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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.arrow.vector;
/**
* Configuration class to determine if null checking should be enabled or disabled for the "get" methods.
* For example, the get method of class org.apache.arrow.vector.Float8Vector first checks if the value
* at the given index is null, before retrieving the value. This configuration will turn on and off such checks.
*
* Null checking is on by default. You can disable it by setting either the system property or the
* environmental variable to "false". The system property is named "arrow.enable_null_check_for_get" and
* the environmental variable is named "ARROW_ENABLE_NULL_CHECK_FOR_GET".
* When both the system property and the environmental variable are set, the system property takes precedence.
*
*
* Disabling null-checking in the "get" methods may lead to performance improvements.
* For example, suppose we have the following micro-benchmark:
*
*
*
{@code
*
* Float8Vector vector = ...
*
* public void test() {
* sum = 0;
* for (int i = 0; i < 1024; i++) {
* vector.set(i, i + 10.0);
* safeSum += vector.get(i);
* }
* }
*
* }
*
*
* Performance evaluations of the micro-benchmark with the JMH framework reveal that, disabling null checking
* has the following effects:
* 1. The amounts of byte code and assembly code generated by JIT are both smaller.
* 2. The performance improves by about 30% (2.819 ± 0.005 us/op vs. 4.069 ± 0.004 us/op).
*
*
* Therefore, for scenarios where the user can be sure that the null-checking is unnecessary,
* it is beneficial to disable it with this configuration.
*
*/
public class NullCheckingForGet {
/**
* The flag to indicate if null checking is enabled for "get" methods.
*/
public static final boolean NULL_CHECKING_ENABLED;
static {
String envProperty = System.getenv("ARROW_ENABLE_NULL_CHECK_FOR_GET");
String sysProperty = System.getProperty("arrow.enable_null_check_for_get");
// The system property has a higher priority than the environmental variable.
String flagValue = sysProperty;
if (flagValue == null) {
flagValue = envProperty;
}
// The flag is set to false only if the system property/environmental
// variable is explicitly set to "false".
NULL_CHECKING_ENABLED = !"false".equals(flagValue);
}
private NullCheckingForGet() {
}
}