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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.chukwa.datacollection.adaptor.filetailer;
20  
21  import java.io.IOException;
22  import java.io.RandomAccessFile;
23  import org.apache.hadoop.chukwa.datacollection.adaptor.*;
24  import org.apache.hadoop.chukwa.util.ExceptionUtil;
25  
26  /**
27   * An adaptor that repeatedly tails a specified file, sending the new bytes.
28   * This class does not split out records, but just sends everything up to end of
29   * file. Subclasses can alter this behavior by overriding extractRecords().
30   * 
31   */
32  public class FileTailingAdaptor extends LWFTAdaptor {
33  
34  
35    public static int MAX_RETRIES = 300;
36    public static int GRACEFUL_PERIOD = 3 * 60 * 1000; // 3 minutes
37  
38    private int attempts = 0;
39    private long gracefulPeriodExpired = 0l;
40    private boolean adaptorInError = false;
41  
42    protected RandomAccessFile reader = null;
43  
44    public void start(long bytes) {
45      super.start(bytes);
46      log.info("chukwaAgent.fileTailingAdaptor.maxReadSize: " + MAX_READ_SIZE);
47      this.attempts = 0;
48  
49      log.info("started file tailer " + adaptorID +  "  on file " + toWatch
50          + " with first byte at offset " + offsetOfFirstByte);
51    }
52   
53    
54    @Override
55    public long shutdown(AdaptorShutdownPolicy shutdownPolicy) {
56      
57      log.info("Enter Shutdown:" + shutdownPolicy.name() + " - ObjectId:" + this);
58      
59      switch(shutdownPolicy) {
60        case GRACEFULLY : 
61        case WAIT_TILL_FINISHED :{
62          if (toWatch.exists()) {
63            int retry = 0;
64            tailer.stopWatchingFile(this);
65            TerminatorThread lastTail = new TerminatorThread(this);
66            lastTail.setDaemon(true);
67            lastTail.start();
68            
69            if (shutdownPolicy.ordinal() == AdaptorShutdownPolicy.GRACEFULLY.ordinal()) {
70              while (lastTail.isAlive() && retry < 60) {
71                try {
72                  log.info("GRACEFULLY Retry:" + retry);
73                  Thread.sleep(1000);
74                  retry++;
75                } catch (InterruptedException ex) {
76                }
77              }
78            } else {
79              while (lastTail.isAlive()) {
80                try {
81                  if (retry%100 == 0) {
82                    log.info("WAIT_TILL_FINISHED Retry:" + retry);
83                  }
84                  Thread.sleep(1000);
85                  retry++;
86                } catch (InterruptedException ex) {
87                }
88              } 
89            }          
90          }
91        }
92        break;
93        
94        case HARD_STOP:
95        default:
96          tailer.stopWatchingFile(this);
97          try {
98            if (reader != null) {
99              reader.close();
100           }
101           reader = null;
102         } catch(Throwable e) {
103          log.warn("Exception while closing reader:",e);
104         }
105         break;
106     }
107     log.info("Exit Shutdown:" + shutdownPolicy.name()+ " - ObjectId:" + this);
108     return fileReadOffset + offsetOfFirstByte;
109   }
110   
111 
112   /**
113    * Looks at the tail of the associated file, adds some of it to event queue
114    * This method is not thread safe. Returns true if there's more data in the
115    * file
116    * 
117    * @param eq the queue to write Chunks into
118    */
119   @Override
120   public synchronized boolean tailFile()
121       throws InterruptedException {
122     boolean hasMoreData = false;
123 
124     try {
125       if ((adaptorInError == true)
126           && (System.currentTimeMillis() > gracefulPeriodExpired)) {
127         if (!toWatch.exists()) {
128           log.warn("Adaptor|" + adaptorID + "|attempts=" + attempts
129               + "| File does not exist: " + toWatch.getAbsolutePath()
130               + ", streaming policy expired.  File removed from streaming.");
131         } else if (!toWatch.canRead()) {
132           log.warn("Adaptor|" + adaptorID + "|attempts=" + attempts
133               + "| File cannot be read: " + toWatch.getAbsolutePath()
134               + ", streaming policy expired.  File removed from streaming.");
135         } else {
136           // Should have never been there
137           adaptorInError = false;
138           gracefulPeriodExpired = 0L;
139           attempts = 0;
140           return false;
141         }
142 
143         deregisterAndStop();
144         return false;
145       } else if (!toWatch.exists() || !toWatch.canRead()) {
146         if (adaptorInError == false) {
147           long now = System.currentTimeMillis();
148           gracefulPeriodExpired = now + GRACEFUL_PERIOD;
149           adaptorInError = true;
150           attempts = 0;
151           log.warn("failed to stream data for: " + toWatch.getAbsolutePath()
152               + ", graceful period will Expire at now:" + now + " + "
153               + GRACEFUL_PERIOD + " secs, i.e:" + gracefulPeriodExpired);
154         } else if (attempts % 10 == 0) {
155           log.info("failed to stream data for: " + toWatch.getAbsolutePath()
156               + ", attempt: " + attempts);
157         }
158 
159         attempts++;
160         return false; // no more data
161       }
162 
163       if (reader == null) {
164         reader = new RandomAccessFile(toWatch, "r");
165         log.info("Adaptor|" + adaptorID
166             + "|Opening the file for the first time|seek|" + fileReadOffset);
167       }
168 
169       long len = 0L;
170       try {
171         RandomAccessFile newReader = new RandomAccessFile(toWatch, "r");
172         len = reader.length();
173         long newLength = newReader.length();
174         if (newLength < len && fileReadOffset >= len) {
175           if (reader != null) {
176             reader.close();
177           }
178           
179           reader = newReader;
180           fileReadOffset = 0L;
181           log.debug("Adaptor|"+ adaptorID + "| File size mismatched, rotating: "
182               + toWatch.getAbsolutePath());
183         } else {
184           try {
185             if (newReader != null) {
186               newReader.close();
187             }
188             newReader =null;
189           } catch (Throwable e) {
190             log.debug(ExceptionUtil.getStackTrace(e));
191           }
192         }
193       } catch (IOException e) {
194         log.debug(ExceptionUtil.getStackTrace(e));
195       }
196       if (len >= fileReadOffset) {
197         if (offsetOfFirstByte > fileReadOffset) {
198           // If the file rotated, the recorded offsetOfFirstByte is greater than
199           // file size,
200           // reset the first byte position to beginning of the file.
201           fileReadOffset = 0;
202           offsetOfFirstByte = 0L;
203           log.warn("offsetOfFirstByte>fileReadOffset, resetting offset to 0");
204         }
205         hasMoreData = slurp(len, reader);
206 
207       } else {
208         // file has rotated and no detection
209         if (reader != null) {
210           reader.close();
211         }
212         
213         reader = null;
214         fileReadOffset = 0L;
215         offsetOfFirstByte = 0L;
216         hasMoreData = true;
217         log.warn("Adaptor|" + adaptorID + "| file: " + toWatch.getPath()
218             + ", has rotated and no detection - reset counters to 0L");
219       }
220     } catch (IOException e) {
221       log.warn("failure reading " + toWatch, e);
222     }
223     attempts = 0;
224     adaptorInError = false;
225     return hasMoreData;
226   }
227 
228 
229 }