Start caching top-menus and version
We want to reduce QPS to Gerrit where easily possible. The framework for
this is already in place: On every Response, we can set caching.
We don't want caching to impact users by showing them stale data that is
in the critical path of their work. For admins, this is slightly more
acceptable.
To start with, we cache /server/version (30s) and /server/top-menus
(300s). These only change if Gerrit gets upgraded or plugins that
contribute top-menus reload.
Change-Id: I33ef5792bffba79bde5d7e7dda6b4291f2db9cc7
diff --git a/Documentation/config-plugins.txt b/Documentation/config-plugins.txt
index cda02fb..3a80910 100644
--- a/Documentation/config-plugins.txt
+++ b/Documentation/config-plugins.txt
@@ -9,6 +9,10 @@
link:config-gerrit.html#plugins.checkFrequency[a few minutes] until
the server picks up new and updated plugins.
+Due to caching, you might need to flush your browser cache after
+installing a plugin. Users will usually see the result within
+several minutes.
+
Plugins can also be installed via
link:rest-api-plugins.html#install-plugin[REST] and
link:cmd-plugin-install.html[SSH].
diff --git a/java/com/google/gerrit/server/config/ConfigResource.java b/java/com/google/gerrit/server/config/ConfigResource.java
index ec0e0c2..4275dc4 100644
--- a/java/com/google/gerrit/server/config/ConfigResource.java
+++ b/java/com/google/gerrit/server/config/ConfigResource.java
@@ -14,11 +14,22 @@
package com.google.gerrit.server.config;
+import com.google.gerrit.extensions.restapi.CacheControl;
import com.google.gerrit.extensions.restapi.RestResource;
import com.google.gerrit.extensions.restapi.RestView;
import com.google.inject.TypeLiteral;
+import java.util.concurrent.TimeUnit;
public class ConfigResource implements RestResource {
public static final TypeLiteral<RestView<ConfigResource>> CONFIG_KIND =
new TypeLiteral<RestView<ConfigResource>>() {};
+
+ /**
+ * Default cache control that gets set on the 'Cache-Control' header for responses on this
+ * resource that are cachable.
+ *
+ * <p>Not all resources are cacheable and in fact the vast majority might not be. Caching is a
+ * trade-off between the freshness of data and the number of QPS that the web UI sends.
+ */
+ public static CacheControl DEFAULT_CACHE_CONTROL = CacheControl.PRIVATE(300, TimeUnit.SECONDS);
}
diff --git a/java/com/google/gerrit/server/restapi/config/GetVersion.java b/java/com/google/gerrit/server/restapi/config/GetVersion.java
index 8135719..ee206d6 100644
--- a/java/com/google/gerrit/server/restapi/config/GetVersion.java
+++ b/java/com/google/gerrit/server/restapi/config/GetVersion.java
@@ -15,19 +15,22 @@
package com.google.gerrit.server.restapi.config;
import com.google.gerrit.common.Version;
+import com.google.gerrit.extensions.restapi.CacheControl;
import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
+import com.google.gerrit.extensions.restapi.Response;
import com.google.gerrit.extensions.restapi.RestReadView;
import com.google.gerrit.server.config.ConfigResource;
import com.google.inject.Singleton;
+import java.util.concurrent.TimeUnit;
@Singleton
public class GetVersion implements RestReadView<ConfigResource> {
@Override
- public String apply(ConfigResource resource) throws ResourceNotFoundException {
+ public Response<String> apply(ConfigResource resource) throws ResourceNotFoundException {
String version = Version.getVersion();
if (version == null) {
throw new ResourceNotFoundException();
}
- return version;
+ return Response.ok(version).caching(CacheControl.PRIVATE(30, TimeUnit.SECONDS));
}
}
diff --git a/java/com/google/gerrit/server/restapi/config/ListTopMenus.java b/java/com/google/gerrit/server/restapi/config/ListTopMenus.java
index c296a7d..2feb580 100644
--- a/java/com/google/gerrit/server/restapi/config/ListTopMenus.java
+++ b/java/com/google/gerrit/server/restapi/config/ListTopMenus.java
@@ -14,8 +14,10 @@
package com.google.gerrit.server.restapi.config;
+import com.google.gerrit.extensions.restapi.Response;
import com.google.gerrit.extensions.restapi.RestReadView;
import com.google.gerrit.extensions.webui.TopMenu;
+import com.google.gerrit.extensions.webui.TopMenu.MenuEntry;
import com.google.gerrit.server.config.ConfigResource;
import com.google.gerrit.server.plugincontext.PluginSetContext;
import com.google.inject.Inject;
@@ -33,9 +35,9 @@
}
@Override
- public List<TopMenu.MenuEntry> apply(ConfigResource resource) {
+ public Response<List<MenuEntry>> apply(ConfigResource resource) {
List<TopMenu.MenuEntry> entries = new ArrayList<>();
extensions.runEach(extension -> entries.addAll(extension.getEntries()));
- return entries;
+ return Response.ok(entries).caching(ConfigResource.DEFAULT_CACHE_CONTROL);
}
}
