Table of Contents

Searcher manager

SearcherManager keeps a current IndexSearcher open and swaps in a fresh one when a new commit is detected. Use it to share a searcher across many concurrent queries.

Set up

using Rowles.LeanLucene.Search.Searcher;
using Rowles.LeanLucene.Store;

using var dir = new MMapDirectory("./index");
using var manager = new SearcherManager(dir, new SearcherManagerConfig
{
    RefreshInterval = TimeSpan.FromSeconds(1),
    SearcherConfig  = new IndexSearcherConfig { EnableQueryCache = true },
});

A background loop polls for new commits at RefreshInterval.

Acquire and release

Prefer AcquireLease for new code:

using var lease = manager.AcquireLease();
var hits = lease.Searcher.Search(query, 10);

The older acquire/release pair is still available:

var searcher = manager.Acquire();
try
{
    var hits = searcher.Search(query, 10);
}
finally
{
    manager.Release(searcher);
}

Or use the convenience method:

var hits = manager.UsingSearcher(s => s.Search(query, 10));

Forcing a refresh

bool refreshed = manager.MaybeRefresh();          // sync
bool refreshedAsync = await manager.MaybeRefreshAsync();

Returns true when a newer commit was loaded.

Refresh failures

Refresh errors are captured instead of crashing the background loop:

manager.RefreshFailed += (_, e) =>
    logger.LogWarning(e.Error, "Searcher refresh failed {Count} time(s)", e.ConsecutiveFailures);

if (manager.LastRefreshError is not null)
    Console.Error.WriteLine(manager.LastRefreshError.Message);

See also

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