Adding a deprecation info check for fixed_auto_queue_size threadpool settings (#76995)

The fixed_auto_queue_size threadpool has been removed in 8.0. This commit checks for configuration that is
specific to that threadpool type and issues a deprecation info API message about it.
Relates #42404 #52280

Author: masseyke

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java

@@ -97,6 +97,7 @@ private DeprecationChecks() {
                     NodeDeprecationChecks::checkImplicitlyDisabledSecurityOnBasicAndTrial,
                     NodeDeprecationChecks::checkSearchRemoteSettings,
                     NodeDeprecationChecks::checkMonitoringExporterPassword,
+                    NodeDeprecationChecks::checkFixedAutoQueueSizeThreadpool,
                     NodeDeprecationChecks::checkJoinTimeoutSetting,
                     NodeDeprecationChecks::checkClusterRoutingAllocationIncludeRelocationsSetting,
                     NodeDeprecationChecks::checkClusterRoutingRequireSetting,

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/NodeDeprecationChecks.java

@@ -665,6 +665,42 @@ static DeprecationIssue checkClusterRoutingAllocationIncludeRelocationsSetting(f
         );
     }
 
+    static DeprecationIssue checkFixedAutoQueueSizeThreadpool(final Settings settings,
+                                                              final PluginsAndModules pluginsAndModules,
+                                                              final ClusterState clusterState,
+                                                              final XPackLicenseState licenseState) {
+        List<Setting<Integer>> deprecatedSettings = new ArrayList<>();
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search.min_queue_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search.max_queue_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search.auto_queue_frame_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search.target_response_time", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search_throttled.min_queue_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search_throttled.max_queue_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search_throttled.auto_queue_frame_size", 1, Setting.Property.Deprecated));
+        deprecatedSettings.add(Setting.intSetting("thread_pool.search_throttled.target_response_time", 1, Setting.Property.Deprecated));
+        List<Setting<Integer>> existingSettings =
+            deprecatedSettings.stream().filter(deprecatedSetting -> deprecatedSetting.exists(settings)).collect(Collectors.toList());
+        if (existingSettings.isEmpty()) {
+            return null;
+        }
+        final String settingNames = existingSettings.stream().map(Setting::getKey).collect(Collectors.joining(","));
+        final String message = String.format(
+            Locale.ROOT,
+            "cannot use properties [%s] because fixed_auto_queue_size threadpool type has been deprecated and will be removed in the next" +
+                " major version",
+            settingNames
+        );
+        final String details = String.format(
+            Locale.ROOT,
+            "cannot use properties [%s] because fixed_auto_queue_size threadpool type has been deprecated and will be removed in the next" +
+                " major version",
+            settingNames
+        );
+        final String url = "https://www.elastic.co/guide/en/elasticsearch/reference/master/migrating-8.0" +
+            ".html#breaking_80_threadpool_changes";
+        return new DeprecationIssue(DeprecationIssue.Level.CRITICAL, message, url, details, false, null);
+    }
+
     static DeprecationIssue checkClusterRoutingRequireSetting(final Settings settings,
                                                               final PluginsAndModules pluginsAndModules,
                                                               final ClusterState clusterState,

x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/NodeDeprecationChecksTests.java

@@ -961,6 +961,44 @@ public void testImplicitlyConfiguredSecurityOnGoldPlus() {
         assertThat(issues, empty());
     }
 
+    public void testCheckFixedAutoQueueSizeThreadpool() {
+        String settingKey = "thread_pool.search.min_queue_size";
+        String settingValue = "";
+        Settings settings = Settings.builder()
+            .put("thread_pool.search.min_queue_size", randomIntBetween(30, 100))
+            .put("thread_pool.search.max_queue_size", randomIntBetween(1, 25))
+            .put("thread_pool.search.auto_queue_frame_size", randomIntBetween(1, 25))
+            .put("thread_pool.search.target_response_time", randomIntBetween(1, 25))
+            .put("thread_pool.search_throttled.min_queue_size", randomIntBetween(30, 100))
+            .put("thread_pool.search_throttled.max_queue_size", randomIntBetween(1, 25))
+            .put("thread_pool.search_throttled.auto_queue_frame_size", randomIntBetween(1, 25))
+            .put("thread_pool.search_throttled.target_response_time", randomIntBetween(1, 25))
+            .build();
+        final ClusterState clusterState = ClusterState.EMPTY_STATE;
+        final DeprecationIssue expectedIssue = new DeprecationIssue(DeprecationIssue.Level.CRITICAL,
+            "cannot use properties [thread_pool.search.min_queue_size,thread_pool.search.max_queue_size,thread_pool.search" +
+                ".auto_queue_frame_size,thread_pool.search.target_response_time,thread_pool.search_throttled.min_queue_size," +
+                "thread_pool.search_throttled.max_queue_size,thread_pool.search_throttled.auto_queue_frame_size,thread_pool" +
+                ".search_throttled.target_response_time] because fixed_auto_queue_size threadpool type has been deprecated" +
+                " and will be removed in the next major version",
+            "https://www.elastic.co/guide/en/elasticsearch/reference/master/migrating-8.0.html#breaking_80_threadpool_changes",
+            "cannot use properties [thread_pool.search.min_queue_size,thread_pool.search.max_queue_size,thread_pool.search" +
+                ".auto_queue_frame_size,thread_pool.search.target_response_time,thread_pool.search_throttled.min_queue_size," +
+                "thread_pool.search_throttled.max_queue_size,thread_pool.search_throttled.auto_queue_frame_size,thread_pool" +
+                ".search_throttled.target_response_time] because fixed_auto_queue_size threadpool type has been deprecated" +
+                " and will be removed in the next major version",
+            false, null
+        );
+        final XPackLicenseState licenseState = mock(XPackLicenseState.class);
+        when(licenseState.getOperationMode())
+            .thenReturn(randomValueOtherThanMany((m -> m.equals(License.OperationMode.BASIC) || m.equals(License.OperationMode.TRIAL)),
+                () -> randomFrom(License.OperationMode.values())));
+        assertThat(
+            NodeDeprecationChecks.checkFixedAutoQueueSizeThreadpool(settings, null, clusterState, licenseState),
+            equalTo(expectedIssue)
+        );
+    }
+
     public void testTierAllocationSettings() {
         String settingValue = DataTier.DATA_HOT;
         final Settings settings = settings(Version.CURRENT)