Hi,
a patch similar to this was proposed a year ago but then got lost. I will
apply it unless someone objects. It fixes the problem that you cannot
safely use IndexReader.getCurrentVersion() to detect changes, as the
version number is reset to 0 if the index is re-created.
Also see
http://www.mail-archive.com/lucene-dev%40jakarta.apache.org/msg06143.html
Regards
Daniel
--
http://www.danielnaber.de
Index: /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/IndexReader.java
===================================================================
--- /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/IndexReader.java (Revision 178894)
+++ /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/IndexReader.java (Arbeitskopie)
@@ -224,6 +224,7 @@
* @param directory where the index resides.
* @return version number.
* @throws IOException if segments file cannot be read
+ * @deprecated use [EMAIL PROTECTED] #isCurrent()} instead
*/
public static long getCurrentVersion(String directory) throws IOException {
return getCurrentVersion(new File(directory));
@@ -236,6 +237,7 @@
* @param directory where the index resides.
* @return version number.
* @throws IOException if segments file cannot be read
+ * @deprecated use [EMAIL PROTECTED] #isCurrent()} instead
*/
public static long getCurrentVersion(File directory) throws IOException {
Directory dir = FSDirectory.getDirectory(directory, false);
@@ -251,12 +253,27 @@
* @param directory where the index resides.
* @return version number.
* @throws IOException if segments file cannot be read.
+ * @deprecated use [EMAIL PROTECTED] #isCurrent()} instead
*/
public static long getCurrentVersion(Directory directory) throws IOException {
return SegmentInfos.readCurrentVersion(directory);
}
/**
+ * Check whether this IndexReader still works on a current version of the index.
+ * If this is not the case you will need to re-open the IndexReader to
+ * make sure you see the latest changes made to the index.
+ *
+ * @throws IOException
+ */
+ public boolean isCurrent() throws IOException {
+ if (SegmentInfos.readCurrentVersion(directory) > segmentInfos.getVersion()) {
+ return false;
+ }
+ return true;
+ }
+
+ /**
* Return an array of term frequency vectors for the specified document.
* The array contains a vector for each vectorized field in the document.
* Each vector contains terms and frequencies for all terms in a given vectorized field.
Index: /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/SegmentInfos.java
===================================================================
--- /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/SegmentInfos.java (Revision 171375)
+++ /home/dnaber/workspace/LuceneSVN/src/java/org/apache/lucene/index/SegmentInfos.java (Arbeitskopie)
@@ -29,7 +29,11 @@
public static final int FORMAT = -1;
public int counter = 0; // used to name new segments
- private long version = 0; //counts how often the index has been changed by adding or deleting docs
+ /**
+ * counts how often the index has been changed by adding or deleting docs.
+ * starting with the current time in milliseconds forces to create unique version numbers.
+ */
+ private long version = System.currentTimeMillis();
public final SegmentInfo info(int i) {
return (SegmentInfo) elementAt(i);
@@ -59,7 +63,7 @@
if(format >= 0){ // in old format the version number may be at the end of the file
if (input.getFilePointer() >= input.length())
- version = 0; // old file format without version number
+ version = System.currentTimeMillis(); // old file format without version number
else
version = input.readLong(); // read version
}
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