Yueyu Lin,
Your patch below looks suspiciously like the double-checked locking
anti-pattern, and is not guaranteed to work.
There really isn't a way to safely lazily initialize without using
synchronized or volatile.
-Yonik
http://incubator.apache.org/solr Solr, the open-source Lucene search server
On 5/9/06, yueyu lin <[EMAIL PROTECTED]> wrote:
Yes, the modification is still synchronized and the first thread will be
responsible for reading first. And then other threads will not read and the
synchronization is unnecessary.
private void ensureIndexIsRead() throws IOException {
if (indexTerms != null) // index already read
return; // do nothing
synchronized(this){
System.out.println("Read [EMAIL PROTECTED]@");
if(indexTerms != null){
System.out.println ("Someone read it.return-_-");
return ;
}
readIndex ();
}
}
private synchronized void readIndex() throws IOException{
Term[] m_indexTerms = null;
try {
int indexSize = (int)indexEnum.size; // otherwise read
index
m_indexTerms = new Term[indexSize];
indexInfos = new TermInfo[indexSize];
indexPointers = new long[indexSize];
for (int i = 0; indexEnum.next(); i++) {
m_indexTerms[i] = indexEnum.term();
indexInfos[i] = indexEnum.termInfo();
indexPointers[i] = indexEnum.indexPointer;
}
} finally {
indexEnum.close();
indexEnum = null;
indexTerms = m_indexTerms;
}
}
That's a small trick I learned when I was developing a busy stock system.
If the method ensureIndexIsRead() is synchronized, it will be blocked for a
while, although even 2 lines codes.
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