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Reference Guide
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1 // @(#)root/tree:$Id$
2 // Author: Rene Brun 19/01/96
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  *************************************************************************/
12 #ifndef ROOT_TBasket
13 #define ROOT_TBasket
15 //////////////////////////////////////////////////////////////////////////
16 // //
17 // TBasket //
18 // //
19 // The TBasket objects are created at run time to collect TTree entries //
20 // in buffers. When a Basket is full, it is written to the file. //
21 // The Basket is kept in memory if there is enough space. //
22 // (see the fMaxVirtualsize of TTree). //
23 // //
24 // The Basket class derives from TKey. //
25 //////////////////////////////////////////////////////////////////////////
28 #include "TKey.h"
30 class TFile;
31 class TTree;
32 class TBranch;
34 class TBasket : public TKey {
36 private:
37  TBasket(const TBasket&); ///< TBasket objects are not copiable.
38  TBasket& operator=(const TBasket&); ///< TBasket objects are not copiable.
40  // Internal corner cases for ReadBasketBuffers
44  // Helper for managing the compressed buffer.
47  // Handles special logic around deleting / reseting the entry offset pointer.
48  void ResetEntryOffset();
50  // Get entry offset as result of a calculation.
53  // Returns true if the underlying TLeaf can regenerate the entry offsets for us.
56 protected:
57  Int_t fBufferSize{0}; ///< fBuffer length in bytes
58  Int_t fNevBufSize{0}; ///< Length in Int_t of fEntryOffset OR fixed length of each entry if fEntryOffset is null!
59  Int_t fNevBuf{0}; ///< Number of entries in basket
60  Int_t fLast{0}; ///< Pointer to last used byte in basket
61  Bool_t fHeaderOnly{kFALSE}; ///< True when only the basket header must be read/written
62  UChar_t fIOBits{0}; ///<!IO feature flags. Serialized in custom portion of streamer to avoid forward compat issues unless needed.
63  Bool_t fOwnsCompressedBuffer{kFALSE}; ///<! Whether or not we own the compressed buffer.
64  Bool_t fReadEntryOffset{kFALSE}; ///<!Set to true if offset array was read from a file.
65  Int_t *fDisplacement{nullptr}; ///<![fNevBuf] Displacement of entries in fBuffer(TKey)
66  Int_t *fEntryOffset{nullptr}; ///<[fNevBuf] Offset of entries in fBuffer(TKey); generated at runtime. Special value
67  /// of `-1` indicates that the offset generation MUST be performed on first read.
68  TBranch *fBranch{nullptr}; ///<Pointer to the basket support branch
69  TBuffer *fCompressedBufferRef{nullptr}; ///<! Compressed buffer.
70  Int_t fLastWriteBufferSize{0}; ///<! Size of the buffer last time we wrote it to disk
72 public:
73  // The IO bits flag is to provide improved forward-compatibility detection.
74  // Any new non-forward compatibility flags related serialization should be
75  // added here. When a new flag is added, set it in the kSupported field;
76  //
77  // The values and names of this (and EUnsupportedIOBits) enum need not be aligned
78  // with the values of the various TIOFeatures enums, as there's a clean separation
79  // between these two interfaces. Practically, it is reasonable to keep them as aligned
80  // as possible in order to avoid confusion.
81  //
82  // If (fIOBits & ~kSupported) is non-zero -- i.e., an unknown IO flag is set
83  // in the fIOBits -- then the zombie flag will be set for this object.
84  //
85  enum class EIOBits : Char_t {
86  // The following to bits are reserved for now; when supported, set
87  // kSupported = kGenerateOffsetMap | kBasketClassMap
89  // kBasketClassMap = BIT(1),
91  };
92  // This enum covers IOBits that are known to this ROOT release but
93  // not supported; provides a mechanism for us to have experimental
94  // changes that are not going go into a supported release.
95  //
96  // (kUnsupported | kSupported) should result in the '|' of all IOBits.
97  enum class EUnsupportedIOBits : Char_t { kUnsupported = 0 };
98  // The number of known, defined IOBits.
99  static constexpr int kIOBitCount = 1;
101  TBasket();
102  TBasket(TDirectory *motherDir);
103  TBasket(const char *name, const char *title, TBranch *branch);
104  virtual ~TBasket();
106  virtual void AdjustSize(Int_t newsize);
107  virtual void DeleteEntryOffset();
108  virtual Int_t DropBuffers();
109  TBranch *GetBranch() const {return fBranch;}
110  Int_t GetBufferSize() const {return fBufferSize;}
113  {
114  return R__likely(fEntryOffset != reinterpret_cast<Int_t *>(-1)) ? fEntryOffset : GetCalculatedEntryOffset();
115  }
116  Int_t GetEntryPointer(Int_t Entry);
117  Int_t GetNevBuf() const {return fNevBuf;}
118  Int_t GetNevBufSize() const {return fNevBufSize;}
119  Int_t GetLast() const {return fLast;}
120  virtual void MoveEntries(Int_t dentries);
121  virtual void PrepareBasket(Long64_t /* entry */) {};
122  Int_t ReadBasketBuffers(Long64_t pos, Int_t len, TFile *file);
123  Int_t ReadBasketBytes(Long64_t pos, TFile *file);
124  virtual void Reset();
126  Int_t LoadBasketBuffers(Long64_t pos, Int_t len, TFile *file, TTree *tree = 0);
127  Long64_t CopyTo(TFile *to);
129  void SetBranch(TBranch *branch) { fBranch = branch; }
131  virtual void SetReadMode();
132  virtual void SetWriteMode();
133  inline void Update(Int_t newlast) { Update(newlast,newlast); };
134  virtual void Update(Int_t newlast, Int_t skipped);
135  virtual Int_t WriteBuffer();
137  ClassDef(TBasket, 3); // the TBranch buffers
138 };
140 #endif
void ResetEntryOffset()
Definition: TBasket.cxx:431
Int_t * GetEntryOffset()
Definition: TBasket.h:112
Int_t ReadBasketBytes(Long64_t pos, TFile *file)
Read basket buffers in memory and cleanup.
Definition: TBasket.cxx:686
Bool_t fHeaderOnly
True when only the basket header must be read/written.
Definition: TBasket.h:61
Bool_t fReadEntryOffset
!Set to true if offset array was read from a file.
Definition: TBasket.h:64
Int_t fLastWriteBufferSize
! Size of the buffer last time we wrote it to disk
Definition: TBasket.h:70
virtual void SetReadMode()
Set read mode of basket.
Definition: TBasket.cxx:783
void Update(Int_t newlast)
Definition: TBasket.h:133
Int_t ReadBasketBuffers(Long64_t pos, Int_t len, TFile *file)
Read basket buffers in memory and cleanup.
Definition: TBasket.cxx:454
long long Long64_t
Definition: RtypesCore.h:69
Int_t * fDisplacement
![fNevBuf] Displacement of entries in fBuffer(TKey)
Definition: TBasket.h:65
Int_t GetNevBufSize() const
Definition: TBasket.h:118
Int_t fBufferSize
fBuffer length in bytes
Definition: TBasket.h:57
Int_t * fEntryOffset
[fNevBuf] Offset of entries in fBuffer(TKey); generated at runtime.
Definition: TBasket.h:66
#define BIT(n)
Definition: Rtypes.h:78
TBranch * fBranch
Pointer to the basket support branch.
Definition: TBasket.h:68
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format...
Definition: TFile.h:47
Buffer base class used for serializing objects.
Definition: TBuffer.h:40
int Int_t
Definition: RtypesCore.h:41
bool Bool_t
Definition: RtypesCore.h:59
Int_t fNevBuf
Number of entries in basket.
Definition: TBasket.h:59
void SetBranch(TBranch *branch)
Definition: TBasket.h:129
static constexpr int kIOBitCount
Definition: TBasket.h:99
#define ClassDef(name, id)
Definition: Rtypes.h:320
Definition: TBasket.h:85
virtual void Reset()
Reset the basket to the starting state.
Definition: TBasket.cxx:701
#define R__likely(expr)
Definition: RConfig.h:579
virtual Int_t WriteBuffer()
Write buffer of this basket on the current file.
Definition: TBasket.cxx:989
Bool_t CanGenerateOffsetArray()
Determine whether we can generate the offset array when this branch is read.
Definition: TBasket.cxx:208
Book space in a file, create I/O buffers, to fill them, (un)compress them.
Definition: TKey.h:24
TBranch * GetBranch() const
Definition: TBasket.h:109
void InitializeCompressedBuffer(Int_t len, TFile *file)
Initialize the compressed buffer; either from the TTree or create a local one.
Definition: TBasket.cxx:422
UChar_t fIOBits
!IO feature flags. Serialized in custom portion of streamer to avoid forward compat issues unless nee...
Definition: TBasket.h:62
Bool_t fOwnsCompressedBuffer
! Whether or not we own the compressed buffer.
Definition: TBasket.h:63
Int_t * GetDisplacement() const
Definition: TBasket.h:111
virtual void AdjustSize(Int_t newsize)
Increase the size of the current fBuffer up to newsize.
Definition: TBasket.cxx:121
Int_t GetLast() const
Definition: TBasket.h:119
Int_t ReadBasketBuffersUncompressedCase()
By-passing buffer unzipping has been requested and is possible (only 1 entry in this basket)...
Definition: TBasket.cxx:348
Int_t GetEntryPointer(Int_t Entry)
Get pointer to buffer for internal entry.
Definition: TBasket.cxx:220
Manages buffers for branches of a Tree.
Definition: TBasket.h:34
TBuffer * fCompressedBufferRef
! Compressed buffer.
Definition: TBasket.h:69
Int_t fNevBufSize
Length in Int_t of fEntryOffset OR fixed length of each entry if fEntryOffset is null! ...
Definition: TBasket.h:58
const Bool_t kFALSE
Definition: RtypesCore.h:88
Describe directory structure in memory.
Definition: TDirectory.h:34
virtual ~TBasket()
Basket destructor.
Definition: TBasket.cxx:103
TBasket & operator=(const TBasket &)
TBasket objects are not copiable.
char Char_t
Definition: RtypesCore.h:29
Int_t GetNevBuf() const
Definition: TBasket.h:117
virtual void DeleteEntryOffset()
Delete fEntryOffset array.
Definition: TBasket.cxx:154
virtual Int_t DropBuffers()
Drop buffers of this basket if it is not the current basket.
Definition: TBasket.cxx:163
virtual void PrepareBasket(Long64_t)
Definition: TBasket.h:121
Definition: file.py:1
Int_t fLast
Pointer to last used byte in basket.
Definition: TBasket.h:60
Int_t * GetCalculatedEntryOffset()
Calculates the entry offset array, if possible.
Definition: TBasket.cxx:185
Int_t GetBufferSize() const
Definition: TBasket.h:110
Definition: tree.py:1
A TTree object has a header with a name and a title.
Definition: TTree.h:70
Long64_t CopyTo(TFile *to)
Copy the basket of this branch onto the file to.
Definition: TBasket.cxx:136
unsigned char UChar_t
Definition: RtypesCore.h:34
void SetNevBufSize(Int_t n)
Definition: TBasket.h:130
Int_t ReadBasketBuffersUnzip(char *, Int_t, Bool_t, TFile *)
We always create the TBuffer for the basket but it hold the buffer from the cache.
Definition: TBasket.cxx:370
A TTree is a list of TBranches.
Definition: TBranch.h:62
const Int_t n
Definition: legend1.C:16
Default contructor.
Definition: TBasket.cxx:46
virtual void SetWriteMode()
Set write mode of basket.
Definition: TBasket.cxx:792
char name[80]
Definition: TGX11.cxx:109
Definition: TBasket.h:97
Int_t LoadBasketBuffers(Long64_t pos, Int_t len, TFile *file, TTree *tree=0)
Load basket buffers in memory without unziping.
Definition: TBasket.cxx:235
virtual void MoveEntries(Int_t dentries)
Remove the first dentries of this basket, moving entries at dentries to the start of the buffer...
Definition: TBasket.cxx:300