cassandra-trunk/src/java/org/apache/cassandra/tools/SSTableLevelResetter.java
/*
 * 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.cassandra.tools;

import java.io.PrintStream;
import java.util.Map;
import java.util.Set;

import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Directories;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.io.sstable.Component;
import org.apache.cassandra.io.sstable.Descriptor;
import org.apache.cassandra.io.sstable.format.SSTableFormat.Components;
import org.apache.cassandra.io.sstable.format.StatsComponent;
import org.apache.cassandra.io.sstable.metadata.StatsMetadata;
import org.apache.cassandra.schema.Schema;
import org.apache.cassandra.utils.JVMStabilityInspector;

/**
 * Reset level to 0 on a given set of sstables
 */
public class SSTableLevelResetter
{
    /**
     * @param args a list of sstables whose metadata we are changing
     */
    public static void main(String[] args)
    {
        PrintStream out = System.out;
        if (args.length == 0)
        {
            out.println("This command should be run with Cassandra stopped!");
            out.println("Usage: sstablelevelreset <keyspace> <table>");
            System.exit(1);
        }

        if (!args[0].equals("--really-reset") || args.length != 3)
        {
            out.println("This command should be run with Cassandra stopped, otherwise you will get very strange behavior");
            out.println("Verify that Cassandra is not running and then execute the command like this:");
            out.println("Usage: sstablelevelreset --really-reset <keyspace> <table>");
            System.exit(1);
        }

        Util.initDatabaseDescriptor();

        // TODO several daemon threads will run from here.
        // So we have to explicitly call System.exit.
        try
        {
            // load keyspace descriptions.
            Schema.instance.loadFromDisk();

            String keyspaceName = args[1];
            String columnfamily = args[2];
            // validate columnfamily
            if (Schema.instance.getTableMetadataRef(keyspaceName, columnfamily) == null)
            {
                System.err.println("ColumnFamily not found: " + keyspaceName + "/" + columnfamily);
                System.exit(1);
            }

            // remove any leftovers in the transaction log
            Keyspace keyspace = Keyspace.openWithoutSSTables(keyspaceName);
            ColumnFamilyStore cfs = keyspace.getColumnFamilyStore(columnfamily);
            if (!LifecycleTransaction.removeUnfinishedLeftovers(cfs))
            {
                throw new RuntimeException(String.format("Cannot remove temporary or obsoleted files for %s.%s " +
                                                         "due to a problem with transaction log files.",
                                                         keyspace, columnfamily));
            }

            Directories.SSTableLister lister = cfs.getDirectories().sstableLister(Directories.OnTxnErr.THROW).skipTemporary(true);
            boolean foundSSTable = false;
            for (Map.Entry<Descriptor, Set<Component>> sstable : lister.list().entrySet())
            {
                if (sstable.getValue().contains(Components.STATS))
                {
                    foundSSTable = true;
                    Descriptor descriptor = sstable.getKey();
                    StatsMetadata metadata = StatsComponent.load(descriptor).statsMetadata();
                    if (metadata.sstableLevel > 0)
                    {
                        out.println("Changing level from " + metadata.sstableLevel + " to 0 on " + descriptor.fileFor(Components.DATA));
                        descriptor.getMetadataSerializer().mutateLevel(descriptor, 0);
                    }
                    else
                    {
                        out.println("Skipped " + descriptor.fileFor(Components.DATA) + " since it is already on level 0");
                    }
                }
            }

            if (!foundSSTable)
            {
                out.println("Found no sstables, did you give the correct keyspace/table?");
            }
        }
        catch (Throwable t)
        {
            JVMStabilityInspector.inspectThrowable(t);
            t.printStackTrace();
            System.exit(1);
        }
        System.exit(0);
    }
}
