| /** |
| * 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.hadoop.hdfs.server.namenode; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class ContentSummaryComputationContext { |
| private FSDirectory dir = null; |
| private FSNamesystem fsn = null; |
| private Content.Counts counts = null; |
| private long nextCountLimit = 0; |
| private long limitPerRun = 0; |
| private long yieldCount = 0; |
| |
| /** |
| * Constructor |
| * |
| * @param dir The FSDirectory instance |
| * @param fsn The FSNamesystem instance |
| * @param limitPerRun allowed number of operations in one |
| * locking period. 0 or a negative number means |
| * no limit (i.e. no yielding) |
| */ |
| public ContentSummaryComputationContext(FSDirectory dir, |
| FSNamesystem fsn, long limitPerRun) { |
| this.dir = dir; |
| this.fsn = fsn; |
| this.limitPerRun = limitPerRun; |
| this.nextCountLimit = limitPerRun; |
| this.counts = Content.Counts.newInstance(); |
| } |
| |
| /** Constructor for blocking computation. */ |
| public ContentSummaryComputationContext() { |
| this(null, null, 0); |
| } |
| |
| /** Return current yield count */ |
| public long getYieldCount() { |
| return yieldCount; |
| } |
| |
| /** |
| * Relinquish locks held during computation for a short while |
| * and reacquire them. This will give other threads a chance |
| * to acquire the contended locks and run. |
| * |
| * @return true if locks were released and reacquired. |
| */ |
| public boolean yield() { |
| // Are we set up to do this? |
| if (limitPerRun <= 0 || dir == null || fsn == null) { |
| return false; |
| } |
| |
| // Have we reached the limit? |
| long currentCount = counts.get(Content.FILE) + |
| counts.get(Content.SYMLINK) + |
| counts.get(Content.DIRECTORY) + |
| counts.get(Content.SNAPSHOTTABLE_DIRECTORY); |
| if (currentCount <= nextCountLimit) { |
| return false; |
| } |
| |
| // Update the next limit |
| nextCountLimit = currentCount + limitPerRun; |
| |
| boolean hadDirReadLock = dir.hasReadLock(); |
| boolean hadDirWriteLock = dir.hasWriteLock(); |
| boolean hadFsnReadLock = fsn.hasReadLock(); |
| boolean hadFsnWriteLock = fsn.hasWriteLock(); |
| |
| // sanity check. |
| if (!hadDirReadLock || !hadFsnReadLock || hadDirWriteLock || |
| hadFsnWriteLock || dir.getReadHoldCount() != 1 || |
| fsn.getReadHoldCount() != 1) { |
| // cannot relinquish |
| return false; |
| } |
| |
| // unlock |
| dir.readUnlock(); |
| fsn.readUnlock(); |
| |
| try { |
| Thread.sleep(1); |
| } catch (InterruptedException ie) { |
| } finally { |
| // reacquire |
| fsn.readLock(); |
| dir.readLock(); |
| } |
| yieldCount++; |
| return true; |
| } |
| |
| /** Get the content counts */ |
| public Content.Counts getCounts() { |
| return counts; |
| } |
| } |