Removed FEATURE_DICTIONARY_REMOVE_CONTINUEENUMERATION from the codebase

Directory.Build.targets

@@ -46,7 +46,6 @@
   <PropertyGroup Condition=" $(TargetFramework.StartsWith('netcoreapp3.')) Or $(TargetFramework.StartsWith('net5.')) Or $(TargetFramework.StartsWith('net6.')) Or $(TargetFramework.StartsWith('net7.')) Or $(TargetFramework.StartsWith('net8.')) ">
 
     <DefineConstants>$(DefineConstants);FEATURE_ARGITERATOR</DefineConstants>
-    <DefineConstants>$(DefineConstants);FEATURE_DICTIONARY_REMOVE_CONTINUEENUMERATION</DefineConstants>
     <DefineConstants>$(DefineConstants);FEATURE_PROCESS_KILL_ENTIREPROCESSTREE</DefineConstants>
     <DefineConstants>$(DefineConstants);FEATURE_STRING_CONCAT_READONLYSPAN</DefineConstants>
 

src/Lucene.Net.Facet/Taxonomy/WriterCache/NameIntCacheLRU.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using JCG = J2N.Collections.Generic;
 
 namespace Lucene.Net.Facet.Taxonomy.WriterCache
 {
@@ -162,13 +163,7 @@ private void CreateCache(int maxSize)
             }
             else
             {
-#if FEATURE_DICTIONARY_REMOVE_CONTINUEENUMERATION
-                cache = new Dictionary<TName, int>(capacity: 1000);
-#else
-                // LUCENENET specific - we use ConcurrentDictionary here because it supports deleting while
-                // iterating through the collection, but Dictionary does not.
-                cache = new ConcurrentDictionary<TName, int>(concurrencyLevel: 3, capacity: 1000); //no need for LRU
-#endif
+                cache = new JCG.Dictionary<TName, int>(capacity: 1000);
             }
         }
 
@@ -255,4 +250,4 @@ bool IInternalNameInt32CacheLru.MakeRoomLRU()
             return true;
         }
     }
-}
+}

src/Lucene.Net.TestFramework/Util/Fst/FSTTester.cs

@@ -833,13 +833,9 @@ private void VerifyPruned(int inputMode, FST<T> fst, int prune1, int prune2)
 
             // build all prefixes
 
-#if FEATURE_DICTIONARY_REMOVE_CONTINUEENUMERATION
-            IDictionary<Int32sRef, CountMinOutput<T>> prefixes = new Dictionary<Int32sRef, CountMinOutput<T>>();
-#else
-            // LUCENENET: We use ConcurrentDictionary<TKey, TValue> because Dictionary<TKey, TValue> doesn't support
-            // deletion while iterating, but ConcurrentDictionary does.
-            IDictionary<Int32sRef, CountMinOutput<T>> prefixes = new ConcurrentDictionary<Int32sRef, CountMinOutput<T>>();
-#endif
+            // LUCENENET specific - using concrete type for the readerMap field, since it will eliminate boxing to an interface on GetEnumerator() calls
+            JCG.Dictionary<Int32sRef, CountMinOutput<T>> prefixes = new JCG.Dictionary<Int32sRef, CountMinOutput<T>>();
+
             Int32sRef scratch = new Int32sRef(10);
             foreach (InputOutput<T> pair in pairs)
             {
@@ -927,7 +923,7 @@ private void VerifyPruned(int inputMode, FST<T> fst, int prune1, int prune2)
                     if (!keep)
                     {
                         //it.remove();
-                        prefixes.Remove(ent);
+                        prefixes.Remove(prefix);
                         //System.out.println("    remove");
                     }
                     else
@@ -1028,4 +1024,4 @@ private void VerifyPruned(int inputMode, FST<T> fst, int prune1, int prune2)
             }
         }
     }
-}
+}

src/Lucene.Net/Index/IndexWriter.cs

@@ -471,13 +471,8 @@ public ReaderPool(IndexWriter outerInstance)
                 this.outerInstance = outerInstance;
             }
 
-#if FEATURE_DICTIONARY_REMOVE_CONTINUEENUMERATION
-            private readonly IDictionary<SegmentCommitInfo, ReadersAndUpdates> readerMap = new Dictionary<SegmentCommitInfo, ReadersAndUpdates>();
-#else
-            // LUCENENET: We use ConcurrentDictionary<TKey, TValue> because Dictionary<TKey, TValue> doesn't support
-            // deletion while iterating, but ConcurrentDictionary does.
-            private readonly IDictionary<SegmentCommitInfo, ReadersAndUpdates> readerMap = new ConcurrentDictionary<SegmentCommitInfo, ReadersAndUpdates>();
-#endif
+            // LUCENENET specific - using concrete type for the readerMap field, since it will eliminate boxing to an interface on GetEnumerator() calls
+            private readonly JCG.Dictionary<SegmentCommitInfo, ReadersAndUpdates> readerMap = new JCG.Dictionary<SegmentCommitInfo, ReadersAndUpdates>();
 
             // used only by asserts
             public virtual bool InfoIsLive(SegmentCommitInfo info)