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TFileCacheRead.h
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1 // @(#)root/io:$Id$
2 // Author: Rene Brun 19/05/2006
3 
4 /*************************************************************************
5  * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
6  * All rights reserved. *
7  * *
8  * For the licensing terms see $ROOTSYS/LICENSE. *
9  * For the list of contributors see $ROOTSYS/README/CREDITS. *
10  *************************************************************************/
11 
12 #ifndef ROOT_TFileCacheRead
13 #define ROOT_TFileCacheRead
14 
15 #include "TObject.h"
16 
17 #include "TFile.h"
18 
19 class TBranch;
20 class TFilePrefetch;
21 
22 class TFileCacheRead : public TObject {
23 
24 protected:
25  TFilePrefetch *fPrefetch; ///<! Object that does the asynchronous reading in another thread
26  Int_t fBufferSizeMin; ///< Original size of fBuffer
27  Int_t fBufferSize; ///< Allocated size of fBuffer (at a given time)
28  Int_t fBufferLen; ///< Current buffer length (<= fBufferSize)
29 
30  Long64_t fBytesRead; ///< Number of bytes read for this cache
31  Long64_t fBytesReadExtra; ///< Number of extra bytes (overhead) read by the readahead buffer
32  Int_t fReadCalls; ///< Number of read calls for this cache
33  Long64_t fNoCacheBytesRead; ///< Number of bytes read by basket to fill cached tree
34  Int_t fNoCacheReadCalls; ///< Number of read calls by basket to fill cached tree
35 
36  Bool_t fAsyncReading;
37  Bool_t fEnablePrefetching;///< reading by prefetching asynchronously
38 
39  Int_t fNseek; ///< Number of blocks to be prefetched
40  Int_t fNtot; ///< Total size of prefetched blocks
41  Int_t fNb; ///< Number of long buffers
42  Int_t fSeekSize; ///< Allocated size of fSeek
43  Long64_t *fSeek; ///<[fNseek] Position on file of buffers to be prefetched
44  Long64_t *fSeekSort; ///<[fNseek] Position on file of buffers to be prefetched (sorted)
45  Int_t *fSeekIndex; ///<[fNseek] sorted index table of fSeek
46  Long64_t *fPos; ///<[fNb] start of long buffers
47  Int_t *fSeekLen; ///<[fNseek] Length of buffers to be prefetched
48  Int_t *fSeekSortLen; ///<[fNseek] Length of buffers to be prefetched (sorted)
49  Int_t *fSeekPos; ///<[fNseek] Position of sorted blocks in fBuffer
50  Int_t *fLen; ///<[fNb] Length of long buffers
51  TFile *fFile; ///< Pointer to file
52  char *fBuffer; ///<[fBufferSize] buffer of contiguous prefetched blocks
53  Bool_t fIsSorted; ///< True if fSeek array is sorted
54  Bool_t fIsTransferred; ///< True when fBuffer contains something valid
55  Long64_t fPrefetchedBlocks; ///< Number of blocks prefetched.
56 
57  //variables for the second block prefetched with the same semantics as for the first one
58  Int_t fBNseek;
59  Int_t fBNtot;
60  Int_t fBNb;
61  Int_t fBSeekSize;
62  Long64_t *fBSeek; ///<[fBNseek]
63  Long64_t *fBSeekSort; ///<[fBNseek]
64  Int_t *fBSeekIndex; ///<[fBNseek]
65  Long64_t *fBPos; ///<[fBNb]
66  Int_t *fBSeekLen; ///<[fBNseek]
67  Int_t *fBSeekSortLen; ///<[fBNseek]
68  Int_t *fBSeekPos; ///<[fBNseek]
69  Int_t *fBLen; ///<[fBNb]
70  Bool_t fBIsSorted;
71  Bool_t fBIsTransferred;
72 
73  void SetEnablePrefetchingImpl(Bool_t setPrefetching = kFALSE); // Can not be virtual as it is called from the constructor.
74 
75 private:
76  TFileCacheRead(const TFileCacheRead &) = delete; //cannot be copied
77  TFileCacheRead& operator=(const TFileCacheRead &) = delete;
78 
79 public:
80  TFileCacheRead();
81  TFileCacheRead(TFile *file, Int_t buffersize, TObject *tree = nullptr);
82  virtual ~TFileCacheRead();
83  virtual Int_t AddBranch(TBranch * /*b*/, Bool_t /*subbranches*/ = kFALSE) { return 0; }
84  virtual Int_t AddBranch(const char * /*branch*/, Bool_t /*subbranches*/ = kFALSE) { return 0; }
85  virtual void AddNoCacheBytesRead(Long64_t len) { fNoCacheBytesRead += len; }
86  virtual void AddNoCacheReadCalls(Int_t reads) { fNoCacheReadCalls += reads; }
87  virtual void Close(Option_t *option="");
88  virtual Int_t GetBufferSize() const { return fBufferSize; };
89  virtual Long64_t GetBytesRead() const { return fBytesRead; }
90  virtual Long64_t GetNoCacheBytesRead() const { return fNoCacheBytesRead; }
91  virtual Long64_t GetBytesReadExtra() const { return fBytesReadExtra; }
92  TFile *GetFile() const { return fFile; } // Return the TFile being cached.
93  Int_t GetNseek() const { return fNseek; } // Return the number of blocks in the current cache.
94  Int_t GetNtot() const { return fNtot; } // Return the total size of the prefetched blocks.
95  virtual Int_t GetReadCalls() const { return fReadCalls; }
96  virtual Int_t GetNoCacheReadCalls() const { return fNoCacheReadCalls; }
97  virtual Int_t GetUnzipBuffer(char ** /*buf*/, Long64_t /*pos*/, Int_t /*len*/, Bool_t * /*free*/) { return -1; }
98  Long64_t GetPrefetchedBlocks() const { return fPrefetchedBlocks; }
99  virtual Bool_t IsAsyncReading() const { return fAsyncReading; };
100  virtual void SetEnablePrefetching(Bool_t setPrefetching = kFALSE);
101  virtual Bool_t IsEnablePrefetching() const { return fEnablePrefetching; };
102  virtual Bool_t IsLearning() const {return kFALSE;}
103  virtual Int_t LearnBranch(TBranch * /*b*/, Bool_t /*subbranches*/ = kFALSE) { return 0; }
104  virtual void Prefetch(Long64_t pos, Int_t len);
105  virtual void Print(Option_t *option="") const;
106  virtual Int_t ReadBufferExt(char *buf, Long64_t pos, Int_t len, Int_t &loc);
107  virtual Int_t ReadBufferExtNormal(char *buf, Long64_t pos, Int_t len, Int_t &loc);
108  virtual Int_t ReadBufferExtPrefetch(char *buf, Long64_t pos, Int_t len, Int_t &loc);
109  virtual Int_t ReadBuffer(char *buf, Long64_t pos, Int_t len);
110  virtual Int_t SetBufferSize(Int_t buffersize);
111  virtual void SetFile(TFile *file, TFile::ECacheAction action = TFile::kDisconnect);
112  virtual void SetSkipZip(Bool_t /*skip*/ = kTRUE) {} // This function is only used by TTreeCacheUnzip (ignore it)
113  virtual void Sort();
114  virtual void SecondSort(); //Method used to sort and merge the chunks in the second block
115  virtual void SecondPrefetch(Long64_t, Int_t); //Used to add chunks to the second block
116  virtual TFilePrefetch* GetPrefetchObj();
117  virtual void WaitFinishPrefetch(); //Gracefully join the prefetching thread
118 
119  ClassDef(TFileCacheRead,2) //TFile cache when reading
120 };
121 
122 #endif