retrieve and show next block median fee rate in recent blocks view where available

src/main/java/com/sparrowwallet/sparrow/AppServices.java

@@ -136,6 +136,8 @@ public class AppServices {
 
     private static Map<Integer, Double> targetBlockFeeRates;
 
+    private static Double nextBlockMedianFeeRate;
+
     private static final TreeMap<Date, Set<MempoolRateSize>> mempoolHistogram = new TreeMap<>();
 
     private static Double minimumRelayFeeRate;
@@ -748,6 +750,10 @@ public class AppServices {
         return Math.max(minRate, Transaction.DUST_RELAY_TX_FEE);
     }
 
+    public static Double getNextBlockMedianFeeRate() {
+        return nextBlockMedianFeeRate == null ? getDefaultFeeRate() : nextBlockMedianFeeRate;
+    }
+
     public static double getFallbackFeeRate() {
         return Network.get() == Network.MAINNET ? FALLBACK_FEE_RATE : TESTNET_FALLBACK_FEE_RATE;
     }
@@ -1249,11 +1255,13 @@ public class AppServices {
         if(AppServices.currentBlockHeight != null) {
             blockSummaries.keySet().removeIf(height -> AppServices.currentBlockHeight - height > 5);
         }
+        nextBlockMedianFeeRate = event.getNextBlockMedianFeeRate();
     }
 
     @Subscribe
     public void feesUpdated(FeeRatesUpdatedEvent event) {
         targetBlockFeeRates = event.getTargetBlockFeeRates();
+        nextBlockMedianFeeRate = event.getNextBlockMedianFeeRate();
     }
 
     @Subscribe

src/main/java/com/sparrowwallet/sparrow/control/RecentBlocksView.java

@@ -57,7 +57,7 @@ public class RecentBlocksView extends Pane {
     }
 
     public void updateFeeRatesSource(FeeRatesSource feeRatesSource) {
-        tooltip.setText("Fee rate estimate from " + feeRatesSource.getDescription());
+        tooltip.setText("Fee rates from " + feeRatesSource.getDescription());
         if(getCubes() != null && !getCubes().isEmpty()) {
             getCubes().getFirst().setFeeRatesSource(feeRatesSource);
         }
@@ -108,7 +108,7 @@ public class RecentBlocksView extends Pane {
         }
     }
 
-    public void addNewBlock(List<BlockSummary> latestBlocks, Double currentFeeRate) {
+    private void addNewBlock(List<BlockSummary> latestBlocks, Double currentFeeRate) {
         if(getCubes().isEmpty()) {
             return;
         }

src/main/java/com/sparrowwallet/sparrow/event/BlockSummaryEvent.java

@@ -6,12 +6,18 @@ import java.util.Map;
 
 public class BlockSummaryEvent {
     private final Map<Integer, BlockSummary> blockSummaryMap;
+    private final Double nextBlockMedianFeeRate;
 
-    public BlockSummaryEvent(Map<Integer, BlockSummary> blockSummaryMap) {
+    public BlockSummaryEvent(Map<Integer, BlockSummary> blockSummaryMap, Double nextBlockMedianFeeRate) {
         this.blockSummaryMap = blockSummaryMap;
+        this.nextBlockMedianFeeRate = nextBlockMedianFeeRate;
     }
 
     public Map<Integer, BlockSummary> getBlockSummaryMap() {
         return blockSummaryMap;
     }
+
+    public Double getNextBlockMedianFeeRate() {
+        return nextBlockMedianFeeRate;
+    }
 }

src/main/java/com/sparrowwallet/sparrow/event/FeeRatesUpdatedEvent.java

@@ -7,13 +7,23 @@ import java.util.Set;
 
 public class FeeRatesUpdatedEvent extends MempoolRateSizesUpdatedEvent {
     private final Map<Integer, Double> targetBlockFeeRates;
+    private final Double nextBlockMedianFeeRate;
 
     public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Set<MempoolRateSize> mempoolRateSizes) {
+        this(targetBlockFeeRates, mempoolRateSizes, null);
+    }
+
+    public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Set<MempoolRateSize> mempoolRateSizes, Double nextBlockMedianFeeRate) {
         super(mempoolRateSizes);
         this.targetBlockFeeRates = targetBlockFeeRates;
+        this.nextBlockMedianFeeRate = nextBlockMedianFeeRate;
     }
 
     public Map<Integer, Double> getTargetBlockFeeRates() {
         return targetBlockFeeRates;
     }
+
+    public Double getNextBlockMedianFeeRate() {
+        return nextBlockMedianFeeRate;
+    }
 }

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

@@ -936,6 +936,20 @@ public class ElectrumServer {
         return targetBlocksFeeRatesSats;
     }
 
+    public Double getNextBlockMedianFeeRate() {
+        FeeRatesSource feeRatesSource = Config.get().getFeeRatesSource();
+        feeRatesSource = (feeRatesSource == null ? FeeRatesSource.MEMPOOL_SPACE : feeRatesSource);
+        if(feeRatesSource.supportsNetwork(Network.get())) {
+            try {
+                return feeRatesSource.getNextBlockMedianFeeRate();
+            } catch(Exception e) {
+                return null;
+            }
+        }
+
+        return null;
+    }
+
     public Map<Integer, Double> getDefaultFeeEstimates(List<Integer> targetBlocks) throws ServerException {
         try {
             Map<Integer, Double> targetBlocksFeeRatesBtcKb = electrumServerRpc.getFeeEstimates(getTransport(), targetBlocks);
@@ -1460,8 +1474,9 @@ public class ElectrumServer {
                             if(elapsed > FEE_RATES_PERIOD) {
                                 Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(AppServices.TARGET_BLOCKS_RANGE, false);
                                 Set<MempoolRateSize> mempoolRateSizes = electrumServer.getMempoolRateSizes();
+                                Double nextBlockMedianFeeRate = electrumServer.getNextBlockMedianFeeRate();
                                 feeRatesRetrievedAt = System.currentTimeMillis();
-                                return new FeeRatesUpdatedEvent(blockTargetFeeRates, mempoolRateSizes);
+                                return new FeeRatesUpdatedEvent(blockTargetFeeRates, mempoolRateSizes, nextBlockMedianFeeRate);
                             }
                         } else {
                             closeConnection();
@@ -1939,7 +1954,8 @@ public class ElectrumServer {
                 protected FeeRatesUpdatedEvent call() throws ServerException {
                     ElectrumServer electrumServer = new ElectrumServer();
                     Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(AppServices.TARGET_BLOCKS_RANGE, false);
-                    return new FeeRatesUpdatedEvent(blockTargetFeeRates, null);
+                    Double nextBlockMedianFeeRate = electrumServer.getNextBlockMedianFeeRate();
+                    return new FeeRatesUpdatedEvent(blockTargetFeeRates, null, nextBlockMedianFeeRate);
                 }
             };
         }
@@ -1989,7 +2005,11 @@ public class ElectrumServer {
                         subscribeRecent(electrumServer);
                     }
 
-                    return new BlockSummaryEvent(blockSummaryMap);
+                    Double nextBlockMedianFeeRate = null;
+                    if(!isBlockstorm(totalBlocks)) {
+                        nextBlockMedianFeeRate = electrumServer.getNextBlockMedianFeeRate();
+                    }
+                    return new BlockSummaryEvent(blockSummaryMap, nextBlockMedianFeeRate);
                 }
             };
         }
@@ -2054,7 +2074,7 @@ public class ElectrumServer {
                     };
                 }
             };
-            broadcastService.setDelay(Duration.seconds(Math.random() * 60 ));
+            broadcastService.setDelay(Duration.seconds(Math.random() * 60 * 10));
             broadcastService.setPeriod(Duration.hours(1));
             broadcastService.setOnSucceeded(_ -> broadcastService.cancel());
             broadcastService.setOnFailed(_ -> broadcastService.cancel());

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

@@ -34,6 +34,12 @@ public enum FeeRatesSource {
             return getThreeTierFeeRates(this, defaultblockTargetFeeRates, url);
         }
 
+        @Override
+        public Double getNextBlockMedianFeeRate() throws Exception {
+            String url = getApiUrl() + "v1/fees/mempool-blocks";
+            return requestNextBlockMedianFeeRate(this, url);
+        }
+
         @Override
         public BlockSummary getBlockSummary(Sha256Hash blockId) throws Exception {
             String url = getApiUrl() + "v1/block/" + Utils.bytesToHex(blockId.getReversedBytes());
@@ -130,6 +136,10 @@ public enum FeeRatesSource {
 
     public abstract Map<Integer, Double> getBlockTargetFeeRates(Map<Integer, Double> defaultblockTargetFeeRates);
 
+    public Double getNextBlockMedianFeeRate() throws Exception {
+        throw new UnsupportedOperationException(name + " does not support retrieving the next block median fee rate");
+    }
+
     public BlockSummary getBlockSummary(Sha256Hash blockId) throws Exception {
         throw new UnsupportedOperationException(name + " does not support block summaries");
     }
@@ -199,6 +209,30 @@ public enum FeeRatesSource {
         return httpClientService.requestJson(url, ThreeTierRates.class, null);
     }
 
+    protected static Double requestNextBlockMedianFeeRate(FeeRatesSource feeRatesSource, String url) throws Exception {
+        if(log.isInfoEnabled()) {
+            log.info("Requesting next block median fee rate from " + url);
+        }
+
+        HttpClientService httpClientService = AppServices.getHttpClientService();
+        try {
+            MempoolBlock[] mempoolBlocks = feeRatesSource.requestMempoolBlocks(url, httpClientService);
+            return mempoolBlocks.length > 0 ? mempoolBlocks[0].medianFee : null;
+        } catch (Exception e) {
+            if(log.isDebugEnabled()) {
+                log.warn("Error retrieving next block median fee rate from " + url, e);
+            } else {
+                log.warn("Error retrieving next block median fee rate from " + url + " (" + e.getMessage() + ")");
+            }
+
+            throw e;
+        }
+    }
+
+    protected MempoolBlock[] requestMempoolBlocks(String url, HttpClientService httpClientService) throws Exception {
+        return httpClientService.requestJson(url, MempoolBlock[].class, null);
+    }
+
     protected static BlockSummary requestBlockSummary(FeeRatesSource feeRatesSource, String url) throws Exception {
         if(log.isInfoEnabled()) {
             log.info("Requesting block summary from " + url);
@@ -309,6 +343,8 @@ public enum FeeRatesSource {
         }
     }
 
+    protected record MempoolBlock(Integer nTx, Double medianFee) {}
+
     protected record MempoolBlockSummary(String id, Integer height, Long timestamp, Integer tx_count, Integer weight, MempoolBlockSummaryExtras extras) {
         public Double getMedianFee() {
             return extras == null ? null : extras.medianFee();

src/main/java/com/sparrowwallet/sparrow/wallet/SendController.java

@@ -326,7 +326,7 @@ public class SendController extends WalletFormController implements Initializabl
         recentBlocksView.visibleProperty().bind(Bindings.equal(feeRatesSelectionProperty, FeeRatesSelection.RECENT_BLOCKS));
         List<BlockSummary> blockSummaries = AppServices.getBlockSummaries().values().stream().sorted().toList();
         if(!blockSummaries.isEmpty()) {
-            recentBlocksView.update(blockSummaries, AppServices.getDefaultFeeRate());
+            recentBlocksView.update(blockSummaries, AppServices.getNextBlockMedianFeeRate());
         }
 
         feeRatesSelectionProperty.addListener((_, oldValue, newValue) -> {
@@ -1411,7 +1411,12 @@ public class SendController extends WalletFormController implements Initializabl
             setFeeRatePriority(getFeeRangeRate());
         }
         feeRange.updateTrackHighlight();
-        recentBlocksView.updateFeeRate(event.getTargetBlockFeeRates());
+
+        if(event.getNextBlockMedianFeeRate() != null) {
+            recentBlocksView.updateFeeRate(event.getNextBlockMedianFeeRate());
+        } else {
+            recentBlocksView.updateFeeRate(event.getTargetBlockFeeRates());
+        }
 
         if(updateDefaultFeeRate) {
             if(getFeeRate() != null && Long.valueOf((long)getFallbackFeeRate()).equals(getFeeRate().longValue())) {
@@ -1435,7 +1440,7 @@ public class SendController extends WalletFormController implements Initializabl
 
     @Subscribe
     public void blockSummary(BlockSummaryEvent event) {
-        Platform.runLater(() -> recentBlocksView.update(AppServices.getBlockSummaries().values().stream().sorted().toList(), AppServices.getDefaultFeeRate()));
+        Platform.runLater(() -> recentBlocksView.update(AppServices.getBlockSummaries().values().stream().sorted().toList(), AppServices.getNextBlockMedianFeeRate()));
     }
 
     @Subscribe