annotate src/cachingfilter/CachingFilter.java @ 0:7ecd1a4ef557

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author Franklin Schmidt <fschmidt@gmail.com>
date Thu, 21 Mar 2019 19:15:52 -0600
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1 package cachingfilter;
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2
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3 import java.io.File;
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4 import java.io.FileFilter;
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5 import java.io.FilenameFilter;
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6 import java.io.IOException;
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7 import java.io.ObjectInputStream;
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8 import java.io.BufferedInputStream;
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9 import java.io.FileInputStream;
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10 import java.io.BufferedOutputStream;
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11 import java.io.FileOutputStream;
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12 import java.io.ObjectOutputStream;
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13 import java.util.Set;
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14 import java.util.HashSet;
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15 import java.util.concurrent.CopyOnWriteArraySet;
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16 import java.util.concurrent.Executors;
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17 import java.util.concurrent.ScheduledExecutorService;
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18 import java.util.concurrent.TimeUnit;
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19 import javax.servlet.Filter;
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20 import javax.servlet.FilterChain;
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21 import javax.servlet.FilterConfig;
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22 import javax.servlet.ServletException;
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23 import javax.servlet.ServletRequest;
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24 import javax.servlet.ServletResponse;
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25 import javax.servlet.http.HttpServletRequest;
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26 import javax.servlet.http.HttpServletResponse;
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27 import org.slf4j.Logger;
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28 import org.slf4j.LoggerFactory;
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29
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30
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31 public final class CachingFilter implements Filter {
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32 private static final Logger logger = LoggerFactory.getLogger(CachingFilter.class);
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33
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34 static final Locker<String> locker = new Locker<String>();
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35
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36 // private static final long sweepFreqSeconds = 60*60*24;
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37 // private static final long expiryPeriodMillis = 1000L*60*60*24*10;
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38 private static final long sweepFreqSeconds = 60*60;
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39 private static final long expiryPeriodMillis = 1000L*60*60*24;
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40
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41 static final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
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42
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43 private File dir;
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44 private boolean hasDelayedDelete;
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45 private final Set<String> encodings = new HashSet<String>();
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46
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47 public void init(FilterConfig filterConfig)
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48 throws ServletException
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49 {
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50 String dirS = filterConfig.getInitParameter("dir");
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51 if( dirS == null )
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52 throw new ServletException("'dir' init parameter must be set");
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53 dir = new File(dirS);
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54 dir.mkdirs();
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55
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56 String acceptEncoding = filterConfig.getInitParameter("acceptEncoding");
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57 if( acceptEncoding == null )
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58 throw new ServletException("'acceptEncoding' init parameter must be set");
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59 for( String encoding : acceptEncoding.split(",") ) {
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60 encoding = encoding.trim();
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61 if( encoding.length() > 0 )
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62 encodings.add(encoding);
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63 }
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64
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65 String hasDelayedDeleteS = filterConfig.getInitParameter("hasDelayedDelete");
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66 if( hasDelayedDeleteS == null )
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67 throw new ServletException("'hasDelayedDelete' init parameter must be set");
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68 hasDelayedDelete = Boolean.parseBoolean(hasDelayedDeleteS);
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69
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70 Runnable sweeper = new Runnable() {
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71 public void run() {
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72 try {
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73 logger.error("starting sweep");
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74 final int[] total = new int[1];
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75 final long expired = System.currentTimeMillis() - expiryPeriodMillis;
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76 File[] files = dir.listFiles(new FileFilter(){
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77 public boolean accept(File file) {
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78 total[0]++;
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79 return file.lastModified() < expired && file.getName().charAt(0) != '~';
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80 }
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81 });
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82 int n = 0;
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83 for( File file : files ) {
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84 String name = file.getName();
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85 locker.lock(name);
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86 try {
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87 if( newCachedPage(name).delete() )
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88 n++;
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89 } finally {
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90 locker.unlock(name);
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91 }
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92 }
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93 logger.error("finished sweep, deleted "+n+" pages out of "+files.length+" candidates, "+total[0]+" total");
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94 } catch(RuntimeException e) {
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95 logger.error("exception in sweeper",e);
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96 throw e;
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97 } catch(Error e) {
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98 logger.error("error in sweeper",e);
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99 System.exit(-1);
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100 }
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101 }
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102 };
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103 executor.scheduleWithFixedDelay( sweeper, sweepFreqSeconds, sweepFreqSeconds, TimeUnit.SECONDS );
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104 }
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105
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106 public void destroy() {}
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107
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108 public static void shutdown() {}
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109
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110 CachedPage newCachedPage(String name) {
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111 if( name.length() == 0 )
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112 throw new RuntimeException("empty filenames not allowed");
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113 if( name.charAt(0) == '~' )
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114 throw new RuntimeException("invalid filename: "+name);
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115 return hasDelayedDelete ? new CachedFile(dir,name) : new CachedDir(dir,name);
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116 }
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117
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118 public void doFilter(
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119 ServletRequest req,
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120 ServletResponse res,
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121 FilterChain chain
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122 )
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123 throws IOException, ServletException
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124 {
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125 HttpServletRequest request = (HttpServletRequest)req;
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126 HttpServletResponse response = (HttpServletResponse)res;
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127 if( !"GET".equals( request.getMethod() ) ) {
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128 chain.doFilter(request,response);
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129 return;
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130 }
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131 CachingRequestWrapper wrappedRequest = new CachingRequestWrapper(request);
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132 CachingResponseWrapper wrappedResponse = new CachingResponseWrapper(this,wrappedRequest,response);
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133 boolean isDone = false;
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134 try {
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135 chain.doFilter(wrappedRequest,wrappedResponse);
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136 isDone = true;
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137 } finally {
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138 wrappedResponse.finish(isDone);
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139 }
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140
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141 }
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142
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143 public Set<String> getEncodings() {
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144 return encodings;
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145 }
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146
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147 }