leveldb::anonymous_namespace{merger.cc}::MergingIterator Class Reference

Inheritance diagram for leveldb::anonymous_namespace{merger.cc}::MergingIterator:

Collaboration diagram for leveldb::anonymous_namespace{merger.cc}::MergingIterator:

Public Member Functions
	MergingIterator (const Comparator *comparator, Iterator **children, int n)
virtual	~MergingIterator ()
virtual bool	Valid () const
virtual void	SeekToFirst ()
virtual void	SeekToLast ()
virtual void	Seek (const Slice &target)
virtual void	Next ()
virtual void	Prev ()
virtual Slice	key () const
virtual Slice	value () const
virtual Status	status () const
Public Member Functions inherited from leveldb::Iterator
	Iterator ()
virtual	~Iterator ()
void	RegisterCleanup (CleanupFunction function, void *arg1, void *arg2)

Private Types
enum	Direction { kForward, kReverse }

Private Member Functions
void	FindSmallest ()
void	FindLargest ()

Private Attributes
const Comparator *	comparator_
IteratorWrapper *	children_
int	n_
IteratorWrapper *	current_
Direction	direction_

Additional Inherited Members
Public Types inherited from leveldb::Iterator
typedef void(*	CleanupFunction) (void *arg1, void *arg2)

Detailed Description

Definition at line 14 of file merger.cc.

Member Enumeration Documentation

Direction

enum leveldb::anonymous_namespace{merger.cc}::MergingIterator::Direction

private

Enumerator
kForward
kReverse

Definition at line 148 of file merger.cc.

                 {
    kForward,
    kReverse
  };

Constructor & Destructor Documentation

MergingIterator()

leveldb::anonymous_namespace{merger.cc}::MergingIterator::MergingIterator ( const Comparator *  comparator, Iterator **  children, int  n  )

inline

Definition at line 16 of file merger.cc.

      : comparator_(comparator),
        children_(new IteratorWrapper[n]),
        n_(n),
        current_(NULL),
        direction_(kForward) {
    for (int i = 0; i < n; i++) {
      children_[i].Set(children[i]);
    }
  }

~MergingIterator()

virtual leveldb::anonymous_namespace{merger.cc}::MergingIterator::~MergingIterator ( )

inlinevirtual

Definition at line 27 of file merger.cc.

                             {
    delete[] children_;
  }

Member Function Documentation

FindLargest()

void leveldb::anonymous_namespace{merger.cc}::MergingIterator::FindLargest ( )

private

Definition at line 170 of file merger.cc.

                                  {
  IteratorWrapper* largest = NULL;
  for (int i = n_-1; i >= 0; i--) {
    IteratorWrapper* child = &children_[i];
    if (child->Valid()) {
      if (largest == NULL) {
        largest = child;
      } else if (comparator_->Compare(child->key(), largest->key()) > 0) {
        largest = child;
      }
    }
  }
  current_ = largest;
}

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FindSmallest()

void leveldb::anonymous_namespace{merger.cc}::MergingIterator::FindSmallest ( )

private

Definition at line 155 of file merger.cc.

                                   {
  IteratorWrapper* smallest = NULL;
  for (int i = 0; i < n_; i++) {
    IteratorWrapper* child = &children_[i];
    if (child->Valid()) {
      if (smallest == NULL) {
        smallest = child;
      } else if (comparator_->Compare(child->key(), smallest->key()) < 0) {
        smallest = child;
      }
    }
  }
  current_ = smallest;
}

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key()

virtual Slice leveldb::anonymous_namespace{merger.cc}::MergingIterator::key ( ) const

inlinevirtual

Implements leveldb::Iterator.

Definition at line 114 of file merger.cc.

                            {
    assert(Valid());
    return current_->key();
  }

Next()

virtual void leveldb::anonymous_namespace{merger.cc}::MergingIterator::Next ( )

inlinevirtual

Implements leveldb::Iterator.

Definition at line 59 of file merger.cc.

                      {
    assert(Valid());

    // Ensure that all children are positioned after key().
    // If we are moving in the forward direction, it is already
    // true for all of the non-current_ children since current_ is
    // the smallest child and key() == current_->key().  Otherwise,
    // we explicitly position the non-current_ children.
    if (direction_ != kForward) {
      for (int i = 0; i < n_; i++) {
        IteratorWrapper* child = &children_[i];
        if (child != current_) {
          child->Seek(key());
          if (child->Valid() &&
              comparator_->Compare(key(), child->key()) == 0) {
            child->Next();
          }
        }
      }
      direction_ = kForward;
    }

    current_->Next();
    FindSmallest();
  }

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Prev()

virtual void leveldb::anonymous_namespace{merger.cc}::MergingIterator::Prev ( )

inlinevirtual

Implements leveldb::Iterator.

Definition at line 85 of file merger.cc.

                      {
    assert(Valid());

    // Ensure that all children are positioned before key().
    // If we are moving in the reverse direction, it is already
    // true for all of the non-current_ children since current_ is
    // the largest child and key() == current_->key().  Otherwise,
    // we explicitly position the non-current_ children.
    if (direction_ != kReverse) {
      for (int i = 0; i < n_; i++) {
        IteratorWrapper* child = &children_[i];
        if (child != current_) {
          child->Seek(key());
          if (child->Valid()) {
            // Child is at first entry >= key().  Step back one to be < key()
            child->Prev();
          } else {
            // Child has no entries >= key().  Position at last entry.
            child->SeekToLast();
          }
        }
      }
      direction_ = kReverse;
    }

    current_->Prev();
    FindLargest();
  }

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Seek()

virtual void leveldb::anonymous_namespace{merger.cc}::MergingIterator::Seek ( const Slice &  target )

inlinevirtual

Implements leveldb::Iterator.

Definition at line 51 of file merger.cc.

                                         {
    for (int i = 0; i < n_; i++) {
      children_[i].Seek(target);
    }
    FindSmallest();
    direction_ = kForward;
  }

SeekToFirst()

virtual void leveldb::anonymous_namespace{merger.cc}::MergingIterator::SeekToFirst ( )

inlinevirtual

Implements leveldb::Iterator.

Definition at line 35 of file merger.cc.

                             {
    for (int i = 0; i < n_; i++) {
      children_[i].SeekToFirst();
    }
    FindSmallest();
    direction_ = kForward;
  }

SeekToLast()

virtual void leveldb::anonymous_namespace{merger.cc}::MergingIterator::SeekToLast ( )

inlinevirtual

Implements leveldb::Iterator.

Definition at line 43 of file merger.cc.

                            {
    for (int i = 0; i < n_; i++) {
      children_[i].SeekToLast();
    }
    FindLargest();
    direction_ = kReverse;
  }

status()

virtual Status leveldb::anonymous_namespace{merger.cc}::MergingIterator::status ( ) const

inlinevirtual

Implements leveldb::Iterator.

Definition at line 124 of file merger.cc.

                                {
    Status status;
    for (int i = 0; i < n_; i++) {
      status = children_[i].status();
      if (!status.ok()) {
        break;
      }
    }
    return status;
  }

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Valid()

virtual bool leveldb::anonymous_namespace{merger.cc}::MergingIterator::Valid ( ) const

inlinevirtual

Implements leveldb::Iterator.

Definition at line 31 of file merger.cc.

                             {
    return (current_ != NULL);
  }

value()

virtual Slice leveldb::anonymous_namespace{merger.cc}::MergingIterator::value ( ) const

inlinevirtual

Implements leveldb::Iterator.

Definition at line 119 of file merger.cc.

                              {
    assert(Valid());
    return current_->value();
  }

Member Data Documentation

children_

IteratorWrapper* leveldb::anonymous_namespace{merger.cc}::MergingIterator::children_

private

Definition at line 143 of file merger.cc.

comparator_

const Comparator* leveldb::anonymous_namespace{merger.cc}::MergingIterator::comparator_

private

Definition at line 142 of file merger.cc.

current_

IteratorWrapper* leveldb::anonymous_namespace{merger.cc}::MergingIterator::current_

private

Definition at line 145 of file merger.cc.

direction_

Direction leveldb::anonymous_namespace{merger.cc}::MergingIterator::direction_

private

Definition at line 152 of file merger.cc.

n_

int leveldb::anonymous_namespace{merger.cc}::MergingIterator::n_

private

Definition at line 144 of file merger.cc.

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

• table/merger.cc