From 9e6cb5e500d536a37116a45c4fd5edbe10e8571a Mon Sep 17 00:00:00 2001
From: Carsten Otto <git@c-otto.de>
Date: Fri, 5 Nov 2021 18:28:02 +0100
Subject: [PATCH] cache node information

---
 .../cotto/lndmanagej/grpc/GrpcNodeInfo.java   | 29 ++++++++++++++++++-
 .../de/cotto/lndmanagej/grpc/GrpcService.java |  4 +--
 .../lndmanagej/grpc/GrpcNodeInfoTest.java     | 10 ++++++-
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcNodeInfo.java b/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcNodeInfo.java
index dcc58620..1f1a27b2 100644
--- a/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcNodeInfo.java
+++ b/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcNodeInfo.java
@@ -1,20 +1,47 @@
 package de.cotto.lndmanagej.grpc;
 
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
 import de.cotto.lndmanagej.model.Node;
 import lnrpc.LightningNode;
 import lnrpc.NodeInfo;
 import org.springframework.stereotype.Component;
 
+import javax.annotation.Nonnull;
+import java.util.concurrent.TimeUnit;
+
 @Component
 public class GrpcNodeInfo {
+    private static final int MAXIMUM_SIZE = 500;
+    private static final int CACHE_EXPIRY_MINUTES = 30;
+
     private final GrpcService grpcService;
+    private final LoadingCache<String, Node> cache;
 
     public GrpcNodeInfo(GrpcService grpcService) {
         this.grpcService = grpcService;
+        CacheLoader<String, Node> loader = new CacheLoader<>() {
+            @Override
+            public Node load(@Nonnull String pubkey) {
+                return getNodeWithoutCache(pubkey);
+            }
+        };
+        cache = CacheBuilder.newBuilder()
+                .expireAfterWrite(CACHE_EXPIRY_MINUTES, TimeUnit.MINUTES)
+                .maximumSize(MAXIMUM_SIZE)
+                .build(loader);
     }
 
     public Node getNode(String pubkey) {
-        NodeInfo nodeInfo = grpcService.getNodeInfo(pubkey);
+        return cache.getUnchecked(pubkey);
+    }
+
+    private Node getNodeWithoutCache(String pubkey) {
+        NodeInfo nodeInfo = grpcService.getNodeInfo(pubkey).orElse(null);
+        if (nodeInfo == null) {
+            return Node.builder().withPubkey(pubkey).build();
+        }
         LightningNode node = nodeInfo.getNode();
         return Node.builder()
                 .withPubkey(pubkey)
diff --git a/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcService.java b/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcService.java
index 584d21aa..e65eff32 100644
--- a/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcService.java
+++ b/grpc-adapter/src/main/java/de/cotto/lndmanagej/grpc/GrpcService.java
@@ -70,7 +70,7 @@ public class GrpcService {
                 .orElse(List.of());
     }
 
-    public NodeInfo getNodeInfo(String pubkey) {
-        return lightningStub.getNodeInfo(NodeInfoRequest.newBuilder().setPubKey(pubkey).build());
+    public Optional<NodeInfo> getNodeInfo(String pubkey) {
+        return get(() -> lightningStub.getNodeInfo(NodeInfoRequest.newBuilder().setPubKey(pubkey).build()));
     }
 }
diff --git a/grpc-adapter/src/test/java/de/cotto/lndmanagej/grpc/GrpcNodeInfoTest.java b/grpc-adapter/src/test/java/de/cotto/lndmanagej/grpc/GrpcNodeInfoTest.java
index 63d3f2d2..abdaa57f 100644
--- a/grpc-adapter/src/test/java/de/cotto/lndmanagej/grpc/GrpcNodeInfoTest.java
+++ b/grpc-adapter/src/test/java/de/cotto/lndmanagej/grpc/GrpcNodeInfoTest.java
@@ -9,6 +9,8 @@ import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
+import java.util.Optional;
+
 import static de.cotto.lndmanagej.model.NodeFixtures.NODE;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.when;
@@ -27,7 +29,7 @@ class GrpcNodeInfoTest {
                 .setAlias(NODE.alias())
                 .setLastUpdate(NODE.lastUpdate())
                 .build());
-        when(grpcService.getNodeInfo(NODE.pubkey())).thenReturn(node.build());
+        when(grpcService.getNodeInfo(NODE.pubkey())).thenReturn(Optional.of(node.build()));
     }
 
     @Test
@@ -44,4 +46,10 @@ class GrpcNodeInfoTest {
     void getNode_sets_last_update() {
         assertThat(grpcNodeInfo.getNode(NODE.pubkey()).lastUpdate()).isEqualTo(NODE.lastUpdate());
     }
+
+    @Test
+    void getNode_error() {
+        when(grpcService.getNodeInfo(NODE.pubkey())).thenReturn(Optional.empty());
+        assertThat(grpcNodeInfo.getNode(NODE.pubkey()).alias()).isEqualTo(NODE.pubkey());
+    }
 }
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