From b03114c536e7b1d633854ddf2f9746ce8f9c0b58 Mon Sep 17 00:00:00 2001
From: Carsten Otto <git@c-otto.de>
Date: Fri, 12 Nov 2021 11:50:35 +0100
Subject: [PATCH] add cache for synced-to-chain

---
 .../lndmanagej/service/OwnNodeService.java    | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/application/src/main/java/de/cotto/lndmanagej/service/OwnNodeService.java b/application/src/main/java/de/cotto/lndmanagej/service/OwnNodeService.java
index 7dc444eb..684d12a2 100644
--- a/application/src/main/java/de/cotto/lndmanagej/service/OwnNodeService.java
+++ b/application/src/main/java/de/cotto/lndmanagej/service/OwnNodeService.java
@@ -1,17 +1,41 @@
 package de.cotto.lndmanagej.service;
 
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
 import de.cotto.lndmanagej.grpc.GrpcGetInfo;
 import org.springframework.stereotype.Component;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.concurrent.TimeUnit;
+
 @Component
 public class OwnNodeService {
+    private static final int CACHE_EXPIRY_SECONDS = 30;
+
     private final GrpcGetInfo grpcGetInfo;
+    private final LoadingCache<String, Boolean> syncedToChainCache;
 
     public OwnNodeService(GrpcGetInfo grpcGetInfo) {
         this.grpcGetInfo = grpcGetInfo;
+        CacheLoader<String, Boolean> loader = new CacheLoader<>() {
+            @Nonnull
+            @Override
+            public Boolean load(@Nullable String ignored) {
+                return isSyncedToChainWithoutCache();
+            }
+        };
+        syncedToChainCache = CacheBuilder.newBuilder()
+                .expireAfterWrite(CACHE_EXPIRY_SECONDS, TimeUnit.SECONDS)
+                .build(loader);
     }
 
     public boolean isSyncedToChain() {
+        return syncedToChainCache.getUnchecked("");
+    }
+
+    private boolean isSyncedToChainWithoutCache() {
         return grpcGetInfo.isSyncedToChain().orElse(false);
     }
 }