public class SearcherLifetimeManager extends Object implements Closeable
SearcherLifetimeManager mgr = new SearcherLifetimeManager();Per search-request, if it's a "new" search request, then obtain the latest searcher you have (for example, by using
SearcherManager
), and then record this
searcher:
// Record the current searcher, and save the returend // token into user's search results (eg as a hidden // HTML form field): long token = mgr.record(searcher);When a follow-up search arrives, for example the user clicks next page, drills down/up, etc., take the token that you saved from the previous search and:
// If possible, obtain the same searcher as the last // search: IndexSearcher searcher = mgr.acquire(token); if (searcher != null) { // Searcher is still here try { // do searching... } finally { mgr.release(searcher); // Do not use searcher after this! searcher = null; } } else { // Searcher was pruned -- notify user session timed // out, or, pull fresh searcher again }Finally, in a separate thread, ideally the same thread that's periodically reopening your searchers, you should periodically prune old searchers:
mgr.prune(new PruneByAge(600.0));
NOTE: keeping many searchers around means
you'll use more resources (open files, RAM) than a single
searcher. However, as long as you are using DirectoryReader.openIfChanged(DirectoryReader)
, the searchers
will usually share almost all segments and the added resource usage
is contained. When a large merge has completed, and
you reopen, because that is a large change, the new
searcher will use higher additional RAM than other
searchers; but large merges don't complete very often and
it's unlikely you'll hit two of them in your expiration
window. Still you should budget plenty of heap in the
JVM to have a good safety margin.
Modifier and Type | Class and Description |
---|---|
static class |
SearcherLifetimeManager.PruneByAge
Simple pruner that drops any searcher older by
more than the specified seconds, than the newest
searcher.
|
static interface |
SearcherLifetimeManager.Pruner
|
Constructor and Description |
---|
SearcherLifetimeManager() |
Modifier and Type | Method and Description |
---|---|
IndexSearcher |
acquire(long version)
Retrieve a previously recorded
IndexSearcher , if it
has not yet been closed |
void |
close()
Close this to future searching; any searches still in
process in other threads won't be affected, and they
should still call
release(org.apache.lucene.search.IndexSearcher) after they are
done. |
void |
prune(SearcherLifetimeManager.Pruner pruner)
Calls provided
SearcherLifetimeManager.Pruner to prune entries. |
long |
record(IndexSearcher searcher)
Records that you are now using this IndexSearcher.
|
void |
release(IndexSearcher s)
Release a searcher previously obtained from
acquire(long) . |
public long record(IndexSearcher searcher) throws IOException
IndexSearcher
, for example from SearcherManager
. It's fine if you already passed the
same searcher to this method before.
This returns the long token that you can later pass
to acquire(long)
to retrieve the same IndexSearcher.
You should record this long token in the search results
sent to your user, such that if the user performs a
follow-on action (clicks next page, drills down, etc.)
the token is returned.
IOException
public IndexSearcher acquire(long version)
IndexSearcher
, if it
has not yet been closed
NOTE: this may return null when the requested searcher has already timed out. When this happens you should notify your user that their session timed out and that they'll have to restart their search.
If this returns a non-null result, you must match
later call release(org.apache.lucene.search.IndexSearcher)
on this searcher, best
from a finally clause.
public void release(IndexSearcher s) throws IOException
acquire(long)
.
NOTE: it's fine to call this after close.
IOException
public void prune(SearcherLifetimeManager.Pruner pruner) throws IOException
SearcherLifetimeManager.Pruner
to prune entries. The
entries are passed to the Pruner in sorted (newest to
oldest IndexSearcher) order.
NOTE: you must peridiocally call this, ideally from the same background thread that opens new searchers.
IOException
public void close() throws IOException
release(org.apache.lucene.search.IndexSearcher)
after they are
done.
NOTE: you must ensure no other threads are
calling record(org.apache.lucene.search.IndexSearcher)
while you call close();
otherwise it's possible not all searcher references
will be freed.
close
in interface Closeable
close
in interface AutoCloseable
IOException
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