| /* |
| * 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.distributedlog.common.util; |
| |
| /** |
| * A simple limiter interface which tracks acquire/release of permits, for |
| * example for tracking outstanding writes. |
| */ |
| public interface PermitLimiter { |
| |
| PermitLimiter NULL_PERMIT_LIMITER = new PermitLimiter() { |
| @Override |
| public boolean acquire() { |
| return true; |
| } |
| @Override |
| public void release(int permits) { |
| } |
| |
| @Override |
| public void close() { |
| |
| } |
| }; |
| |
| /** |
| * Acquire a permit. |
| * |
| * @return true if successfully acquire a permit, otherwise false. |
| */ |
| boolean acquire(); |
| |
| /** |
| * Release a permit. |
| */ |
| void release(int permits); |
| |
| /** |
| * Close the resources created by the limiter. |
| */ |
| void close(); |
| } |