Reduce lock time

dotnet · Feb 12, 2019 · c175b05 · c175b05
1 parent ea5199c
commit c175b05
Showing 1 changed file with 32 additions and 13 deletions.
diff --git a/src/System.IO.Pipelines/src/System/IO/Pipelines/Pipe.cs b/src/System.IO.Pipelines/src/System/IO/Pipelines/Pipe.cs
@@ -42,7 +42,9 @@ public sealed partial class Pipe
         private readonly PipeScheduler _readerScheduler;
         private readonly PipeScheduler _writerScheduler;
 
+        private int _pooledSegmentCount;
         private readonly BufferSegment[] _bufferSegmentPool;
+        private readonly BufferSegment[] _bufferSegmentsToReturn;
 
         private readonly DefaultPipeReader _reader;
         private readonly DefaultPipeWriter _writer;
@@ -52,7 +54,6 @@ public sealed partial class Pipe
         private long _length;
         private long _currentWriteLength;
 
-        private int _pooledSegmentCount;
 
         private PipeAwaitable _readerAwaitable;
         private PipeAwaitable _writerAwaitable;
@@ -97,6 +98,7 @@ public Pipe(PipeOptions options)
             }
 
             _bufferSegmentPool = new BufferSegment[SegmentPoolSize];
+            _bufferSegmentsToReturn = new BufferSegment[SegmentPoolSize];
 
             _operationState = default;
             _readerCompletion = default;
@@ -257,25 +259,39 @@ private void ReturnSegments(BufferSegment from, BufferSegment toExclusive)
             Debug.Assert(from != null);
             Debug.Assert(from != toExclusive);
 
+            // Reset the Segments and return their data out of lock
+            BufferSegment[] segmentToReturn = _bufferSegmentsToReturn;
+            int count = 0;
+            do
+            {
+                BufferSegment next = from.NextSegment;
+                Debug.Assert(next != null || toExclusive == null);
+
+                from.ResetMemory();
+
+                if ((uint)count < (uint)segmentToReturn.Length)
+                {
+                    segmentToReturn[count] = from;
+                    count++;
+                }
+
+                from = next;
+            } while (from != toExclusive);
+
+            // Add the Segments back to pool under lock
             BufferSegment[] segmentPool = _bufferSegmentPool;
             lock (segmentPool)
             {
                 int index = _pooledSegmentCount;
-                do
+                for (int i = 0; i < count; i++)
                 {
-                    BufferSegment next = from.NextSegment;
-                    Debug.Assert(next != null || toExclusive == null);
-
-                    from.ResetMemory();
-
                     if ((uint)index < (uint)segmentPool.Length)
                     {
-                        segmentPool[index] = from;
+                        segmentPool[index] = segmentToReturn[i];
                         index++;
                     }
-
-                    from = next;
-                } while (from != toExclusive);
+                    segmentToReturn[i] = null;
+                }
 
                 _pooledSegmentCount = index;
             }
@@ -786,9 +802,12 @@ private void CompletePipe()
                 _readTail = null;
             }
 
-            if (segment != null)
+            while (segment != null)
             {
-                ReturnSegments(segment, toExclusive: null);
+                BufferSegment returnSegment = segment;
+                segment = segment.NextSegment;
+
+                returnSegment.ResetMemory();
             }
         }