hbase-server/src/main/java/org/apache/hadoop/hbase/master/ClusterSchema.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.master;
  19
  20 import java.io.IOException;
  21 import java.io.InterruptedIOException;
  22 import java.util.List;
  23
  24 import org.apache.hadoop.hbase.NamespaceDescriptor;
  25 import org.apache.hadoop.hbase.master.procedure.ProcedurePrepareLatch;
  26 import org.apache.yetus.audience.InterfaceAudience;
  27 import org.apache.hadoop.hbase.util.NonceKey;
  28
  29 /**
  30  * View and edit the current cluster schema. Use this API making any modification to
  31  * namespaces, tables, etc.
  32  *
  33  * <h2>Implementation Notes</h2>
  34  * Nonces are for when operation is non-idempotent to ensure once-only semantic, even
  35  * across process failures.
  36  */
  37 // ClusterSchema is introduced to encapsulate schema modification. Currently the different aspects
  38 // are spread about the code base. This effort is about cleanup, shutting down access, and
  39 // coalescing common code. In particular, we'd contain filesystem modification. Other
  40 // benefits are to make all schema modification work the same way (one way to do an operation only
  41 // rather than the current approach where how an operation is done varies with context) and to make
  42 // it so clusterschema modification can stand apart from Master to faciliate standalone
  43 // testing. It is part of the filesystem refactor project that undoes the dependency on a
  44 // layout in HDFS that mimics our model of tables have regions have column families have files.
  45 // With this Interface in place, with all modifications going via this route where no filesystem
  46 // particulars are exposed, redoing our internals will take less effort.
  47 //
  48 // Currently ClusterSchema Interface will include namespace and table manipulation. Ideally a
  49 // form of this Interface will go all the ways down to the file manipulation level but currently
  50 // TBD.
  51 //
  52 // ClusterSchema is private to the Master; only the Master knows current cluster state and has
  53 // means of editing/altering it.
  54 //
  55 // TODO: Remove Server argument when MasterServices are passed.
  56 // TODO: We return Future<ProcedureInfo> in the below from most methods. It may change to return
  57 // a ProcedureFuture subsequently.
  58 @InterfaceAudience.Private
  59 public interface ClusterSchema {
  60   /**
  61    * Timeout for cluster operations in milliseconds.
  62    */
  63   public static final String HBASE_MASTER_CLUSTER_SCHEMA_OPERATION_TIMEOUT_KEY =
  64       "hbase.master.cluster.schema.operation.timeout";
  65   /**
  66    * Default operation timeout in milliseconds.
  67    */
  68   public static final int DEFAULT_HBASE_MASTER_CLUSTER_SCHEMA_OPERATION_TIMEOUT =
  69       5 * 60 * 1000;
  70
  71   /**
  72    * For internals use only. Do not use! Provisionally part of this Interface.
  73    * Prefer the high-level APIs available elsewhere in this API.
  74    * @return Instance of {@link TableNamespaceManager}
  75    */
  76   // TODO: Remove from here. Keep internal. This Interface is too high-level to host this accessor.
  77   TableNamespaceManager getTableNamespaceManager();
  78
  79   /**
  80    * Create a new Namespace.
  81    * @param namespaceDescriptor descriptor for new Namespace
  82    * @param nonceKey A unique identifier for this operation from the client or process.
  83    * @param latch A latch to block on for precondition validation
  84    * @return procedure id
  85    * @throws IOException Throws {@link ClusterSchemaException} and {@link InterruptedIOException}
  86    *    as well as {@link IOException}
  87    */
  88   long createNamespace(NamespaceDescriptor namespaceDescriptor, NonceKey nonceKey, ProcedurePrepareLatch latch)
  89   throws IOException;
  90
  91   /**
  92    * Modify an existing Namespace.
  93    * @param nonceKey A unique identifier for this operation from the client or process.
  94    * @param latch A latch to block on for precondition validation
  95    * @return procedure id
  96    * @throws IOException Throws {@link ClusterSchemaException} and {@link InterruptedIOException}
  97    *    as well as {@link IOException}
  98    */
  99   long modifyNamespace(NamespaceDescriptor descriptor, NonceKey nonceKey, ProcedurePrepareLatch latch)
 100   throws IOException;
 101
 102   /**
 103    * Delete an existing Namespace.
 104    * Only empty Namespaces (no tables) can be removed.
 105    * @param nonceKey A unique identifier for this operation from the client or process.
 106    * @param latch A latch to block on for precondition validation
 107    * @return procedure id
 108    * @throws IOException Throws {@link ClusterSchemaException} and {@link InterruptedIOException}
 109    *    as well as {@link IOException}
 110    */
 111   long deleteNamespace(String name, NonceKey nonceKey, ProcedurePrepareLatch latch)
 112   throws IOException;
 113
 114   /**
 115    * Get a Namespace
 116    * @param name Name of the Namespace
 117    * @return Namespace descriptor for <code>name</code>
 118    * @throws IOException Throws {@link ClusterSchemaException} and {@link InterruptedIOException}
 119    *    as well as {@link IOException}
 120    */
 121   // No Future here because presumption is that the request will go against cached metadata so
 122   // return immediately -- no need of running a Procedure.
 123   NamespaceDescriptor getNamespace(String name) throws IOException;
 124
 125   /**
 126    * Get all Namespaces
 127    * @return All Namespace descriptors
 128    */
 129   List<NamespaceDescriptor> getNamespaces() throws IOException;
 130 }