent(false, "Retrieving transaction [" + txid.substring(0, 6) + "]"));
             try {
-                String rawTxHex = client.createRequest().returnAs(String.class).method("blockchain.transaction.get").id(idCounter.incrementAndGet()).params(txid).execute();
+                String rawTxHex = new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, List.of(IllegalStateException.class, IllegalArgumentException.class)).getResult(() ->
+                        client.createRequest().returnAs(String.class).method("blockchain.transaction.get").id(idCounter.incrementAndGet()).params(txid).execute());
                 result.put(txid, rawTxHex);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
+            } catch(Exception e) {
-            } catch(JsonRpcException | IllegalStateException | IllegalArgumentException | InterruptedException e) {
                 result.put(txid, Sha256Hash.ZERO_HASH.toString());
             }
         }
@@ -175,9 +180,9 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         Map<String, VerboseTransaction> result = new LinkedHashMap<>();
         for(String txid : txids) {
             try {
-                VerboseTransaction verboseTransaction = client.createRequest().returnAs(VerboseTransaction.class).method("blockchain.transaction.get").id(idCounter.incrementAndGet()).params(txid, true).execute();
+                VerboseTransaction verboseTransaction = new RetryLogic<VerboseTransaction>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+                        client.createRequest().returnAs(VerboseTransaction.class).method("blockchain.transaction.get").id(idCounter.incrementAndGet()).params(txid, true).execute());
                 result.put(txid, verboseTransaction);
-                Thread.sleep(PER_REQUEST_DELAY_MILLIS);
             } catch(Exception e) {
                 //electrs-esplora does not currently support the verbose parameter, so try to fetch an incomplete VerboseTransaction without it
                 //Note that without the script hash associated with the transaction, we can't get a block height as there is no way in the Electrum RPC protocol to do this
@@ -223,14 +228,14 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         for(Integer targetBlock : targetBlocks) {
             if(targetBlock <= MAX_TARGET_BLOCKS) {
                 try {
-                    Double targetBlocksFeeRateBtcKb = client.createRequest().returnAs(Double.class).method("blockchain.estimatefee").id(idCounter.incrementAndGet()).params(targetBlock).execute();
+                    Double targetBlocksFeeRateBtcKb = new RetryLogic<Double>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+                            client.createRequest().returnAs(Double.class).method("blockchain.estimatefee").id(idCounter.incrementAndGet()).params(targetBlock).execute());
                     result.put(targetBlock, targetBlocksFeeRateBtcKb);
-                    Thread.sleep(PER_REQUEST_DELAY_MILLIS);
-                } catch(IllegalStateException | IllegalArgumentException | InterruptedException e) {
-                    log.warn("Failed to retrieve fee rate for target blocks: " + targetBlock + " (" + e.getMessage() + ")");
-                    result.put(targetBlock, result.values().stream().mapToDouble(v -> v).min().orElse(0.0001d));
                 } catch(JsonRpcException e) {
                     throw new ElectrumServerRpcException("Failed to retrieve fee rate for target blocks: " + targetBlock, e);
+                } catch(Exception e) {
+                    log.warn("Failed to retrieve fee rate for target blocks: " + targetBlock + " (" + e.getMessage() + ")");
+                    result.put(targetBlock, result.values().stream().mapToDouble(v -> v).min().orElse(0.0001d));
                 }
             } else {
                 result.put(targetBlock, result.values().stream().mapToDouble(v -> v).min().orElse(0.0001d));
@@ -244,8 +249,9 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public Double getMinimumRelayFee(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(Double.class).method("blockchain.relayfee").id(idCounter.incrementAndGet()).execute();
+            return new RetryLogic<Double>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(JsonRpcException e) {
+                    client.createRequest().returnAs(Double.class).method("blockchain.relayfee").id(idCounter.incrementAndGet()).execute());
+        } catch(Exception e) {
             throw new ElectrumServerRpcException("Error getting minimum relay fee", e);
         }
     }
@@ -254,11 +260,12 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     public String broadcastTransaction(Transport transport, String txHex) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            return client.createRequest().returnAs(String.class).method("blockchain.transaction.broadcast").id(idCounter.incrementAndGet()).params(txHex).execute();
+            return new RetryLogic<String>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-        } catch(IllegalStateException | IllegalArgumentException e) {
+                    client.createRequest().returnAs(String.class).method("blockchain.transaction.broadcast").id(idCounter.incrementAndGet()).params(txHex).execute());
-            throw new ElectrumServerRpcException(e.getMessage(), e);
         } catch(JsonRpcException e) {
             throw new ElectrumServerRpcException(e.getErrorMessage().getMessage(), e);
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException(e.getMessage(), e);
         }
     }
 }

src/main/java/com/sparrowwallet/sparrow/net/TcpTransport.java

@@ -19,6 +19,7 @@ public class TcpTransport implements Transport, Closeable {
     private static final Logger log = LoggerFactory.getLogger(TcpTransport.class);
 
     public static final int DEFAULT_PORT = 50001;
+    private static final int READ_TIMEOUT_SECS = 3;
 
     protected final HostAndPort server;
     protected final SocketFactory socketFactory;
@@ -64,7 +65,7 @@ public class TcpTransport implements Transport, Closeable {
 
     private String readResponse() throws IOException {
         try {
-            if(!readLock.tryLock(60, TimeUnit.SECONDS)) {
+            if(!readLock.tryLock(READ_TIMEOUT_SECS, TimeUnit.SECONDS)) {
                 throw new IOException("No response from server");
             }
         } catch(InterruptedException e) {