Bug Fix: Re-ported ControlledRealTimeReopenThread and added 2 new tests

src/Lucene.Net.Tests/Search/TestControlledRealTimeReopenThread.cs

@@ -1,17 +1,22 @@
 using J2N.Threading;
 using J2N.Threading.Atomic;
+using Lucene.Net.Analysis.Standard;
+using Lucene.Net.Documents;
 using Lucene.Net.Index.Extensions;
+using Lucene.Net.Store;
 using Lucene.Net.Util;
 using NUnit.Framework;
 using RandomizedTesting.Generators;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using Assert = Lucene.Net.TestFramework.Assert;
 using Console = Lucene.Net.Util.SystemConsole;
+using Assert = Lucene.Net.TestFramework.Assert;
+
 
 namespace Lucene.Net.Search
 {
@@ -55,7 +60,6 @@ namespace Lucene.Net.Search
     using TextField = Lucene.Net.Documents.TextField;
     using ThreadedIndexingAndSearchingTestCase = Lucene.Net.Index.ThreadedIndexingAndSearchingTestCase;
     using TrackingIndexWriter = Lucene.Net.Index.TrackingIndexWriter;
-    //using ThreadInterruptedException = Lucene.Net.Util.ThreadInterruptedException;
     using Version = Lucene.Net.Util.LuceneVersion;
 
     [SuppressCodecs("SimpleText", "Memory", "Direct")]
@@ -396,10 +400,12 @@ public virtual void TestThreadStarvationNoDeleteNRTReader()
             LatchedIndexWriter _writer = new LatchedIndexWriter(d, conf, latch, signal);
             TrackingIndexWriter writer = new TrackingIndexWriter(_writer);
             SearcherManager manager = new SearcherManager(_writer, false, null);
+
             Document doc = new Document();
             doc.Add(NewTextField("test", "test", Field.Store.YES));
             writer.AddDocument(doc);
             manager.MaybeRefresh();
+
             var t = new ThreadAnonymousClass(this, latch, signal, writer, manager);
             t.Start();
             _writer.waitAfterUpdate = true; // wait in addDocument to let some reopens go through
@@ -416,6 +422,7 @@ public virtual void TestThreadStarvationNoDeleteNRTReader()
             {
                 manager.Release(searcher);
             }
+
             ControlledRealTimeReopenThread<IndexSearcher> thread = new ControlledRealTimeReopenThread<IndexSearcher>(writer, manager, 0.01, 0.01);
             thread.Start(); // start reopening
             if (Verbose)
@@ -427,6 +434,7 @@ public virtual void TestThreadStarvationNoDeleteNRTReader()
             var waiter = new ThreadAnonymousClass2(this, lastGen, thread, finished);
             waiter.Start();
             manager.MaybeRefresh();
+
             waiter.Join(1000);
             if (!finished)
             {
@@ -734,5 +742,259 @@ public override void Run()
                 }
             }
         }
+
+
+        /// <summary>
+        /// This test was purposely written in a way that demonstrates how to use the
+        /// ControlledRealTimeReopenThread.  It contains seperate Asserts for each of
+        /// several use cases rather then trying to brake these use cases up into
+        /// seperate unit tests.  This combined approach makes the behavior of 
+        /// ControlledRealTimeReopenThread easier to understand.
+        /// </summary>
+        // LUCENENET specific - An extra test to demonstrate use of ControlledRealTimeReopen.
+        [Test]
+        public void TestStraightForwardDemonstration()
+        {
+
+            RAMDirectory indexDir = new RAMDirectory();
+
+            Analyzer standardAnalyzer = new StandardAnalyzer(TEST_VERSION_CURRENT);
+            IndexWriterConfig indexConfig = new IndexWriterConfig(TEST_VERSION_CURRENT, standardAnalyzer);
+            IndexWriter indexWriter = new IndexWriter(indexDir, indexConfig);
+            TrackingIndexWriter trackingWriter = new TrackingIndexWriter(indexWriter);
+
+            Document doc = new Document();
+            doc.Add(new Int32Field("id", 1, Field.Store.YES));
+            doc.Add(new StringField("name", "Doc1", Field.Store.YES));
+            trackingWriter.AddDocument(doc);
+
+            SearcherManager searcherManager = new SearcherManager(indexWriter, applyAllDeletes: true, null);
+
+            //Reopen SearcherManager every 1 secs via background thread if no thread waiting for newer generation.
+            //Reopen SearcherManager after .2 secs if another thread IS waiting on a newer generation.  
+            var controlledRealTimeReopenThread = new ControlledRealTimeReopenThread<IndexSearcher>(trackingWriter, searcherManager, 1, 0.2);
+
+            //Start() will start a seperate thread that will invoke the object's Run(). However,
+            //calling Run() directly would execute that code on the current thread rather then a new thread
+            //which would defeat the purpose of using controlledRealTimeReopenThread. This aspect of the API
+            //is not as intuitive as it could be. ie. Call Start() not Run().
+            controlledRealTimeReopenThread.IsBackground = true;                     //Set as a background thread
+            controlledRealTimeReopenThread.Name = "Controlled Real Time Reopen Thread";
+            controlledRealTimeReopenThread.Priority = (ThreadPriority)Math.Min((int)Thread.CurrentThread.Priority + 2, (int)ThreadPriority.Highest);
+            controlledRealTimeReopenThread.Start();
+
+            //An indexSearcher only sees Doc1
+            IndexSearcher indexSearcher = searcherManager.Acquire();
+            try
+            {
+                TopDocs topDocs = indexSearcher.Search(new MatchAllDocsQuery(), 1);
+                assertEquals(1, topDocs.TotalHits);             //There is only one doc
+            }
+            finally
+            {
+                searcherManager.Release(indexSearcher);
+            }
+
+            //Add a 2nd document
+            doc = new Document();
+            doc.Add(new Int32Field("id", 2, Field.Store.YES));
+            doc.Add(new StringField("name", "Doc2", Field.Store.YES));
+            trackingWriter.AddDocument(doc);
+
+            //Demonstrate that we can only see the first doc because we haven't 
+            //waited 1 sec or called WaitForGeneration
+            indexSearcher = searcherManager.Acquire();
+            try
+            {
+                TopDocs topDocs = indexSearcher.Search(new MatchAllDocsQuery(), 1);
+                assertEquals(1, topDocs.TotalHits);             //Can see both docs due to auto refresh after 1.1 secs
+            }
+            finally
+            {
+                searcherManager.Release(indexSearcher);
+            }
+
+
+            //Demonstrate that we can see both docs after we wait a little more
+            //then 1 sec so that controlledRealTimeReopenThread max interval is exceeded
+            //and it calls MaybeRefresh
+            Thread.Sleep(1100);     //wait 1.1 secs as ms
+            indexSearcher = searcherManager.Acquire();
+            try
+            {
+                TopDocs topDocs = indexSearcher.Search(new MatchAllDocsQuery(), 1);
+                assertEquals(2, topDocs.TotalHits);             //Can see both docs due to auto refresh after 1.1 secs
+            }
+            finally
+            {
+                searcherManager.Release(indexSearcher);
+            }
+
+
+            //Add a 3rd document
+            doc = new Document();
+            doc.Add(new Int32Field("id", 3, Field.Store.YES));
+            doc.Add(new StringField("name", "Doc3", Field.Store.YES));
+            long generation = trackingWriter.AddDocument(doc);
+
+            //Demonstrate that if we call WaitForGeneration our wait will be
+            // .2 secs or less (the min interval we set earlier) and then we will
+            //see all 3 documents.
+            Stopwatch stopwatch = Stopwatch.StartNew();
+            controlledRealTimeReopenThread.WaitForGeneration(generation);
+            stopwatch.Stop();
+            assertTrue(stopwatch.Elapsed.TotalMilliseconds <= 200 + 30);   //30ms is fudged factor to account for call overhead.
+
+            indexSearcher = searcherManager.Acquire();
+            try
+            {
+                TopDocs topDocs = indexSearcher.Search(new MatchAllDocsQuery(), 1);
+                assertEquals(3, topDocs.TotalHits);             //Can see both docs due to auto refresh after 1.1 secs
+            }
+            finally
+            {
+                searcherManager.Release(indexSearcher);
+            }
+
+            controlledRealTimeReopenThread.Dispose();
+            searcherManager.Dispose();
+            indexWriter.Dispose();
+            indexDir.Dispose();
+        }
+
+
+
+        /// <summary>
+        /// In this test multiple threads are created each of which is waiting on the same 
+        /// generation before doing a search.  These threads will all stack up on the 
+        /// WaitForGeneration(generation) call.  All threads should return from this call
+        /// in approximately in the time expected, namely the value for targetMinStaleSec passed
+        /// to ControlledRealTimeReopenThread in it's constructor.
+        /// </summary>
+        // LUCENENET specific - An extra test to test multithreaded use of ControlledRealTimeReopen.
+        [Test]
+        public void TestMultithreadedWaitForGeneration()
+        {
+            Thread CreateWorker(int threadNum, ControlledRealTimeReopenThread<IndexSearcher> controlledReopen, long generation,
+                                SearcherManager searcherManager, List<ThreadOutput> outputList)
+            {
+                ThreadStart threadStart = delegate
+                {
+
+                    Stopwatch stopwatch = Stopwatch.StartNew();
+                    controlledReopen.WaitForGeneration(generation);
+                    stopwatch.Stop();
+                    double milliSecsWaited = stopwatch.Elapsed.TotalMilliseconds;
+
+                    int numRecs = 0;
+                    IndexSearcher indexSearcher = searcherManager.Acquire();
+                    try
+                    {
+                        TopDocs topDocs = indexSearcher.Search(new MatchAllDocsQuery(), 1);
+                        numRecs = topDocs.TotalHits;
+                    }
+                    finally
+                    {
+                        searcherManager.Release(indexSearcher);
+                    }
+
+                    lock (outputList)
+                    {
+                        outputList.Add(new ThreadOutput { ThreadNum = threadNum, NumRecs = numRecs, MilliSecsWaited = milliSecsWaited });
+                    }
+
+                };
+                return new Thread(threadStart);
+            }
+
+            int threadCount = 3;
+            List<ThreadOutput> outputList = new List<ThreadOutput>();
+
+            RAMDirectory indexDir = new RAMDirectory();
+            Analyzer standardAnalyzer = new StandardAnalyzer(TEST_VERSION_CURRENT);
+            IndexWriterConfig indexConfig = new IndexWriterConfig(TEST_VERSION_CURRENT, standardAnalyzer);
+            IndexWriter indexWriter = new IndexWriter(indexDir, indexConfig);
+            TrackingIndexWriter trackingWriter = new TrackingIndexWriter(indexWriter);
+
+            //Add two documents
+            Document doc = new Document();
+            doc.Add(new Int32Field("id", 1, Field.Store.YES));
+            doc.Add(new StringField("name", "Doc1", Field.Store.YES));
+            long generation = trackingWriter.AddDocument(doc);
+
+            doc.Add(new Int32Field("id", 2, Field.Store.YES));
+            doc.Add(new StringField("name", "Doc3", Field.Store.YES));
+            generation = trackingWriter.AddDocument(doc);
+
+            SearcherManager searcherManager = new SearcherManager(indexWriter, applyAllDeletes: true, null);
+
+            //Reopen SearcherManager every 2 secs via background thread if no thread waiting for newer generation.
+            //Reopen SearcherManager after .2 secs if another thread IS waiting on a newer generation.  
+            double maxRefreshSecs = 2.0;
+            double minRefreshSecs = .2;
+            var controlledRealTimeReopenThread = new ControlledRealTimeReopenThread<IndexSearcher>(trackingWriter, searcherManager, maxRefreshSecs, minRefreshSecs);
+
+            //Start() will start a seperate thread that will invoke the object's Run(). However,
+            //calling Run() directly would execute that code on the current thread rather then a new thread
+            //which would defeat the purpose of using controlledRealTimeReopenThread. This aspect of the API
+            //is not as intuitive as it could be. ie. Call Start() not Run().
+            controlledRealTimeReopenThread.IsBackground = true;                     //Set as a background thread
+            controlledRealTimeReopenThread.Name = "Controlled Real Time Reopen Thread";
+            controlledRealTimeReopenThread.Priority = (ThreadPriority)Math.Min((int)Thread.CurrentThread.Priority + 2, (int)ThreadPriority.Highest);
+            controlledRealTimeReopenThread.Start();
+
+
+            //Create the threads for doing searchers
+            List<Thread> threadList = new List<Thread>();
+            for (int i = 1; i <= threadCount; i++)
+            {
+                threadList.Add(CreateWorker(i, controlledRealTimeReopenThread, generation, searcherManager, outputList));
+            }
+
+            //Start all the threads
+            foreach (Thread thread in threadList)
+            {
+                thread.Start();
+            }
+
+            //wait for the threads to finish.
+            foreach (Thread thread in threadList)
+            {
+                thread.Join();                          //will wait here until the thread terminates.
+            }
+
+            //Now make sure that no thread waited longer then our min refresh time
+            //plus a small fudge factor. Also verify that all threads resported back and
+            //each saw 2 records.
+
+            //Verify all threads reported back a result.
+            assertEquals(threadCount, outputList.Count);
+
+            int millisecsPerSec = 1000;
+            foreach (ThreadOutput output in outputList)
+            {
+                //Verify the thread saw exactly 2 docs
+                assertEquals(2, output.NumRecs);
+
+                //Verify the thread wait time was around what was expected.
+                Assert.True(output.MilliSecsWaited <= (minRefreshSecs * millisecsPerSec) + 30);   //30ms is fudged factor to account for call overhead
+            }
+
+            controlledRealTimeReopenThread.Dispose();                       //will kill and join to the thread
+            Assert.False(controlledRealTimeReopenThread.IsAlive);           //to prove that Dispose really does kill the thread.
+
+            searcherManager.Dispose();
+            indexWriter.Dispose();
+            indexDir.Dispose();
+
+        }
+
+        [DebuggerDisplay("ThreadNum:{ThreadNum}, NumRecs:{NumRecs}, MilliSecsWaited:{MilliSecsWaited}")]
+        public class ThreadOutput
+        {
+            public int ThreadNum { get; set; }
+            public int NumRecs { get; set; }
+            public double MilliSecsWaited { get; set; }
+        }
     }
 }