ShowBackendsCommand.java

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// 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
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//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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package org.apache.doris.nereids.trees.plans.commands;

import org.apache.doris.analysis.RedirectStatus;
import org.apache.doris.catalog.Column;
import org.apache.doris.catalog.Env;
import org.apache.doris.catalog.InfoSchemaDb;
import org.apache.doris.catalog.ScalarType;
import org.apache.doris.common.ErrorCode;
import org.apache.doris.common.ErrorReport;
import org.apache.doris.common.proc.BackendsProcDir;
import org.apache.doris.datasource.InternalCatalog;
import org.apache.doris.mysql.privilege.PrivPredicate;
import org.apache.doris.nereids.trees.plans.PlanType;
import org.apache.doris.nereids.trees.plans.visitor.PlanVisitor;
import org.apache.doris.qe.ConnectContext;
import org.apache.doris.qe.ShowResultSet;
import org.apache.doris.qe.ShowResultSetMetaData;
import org.apache.doris.qe.StmtExecutor;

import java.util.Comparator;
import java.util.List;

/**
 * show backends command
 */
public class ShowBackendsCommand extends ShowCommand {

    /**
     * constructor
     */
    public ShowBackendsCommand() {
        super(PlanType.SHOW_BACKENDS_COMMAND);
    }

    public ShowResultSetMetaData getMetaData() {
        ShowResultSetMetaData.Builder builder = ShowResultSetMetaData.builder();
        for (String title : BackendsProcDir.TITLE_NAMES) {
            builder.addColumn(new Column(title, ScalarType.createVarchar(30)));
        }
        return builder.build();
    }

    @Override
    public ShowResultSet doRun(ConnectContext ctx, StmtExecutor executor) throws Exception {
        if (!Env.getCurrentEnv().getAccessManager().checkDbPriv(ConnectContext.get(),
                InternalCatalog.INTERNAL_CATALOG_NAME, InfoSchemaDb.DATABASE_NAME, PrivPredicate.SELECT)) {
            ErrorReport.reportAnalysisException(ErrorCode.ERR_DB_ACCESS_DENIED_ERROR,
                    PrivPredicate.SELECT.getPrivs().toString(), InfoSchemaDb.DATABASE_NAME);
        }

        List<List<String>> backendInfos = BackendsProcDir.getBackendInfos();
        backendInfos.sort(new Comparator<List<String>>() {
            @Override
            public int compare(List<String> o1, List<String> o2) {
                return Long.compare(Long.parseLong(o1.get(0)), Long.parseLong(o2.get(0)));
            }
        });

        return new ShowResultSet(getMetaData(), backendInfos);
    }

    @Override
    public <R, C> R accept(PlanVisitor<R, C> visitor, C context) {
        return visitor.visitShowBackendsCommand(this, context);
    }

    @Override
    public RedirectStatus toRedirectStatus() {
        if (ConnectContext.get().getSessionVariable().getForwardToMaster()) {
            return RedirectStatus.FORWARD_NO_SYNC;
        } else {
            return RedirectStatus.NO_FORWARD;
        }
    }
}