leveldb::InternalKeyComparator Class Reference

#include <dbformat.h>

Inheritance diagram for leveldb::InternalKeyComparator:

Collaboration diagram for leveldb::InternalKeyComparator:

Public Member Functions
	InternalKeyComparator (const Comparator *c)
virtual const char *	Name () const
virtual int	Compare (const Slice &a, const Slice &b) const
virtual void	FindShortestSeparator (std::string *start, const Slice &limit) const
virtual void	FindShortSuccessor (std::string *key) const
const Comparator *	user_comparator () const
int	Compare (const InternalKey &a, const InternalKey &b) const
Public Member Functions inherited from leveldb::Comparator
int	operator() (const Key &a, const Key &b) const
virtual	~Comparator ()

Private Attributes
const Comparator *	user_comparator_

Detailed Description

Definition at line 113 of file dbformat.h.

Constructor & Destructor Documentation

InternalKeyComparator()

leveldb::InternalKeyComparator::InternalKeyComparator ( const Comparator *  c )

inlineexplicit

Definition at line 117 of file dbformat.h.

: user_comparator_(c) { }

Member Function Documentation

Compare() [1/2]

int leveldb::InternalKeyComparator::Compare ( const Slice &  a, const Slice &  b  ) const

virtual

Implements leveldb::Comparator.

Definition at line 50 of file dbformat.cc.

                                                                             {
  // Order by:
  //    increasing user key (according to user-supplied comparator)
  //    decreasing sequence number
  //    decreasing type (though sequence# should be enough to disambiguate)
  int r = user_comparator_->Compare(ExtractUserKey(akey), ExtractUserKey(bkey));
  if (r == 0) {
    const uint64_t anum = DecodeFixed64(akey.data() + akey.size() - 8);
    const uint64_t bnum = DecodeFixed64(bkey.data() + bkey.size() - 8);
    if (anum > bnum) {
      r = -1;
    } else if (anum < bnum) {
      r = +1;
    }
  }
  return r;
}

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Compare() [2/2]

int leveldb::InternalKeyComparator::Compare ( const InternalKey &  a, const InternalKey &  b  ) const

inline

Definition at line 171 of file dbformat.h.

                                                      {
  return Compare(a.Encode(), b.Encode());
}

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FindShortestSeparator()

void leveldb::InternalKeyComparator::FindShortestSeparator ( std::string *  start, const Slice &  limit  ) const

virtual

Implements leveldb::Comparator.

Definition at line 68 of file dbformat.cc.

                                {
  // Attempt to shorten the user portion of the key
  Slice user_start = ExtractUserKey(*start);
  Slice user_limit = ExtractUserKey(limit);
  std::string tmp(user_start.data(), user_start.size());
  user_comparator_->FindShortestSeparator(&tmp, user_limit);
  if (tmp.size() < user_start.size() &&
      user_comparator_->Compare(user_start, tmp) < 0) {
    // User key has become shorter physically, but larger logically.
    // Tack on the earliest possible number to the shortened user key.
    PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
    assert(this->Compare(*start, tmp) < 0);
    assert(this->Compare(tmp, limit) < 0);
    start->swap(tmp);
  }
}

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FindShortSuccessor()

void leveldb::InternalKeyComparator::FindShortSuccessor ( std::string *  key ) const

virtual

Implements leveldb::Comparator.

Definition at line 87 of file dbformat.cc.

                                                                   {
  Slice user_key = ExtractUserKey(*key);
  std::string tmp(user_key.data(), user_key.size());
  user_comparator_->FindShortSuccessor(&tmp);
  if (tmp.size() < user_key.size() &&
      user_comparator_->Compare(user_key, tmp) < 0) {
    // User key has become shorter physically, but larger logically.
    // Tack on the earliest possible number to the shortened user key.
    PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
    assert(this->Compare(*key, tmp) < 0);
    key->swap(tmp);
  }
}

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Name()

const char * leveldb::InternalKeyComparator::Name ( ) const

virtual

Implements leveldb::Comparator.

Definition at line 46 of file dbformat.cc.

                                              {
  return "leveldb.InternalKeyComparator";
}

user_comparator()

const Comparator* leveldb::InternalKeyComparator::user_comparator ( ) const

inline

Definition at line 125 of file dbformat.h.

{ return user_comparator_; }

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Member Data Documentation

user_comparator_

const Comparator* leveldb::InternalKeyComparator::user_comparator_

private

Definition at line 115 of file dbformat.h.

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The documentation for this class was generated from the following files:

• db/dbformat.h
• db/dbformat.cc