[GitHub] [hbase] frostruan commented on a change in pull request #3716: HBASE-26323 introduce a SnapshotProcedure

[GitBox <gi...@apache.org>]

frostruan commented on a change in pull request #3716:
URL: https://github.com/apache/hbase/pull/3716#discussion_r721434067



##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/SnapshotProcedure.java
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@@ -0,0 +1,408 @@
+/*
+ * 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.hadoop.hbase.master.procedure;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.stream.Collectors;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.client.RegionReplicaUtil;
+import org.apache.hadoop.hbase.client.TableDescriptor;
+import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
+import org.apache.hadoop.hbase.client.TableState;
+import org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher;
+import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
+import org.apache.hadoop.hbase.master.MetricsSnapshot;
+import org.apache.hadoop.hbase.master.snapshot.MasterSnapshotVerifier;
+import org.apache.hadoop.hbase.mob.MobUtils;
+import org.apache.hadoop.hbase.monitoring.MonitoredTask;
+import org.apache.hadoop.hbase.monitoring.TaskMonitor;
+import org.apache.hadoop.hbase.procedure2.Procedure;
+import org.apache.hadoop.hbase.procedure2.ProcedureStateSerializer;
+import org.apache.hadoop.hbase.procedure2.ProcedureSuspendedException;
+import org.apache.hadoop.hbase.procedure2.ProcedureYieldException;
+import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
+import org.apache.hadoop.hbase.snapshot.CorruptedSnapshotException;
+import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils;
+import org.apache.hadoop.hbase.snapshot.SnapshotManifest;
+import org.apache.hadoop.hbase.util.CommonFSUtils;
+import org.apache.hadoop.hbase.util.ModifyRegionUtils;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.SnapshotProcedureStateData;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.SnapshotState;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription;
+
+/**
+ *  A procedure used to take snapshot on tables.
+ */
+@InterfaceAudience.Private
+public class SnapshotProcedure
+    extends AbstractStateMachineTableProcedure<SnapshotState> {
+  private static final Logger LOG = LoggerFactory.getLogger(SnapshotProcedure.class);
+  private final MetricsSnapshot metricsSnapshot = new MetricsSnapshot();
+
+  private Configuration conf;
+  private SnapshotDescription snapshot;
+  private Path rootDir;
+  private Path snapshotDir;
+  private Path workingDir;
+  private FileSystem workingDirFS;
+  private TableName snapshotTable;
+  private MonitoredTask status;
+  private SnapshotManifest snapshotManifest;
+  private TableDescriptor htd;
+  private ForeignExceptionDispatcher monitor;
+
+  public SnapshotProcedure() { }
+
+  public SnapshotProcedure(final MasterProcedureEnv env, final SnapshotDescription snapshot) {
+    super(env);
+    this.snapshot = snapshot;
+  }
+
+  @Override
+  public TableName getTableName() {
+    return TableName.valueOf(snapshot.getTable());
+  }
+
+  @Override
+  public TableOperationType getTableOperationType() {
+    return TableOperationType.SNAPSHOT;
+  }
+
+  @Override
+  protected LockState acquireLock(MasterProcedureEnv env) {
+    // AbstractStateMachineTableProcedure acquires exclusive table lock by default,
+    // but we may need to downgrade it to shared lock for some reasons:
+    // a. exclusive lock has a negative effect on assigning region. See HBASE-21480 for details.
+    // b. we want to support taking multiple different snapshots on same table on the same time.
+    if (env.getProcedureScheduler().waitTableSharedLock(this, getTableName())) {

Review comment:
       Thanks for reviewing @Apache9 . Yes, shared table lock is not enough, so there is some extra work in SnapshotManager. Before SplitTableRegionProcedure/MergeTableRegionsProcedure runs,  they will check if the table is in snapshot. If table is in snapshot, the procedure will stop. In SnapshotManager, we have a map whose key is SnapshotDescription and value is SnapshotProcedure id. The map will be rebuild when master restarts. Would you mind taking a look on those?




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