From 8fea5c8c2705097b92a2e010b435ff9a6df83f8a Mon Sep 17 00:00:00 2001
From: Michal Simon <michal.simon@cern.ch>
Date: Tue, 9 May 2017 17:15:18 +0200
Subject: [PATCH] [XrdCl] Fix: xcp hangs if there are no valid sources.

---
 src/XrdCl/XrdClXCpCtx.cc | 20 ++++++++++++--------
 src/XrdCl/XrdClXCpCtx.hh | 20 +++++++++++++++++++-
 src/XrdCl/XrdClXCpSrc.cc |  8 ++++++++
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/src/XrdCl/XrdClXCpCtx.cc b/src/XrdCl/XrdClXCpCtx.cc
index e40061c2463..a44c0afdce6 100644
--- a/src/XrdCl/XrdClXCpCtx.cc
+++ b/src/XrdCl/XrdClXCpCtx.cc
@@ -148,15 +148,8 @@ XRootDStatus XCpCtx::GetChunk( XrdCl::ChunkInfo &ci )
     return XRootDStatus( stOK, suDone );
   }
 
-  // check if there are any active sources
-  size_t nbRunning = 0;
-  std::list<XCpSrc*>::iterator itr;
-  for( itr = pSources.begin() ; itr != pSources.end() ; ++ itr)
-    if( (*itr)->IsRunning() )
-      ++nbRunning;
-
   // if we don't have active sources it means we failed
-  if( nbRunning == 0 )
+  if( GetRunning() == 0 )
   {
     XrdSysCondVarHelper lck( pDoneCV );
     pDone = true;
@@ -191,5 +184,16 @@ bool XCpCtx::AllDone()
   return pDone;
 }
 
+size_t XCpCtx::GetRunning()
+{
+  // count active sources
+  size_t nbRunning = 0;
+  std::list<XCpSrc*>::iterator itr;
+  for( itr = pSources.begin() ; itr != pSources.end() ; ++ itr)
+    if( (*itr)->IsRunning() )
+      ++nbRunning;
+  return nbRunning;
+}
+
 
 } /* namespace XrdCl */
diff --git a/src/XrdCl/XrdClXCpCtx.hh b/src/XrdCl/XrdClXCpCtx.hh
index 6179f60e086..7c875b0ddea 100644
--- a/src/XrdCl/XrdClXCpCtx.hh
+++ b/src/XrdCl/XrdClXCpCtx.hh
@@ -126,7 +126,7 @@ class XCpCtx
     int64_t GetSize()
     {
       XrdSysCondVarHelper lck( pFileSizeCV );
-      while( pFileSize < 0 ) pFileSizeCV.Wait();
+      while( pFileSize < 0 && GetRunning() > 0 ) pFileSizeCV.Wait();
       return pFileSize;
     }
 
@@ -186,8 +186,26 @@ class XCpCtx
      */
     bool AllDone();
 
+    /**
+     * Notify those who are waiting for initialization.
+     * In particular the GetSize() caller will be waiting
+     * on the result of initialization.
+     */
+    void NotifyInitExpectant()
+    {
+      pFileSizeCV.Broadcast();
+    }
+
+
   private:
 
+    /**
+     * Returns the number of active sources
+     *
+     * @return : number of active sources
+     */
+    size_t GetRunning();
+
     /**
      * Destructor (private).
      *
diff --git a/src/XrdCl/XrdClXCpSrc.cc b/src/XrdCl/XrdClXCpSrc.cc
index be8f5e6c892..ad53981a9de 100644
--- a/src/XrdCl/XrdClXCpSrc.cc
+++ b/src/XrdCl/XrdClXCpSrc.cc
@@ -131,6 +131,14 @@ void XCpSrc::StartDownloading()
   if( !st.IsOK() )
   {
     pRunning = false;
+    // notify those who wait for the file
+    // size, they wont get it from this
+    // source
+    pCtx->NotifyInitExpectant();
+    // put a null chunk so we are sure
+    // the main thread doesn't get stuck
+    // at the sync queue
+    pCtx->PutChunk( 0 );
     return;
   }