Umesh Krishnaswamy | 345ee99 | 2012-12-13 20:29:48 -0800 | [diff] [blame] | 1 | /** |
| 2 | * Copyright 2011, Big Switch Networks, Inc. |
| 3 | * Originally created by David Erickson, Stanford University |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 6 | * not use this file except in compliance with the License. You may obtain |
| 7 | * a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 13 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 14 | * License for the specific language governing permissions and limitations |
| 15 | * under the License. |
| 16 | **/ |
| 17 | |
| 18 | package net.floodlightcontroller.core.internal; |
| 19 | |
| 20 | import java.util.concurrent.CountDownLatch; |
| 21 | import java.util.concurrent.ExecutionException; |
| 22 | import java.util.concurrent.Future; |
| 23 | import java.util.concurrent.TimeUnit; |
| 24 | import java.util.concurrent.TimeoutException; |
| 25 | |
| 26 | import org.openflow.protocol.OFMessage; |
| 27 | import org.openflow.protocol.OFType; |
| 28 | |
| 29 | import net.floodlightcontroller.core.IOFSwitch; |
| 30 | import net.floodlightcontroller.threadpool.IThreadPoolService; |
| 31 | |
| 32 | /** |
| 33 | * A Future object used to retrieve asynchronous OFMessage replies. Unregisters |
| 34 | * and cancels itself by default after 60 seconds. This class is meant to be |
| 35 | * sub-classed and proper behavior added to the handleReply method, and |
| 36 | * termination of the Future to be handled in the isFinished method. |
| 37 | * |
| 38 | * @author David Erickson (daviderickson@cs.stanford.edu) |
| 39 | */ |
| 40 | public abstract class OFMessageFuture<V> implements Future<V> { |
| 41 | |
| 42 | protected IThreadPoolService threadPool; |
| 43 | protected volatile boolean canceled; |
| 44 | protected CountDownLatch latch; |
| 45 | protected OFType responseType; |
| 46 | protected volatile V result; |
| 47 | protected IOFSwitch sw; |
| 48 | protected Runnable timeoutTimer; |
| 49 | protected int transactionId; |
| 50 | protected static final long DEFAULT_TIMEOUT = 60; |
| 51 | protected static final TimeUnit DEFAULT_TIMEOUT_UNIT = TimeUnit.SECONDS; |
| 52 | |
| 53 | public OFMessageFuture(IThreadPoolService tp, |
| 54 | IOFSwitch sw, OFType responseType, int transactionId) { |
| 55 | this(tp, sw, responseType, transactionId, |
| 56 | DEFAULT_TIMEOUT, DEFAULT_TIMEOUT_UNIT); |
| 57 | } |
| 58 | |
| 59 | public OFMessageFuture(IThreadPoolService tp, |
| 60 | IOFSwitch sw, OFType responseType, int transactionId, long timeout, TimeUnit unit) { |
| 61 | this.threadPool = tp; |
| 62 | this.canceled = false; |
| 63 | this.latch = new CountDownLatch(1); |
| 64 | this.responseType = responseType; |
| 65 | this.sw = sw; |
| 66 | this.transactionId = transactionId; |
| 67 | |
| 68 | final OFMessageFuture<V> future = this; |
| 69 | timeoutTimer = new Runnable() { |
| 70 | @Override |
| 71 | public void run() { |
| 72 | if (timeoutTimer == this) |
| 73 | future.cancel(true); |
| 74 | } |
| 75 | }; |
| 76 | threadPool.getScheduledExecutor().schedule(timeoutTimer, timeout, unit); |
| 77 | } |
| 78 | |
| 79 | protected void unRegister() { |
| 80 | this.timeoutTimer = null; |
| 81 | } |
| 82 | |
| 83 | |
| 84 | public void deliverFuture(IOFSwitch sw, OFMessage msg) { |
| 85 | if (transactionId == msg.getXid()) { |
| 86 | handleReply(sw, msg); |
| 87 | if (isFinished()) { |
| 88 | unRegister(); |
| 89 | this.latch.countDown(); |
| 90 | } |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * Used to handle the specific expected message this Future was reigstered |
| 96 | * for, the specified msg parameter is guaranteed to match the type and |
| 97 | * transaction id specified. |
| 98 | * @param sw |
| 99 | * @param msg |
| 100 | * @return |
| 101 | */ |
| 102 | protected abstract void handleReply(IOFSwitch sw, OFMessage msg); |
| 103 | |
| 104 | /** |
| 105 | * Called directly after handleReply, subclasses implement this method to |
| 106 | * indicate when the future can deregister itself from receiving future |
| 107 | * messages, and when it is safe to return the results to any waiting |
| 108 | * threads. |
| 109 | * @return when this Future has completed its work |
| 110 | */ |
| 111 | protected abstract boolean isFinished(); |
| 112 | |
| 113 | /* (non-Javadoc) |
| 114 | * @see java.util.concurrent.Future#cancel(boolean) |
| 115 | */ |
| 116 | @Override |
| 117 | public boolean cancel(boolean mayInterruptIfRunning) { |
| 118 | if (isDone()) { |
| 119 | return false; |
| 120 | } else { |
| 121 | unRegister(); |
| 122 | canceled = true; |
| 123 | this.latch.countDown(); |
| 124 | return !isDone(); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | /* (non-Javadoc) |
| 129 | * @see java.util.concurrent.Future#isCancelled() |
| 130 | */ |
| 131 | @Override |
| 132 | public boolean isCancelled() { |
| 133 | return canceled; |
| 134 | } |
| 135 | |
| 136 | /* (non-Javadoc) |
| 137 | * @see java.util.concurrent.Future#isDone() |
| 138 | */ |
| 139 | @Override |
| 140 | public boolean isDone() { |
| 141 | return this.latch.getCount() == 0; |
| 142 | } |
| 143 | |
| 144 | /* (non-Javadoc) |
| 145 | * @see java.util.concurrent.Future#get() |
| 146 | */ |
| 147 | @Override |
| 148 | public V get() throws InterruptedException, ExecutionException { |
| 149 | this.latch.await(); |
| 150 | return result; |
| 151 | } |
| 152 | |
| 153 | /* (non-Javadoc) |
| 154 | * @see java.util.concurrent.Future#get(long, java.util.concurrent.TimeUnit) |
| 155 | */ |
| 156 | @Override |
| 157 | public V get(long timeout, TimeUnit unit) throws InterruptedException, |
| 158 | ExecutionException, TimeoutException { |
| 159 | this.latch.await(timeout, unit); |
| 160 | return result; |
| 161 | } |
| 162 | |
| 163 | public int getTransactionId() { |
| 164 | return transactionId; |
| 165 | } |
| 166 | |
| 167 | public void setTransactionId(int transactionId) { |
| 168 | this.transactionId = transactionId; |
| 169 | } |
| 170 | } |