| /** |
| * 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.bookkeeper.util; |
| |
| /** |
| * Provides misc math functions that don't come standard |
| */ |
| public class MathUtils { |
| private static final long NANOSECONDS_PER_MILLISECOND = 1000000; |
| public static int signSafeMod(long dividend, int divisor) { |
| int mod = (int) (dividend % divisor); |
| |
| if (mod < 0) { |
| mod += divisor; |
| } |
| |
| return mod; |
| |
| } |
| |
| /** |
| * Current time from some arbitrary time base in the past, counting in |
| * milliseconds, and not affected by settimeofday or similar system clock |
| * changes. This is appropriate to use when computing how much longer to |
| * wait for an interval to expire. |
| * |
| * NOTE: only use it for measuring. |
| * http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#nanoTime%28%29 |
| * |
| * @return current time in milliseconds. |
| */ |
| public static long now() { |
| return System.nanoTime() / NANOSECONDS_PER_MILLISECOND; |
| } |
| |
| /** |
| * Current time from some arbitrary time base in the past, counting in |
| * nanoseconds, and not affected by settimeofday or similar system clock |
| * changes. This is appropriate to use when computing how much longer to |
| * wait for an interval to expire. |
| * |
| * NOTE: only use it for measuring. |
| * http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#nanoTime%28%29 |
| * |
| * @return current time in nanoseconds. |
| */ |
| public static long nowInNano() { |
| return System.nanoTime(); |
| } |
| |
| /** |
| * Milliseconds elapsed since the time specified, the input is nanoTime |
| * the only conversion happens when computing the elapsed time |
| * |
| * @param startNanoTime the start of the interval that we are measuring |
| * @return elapsed time in milliseconds. |
| */ |
| public static long elapsedMSec (long startNanoTime) { |
| return (System.nanoTime() - startNanoTime)/ NANOSECONDS_PER_MILLISECOND; |
| } |
| } |