Added an initial check on the error flag

in order to no even move the little finger if a previous task failed
Also added some comments

castor/tape/tapeserver/daemon/DiskReadTask.cpp

@@ -58,16 +58,19 @@ namespace daemon {
     size_t blockId=0;
     size_t migratingFileSize=m_migratedFile->fileSize();
     try{
+      //we first check here to not even try to open the disk  if a previous task has failed
+      //because the disk could the very reason why the previous one failed, 
+      //so dont do the same mistake twice !
+      hasAnotherTaskTailed();
+      
       tape::diskFile::ReadFile sourceFile(m_migratedFile->path());
       
       log::LogContext::ScopedParam sp(lc, log::Param("filePath",m_migratedFile->path()));
       lc.log(LOG_INFO,"Opened file on disk for migration ");
       
       while(migratingFileSize>0){
-        //if a task has signaled an error, we stop our job
-        if(m_errorFlag){
-          throw  castor::tape::exceptions::ErrorFlag();
-        }
+
+        hasAnotherTaskTailed();
         
         MemBlock* const mb = m_nextTask.getFreeBlock();
         AutoPushBlock push(mb,m_nextTask);

castor/tape/tapeserver/daemon/DiskReadTask.hpp

@@ -47,7 +47,12 @@ public:
   
   virtual void execute(log::LogContext& lc);
 private:
-  
+  void hasAnotherTaskTailed() const {
+    //if a task has signaled an error, we stop our job
+    if(m_errorFlag){
+      throw  castor::tape::exceptions::ErrorFlag();
+    }
+  }
   void circulateAllBlocks(size_t fromBlockId);
   /**
    * The task (a TapeWriteTask) that will handle the read blocks

castor/tape/tapeserver/daemon/TapeWriteTask.cpp

@@ -63,16 +63,23 @@ namespace daemon {
     unsigned long ckSum = Payload::zeroAdler32();
     int blockId  = 0;
     try {
+      //we first check here to not even try to move the tape  if a previous task has failed
+      //because the tape- could the very reason why the previous one failed, 
+      //so dont do the same mistake twice !
+      hasAnotherTaskTailed();
+      
+      //try to open the session
       std::auto_ptr<castor::tape::tapeFile::WriteFile> output(openWriteFile(session,lc));
       while(!m_fifo.finished()) {
-        if(m_errorFlag){
-          throw  castor::tape::exceptions::ErrorFlag();
-        }
+
+        //if someone screw somewhere else, we stop
+        hasAnotherTaskTailed();
+        
         MemBlock* const mb = m_fifo.popDataBlock();
         AutoReleaseBlock<MemoryManager> releaser(mb,m_memManager);
         
-        if(/*m_migratingFile->fileid() != static_cast<unsigned int>(mb->m_fileid)
-            *             || */blockId != mb->m_fileBlock  || mb->m_failed ){
+        if(m_fileToMigrate->fileid() != static_cast<unsigned int>(mb->m_fileid)
+                         || blockId != mb->m_fileBlock  || mb->m_failed ){
           LogContext::ScopedParam sp[]={
             LogContext::ScopedParam(lc, Param("received_NSFILEID", mb->m_fileid)),
             LogContext::ScopedParam(lc, Param("expected_NSFBLOCKId", blockId)),
@@ -84,11 +91,13 @@ namespace daemon {
           throw castor::tape::Exception("received a bad block for writing");
         }
 
-        
         ckSum =  mb->m_payload.adler32(ckSum);
         mb->m_payload.write(*output);
         ++blockId;
       }
+      
+      //finish the writing of the file on tape
+      //put the trailer
       output->close();
       reportPacker.reportCompletedJob(*m_fileToMigrate,ckSum);
     } 
@@ -99,11 +108,15 @@ namespace daemon {
       circulateMemBlocks();
     }
     catch(const castor::tape::Exception& e){
-      m_errorFlag.set();
       //we can end up there because
       //we failed to open the WriteFile
       //we received a bad block or a block written failed
-       //close failed
+      //close failed
+      
+      //first set the error flag 
+      m_errorFlag.set();
+
+      //log and circulate blocks
       LogContext::ScopedParam sp(lc, Param("exceptionCode",e.code()));
       LogContext::ScopedParam sp1(lc, Param("exceptionMessage", e.getMessageValue()));
       lc.log(LOG_ERR,"Circulating blocks into TapeWriteTask::execute");

castor/tape/tapeserver/daemon/TapeWriteTask.hpp

@@ -84,7 +84,13 @@ public:
   virtual ~TapeWriteTask();
   
 private:
-  
+    void hasAnotherTaskTailed() const {
+    //if a task has signaled an error, we stop our job
+    if(m_errorFlag){
+      throw  castor::tape::exceptions::ErrorFlag();
+    }
+  }
+    
   void circulateMemBlocks();
   /**
    * Function in charge of opening the WriteFile for m_fileToMigrate