In java, call a synchronized function in a synchronized block, if they have the same mutex object, nothing will happen. If they have different mutex objects, something may be screwed up.
On 5/10/06, Yonik Seeley <[EMAIL PROTECTED]> wrote:
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. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
-- -- Yueyu Lin
