AutoCloseSessionVariable.java

// Licensed to the Apache Software Foundation (ASF) under one
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// 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
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// specific language governing permissions and limitations
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package org.apache.doris.qe;

import com.google.common.collect.Maps;

import java.util.Map;

/**
 * Used to generate new SessionVariables based on the persisted map,
 * and automatically restore to the previous SessionVariables after use.
 */
public class AutoCloseSessionVariable implements AutoCloseable {
    private static final ConnectContext notNullContext = new ConnectContext();
    private ConnectContext connectContext;
    private boolean changed = false;
    private SessionVariable previousVariable;
    private ConnectContext previousConnectContext = notNullContext;

    public AutoCloseSessionVariable(ConnectContext connectContext, Map<String, String> affectQueryResultVariables) {
        if (affectQueryResultVariables == null || affectQueryResultVariables.isEmpty()) {
            return;
        }
        if (connectContext == null) {
            previousConnectContext = null;
            this.connectContext = new ConnectContext();
            this.connectContext.setThreadLocalInfo();
        } else {
            this.changed = true;
            this.connectContext = connectContext;
            this.previousVariable = connectContext.getSessionVariable();
        }
        SessionVariable sessionVariable = new SessionVariable();
        sessionVariable.setAffectQueryResultSessionVariables(
                affectQueryResultVariables == null ? Maps.newHashMap() : affectQueryResultVariables);
        this.connectContext.setSessionVariable(sessionVariable);
    }

    @Override
    public void close() {
        if (previousConnectContext == null) {
            ConnectContext.remove();
            return;
        }
        if (changed) {
            connectContext.setSessionVariable(previousVariable);
        }
    }
}