[XrdCl] Check for closed connection between handling of read and writ…

…e events

src/XrdCl/XrdClAsyncSocketHandler.cc

@@ -51,7 +51,8 @@ namespace XrdCl
     pHSWaitStarted( 0 ),
     pHSWaitSeconds( 0 ),
     pUrl( url ),
-    pTlsHandShakeOngoing( false )
+    pTlsHandShakeOngoing( false ),
+    pCloseCount( 0 )
   {
     Env *env = DefaultEnv::GetEnv();
 
@@ -190,6 +191,7 @@ namespace XrdCl
 
     pPoller->RemoveSocket( pSocket );
     pSocket->Close();
+    pCloseCount.fetch_add( 1, std::memory_order_relaxed );
     return XRootDStatus();
   }
 
@@ -213,6 +215,12 @@ namespace XrdCl
     //--------------------------------------------------------------------------
     type = pSocket->MapEvent( type );
 
+    //--------------------------------------------------------------------------
+    // In case we'll be handling both read and write events be prepared to
+    // detect a close between the handling of each.
+    //--------------------------------------------------------------------------
+    const uint32_t closeCount = pCloseCount.load( std::memory_order_relaxed );
+
     //--------------------------------------------------------------------------
     // Read event
     //--------------------------------------------------------------------------
@@ -241,6 +249,15 @@ namespace XrdCl
         OnTimeoutWhileHandshaking();
     }
 
+    //--------------------------------------------------------------------------
+    // We check to see if any of the read event handlers above may have caused
+    // us to be closed. If so, we may have been re-opened, added to another
+    // poller and now be concurrently handling requests for another connection.
+    // Discontinue processing if a close is detected.
+    //--------------------------------------------------------------------------
+    if( closeCount != pCloseCount.load( std::memory_order_relaxed ) )
+      return;
+
     //--------------------------------------------------------------------------
     // Write event
     //--------------------------------------------------------------------------

src/XrdCl/XrdClAsyncSocketHandler.hh

@@ -31,6 +31,8 @@
 #include "XrdCl/XrdClAsyncMsgWriter.hh"
 #include "XrdCl/XrdClAsyncHSWriter.hh"
 
+#include <atomic>
+
 namespace XrdCl
 {
   class Stream;
@@ -276,6 +278,8 @@ namespace XrdCl
       std::unique_ptr<AsyncMsgReader> rspreader;
       std::unique_ptr<AsyncHSReader>  hsreader;
       std::unique_ptr<AsyncMsgWriter> reqwriter;
+
+      std::atomic<uint32_t>          pCloseCount;
   };
 }