[GitHub] [ignite] sergey-chugunov-1985 commented on a change in pull request #8325: IGNITE-13366 Maintenance Mode for corrupted PDS case

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sergey-chugunov-1985 commented on a change in pull request #8325:
URL: https://github.com/apache/ignite/pull/8325#discussion_r502399395



##########
File path: modules/core/src/main/java/org/apache/ignite/maintenance/MaintenanceRegistry.java
##########
@@ -0,0 +1,132 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.ignite.maintenance;
+
+import java.util.List;
+import java.util.UUID;
+
+import org.apache.ignite.IgniteCheckedException;
+import org.apache.ignite.lang.IgniteExperimental;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * {@link MaintenanceRegistry} is a service local to each Ignite node
+ * that allows to request performing maintenance actions on that particular node.
+ *
+ * <p>
+ *     When a node gets into a situation when some specific actions are required
+ *     it enters the special mode called maintenance mode.
+ *     In maintenance mode it doesn't join to the rest of the cluster but still allows to connect to it
+ *     with control.{sh|bat} script or via JXM interface and perform needed actions.
+ * </p>
+ *
+ * <p>
+ *     Implementing new task for maintenance mode requires several pieces of code.
+ *
+ *     <ul>
+ *         <li>
+ *             First, component requiring Maintenance Mode should be able to register new {@link MaintenanceTask}
+ *             with {@link MaintenanceRegistry#registerMaintenanceTask(MaintenanceTask)} method.
+ *
+ *             Registration could happen automatically (e.g. if component detects some emergency situation
+ *             that requires user intervention)
+ *             or by user request (e.g. for a planned maintenance that requires
+ *             detaching node from the rest of the cluster).
+ *         </li>
+ *         <li>
+ *             Component responsible for handling this {@link MaintenanceTask}
+ *             on startup checks if the task is registered (thus it should go to Maintenance Mode).
+ *             If task is found component provides to {@link MaintenanceRegistry} its own implementation
+ *             of {@link MaintenanceWorkflowCallback} interface
+ *             via method {@link MaintenanceRegistry#registerWorkflowCallback(UUID, MaintenanceWorkflowCallback)}.
+ *         </li>
+ *         <li>
+ *             {@link MaintenanceWorkflowCallback} should provide {@link MaintenanceRegistry} with
+ *             {@link MaintenanceAction}s that are able to resolve maintenance task,
+ *             get information about it and so on.
+ *             Logic of these actions is completely up to the component providing it
+ *             and depends only on particular maintenance task.
+ *         </li>
+ *         <li>
+ *             When maintenance task is fixed, it should be removed from {@link MaintenanceRegistry}
+ *             with call {@link MaintenanceRegistry#unregisterMaintenanceTask(UUID)}.
+ *         </li>
+ *     </ul>
+ * </p>
+ */
+@IgniteExperimental
+public interface MaintenanceRegistry {
+    /**
+     * @return {@code True} if any maintenance task was found.
+     */
+    public boolean isMaintenanceMode();
+
+    /**
+     * @param task {@link MaintenanceTask} object with maintenance information that needs
+     *                                     to be stored to maintenance registry.
+     *
+     * @throws IgniteCheckedException If handling or storing maintenance task failed.
+     *
+     * @return Previously registered {@link MaintenanceTask} with the same ID
+     * or null if no tasks were registered for this ID.
+     */
+    public @Nullable MaintenanceTask registerMaintenanceTask(MaintenanceTask task) throws IgniteCheckedException;
+
+    /**
+     * Deletes {@link MaintenanceTask} of given ID from maintenance registry.
+     *
+     * @param mntcId
+     */
+    public void unregisterMaintenanceTask(UUID mntcId);

Review comment:
       fixed




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