org.apache.druid.common.config.NullHandling.java Source code

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Here is the source code for org.apache.druid.common.config.NullHandling.java

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/*
 * 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.druid.common.config;

import com.google.common.base.Strings;
import com.google.inject.Inject;

import javax.annotation.Nullable;

/**
 * Helper class for NullHandling. This class is used to switch between SQL compatible Null Handling behavior
 * introduced as part of https://github.com/apache/incubator-druid/issues/4349 and the old druid behavior
 * where null values are replaced with default values e.g Null Strings are replaced with empty values.
 */
public class NullHandling {
    public static String NULL_HANDLING_CONFIG_STRING = "druid.generic.useDefaultValueForNull";

    /**
     * use these values to ensure that {@link NullHandling#defaultDoubleValue()},
     * {@link NullHandling#defaultFloatValue()} , {@link NullHandling#defaultFloatValue()}
     * return the same boxed object when returning a constant zero
     */
    public static final Double ZERO_DOUBLE = 0.0d;
    public static final Float ZERO_FLOAT = 0.0f;
    public static final Long ZERO_LONG = 0L;
    public static final byte IS_NULL_BYTE = (byte) 1;
    public static final byte IS_NOT_NULL_BYTE = (byte) 0;

    /**
     * INSTANCE is injected using static injection to avoid adding JacksonInject annotations all over the code.
     * See org.apache.druid.guice.NullHandlingModule for details.
     * It does not take effect in all unit tests since we don't use Guice Injection.
     */
    @Inject
    private static NullValueHandlingConfig INSTANCE = new NullValueHandlingConfig(
            Boolean.valueOf(System.getProperty(NULL_HANDLING_CONFIG_STRING, "true")));

    /**
     * whether nulls should be replaced with default value.
     */
    public static boolean replaceWithDefault() {
        return INSTANCE.isUseDefaultValuesForNull();
    }

    public static boolean sqlCompatible() {
        return !replaceWithDefault();
    }

    @Nullable
    public static String nullToEmptyIfNeeded(@Nullable String value) {
        //CHECKSTYLE.OFF: Regexp
        return replaceWithDefault() ? Strings.nullToEmpty(value) : value;
        //CHECKSTYLE.ON: Regexp
    }

    @Nullable
    public static String emptyToNullIfNeeded(@Nullable String value) {
        //CHECKSTYLE.OFF: Regexp
        return replaceWithDefault() ? Strings.emptyToNull(value) : value;
        //CHECKSTYLE.ON: Regexp
    }

    @Nullable
    public static String defaultStringValue() {
        return replaceWithDefault() ? "" : null;
    }

    @Nullable
    public static Long defaultLongValue() {
        return replaceWithDefault() ? ZERO_LONG : null;
    }

    @Nullable
    public static Float defaultFloatValue() {
        return replaceWithDefault() ? ZERO_FLOAT : null;
    }

    @Nullable
    public static Double defaultDoubleValue() {
        return replaceWithDefault() ? ZERO_DOUBLE : null;
    }

    public static boolean isNullOrEquivalent(@Nullable String value) {
        return replaceWithDefault() ? Strings.isNullOrEmpty(value) : value == null;
    }

}