get and store fee rate histogram

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

@@ -143,6 +143,8 @@ public class AppController implements Initializable {
 
     private static Map<Integer, Double> targetBlockFeeRates;
 
+    private static Map<Long, Long> feeRateHistogram;
+
     private static Double minimumRelayFeeRate;
 
     private static CurrencyRate fiatCurrencyExchangeRate;
@@ -650,6 +652,10 @@ public class AppController implements Initializable {
         return targetBlockFeeRates;
     }
 
+    public static Map<Long, Long> getFeeRateHistogram() {
+        return feeRateHistogram;
+    }
+
     public static Double getMinimumRelayFeeRate() {
         return minimumRelayFeeRate == null ? Transaction.DEFAULT_MIN_RELAY_FEE : minimumRelayFeeRate;
     }
@@ -1429,6 +1435,7 @@ public class AppController implements Initializable {
     public void newConnection(ConnectionEvent event) {
         currentBlockHeight = event.getBlockHeight();
         targetBlockFeeRates = event.getTargetBlockFeeRates();
+        feeRateHistogram = event.getFeeRateHistogram();
         minimumRelayFeeRate = event.getMinimumRelayFeeRate();
         String banner = event.getServerBanner();
         String status = "Connected to " + Config.get().getElectrumServer() + " at height " + event.getBlockHeight();
@@ -1453,6 +1460,7 @@ public class AppController implements Initializable {
     @Subscribe
     public void feesUpdated(FeeRatesUpdatedEvent event) {
         targetBlockFeeRates = event.getTargetBlockFeeRates();
+        feeRateHistogram = event.getFeeRateHistogram();
     }
 
     @Subscribe

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

@@ -12,8 +12,8 @@ public class ConnectionEvent extends FeeRatesUpdatedEvent {
     private final BlockHeader blockHeader;
     private final Double minimumRelayFeeRate;
 
-    public ConnectionEvent(List<String> serverVersion, String serverBanner, int blockHeight, BlockHeader blockHeader, Map<Integer, Double> targetBlockFeeRates, Double minimumRelayFeeRate) {
+    public ConnectionEvent(List<String> serverVersion, String serverBanner, int blockHeight, BlockHeader blockHeader, Map<Integer, Double> targetBlockFeeRates, Map<Long, Long> feeRateHistogram, Double minimumRelayFeeRate) {
-        super(targetBlockFeeRates);
+        super(targetBlockFeeRates, feeRateHistogram);
         this.serverVersion = serverVersion;
         this.serverBanner = serverBanner;
         this.blockHeight = blockHeight;

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

@@ -4,12 +4,18 @@ import java.util.Map;
 
 public class FeeRatesUpdatedEvent {
     private final Map<Integer, Double> targetBlockFeeRates;
+    private final Map<Long, Long> feeRateHistogram;
 
-    public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates) {
+    public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Map<Long, Long> feeRateHistogram) {
         this.targetBlockFeeRates = targetBlockFeeRates;
+        this.feeRateHistogram = feeRateHistogram;
     }
 
     public Map<Integer, Double> getTargetBlockFeeRates() {
         return targetBlockFeeRates;
     }
+
+    public Map<Long, Long> getFeeRateHistogram() {
+        return feeRateHistogram;
+    }
 }

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

@@ -15,6 +15,7 @@ import org.slf4j.LoggerFactory;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.TreeMap;
 import java.util.concurrent.atomic.AtomicLong;
 
 public class BatchedElectrumServerRpc implements ElectrumServerRpc {
@@ -229,6 +230,24 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
         }
     }
 
+    @Override
+    public Map<Long, Long> getFeeRateHistogram(Transport transport) {
+        try {
+            JsonRpcClient client = new JsonRpcClient(transport);
+            Long[][] feesArray = new RetryLogic<Long[][]>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+                    client.createRequest().returnAs(Long[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
+
+            Map<Long, Long> feeRateHistogram = new TreeMap<>();
+            for(Long[] feePair : feesArray) {
+                feeRateHistogram.put(feePair[0], feePair[1]);
+            }
+
+            return feeRateHistogram;
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Error getting fee rate histogram", e);
+        }
+    }
+
     @Override
     public Double getMinimumRelayFee(Transport transport) {
         try {

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

@@ -610,6 +610,10 @@ public class ElectrumServer {
         }
     }
 
+    public Map<Long, Long> getFeeRateHistogram() throws ServerException {
+        return electrumServerRpc.getFeeRateHistogram(getTransport());
+    }
+
     public Double getMinimumRelayFee() throws ServerException {
         Double minFeeRateBtcKb = electrumServerRpc.getMinimumRelayFee(getTransport());
         if(minFeeRateBtcKb != null) {
@@ -760,6 +764,7 @@ public class ElectrumServer {
                         String banner = electrumServer.getServerBanner();
 
                         Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(SendController.TARGET_BLOCKS_RANGE);
+                        Map<Long, Long> feeRateHistogram = electrumServer.getFeeRateHistogram();
                         feeRatesRetrievedAt = System.currentTimeMillis();
 
                         Double minimumRelayFeeRate = electrumServer.getMinimumRelayFee();
@@ -767,7 +772,7 @@ public class ElectrumServer {
                             blockTargetFeeRates.computeIfPresent(blockTarget, (blocks, feeRate) -> feeRate < minimumRelayFeeRate ? minimumRelayFeeRate : feeRate);
                         }
 
-                        return new ConnectionEvent(serverVersion, banner, tip.height, tip.getBlockHeader(), blockTargetFeeRates, minimumRelayFeeRate);
+                        return new ConnectionEvent(serverVersion, banner, tip.height, tip.getBlockHeader(), blockTargetFeeRates, feeRateHistogram, minimumRelayFeeRate);
                     } else {
                         if(reader.isAlive()) {
                             electrumServer.ping();
@@ -775,8 +780,9 @@ public class ElectrumServer {
                             long elapsed = System.currentTimeMillis() - feeRatesRetrievedAt;
                             if(elapsed > FEE_RATES_PERIOD) {
                                 Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(SendController.TARGET_BLOCKS_RANGE);
+                                Map<Long, Long> feeRateHistogram = electrumServer.getFeeRateHistogram();
                                 feeRatesRetrievedAt = System.currentTimeMillis();
-                                return new FeeRatesUpdatedEvent(blockTargetFeeRates);
+                                return new FeeRatesUpdatedEvent(blockTargetFeeRates, feeRateHistogram);
                             }
                         } else {
                             resetConnection();

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

@@ -30,6 +30,8 @@ public interface ElectrumServerRpc {
 
     Map<Integer, Double> getFeeEstimates(Transport transport, List<Integer> targetBlocks);
 
+    Map<Long, Long> getFeeRateHistogram(Transport transport);
+
     Double getMinimumRelayFee(Transport transport);
 
     String broadcastTransaction(Transport transport, String txHex);

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

@@ -246,6 +246,24 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
         return result;
     }
 
+    @Override
+    public Map<Long, Long> getFeeRateHistogram(Transport transport) {
+        try {
+            JsonRpcClient client = new JsonRpcClient(transport);
+            Long[][] feesArray = new RetryLogic<Long[][]>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+                    client.createRequest().returnAs(Long[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
+
+            Map<Long, Long> feeRateHistogram = new TreeMap<>();
+            for(Long[] feePair : feesArray) {
+                feeRateHistogram.put(feePair[0], feePair[1]);
+            }
+
+            return feeRateHistogram;
+        } catch(Exception e) {
+            throw new ElectrumServerRpcException("Error getting fee rate histogram", e);
+        }
+    }
+
     @Override
     public Double getMinimumRelayFee(Transport transport) {
         try {