|
|
|
// 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"
|
|
|
|
|
|
|
|
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
|