From c62634de923a96e47c01458eb6c68c88ca9eafb1 Mon Sep 17 00:00:00 2001
From: 0xb00bface <0xboobface@gmail.com>
Date: Tue, 25 Apr 2023 20:45:23 +0200
Subject: [PATCH] Fix excessive loading of the model notes from the server

---
 .../ctbrec/notes/RemoteModelNotesService.java | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/common/src/main/java/ctbrec/notes/RemoteModelNotesService.java b/common/src/main/java/ctbrec/notes/RemoteModelNotesService.java
index 02d26b82..8520fbee 100644
--- a/common/src/main/java/ctbrec/notes/RemoteModelNotesService.java
+++ b/common/src/main/java/ctbrec/notes/RemoteModelNotesService.java
@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.net.URLEncoder;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
+import java.time.Instant;
 import java.util.*;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
@@ -32,6 +33,9 @@ public class RemoteModelNotesService extends RemoteService implements ModelNotes
     private final HttpClient httpClient;
     private final Config config;
 
+    private Map<String, String> notesCache = Collections.emptyMap();
+    private Instant lastUpdate = Instant.EPOCH;
+
     private final LoadingCache<String, String> cache = CacheBuilder.newBuilder()
             .expireAfterWrite(3, TimeUnit.SECONDS)
             .maximumSize(10000)
@@ -67,16 +71,19 @@ public class RemoteModelNotesService extends RemoteService implements ModelNotes
         });
     }
 
-    private String updateCache(String modelUrl) {
-        try {
-            var modelNotes = loadAllModelNotes();
-            for (Map.Entry<String, String> entry : modelNotes.entrySet()) {
-                cache.put(entry.getKey(), entry.getValue());
+    private synchronized String updateCache(String modelUrl) {
+        if (lastUpdate.isBefore(Instant.now().minusSeconds(3))) {
+            try {
+                notesCache = loadAllModelNotes();
+                lastUpdate = Instant.now();
+                for (Map.Entry<String, String> entry : notesCache.entrySet()) {
+                    cache.put(entry.getKey(), entry.getValue());
+                }
+            } catch (Exception e) {
+                throw new CacheLoader.InvalidCacheLoadException("Loading of model notes from server failed");
             }
-            return modelNotes.get(modelUrl);
-        } catch (Exception e) {
-            throw new CacheLoader.InvalidCacheLoadException("Loading of model notes from server failed");
         }
+        return Optional.ofNullable(notesCache.get(modelUrl)).orElse("");
     }
 
     @Override
@@ -108,7 +115,7 @@ public class RemoteModelNotesService extends RemoteService implements ModelNotes
     public Optional<String> loadModelNotes(String modelUrl) throws IOException {
         try {
             log.trace("Loading model notes for {}", modelUrl);
-            return Optional.of(cache.get(modelUrl));
+            return Optional.ofNullable(cache.get(modelUrl));
         } catch (ExecutionException e) {
             throw new IOException(e);
         }