FailoverDataIO.h

/* This file is Copyright 2000-2008 Meyer Sound Laboratories Inc.  See the included LICENSE.txt file for details. */

#ifndef MuscleFailoverDataIO_h
#define MuscleFailoverDataIO_h

#include "dataio/DataIO.h"
#include "util/Queue.h"

BEGIN_NAMESPACE(muscle);
 
class FailoverDataIO;

class IFailoverNotifyTarget
{
public:
   IFailoverNotifyTarget() {/* empty */}

   virtual ~IFailoverNotifyTarget() {/* empty */}

   virtual void DataIOFailover(const FailoverDataIO & source) = 0;
};

class FailoverDataIO : public DataIO
{
public:
   FailoverDataIO(int logErrorLevel = MUSCLE_LOG_NONE) : _logErrorLevel(logErrorLevel), _target(NULL) {/* empty */}

   virtual ~FailoverDataIO() {/* empty */}

   virtual int32 Read(void * buffer, uint32 size)
   {
      while(HasChild())
      {
         int32 ret = GetChild()->Read(buffer, size);
         if (ret >= 0) return ret;
                  else Failover();
      }
      return -1;
   }

   virtual int32 Write(const void * buffer, uint32 size) 
   {
      while(HasChild())
      {
         int32 ret = GetChild()->Write(buffer, size);
         if (ret >= 0) return ret;
                  else Failover();
      }
      return -1;
   }

   virtual status_t Seek(int64 offset, int whence)
   {
      while(HasChild())
      {
         status_t ret = GetChild()->Seek(offset, whence);
         if (ret == B_NO_ERROR) return ret;
                           else Failover();
      }
      return B_ERROR;
   }

   virtual int64 GetPosition() const {return HasChild() ? GetChild()->GetPosition() : -1;}

   virtual uint64 GetOutputStallLimit() const {return HasChild() ? GetChild()->GetOutputStallLimit() : MUSCLE_TIME_NEVER;}

   virtual void FlushOutput() {if (HasChild()) GetChild()->FlushOutput();}

   virtual void Shutdown() {_childIOs.Clear();}

   virtual const SocketRef & GetSelectSocket() const {return (HasChild()) ? GetChild()->GetSelectSocket() : GetNullSocket();}

   virtual status_t GetReadByteTimeStamp(int32 whichByte, uint64 & retStamp) const {return HasChild() ? GetChild()->GetReadByteTimeStamp(whichByte, retStamp) : B_ERROR;}

   virtual bool HasBufferedOutput() const {return HasChild() ? GetChild()->HasBufferedOutput() : false;}

   virtual void WriteBufferedOutput() {if (HasChild()) GetChild()->WriteBufferedOutput();}

   const Queue<DataIORef> & GetChildDataIOs() const {return _childIOs;}

   Queue<DataIORef> & GetChildDataIOs() {return _childIOs;}

   virtual void Failover() 
   {
      (void) _childIOs.RemoveHead();
      if (HasChild()) LogTime(_logErrorLevel, "FailoverDataIO:  Child IO errored out, failing over to next child ("UINT32_FORMAT_SPEC" children left)!\n", _childIOs.GetNumItems());
                 else LogTime(_logErrorLevel, "FailoverDataIO:  Child IO errored out, no backup children left!\n");
      if (_target) _target->DataIOFailover(*this);
   }
   
   void SetFailoverNotifyTarget(IFailoverNotifyTarget * t) {_target = t;}

   IFailoverNotifyTarget * GetFailoverNotifyTarget() const {return _target;}

private:
   bool HasChild() const {return (_childIOs.HasItems());}
   DataIO * GetChild() const {return (_childIOs.Head()());}

   Queue<DataIORef> _childIOs;
   int _logErrorLevel;
   IFailoverNotifyTarget * _target;
};

END_NAMESPACE(muscle);

#endif

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