Revision 1068d2fa60e768b792912caf602609e66e59d948 authored by Igor Canadi on 23 April 2014, 01:38:10 UTC, committed by Igor Canadi on 23 April 2014, 01:38:10 UTC
This reverts commit ddafceb6c2ecb83b7bdf6711ea1c30d97aeb3b8f.
1 parent ddafceb
prefix_filter_iterator.h
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Wrap an underlying iterator, but exclude any results not starting
// with a given prefix. Seeking to keys not beginning with the prefix
// is invalid, and SeekToLast is not implemented (that would be
// non-trivial), but otherwise this iterator will behave just like the
// underlying iterator would if there happened to be no non-matching
// keys in the dataset.
#pragma once
#include "rocksdb/iterator.h"
#include "rocksdb/slice.h"
#include "rocksdb/slice_transform.h"
namespace rocksdb {
class PrefixFilterIterator : public Iterator {
private:
Iterator* iter_;
const Slice &prefix_;
const SliceTransform *prefix_extractor_;
Status status_;
public:
PrefixFilterIterator(Iterator* iter,
const Slice &prefix,
const SliceTransform* prefix_extractor)
: iter_(iter), prefix_(prefix),
prefix_extractor_(prefix_extractor),
status_(Status::OK()) {
if (prefix_extractor == nullptr) {
status_ = Status::InvalidArgument("A prefix filter may not be used "
"unless a function is also defined "
"for extracting prefixes");
} else if (!prefix_extractor_->InRange(prefix)) {
status_ = Status::InvalidArgument("Must provide a slice for prefix which"
"is a prefix for some key");
}
}
~PrefixFilterIterator() {
delete iter_;
}
Slice key() const { return iter_->key(); }
Slice value() const { return iter_->value(); }
Status status() const {
if (!status_.ok()) {
return status_;
}
return iter_->status();
}
void Next() { iter_->Next(); }
void Prev() { iter_->Prev(); }
void Seek(const Slice& k) {
if (prefix_extractor_->Transform(k) == prefix_) {
iter_->Seek(k);
} else {
status_ = Status::InvalidArgument("Seek must begin with target prefix");
}
}
void SeekToFirst() {
Seek(prefix_);
}
void SeekToLast() {
status_ = Status::NotSupported("SeekToLast is incompatible with prefixes");
}
bool Valid() const {
return (status_.ok() && iter_->Valid() &&
prefix_extractor_->Transform(iter_->key()) == prefix_);
}
};
} // namespace rocksdb
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