[JENKINS-51205] Improve performance of /pluginManager/available service.

core/src/main/java/hudson/PluginManager.java

@@ -144,6 +144,7 @@
 import java.net.JarURLConnection;
 import java.net.URLConnection;
 import java.util.ServiceLoader;
+import java.util.function.Supplier;
 import java.util.jar.JarEntry;
 
 import static java.util.logging.Level.FINE;
@@ -1816,6 +1817,19 @@ public HttpResponse doInstallNecessaryPlugins(StaplerRequest req) throws IOExcep
         return requestedPlugins;
     }
 
+    @Restricted(DoNotUse.class) // table.jelly
+    public MetadataCache createCache() {
+        return new MetadataCache();
+    }
+
+    @Restricted(NoExternalUse.class) // table.jelly
+    public static final class MetadataCache {
+        private final Map<String, Object> data = new HashMap<>();
+        public <T> T of(String key, Class<T> type, Supplier<T> func) {
+            return type.cast(data.computeIfAbsent(key, _ignored -> func.get()));
+        }
+    }
+
     /**
      * {@link ClassLoader} that can see all plugins.
      */

core/src/main/java/hudson/model/UpdateSite.java

@@ -120,11 +120,6 @@
      */
     private transient volatile long retryWindow;
 
-    /**
-     * lastModified time of the data file when it was last read.
-     */
-    private transient long dataLastReadFromFile;
-
     /**
      * Latest data as read from the data file.
      */
@@ -226,6 +221,7 @@ private FormValidation updateData(String json, boolean signatureCheck)
         LOGGER.info("Obtained the latest update center data file for UpdateSource " + id);
         retryWindow = 0;
         getDataFile().write(json);
+        data = new Data(o);
         return FormValidation.ok();
     }
 
@@ -309,23 +305,20 @@ public boolean isDue() {
     public HttpResponse doInvalidateData() {
         Jenkins.getInstance().checkPermission(Jenkins.ADMINISTER);
         dataTimestamp = 0;
+        data = null;
         return HttpResponses.ok();
     }
 
     /**
-     * Loads the update center data, if any and if modified since last read.
+     * Loads the update center data, if any.
      *
      * @return  null if no data is available.
      */
     public Data getData() {
-        TextFile df = getDataFile();
-        if (df.exists() && dataLastReadFromFile != df.file.lastModified()) {
+        if (data == null) {
             JSONObject o = getJSONObject();
-            if (o!=null) {
+            if (o != null) {
                 data = new Data(o);
-                dataLastReadFromFile = df.file.lastModified();
-            } else {
-                data = null;
             }
         }
         return data;
@@ -1094,10 +1087,19 @@ public VersionNumber getNeededDependenciesRequiredCore() {
         }
 
         public boolean isNeededDependenciesForNewerJenkins() {
-            for (Plugin p: getNeededDependencies()) {
-                if (p.isForNewerHudson() || p.isNeededDependenciesForNewerJenkins()) return true;
-            }
-            return false;
+            return isNeededDependenciesForNewerJenkins(new PluginManager.MetadataCache());
+        }
+
+        @Restricted(NoExternalUse.class) // table.jelly
+        public boolean isNeededDependenciesForNewerJenkins(PluginManager.MetadataCache cache) {
+            return cache.of("isNeededDependenciesForNewerJenkins:" + name, Boolean.class, () -> {
+                for (Plugin p : getNeededDependencies()) {
+                    if (p.isForNewerHudson() || p.isNeededDependenciesForNewerJenkins()) {
+                        return true;
+                    }
+                }
+                return false;
+            });
         }
 
         /**
@@ -1109,11 +1111,19 @@ public boolean isNeededDependenciesForNewerJenkins() {
          * specified, it'll return true.
          */
         public boolean isNeededDependenciesCompatibleWithInstalledVersion() {
-            for (Plugin p: getNeededDependencies()) {
-                if (!p.isCompatibleWithInstalledVersion() || !p.isNeededDependenciesCompatibleWithInstalledVersion())
-                    return false;
-            }
-            return true;
+            return isNeededDependenciesCompatibleWithInstalledVersion(new PluginManager.MetadataCache());
+        }
+
+        @Restricted(NoExternalUse.class) // table.jelly
+        public boolean isNeededDependenciesCompatibleWithInstalledVersion(PluginManager.MetadataCache cache) {
+            return cache.of("isNeededDependenciesCompatibleWithInstalledVersion:" + name, Boolean.class, () -> {
+                for (Plugin p : getNeededDependencies()) {
+                    if (!p.isCompatibleWithInstalledVersion() || !p.isNeededDependenciesCompatibleWithInstalledVersion()) {
+                        return false;
+                    }
+                }
+                return true;
+            });
         }
 
         /**

core/src/main/resources/hudson/PluginManager/table.jelly

@@ -72,6 +72,7 @@ THE SOFTWARE.
             <j:choose>
               <j:when test="${!empty(list)}">
                 <j:set var="lastCat" value="" />
+                <j:set var="cache" value="${it.createCache()}"/>
                 <j:forEach var="p" items="${list}">
                   <j:if test="${!isUpdates}">
                     <j:set var="thisCat" value="${p.category}" />
@@ -105,10 +106,10 @@ THE SOFTWARE.
                       <j:if test="${p.isForNewerHudson()}">
                         <div class="compatWarning">${%coreWarning(p.requiredCore)}</div>
                       </j:if>
-                      <j:if test="${!p.isNeededDependenciesCompatibleWithInstalledVersion()}">
+                      <j:if test="${!p.isNeededDependenciesCompatibleWithInstalledVersion(cache)}">
                         <div class="compatWarning">${%depCompatWarning}</div>
                       </j:if>
-                      <j:if test="${p.isNeededDependenciesForNewerJenkins()}">
+                      <j:if test="${p.isNeededDependenciesForNewerJenkins(cache)}">
                         <div class="compatWarning">${%depCoreWarning(p.getNeededDependenciesRequiredCore().toString())}</div>
                       </j:if>
                       <j:if test="${p.hasWarnings()}">