XrdFileCache.hh

#ifndef __XRDFILECACHE_CACHE_HH__
#define __XRDFILECACHE_CACHE_HH__
//----------------------------------------------------------------------------------
// Copyright (c) 2014 by Board of Trustees of the Leland Stanford, Jr., University
// Author: Alja Mrak-Tadel, Matevz Tadel, Brian Bockelman
//----------------------------------------------------------------------------------
// 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 General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with XRootD.  If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------------------
#include <string>
#include <list>

#include "XrdVersion.hh"
#include "XrdSys/XrdSysPthread.hh"
#include "XrdOuc/XrdOucCache2.hh"
#include "XrdOuc/XrdOucCallBack.hh"
#include "XrdCl/XrdClDefaultEnv.hh"
#include "XrdFileCacheFile.hh"
#include "XrdFileCacheDecision.hh"

class XrdOucStream;
class XrdSysError;

namespace XrdCl {
   class Log;
}
namespace XrdFileCache {
class File;
class IO;
}


namespace XrdFileCache
{
   //----------------------------------------------------------------------------
   //! Contains parameters configurable from the xrootd config file.
   //----------------------------------------------------------------------------
   struct Configuration
   {
      Configuration() :
         m_hdfsmode(false),
         m_diskUsageLWM(-1),
         m_diskUsageHWM(-1),
         m_bufferSize(1024*1024),
    	 m_RamAbsAvailable(8*1024*1024),
    	 m_NRamBuffers(-1),
         m_prefetch_max_blocks(10),
         m_hdfsbsize(128*1024*1024) {}

      bool m_hdfsmode;      //!< flag for enabling block-level operation
      std::string m_cache_dir;        //!< path of disk cache
      std::string m_username;         //!< username passed to oss plugin

      long long m_diskUsageLWM;       //!< cache purge low water mark
      long long m_diskUsageHWM;       //!< cache purge high water mark

      long long m_bufferSize;         //!< prefetch buffer size, default 1MB
      long long m_RamAbsAvailable;     //!< available from configuration
      int       m_NRamBuffers;        //!< number of total in-memory cache blocks, cached
      bool      m_prefetch;           //!< prefetch enable state        
      size_t    m_prefetch_max_blocks;//!< maximum number of blocks to prefetch per file

      long long m_hdfsbsize;          //!< used with m_hdfsmode, default 128MB
   };



   //----------------------------------------------------------------------------
   //! Attaches/creates and detaches/deletes cache-io objects for disk based cache.
   //----------------------------------------------------------------------------
   class Cache : public XrdOucCache2
   {
      public:
         //---------------------------------------------------------------------
         //! Constructor
         //---------------------------------------------------------------------
         Cache();

         //---------------------------------------------------------------------
         //! Obtain a new IO object that fronts existing XrdOucCacheIO.
         //---------------------------------------------------------------------
         virtual XrdOucCacheIO2 *Attach(XrdOucCacheIO2 *, int Options=0);

         //---------------------------------------------------------------------
         //! Number of cache-io objects atteched through this cache.
         //---------------------------------------------------------------------
         virtual int isAttached();

         //---------------------------------------------------------------------
         // this is an obsolete method 
         virtual XrdOucCache* Create(XrdOucCache::Parms&, XrdOucCacheIO::aprParms*);

         // Virtual function of XrdOucCache2. Used for deferred open.
         virtual int  Prepare(const char *url, int oflags, mode_t mode);


         // virtual function of XrdOucCache2::Stat()
         virtual int  Stat(const char *url, struct stat &sbuff);

         //--------------------------------------------------------------------
         //! \brief Makes decision if the original XrdOucCacheIO should be cached.
         //!
         //! @param & URL of file
         //!
         //! @return decision if IO object will be cached.
         //--------------------------------------------------------------------
         bool Decide(XrdOucCacheIO*);

         //------------------------------------------------------------------------
         //! Reference XrdFileCache configuration
         //------------------------------------------------------------------------
         const Configuration& RefConfiguration() const { return m_configuration; }


         //---------------------------------------------------------------------
         //! \brief Parse configuration file
         //!
         //! @param logger             xrootd logger
         //! @param config_filename    path to configuration file
         //! @param parameters         optional parameters to be passed
         //!
         //! @return parse status
         //---------------------------------------------------------------------
         bool Config(XrdSysLogger *logger, const char *config_filename, const char *parameters);

         //---------------------------------------------------------------------
         //! Singleton access.
         //---------------------------------------------------------------------
         static Cache &GetInstance();

         //---------------------------------------------------------------------
         //! Version check.
         //---------------------------------------------------------------------
         static bool VCheck(XrdVersionInfo &urVersion) { return true; }

         //---------------------------------------------------------------------
         //! Thread function running disk cache purge periodically.
         //---------------------------------------------------------------------
         void CacheDirCleanup();

         //---------------------------------------------------------------------
         //! Add downloaded block in write queue.
         //---------------------------------------------------------------------
         void AddWriteTask(Block* b, bool from_read);

         //---------------------------------------------------------------------
         //! Check write queue size is not over limit.
         //---------------------------------------------------------------------
         bool HaveFreeWritingSlots();

         //---------------------------------------------------------------------
         //!  \brief Remove blocks from write queue which belong to given prefetch.
         //! This method is used at the time of File destruction.
         //---------------------------------------------------------------------
         void RemoveWriteQEntriesFor(File *f);

         //---------------------------------------------------------------------
         //! Separate task which writes blocks from ram to disk.
         //---------------------------------------------------------------------
         void ProcessWriteTasks();

         bool RequestRAMBlock();

         void RAMBlockReleased();

         void RegisterPrefetchFile(File*);
         void DeRegisterPrefetchFile(File*);

         File* GetNextFileToPrefetch();

         void Prefetch();

         //! Decrease attached count. Called from IO::Detach().
         void Detach(XrdOucCacheIO *);

         XrdOss* GetOss() const { return m_output_fs; }

         XrdSysError& GetSysError() { return m_log; }

        
      private:
         bool ConfigParameters(std::string, XrdOucStream&);
         bool ConfigXeq(char *, XrdOucStream &);
         bool xdlib(XrdOucStream &);
         static Cache   *m_factory;   //!< this object

         XrdSysError       m_log;       //!< XrdFileCache namespace logger
         XrdOucCacheStats  m_stats;     //!< 
         XrdOss           *m_output_fs; //!< disk cache file system

         std::vector<XrdFileCache::Decision*> m_decisionpoints; //!< decision plugins

         std::map<std::string, long long> m_filesInQueue;

         Configuration     m_configuration; //!< configurable parameters

         //! Short log alias.
         XrdCl::Log* clLog() const { return XrdCl::DefaultEnv::GetLog(); }

         XrdSysCondVar      m_prefetch_condVar; //!< central lock for this class

         XrdSysMutex        m_RAMblock_mutex; //!< central lock for this class
         int                m_RAMblocks_used;

         struct WriteQ
         {
            WriteQ() : condVar(0), size(0) {}
            XrdSysCondVar         condVar;  //!< write list condVar
            size_t                size;     //!< cache size of a container
            std::list<Block*>     queue;    //!< container
         };

         WriteQ s_writeQ;

       // prefetching
       typedef std::vector<File*>  PrefetchList;
       PrefetchList  m_prefetchList;
   };

}

#endif