| /* |
| * 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.ratis.rpc; |
| |
| import java.util.Comparator; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| /** |
| * A long ID for RPC calls. |
| * |
| * This class is threadsafe. |
| */ |
| public final class CallId { |
| private static final AtomicLong CALL_ID_COUNTER = new AtomicLong(); |
| |
| private static final Comparator<Long> COMPARATOR = (left, right) -> { |
| final long diff = left - right; |
| // check diff < Long.MAX_VALUE/2 for the possibility of numerical overflow |
| return diff == 0? 0: diff > 0 && diff < Long.MAX_VALUE/2? 1: -1; |
| }; |
| |
| /** @return a long comparator, which takes care the possibility of numerical overflow, for comparing call ids. */ |
| public static Comparator<Long> getComparator() { |
| return COMPARATOR; |
| } |
| |
| /** @return the default value. */ |
| public static long getDefault() { |
| return 0; |
| } |
| |
| /** @return the current value. */ |
| public static long get() { |
| return CALL_ID_COUNTER.get() & Long.MAX_VALUE; |
| } |
| |
| /** @return the current value and then increment. */ |
| public static long getAndIncrement() { |
| return CALL_ID_COUNTER.getAndIncrement() & Long.MAX_VALUE; |
| } |
| |
| private CallId() {} |
| } |