github.com/lbryio/lbcd@v0.22.119/database/ffldb/ldbtreapiter.go (about)

     1  // Copyright (c) 2015-2016 The btcsuite developers
     2  // Use of this source code is governed by an ISC
     3  // license that can be found in the LICENSE file.
     4  
     5  package ffldb
     6  
     7  import (
     8  	"github.com/lbryio/lbcd/database/internal/treap"
     9  	"github.com/syndtr/goleveldb/leveldb/iterator"
    10  	"github.com/syndtr/goleveldb/leveldb/util"
    11  )
    12  
    13  // ldbTreapIter wraps a treap iterator to provide the additional functionality
    14  // needed to satisfy the leveldb iterator.Iterator interface.
    15  type ldbTreapIter struct {
    16  	*treap.Iterator
    17  	tx       *transaction
    18  	released bool
    19  }
    20  
    21  // Enforce ldbTreapIter implements the leveldb iterator.Iterator interface.
    22  var _ iterator.Iterator = (*ldbTreapIter)(nil)
    23  
    24  // Error is only provided to satisfy the iterator interface as there are no
    25  // errors for this memory-only structure.
    26  //
    27  // This is part of the leveldb iterator.Iterator interface implementation.
    28  func (iter *ldbTreapIter) Error() error {
    29  	return nil
    30  }
    31  
    32  // SetReleaser is only provided to satisfy the iterator interface as there is no
    33  // need to override it.
    34  //
    35  // This is part of the leveldb iterator.Iterator interface implementation.
    36  func (iter *ldbTreapIter) SetReleaser(releaser util.Releaser) {
    37  }
    38  
    39  // Release releases the iterator by removing the underlying treap iterator from
    40  // the list of active iterators against the pending keys treap.
    41  //
    42  // This is part of the leveldb iterator.Iterator interface implementation.
    43  func (iter *ldbTreapIter) Release() {
    44  	if !iter.released {
    45  		iter.tx.removeActiveIter(iter.Iterator)
    46  		iter.released = true
    47  	}
    48  }
    49  
    50  // newLdbTreapIter creates a new treap iterator for the given slice against the
    51  // pending keys for the passed transaction and returns it wrapped in an
    52  // ldbTreapIter so it can be used as a leveldb iterator.  It also adds the new
    53  // iterator to the list of active iterators for the transaction.
    54  func newLdbTreapIter(tx *transaction, slice *util.Range) *ldbTreapIter {
    55  	iter := tx.pendingKeys.Iterator(slice.Start, slice.Limit)
    56  	tx.addActiveIter(iter)
    57  	return &ldbTreapIter{Iterator: iter, tx: tx}
    58  }