com.facebook.presto.jdbc.internal.spi.SplitWeight Maven / Gradle / Ivy
/*
* Licensed 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 com.facebook.presto.jdbc.internal.spi;
import com.facebook.presto.jdbc.internal.jackson.annotation.JsonCreator;
import com.facebook.presto.jdbc.internal.jackson.annotation.JsonValue;
import java.math.BigDecimal;
import java.util.Collection;
import java.util.function.Function;
import static java.lang.Math.addExact;
import static java.lang.Math.multiplyExact;
public final class SplitWeight
{
private static final long UNIT_VALUE = 100;
private static final int UNIT_SCALE = 2; // Decimal scale such that (10 ^ UNIT_SCALE) == UNIT_VALUE
private static final SplitWeight STANDARD_WEIGHT = new SplitWeight(UNIT_VALUE);
private final long value;
private SplitWeight(long value)
{
if (value <= 0) {
throw new IllegalArgumentException("value must be > 0, found: " + value);
}
this.value = value;
}
/**
* @return The internal integer representation for this weight value
*/
@JsonValue
public long getRawValue()
{
return value;
}
@Override
public boolean equals(Object other)
{
if (!(other instanceof SplitWeight)) {
return false;
}
return this.value == ((SplitWeight) other).value;
}
@Override
public int hashCode()
{
return Long.hashCode(value);
}
@Override
public String toString()
{
if (value == UNIT_VALUE) {
return "1";
}
return BigDecimal.valueOf(value, -UNIT_SCALE).stripTrailingZeros().toPlainString();
}
@JsonCreator
public static SplitWeight fromRawValue(long value)
{
return value == UNIT_VALUE ? STANDARD_WEIGHT : new SplitWeight(value);
}
public static SplitWeight standard()
{
return STANDARD_WEIGHT;
}
public static SplitWeight fromProportion(double weight)
{
if (weight <= 0 || !Double.isFinite(weight)) {
throw new IllegalArgumentException("Invalid weight: " + weight);
}
// Must round up to avoid small weights rounding to 0
return fromRawValue((long) Math.ceil(weight * UNIT_VALUE));
}
public static long rawValueForStandardSplitCount(int splitCount)
{
if (splitCount < 0) {
throw new IllegalArgumentException("splitCount must be >= 0, found: " + splitCount);
}
return multiplyExact(splitCount, UNIT_VALUE);
}
public static long rawValueSum(Collection collection, Function getter)
{
long sum = 0;
for (T item : collection) {
long value = getter.apply(item).getRawValue();
sum = addExact(sum, value);
}
return sum;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy