/******************************************************************************/
/*                                                                            */
/*                      X r d S s i F i l e R e q . c c                       */
/*                                                                            */
/* (c) 2013 by the Board of Trustees of the Leland Stanford, Jr., University  */
/*   Produced by Andrew Hanushevsky for Stanford University under contract    */
/*              DE-AC02-76-SFO0515 with the Department of Energy              */
/*                                                                            */
/* This file is part of the XRootD software suite.                            */
/*                                                                            */
/* XRootD is free software: you can redistribute it and/or modify it under    */
/* the terms of the GNU Lesser General Public License as published by the     */
/* Free Software Foundation, either version 3 of the License, or (at your     */
/* option) any later version.                                                 */
/*                                                                            */
/* XRootD is distributed in the hope that it will be useful, but WITHOUT      */
/* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or      */
/* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public       */
/* License for more details.                                                  */
/*                                                                            */
/* You should have received a copy of the GNU Lesser General Public License   */
/* along with XRootD in a file called COPYING.LESSER (LGPL license) and file  */
/* COPYING (GPL license).  If not, see <http://www.gnu.org/licenses/>.        */
/*                                                                            */
/* The copyright holder's institutional names and contributor's names may not */
/* be used to endorse or promote products derived from this software without  */
/* specific prior written permission of the institution or contributor.       */
/******************************************************************************/

#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/types.h>

#include "XrdOuc/XrdOucBuffer.hh"
#include "XrdOuc/XrdOucERoute.hh"
#include "XrdOuc/XrdOucErrInfo.hh"
#include "XrdSfs/XrdSfsDio.hh"
#include "XrdSfs/XrdSfsXio.hh"
#include "XrdSsi/XrdSsiAlert.hh"
#include "XrdSsi/XrdSsiFileReq.hh"
#include "XrdSsi/XrdSsiFileResource.hh"
#include "XrdSsi/XrdSsiFileSess.hh"
#include "XrdSsi/XrdSsiRRAgent.hh"
#include "XrdSsi/XrdSsiService.hh"
#include "XrdSsi/XrdSsiSfs.hh"
#include "XrdSsi/XrdSsiStream.hh"
#include "XrdSsi/XrdSsiStats.hh"
#include "XrdSsi/XrdSsiTrace.hh"
#include "XrdSsi/XrdSsiUtils.hh"
#include "XrdSys/XrdSysError.hh"
  
/******************************************************************************/
/*                          L o c a l   M a c r o s                           */
/******************************************************************************/
  
#define DEBUGXQ(x) DEBUG(rID<<sessN<<rspstID[urState]<<reqstID[myState]<<x)

#define DUMPIT(x,y) XrdSsiUtils::b2x(x,y,hexBuff,sizeof(hexBuff),dotBuff)<<dotBuff

/******************************************************************************/
/*                               G l o b a l s                                */
/******************************************************************************/

namespace XrdSsi
{
extern XrdSysError    Log;
extern XrdScheduler  *Sched;
extern XrdSsiService *Service;
extern XrdSsiStats    Stats;
};

using namespace XrdSsi;

/******************************************************************************/
/*                         S t a t i c   L o c a l s                          */
/******************************************************************************/

namespace
{
const char     *rspstID[XrdSsiFileReq::isMax] =
                                      {" [new",   " [begun", " [bound",
                                       " [abort", " [done"
                                      };

const char     *reqstID[XrdSsiFileReq::rsEnd] =
                                      {" wtReq] ", " xqReq] ", " wtRsp] ",
                                       " doRsp] ", " odRsp] ", " erRsp] "
                                      };
};
  
/******************************************************************************/
/*                        S t a t i c   M e m b e r s                         */
/******************************************************************************/
  
XrdSysMutex     XrdSsiFileReq::aqMutex;
XrdSsiFileReq  *XrdSsiFileReq::freeReq = 0;
int             XrdSsiFileReq::freeCnt = 0;
int             XrdSsiFileReq::freeMax = 256;

/******************************************************************************/
/*                              A c t i v a t e                               */
/******************************************************************************/
  
void XrdSsiFileReq::Activate(XrdOucBuffer *oP, XrdSfsXioHandle *bR, int rSz)
{
   EPNAME("Activate");

// Do some debugging
//
   DEBUGXQ((oP ? "oucbuff" : "sfsbuff") <<" rqsz=" <<rSz);

// Do statistics
//
   Stats.statsMutex.Lock();
   Stats.ReqCount++;
   Stats.ReqBytes += rSz;
   if (rSz > Stats.ReqMaxsz) Stats.ReqMaxsz = rSz;
   Stats.statsMutex.UnLock();

// Set request buffer pointers
//
   oucBuff = oP;
   sfsBref = bR;
   reqSize = rSz;

// Now schedule ourselves to process this request. The state is new.
//
   Sched->Schedule((XrdJob *)this);
}

/******************************************************************************/
/*                                 A l e r t                                  */
/******************************************************************************/

void XrdSsiFileReq::Alert(XrdSsiRespInfoMsg &aMsg)
{
   EPNAME("Alert");
   XrdSsiAlert *aP;
   int msgLen;

// Do some debugging
//
   aMsg.GetMsg(msgLen);
   DEBUGXQ(msgLen <<" byte alert presented wtr=" <<respWait);

// Add up statistics
//
   Stats.Bump(Stats.ReqAlerts);

// Lock this object
//
   frqMutex.Lock();

// Validate the length and whether this call is allowed
//
   if (msgLen <= 0 || haveResp || isEnding)
      {frqMutex.UnLock();
       aMsg.RecycleMsg();
       return;
      }

// Allocate an alert object and chain it into the pending queue
//
   aP = XrdSsiAlert::Alloc(aMsg);

// Alerts must be sent in the orer they are presented. So, check if we need
// to chain this and try to send the first in the chain. This only really
// matters if we can send the alert now because the client is waiting.
//
   if (respWait)
      {if (alrtPend)
          {alrtLast->next = aP;
           alrtLast = aP;
           aP = alrtPend;
           alrtPend = alrtPend->next;
          }
       WakeUp(aP);
      } else {
       if (alrtLast) alrtLast->next = aP;
          else alrtPend = aP;
       alrtLast = aP;
      }

// All done
//
   frqMutex.UnLock();
}
  
/******************************************************************************/
/*                                 A l l o c                                  */
/******************************************************************************/

XrdSsiFileReq *XrdSsiFileReq::Alloc(XrdOucErrInfo      *eiP,
                                    XrdSsiFileResource *rP,
                                    XrdSsiFileSess     *fP,
                                    const char         *sID,
                                    const char         *cID,
                                    unsigned int        rnum)
{
   XrdSsiFileReq *nP;

// Check if we can grab this from out queue
//
   aqMutex.Lock();
   if ((nP = freeReq))
      {freeCnt--;
       freeReq = nP->nextReq;
       aqMutex.UnLock();
       nP->Init(cID);
      } else {
       aqMutex.UnLock();
       nP = new XrdSsiFileReq(cID);
      }

// Initialize for processing
//
   if (nP)
      {nP->sessN  = sID;
       nP->fileR  = rP;
       nP->fileP  = fP;
       nP->cbInfo = eiP;
       nP->reqID = rnum;
       snprintf(nP->rID, sizeof(nP->rID), "%u:", rnum);
      }

// Return the pointer
//
   return nP;
}

/******************************************************************************/
/* Private:                     B i n d D o n e                               */
/******************************************************************************/

// This is called with frqMutex locked!

void XrdSsiFileReq::BindDone()
{
   EPNAME("BindDone");

// Do some debugging
//
   DEBUGXQ("Bind called; for request " <<reqID);

// Collect statistics
//
   Stats.Bump(Stats.ReqBound);

// Processing depends on the current state. Only listed states are valid.
// When the state is done, a finished event occuured between the time the
// request was handed off to the service but before the service bound it.
//
   switch(urState)
         {case isBegun:  urState = isBound;
          case isBound:  return;
                         break;
          case isDone:   if (!schedDone)
                            {schedDone = true;
                             Sched->Schedule((XrdJob *)this);
                            }
                         return;
                         break;
          default:       break;
         }

// If we get here then we have an invalid state. Report it but otherwise we
// can't really do anything else. This means some memory may be lost.
//
   Log.Emsg(epname, tident, "Invalid req/rsp state; giving up on object!");
}

/******************************************************************************/
/*                               D i s p o s e                                */
/******************************************************************************/

void XrdSsiFileReq::Dispose()
{
   EPNAME("Dispose");

// Do some debugging
//
   DEBUGXQ("Recycling request...");

// Collect statistics
//
   Stats.Bump(Stats.ReqBound, -1);

// Simply recycle the object
//
   Recycle();
}
  
/******************************************************************************/
/*                                  D o I t                                   */
/******************************************************************************/
  
void XrdSsiFileReq::DoIt()
{
   EPNAME("DoIt");
   bool cancel;

// Processing is determined by the responder's state. Only listed states are
// valid. Others should never occur in this context.
//
   frqMutex.Lock();
   switch(urState)
         {case isNew:    myState = xqReq; urState = isBegun;
                         DEBUGXQ("Calling service processor");
                         frqMutex.UnLock();
                         Stats.Bump(Stats.ReqProcs);
                         Service->ProcessRequest((XrdSsiRequest      &)*this,
                                                 (XrdSsiFileResource &)*fileR);
                         return;
                         break;
          case isAbort:  DEBUGXQ("Skipped calling service processor");
                         frqMutex.UnLock();
                         Stats.Bump(Stats.ReqAborts);
                         Recycle();
                         return;
                         break;
          case isDone:   cancel = (myState != odRsp);
                         DEBUGXQ("Calling Finished(" <<cancel <<')');
                         if (respWait) WakeUp();
                         if (finWait)  finWait->Post();
                         frqMutex.UnLock();
                         Stats.Bump(Stats.ReqFinished);
                         if (cancel) Stats.Bump(Stats.ReqCancels);
                         Finished(cancel);  // This object may be deleted!
                         return;
                         break;
          default:       break;
         }

// If we get here then we have an invalid state. Report it but otherwise we
// can't really do anything else. This means some memory may be lost.
//
   frqMutex.UnLock();
   Log.Emsg(epname, tident, "Invalid req/rsp state; giving up on object!");
}

/******************************************************************************/
/*                                  D o n e                                   */
/******************************************************************************/

// Gets invoked only after query() waitresp signal was sent
  
void XrdSsiFileReq::Done(int &retc, XrdOucErrInfo *eiP, const char *name)
{
   EPNAME("Done");
   XrdSsiMutexMon mHelper(frqMutex);

// We may need to delete the errinfo object if this callback was async. Note
// that the following test is valid even if the file object has been deleted.
//
   if (eiP != fileP->errInfo()) delete eiP;

// Check if we should finalize this request. This will be the case if the
// complete response was sent.
//
   if (myState == odRsp)
      {DEBUGXQ("resp sent; no additional data remains");
       Finalize();
       return;
      }

// Do some debugging
//
   DEBUGXQ("wtrsp sent; resp " <<(haveResp ? "here" : "pend"));

// We are invoked when sync() waitresp has been sent, check if a response was
// posted while this was going on. If so, make sure to send a wakeup. Note
// that the respWait flag is at this moment false as this is called in the
// sync response path for fctl() and the response may have been posted.
//
   if (!haveResp) respWait = true;
      else WakeUp();
}

/******************************************************************************/
/* Private:                         E m s g                                   */
/******************************************************************************/

int XrdSsiFileReq::Emsg(const char    *pfx,    // Message prefix value
                        int            ecode,  // The error code
                        const char    *op)     // Operation being performed
{
   char buffer[2048];

// Count errors
//
   Stats.Bump(Stats.SsiErrs);

// Get correct error code
//
   if (ecode < 0) ecode = -ecode;

// Format the error message
//
   XrdOucERoute::Format(buffer, sizeof(buffer), ecode, op, sessN);

// Put the message in the log
//
   Log.Emsg(pfx, tident, buffer);

// Place the error message in the error object and return
//
   if (cbInfo) cbInfo->setErrInfo(ecode, buffer);
   return SFS_ERROR;
}

/******************************************************************************/

int XrdSsiFileReq::Emsg(const char    *pfx,    // Message prefix value
                        XrdSsiErrInfo &eObj,   // The error description
                        const char    *op)     // Operation being performed
{
   const char *eMsg;
   char buffer[2048];
   int  eNum;

// Count errors
//
   Stats.Bump(Stats.SsiErrs);

// Get correct error code and message
//
   eMsg = eObj.Get(eNum).c_str();
   if (eNum <= 0) eNum = EFAULT;
   if (!eMsg || !(*eMsg)) eMsg = "reason unknown";

// Format the error message
//
   snprintf(buffer, sizeof(buffer), "Unable to %s %s; %s", op, sessN, eMsg);

// Put the message in the log
//
   Log.Emsg(pfx, tident, buffer);

// Place the error message in the error object and return
//
   if (cbInfo) cbInfo->setErrInfo(eNum, buffer);
   return SFS_ERROR;
}
  
/******************************************************************************/
/*                              F i n a l i z e                               */
/******************************************************************************/
  
void XrdSsiFileReq::Finalize()
{
   EPNAME("Finalize");
   XrdSsiMutexMon mHelper(frqMutex);
   bool cancel = (myState != odRsp);

// Release any unsent alerts (prevent any new alerts from being accepted)
//
   isEnding = true;
   if (alrtSent || alrtPend)
      {XrdSsiAlert *dP, *aP = alrtSent;
       if (aP) aP->next = alrtPend;
          else aP       = alrtPend;
       mHelper.UnLock();
       while((dP = aP)) {aP = aP->next; dP->Recycle();}
       mHelper.Lock(frqMutex);
      }

// Processing is determined by the responder's state
//
   switch(urState)
         // Request is being scheduled, so we can simply abort it.
         //
         {case isNew:    DEBUGXQ("Aborting request processing");
                         urState = isAbort;
                         cbInfo  = 0;
                         sessN   = "???";
                         Stats.Bump(Stats.ReqAborts);
                         return;
                         break;

         // Request already handed off but not yet bound. Defer until bound.
         // We need to wait until this occurs to sequence Unprovision().
         //
          case isBegun:  urState = isDone;
                        {XrdSysSemaphore wt4fin(0);
                         finWait = &wt4fin;
                         mHelper.UnLock();
                         wt4fin.Wait();
                        }
                         return;

          // Request is bound so we can finish right off.
          //
          case isBound:  urState = isDone;
                         if (strBuff) {strBuff->Recycle(); strBuff = 0;}
                         DEBUGXQ("Calling Finished(" <<cancel <<')');
                         if (respWait) WakeUp();
                         mHelper.UnLock();
                         Stats.Bump(Stats.ReqFinished);
                         if (cancel) Stats.Bump(Stats.ReqCancels);
                         Finished(cancel); // This object may be deleted!
                         return;
                         break;

          // The following two cases may happen but it's safe to ignore them.
          //
          case isAbort:
          case isDone:   return;
                         break;
          default:       break;
         }

// If we get here then we have an invalid state. Report it but otherwise we
// can't really do anything else. This means some memory may be lost.
//
   Log.Emsg(epname, tident, "Invalid req/rsp state; giving up on object!");
}

/******************************************************************************/
/*                            G e t R e q u e s t                             */
/******************************************************************************/
  
char *XrdSsiFileReq::GetRequest(int &rLen)
{
   EPNAME("GetRequest");

// Do some debugging
//
   DEBUGXQ("sz=" <<reqSize);
   Stats.Bump(Stats.ReqGets);

// The request may come from a ouc buffer or an sfs buffer
//
   rLen = reqSize;
   if (oucBuff) return oucBuff->Data();
   return sfsBref->Buffer();
}

/******************************************************************************/
/* Private:                         I n i t                                   */
/******************************************************************************/

void XrdSsiFileReq::Init(const char *cID)
{
   tident     = (cID ? strdup(cID) : strdup("???"));
   finWait    = 0;
   nextReq    = 0;
   cbInfo     = 0;
   respCB     = 0;
   respCBarg  = 0;
   alrtSent   = 0;
   alrtPend   = 0;
   alrtLast   = 0;
   sessN      = "???";
   oucBuff    = 0;
   sfsBref    = 0;
   strBuff    = 0;
   reqSize    = 0;
   respBuf    = 0;
   respOff    = 0;
   fileSz     = 0; // Also does respLen = 0;
   myState    = wtReq;
   urState    = isNew;
  *rID        = 0;
   schedDone  = false;
   haveResp   = false;
   respWait   = false;
   strmEOF    = false;
   isEnding   = false;
   XrdSsiRRAgent::onServer(this);
   XrdSsiRRAgent::SetMutex(this, &frqMutex);
}

/******************************************************************************/
/* Protected:            P r o c e s s R e s p o n s e                        */
/******************************************************************************/

// This is called via the responder with the responder and request locks held.

bool XrdSsiFileReq::ProcessResponse(const XrdSsiErrInfo  &eInfo,
                                    const XrdSsiRespInfo &Resp)
{
   EPNAME("ProcessResponse");

// Do some debugging
//
   DEBUGXQ("Response presented wtr=" <<respWait);

// Make sure we are still in execute state
//
   if (urState != isBegun && urState != isBound) return false;
   myState = doRsp;
   respOff = 0;

// Handle the response
//
   switch(Resp.rType)
         {case XrdSsiRespInfo::isData:
               DEBUGXQ("Resp data sz="<<Resp.blen);
               respLen = Resp.blen;
               Stats.Bump(Stats.RspData);
               break;
          case XrdSsiRespInfo::isError:
               DEBUGXQ("Resp err rc="<<Resp.eNum<<" msg="<<Resp.eMsg);
               respLen = 0;
               Stats.Bump(Stats.RspErrs);
               break;
          case XrdSsiRespInfo::isFile:
               DEBUGXQ("Resp file fd="<<Resp.fdnum<<" sz="<<Resp.fsize);
               fileSz  = Resp.fsize;
               respOff = 0;
               Stats.Bump(Stats.RspFile);
               break;
          case XrdSsiRespInfo::isStream:
               DEBUGXQ("Resp strm");
               respLen = 0;
               Stats.Bump(Stats.RspStrm);
               break;
          default:
               DEBUGXQ("Resp invalid!!!!");
               return false;
               Stats.Bump(Stats.RspBad);
               break;
         }

// If the client is waiting for the response, wake up the client to get it.
//
   haveResp = true;
   if (respWait) WakeUp();
   return true;
}
  
/******************************************************************************/
/*                                  R e a d                                   */
/******************************************************************************/

XrdSfsXferSize XrdSsiFileReq::Read(bool           &done,      // Out
                                   char           *buff,      // Out
                                   XrdSfsXferSize  blen)      // In
/*
  Function: Read `blen' bytes at `offset' into 'buff' and return the actual
            number of bytes read.

  Input:    buff      - Address of the buffer in which to place the data.
            blen      - The size of the buffer. This is the maximum number
                        of bytes that will be returned.

  Output:   Returns the number of bytes read upon success and SFS_ERROR o/w.
*/
{
   static const char *epname = "read";
   XrdSfsXferSize nbytes;
   XrdSsiRespInfo const *Resp = XrdSsiRRAgent::RespP(this);

// A read should never be issued unless a response has been set
//
   if (myState != doRsp)
      {done = true;
       return (myState == odRsp ? 0 : Emsg(epname, ENOMSG, "read"));
      }

// Fan out based on the kind of response we have
//
   switch(Resp->rType)
         {case XrdSsiRespInfo::isData:
               if (respLen <= 0) {done = true; myState = odRsp; return 0;}
               if (blen >= respLen)
                  {memcpy(buff, Resp->buff+respOff, respLen);
                   blen = respLen; myState = odRsp; done = true;
                  } else {
                   memcpy(buff, Resp->buff+respOff, blen);
                   respLen -= blen; respOff += blen;
                  }
               return blen;
               break;
          case XrdSsiRespInfo::isError:
               cbInfo->setErrInfo(Resp->eNum, Resp->eMsg);
               myState = odRsp; done = true;
               return SFS_ERROR;
               break;
          case XrdSsiRespInfo::isFile:
               if (fileSz <= 0) {done = true; myState = odRsp; return 0;}
               nbytes = pread(Resp->fdnum, buff, blen, respOff);
               if (nbytes <= 0)
                  {done = true;
                   if (!nbytes) {myState = odRsp; return 0;}
                   myState = erRsp;
                   return Emsg(epname, errno, "read");
                  }
               respOff += nbytes; fileSz -= nbytes;
               return nbytes;
               break;
          case XrdSsiRespInfo::isStream:
               nbytes = (Resp->strmP->Type() == XrdSsiStream::isActive ?
                         readStrmA(Resp->strmP, buff, blen)
                      :  readStrmP(Resp->strmP, buff, blen));
               done = strmEOF && strBuff == 0;
               return nbytes;
               break;
          default: break;
         };

// We should never get here
//
   myState = erRsp;
   done    = true;
   return Emsg(epname, EFAULT, "read");
}

/******************************************************************************/
/* Private:                    r e a d S t r m A                              */
/******************************************************************************/
  
XrdSfsXferSize XrdSsiFileReq::readStrmA(XrdSsiStream *strmP,
                                        char *buff, XrdSfsXferSize blen)
{
   static const char *epname = "readStrmA";
   XrdSsiErrInfo  eObj;
   XrdSfsXferSize xlen = 0;


// Copy out data from the stream to fill the buffer
//
do{if (strBuff)
      {if (respLen > blen)
          {memcpy(buff, strBuff->data+respOff, blen);
           respLen -= blen; respOff += blen;
           return xlen+blen;
          }
       memcpy(buff, strBuff->data+respOff, respLen);
       xlen += respLen;
       strBuff->Recycle(); strBuff = 0;
       blen -= respLen; buff += respLen;
      }

   if (!strmEOF && blen)
      {respLen = blen; respOff = 0;
       strBuff = strmP->GetBuff(eObj, respLen, strmEOF);
      }
  } while(strBuff);

// Check if we have data to return
//
   if (strmEOF) {myState = odRsp; return xlen;}
      else if (!blen) return xlen;

// Report the error
//
   myState = erRsp; strmEOF = true;
   return Emsg(epname, eObj, "read stream");
}

/******************************************************************************/
/* Private:                    r e a d S t r m P                              */
/******************************************************************************/
  
XrdSfsXferSize XrdSsiFileReq::readStrmP(XrdSsiStream *strmP,
                                        char *buff, XrdSfsXferSize blen)
{
   static const char *epname = "readStrmP";
   XrdSsiErrInfo  eObj;
   XrdSfsXferSize xlen = 0;
   int dlen = 0;

// Copy out data from the stream to fill the buffer
//
   while(!strmEOF && (dlen = strmP->SetBuff(eObj, buff, blen, strmEOF)) > 0)
        {xlen += dlen;
         if (dlen == blen) return xlen;
         if (dlen  > blen) {eObj.Set(0,EOVERFLOW); break;}
         buff += dlen; blen -= dlen;
        }

// Check if we ended with an zero length read
//
   if (strmEOF || !dlen)  {myState = odRsp; strmEOF = true; return xlen;}

// Return an error
//
   myState = erRsp; strmEOF = true;
   return Emsg(epname, eObj, "read stream");
}
  
/******************************************************************************/
/* Private:                      R e c y c l e                                */
/******************************************************************************/
  
void XrdSsiFileReq::Recycle()
{

// If we have an oucbuffer then we need to recycle it, otherwise if we have
// and sfs buffer, put it on the defered release queue.
//
        if (oucBuff) {oucBuff->Recycle(); oucBuff = 0;}
   else if (sfsBref) {sfsBref->Recycle(); sfsBref = 0;}
   reqSize = 0;

// Add to queue unless we have too many of these. If we add it back to the
// queue; make sure it's a cleaned up object!
//
   aqMutex.Lock();
   if (tident) {free(tident); tident = 0;}
   if (freeCnt >= freeMax) {aqMutex.UnLock(); delete this;}
      else {XrdSsiRRAgent::CleanUp(*this);
            nextReq = freeReq;
            freeReq = this;
            freeCnt++;
            aqMutex.UnLock();
           }
}

/******************************************************************************/
/*                      R e l R e q u e s t B u f f e r                       */
/******************************************************************************/

void XrdSsiFileReq::RelRequestBuffer()
{
   EPNAME("RelReqBuff");
   XrdSsiMutexMon mHelper(frqMutex);

// Do some debugging
//
   DEBUGXQ("called");
   Stats.Bump(Stats.ReqRelBuf);

// Release buffers
//
        if (oucBuff) {oucBuff->Recycle(); oucBuff = 0;}
   else if (sfsBref) {sfsBref->Recycle(); sfsBref = 0;}
   reqSize = 0;
}

/******************************************************************************/
/*                                  S e n d                                   */
/******************************************************************************/

int XrdSsiFileReq::Send(XrdSfsDio *sfDio, XrdSfsXferSize blen)
{
   static const char *epname = "send";
   XrdSsiRespInfo const *Resp = XrdSsiRRAgent::RespP(this);
   XrdOucSFVec sfVec[2];
   int rc;

// A send should never be issued unless a response has been set. Return a
// continuation which will cause Read() to be called to return the error.
//
   if (myState != doRsp) return 1;

// Fan out based on the kind of response we have
//
   switch(Resp->rType)
         {case XrdSsiRespInfo::isData:
               if (blen > 0)
                  {sfVec[1].buffer = (char *)Resp->buff+respOff;
                   sfVec[1].fdnum  = -1;
                   if (blen > respLen)
                      {blen = respLen; myState = odRsp;
                      } else {
                       respLen -= blen; respOff += blen;
                      }
                  } else blen = 0;
               break;
          case XrdSsiRespInfo::isError:
               return 1; // Causes error to be returned via Read()
               break;
          case XrdSsiRespInfo::isFile:
               if (fileSz > 0)
                  {sfVec[1].offset = respOff; sfVec[1].fdnum = Resp->fdnum;
                   if (blen > fileSz)
                      {blen = fileSz; myState = odRsp;}
                   respOff += blen; fileSz -= blen;
                  } else blen = 0;
               break;
          case XrdSsiRespInfo::isStream:
               if (Resp->strmP->Type() == XrdSsiStream::isPassive) return 1;
               return sendStrmA(Resp->strmP, sfDio, blen);
               break;
          default: myState = erRsp;
                   return Emsg(epname, EFAULT, "send");
                   break;
         };

// Send off the data
//
   if (!blen) {sfVec[1].buffer = rID; myState = odRsp;}
   sfVec[1].sendsz = blen;
   rc = sfDio->SendFile(sfVec, 2);

// If send succeeded, indicate the action to be taken
//
   if (!rc) return myState != odRsp;

// The send failed, diagnose the problem
//
   rc = (rc < 0 ? EIO : EFAULT);
   myState = erRsp;
   return Emsg(epname, rc, "send");
}

/******************************************************************************/
/* Private:                    s e n d S t r m A                              */
/******************************************************************************/
  
int XrdSsiFileReq::sendStrmA(XrdSsiStream *strmP,
                             XrdSfsDio *sfDio, XrdSfsXferSize blen)
{
   static const char *epname = "sendStrmA";
   XrdSsiErrInfo  eObj;
   XrdOucSFVec    sfVec[2];
   int rc;

// Check if we need a buffer
//
   if (!strBuff)
      {respLen = blen;
       if (strmEOF || !(strBuff = strmP->GetBuff(eObj, respLen, strmEOF)))
          {myState = odRsp; strmEOF = true;
           if (!strmEOF) Emsg(epname, eObj, "read stream");
           return 1;
          }
       respOff = 0;
      }

// Complete the sendfile vector
//
   sfVec[1].buffer = strBuff->data+respOff;
   sfVec[1].fdnum  = -1;
   if (respLen > blen)
      {sfVec[1].sendsz = blen;
       respLen -= blen; respOff += blen;
      } else {
       sfVec[1].sendsz = respLen;
       respLen = 0;
      }

// Send off the data
//
   rc = sfDio->SendFile(sfVec, 2);

// Release any completed buffer
//
   if (strBuff && !respLen) {strBuff->Recycle(); strBuff = 0;}

// If send succeeded, indicate the action to be taken
//
   if (!rc) return myState != odRsp;

// The send failed, diagnose the problem
//
   rc = (rc < 0 ? EIO : EFAULT);
   myState = erRsp; strmEOF = true;
   return Emsg(epname, rc, "send");
}
  
/******************************************************************************/
/*                          W a n t R e s p o n s e                           */
/******************************************************************************/
  
bool XrdSsiFileReq::WantResponse(XrdOucErrInfo &eInfo)
{
   EPNAME("WantResp");
   XrdSsiMutexMon frqMon;
   const XrdSsiRespInfo *rspP;

// Check if we have a previos alert that was sent (we need to recycle it). We
// don't need a lock for this as it's fully serialized via serial fsctl calls.
//
   if (alrtSent) {alrtSent->Recycle(); alrtSent = 0;}

// Serialize the remainder of this code
//
   frqMon.Lock(frqMutex);
   rspP = XrdSsiRRAgent::RespP(this);

// If we have a pending alert then we need to send it now. Suppress the callback
// as we will recycle the alert on the next call (there should be one).
//
   if (alrtPend)
      {char hexBuff[16], binBuff[8], dotBuff[4];
       alrtSent = alrtPend;
       if (!(alrtPend = alrtPend->next)) alrtLast = 0;
       int n = alrtSent->SetInfo(eInfo, binBuff, sizeof(binBuff));
       eInfo.setErrCB((XrdOucEICB *)0);
       DEBUGXQ(n <<" byte alert (0x" <<DUMPIT(binBuff, n) <<") sent; "
                 <<(alrtPend ? "" : "no ") <<"more pending");
       return true;
      }

// Check if a response is here (well, ProcessResponse was called)
//
// if (rspP->rType)
   if (haveResp)
      {respCBarg   = 0;
       if (fileP->AttnInfo(eInfo, rspP, reqID))
          {    eInfo.setErrCB((XrdOucEICB *)this); myState = odRsp;}
          else eInfo.setErrCB((XrdOucEICB *)0);
       return true;
      }

// Defer this and record the callback arguments. We defer setting respWait
// to true until we know the deferal request has been sent (i.e. when Done()
// is called). This forces ProcessResponse() to not prematurely wakeup the
// client. This is necessitated by the fact that we must release the request
// lock upon return; allowing a response to come in while the deferal request
// is still in transit.
//
   respCB   = eInfo.getErrCB(respCBarg);
   respWait = false;
   return false;
}
  
/******************************************************************************/
/* Private:                       W a k e U p                                 */
/******************************************************************************/
  
void XrdSsiFileReq::WakeUp(XrdSsiAlert *aP) // Called with frqMutex locked!
{
   EPNAME("WakeUp");
   XrdOucErrInfo *wuInfo = 
                  new XrdOucErrInfo(tident,(XrdOucEICB *)0,respCBarg);
   const XrdSsiRespInfo *rspP = XrdSsiRRAgent::RespP(this);
   int respCode = SFS_DATAVEC;

// Do some debugging
//
   DEBUGXQ("respCBarg=" <<Xrd::hex <<respCBarg <<Xrd::dec);

// Setup the wakeup data. This may be for an alert or for an actual response.
// If this is an alert or the complete response, then make sure we get a
// callback to do the finalization. Otherwise, we don't need a callback
// and the callback handler will simply delete the error object for us.
//
   if (aP)
      {char hexBuff[16], binBuff[8], dotBuff[4];
       int n = aP->SetInfo(*wuInfo, binBuff, sizeof(binBuff));
       wuInfo->setErrCB((XrdOucEICB *)aP, respCBarg);
       DEBUGXQ(n <<" byte alert (0x" <<DUMPIT(binBuff, n) <<") sent; "
                 <<(alrtPend ? "" : "no ") <<"more pending");
      } else {
       if (fileP->AttnInfo(*wuInfo, rspP, reqID))
          {wuInfo->setErrCB((XrdOucEICB *)this, respCBarg); myState = odRsp;}
      }

// Tell the client to issue a read now or handle the alert or full response.
//
   respWait = false;
   respCB->Done(respCode, wuInfo, sessN);
   Stats.Bump(Stats.RspCallBK);
}