(search) Reduce the number of db queries a bit by caching data that doesn't change too often

code/services-application/search-service/java/nu/marginalia/search/svc/SearchSiteInfoService.java

@@ -26,6 +26,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.sql.SQLException;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Future;
@@ -69,6 +71,8 @@ public class SearchSiteInfoService {
         this.searchSiteSubscriptions = searchSiteSubscriptions;
     }
 
+    private volatile SiteOverviewModel model = new SiteOverviewModel(List.of(), Instant.EPOCH);
+
     @GET
     @Path("/site")
     public ModelAndView<?> handleOverview(@QueryParam String domain) {
@@ -77,6 +81,27 @@ public class SearchSiteInfoService {
             return new MapModelAndView("redirect.jte", Map.of("url", "/site/"+domain));
         }
 
+        if (model.age().compareTo(Duration.ofMinutes(15)) > 0) {
+            updateModel();
+        }
+
+        return new MapModelAndView("siteinfo/start.jte",
+                Map.of("navbar", NavbarModel.SITEINFO,
+                        "model", model));
+    }
+
+    /**  Update the model if it is older than 15 minutes.
+     *   This query is expensive and should not be run too often,
+     *   and the data doesn't change that often either.
+     *  <p></p>
+     *   This method is synchronized to avoid multiple threads updating the model at the same time.
+     */
+    private synchronized void updateModel() {
+        var currentModel = model;
+        if (currentModel.age().compareTo(Duration.ofMinutes(15)) < 0) {
+            return;
+        }
+
         List<SiteOverviewModel.DiscoveredDomain> domains = new ArrayList<>();
 
         try (var conn = dataSource.getConnection();
@@ -91,13 +116,20 @@ public class SearchSiteInfoService {
             throw new RuntimeException();
         }
 
-        return new MapModelAndView("siteinfo/start.jte",
+        model = new SiteOverviewModel(domains);
-                Map.of("navbar", NavbarModel.SITEINFO,
-                        "model", new SiteOverviewModel(domains)));
     }
 
-    public record SiteOverviewModel(List<DiscoveredDomain> domains) {
+    public record SiteOverviewModel(List<DiscoveredDomain> domains, Instant captureTime) {
+
+        public SiteOverviewModel(List<DiscoveredDomain> domains) {
+            this(domains, Instant.now());
+        }
+
         public record DiscoveredDomain(String name, String timestamp) {}
+
+        public Duration age() {
+            return Duration.between(captureTime, Instant.now());
+        }
     }
 
     @GET

code/services-application/search-service/resources/jte/siteinfo/view/overview.jte

@@ -81,35 +81,6 @@
 
         @endif
 
-
-        @if (!siteInfo.siblingDomains().isEmpty())
-            <div class="mx-3 flex place-items-baseline space-x-2 p-2 bg-gray-100 dark:bg-gray-600 rounded">
-                <i class="fas fa-globe"></i>
-                <span>Related Subdomains</span>
-            </div>
-
-            <table class="min-w-full divide-y divide-gray-200 dark:divide-gray-600 mx-4">
-                <thead>
-                <tr class="bg-gray-50 dark:bg-gray-700">
-                    <th scope="col" class="px-2 py-2 text-left text-xs font-medium text-gray-500 dark:text-gray-100 uppercase tracking-wider">Domain Name</th>
-                </tr>
-                </thead>
-                <tbody class="bg-white dark:bg-gray-800 divide-y divide-gray-200 dark:divide-gray-600 text-xs">
-                @for (DbDomainQueries.DomainWithNode sibling : siteInfo.siblingDomains())
-                    <tr>
-                        <td class="px-3 py-6 md:py-3 whitespace-nowrap">
-                            <a class="text-liteblue dark:text-blue-200" href="/site/${sibling.domain().toString()}">${sibling.domain().toString()}</a>
-
-                            @if (!sibling.isIndexed())
-                                <i class="ml-1 fa-regular fa-question-circle text-gray-400 dark:text-gray-600 text-xs" title="Not indexed"></i>
-                            @endif
-                        </td>
-                    </tr>
-                @endfor
-                </tbody>
-            </table>
-        @endif
-
         @if (siteInfo.domainInformation().isUnknownDomain())
             <div class="mx-3 flex place-items-baseline space-x-2 p-2 bg-gray-100 dark:bg-gray-600 rounded">
                 <i class="fa-regular fa-circle-question"></i>
@@ -178,6 +149,36 @@
             </form>
         @endif
 
+
+        @if (!siteInfo.siblingDomains().isEmpty())
+            <div class="mx-3 flex place-items-baseline space-x-2 p-2 bg-gray-100 dark:bg-gray-600 rounded">
+                <i class="fas fa-globe"></i>
+                <span>Related Subdomains</span>
+            </div>
+
+            <table class="min-w-full divide-y divide-gray-200 dark:divide-gray-600 mx-4">
+                <thead>
+                <tr class="bg-gray-50 dark:bg-gray-700">
+                    <th scope="col" class="px-2 py-2 text-left text-xs font-medium text-gray-500 dark:text-gray-100 uppercase tracking-wider">Domain Name</th>
+                </tr>
+                </thead>
+                <tbody class="bg-white dark:bg-gray-800 divide-y divide-gray-200 dark:divide-gray-600 text-xs">
+                @for (DbDomainQueries.DomainWithNode sibling : siteInfo.siblingDomains())
+                    <tr>
+                        <td class="px-3 py-6 md:py-3 whitespace-nowrap">
+                            <a class="text-liteblue dark:text-blue-200" href="/site/${sibling.domain().toString()}">${sibling.domain().toString()}</a>
+
+                            @if (!sibling.isIndexed())
+                                <i class="ml-1 fa-regular fa-question-circle text-gray-400 dark:text-gray-600 text-xs" title="Not indexed"></i>
+                            @endif
+                        </td>
+                    </tr>
+                @endfor
+                </tbody>
+            </table>
+        @endif
+
+
         @if (siteInfo.isKnown())
             <div class="mx-3 flex place-items-baseline space-x-2 p-2 bg-gray-100 dark:bg-gray-600 rounded">
                 <i class="fas fa-chart-simple"></i>