YugabyteDB (2.13.1.0-b60, 21121d69985fbf76aa6958d8f04a9bfa936293b5)

// Copyright (c) 2011-present, 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.

//

// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions Copyright (c) YugaByte, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied.  See the License for the specific language governing permissions and limitations

// under the License.

//

#ifndef ROCKSDB_TABLE_BLOCK_PREFIX_INDEX_H

#define ROCKSDB_TABLE_BLOCK_PREFIX_INDEX_H

#pragma once

#include <stdint.h>

#include "yb/util/slice.h"

#include "yb/rocksdb/status.h"

namespace rocksdb {

class Comparator;

class Iterator;

class SliceTransform;

// Build a hash-based index to speed up the lookup for "index block".

// BlockHashIndex accepts a key and, if found, returns its restart index within

// that index block.

class BlockPrefixIndex {

 public:

  // Maps a key to a list of data blocks that could potentially contain

  // the key, based on the prefix.

  // Returns the total number of relevant blocks, 0 means the key does

  // not exist.

  uint32_t GetBlocks(const Slice& key, uint32_t** blocks);

  size_t ApproximateMemoryUsage() const {

    return sizeof(BlockPrefixIndex) +

      (num_block_array_buffer_entries_ + num_buckets_) * sizeof(uint32_t);

  }

  // Create hash index by reading from the metadata blocks.

  // @params prefixes: a sequence of prefixes.

  // @params prefix_meta: contains the "metadata" to of the prefixes.

  static Status Create(const SliceTransform* hash_key_extractor,

                       const Slice& prefixes, const Slice& prefix_meta,

                       BlockPrefixIndex** prefix_index);

  ~BlockPrefixIndex() {

    delete[] buckets_;

    delete[] block_array_buffer_;

  }

 private:

  class Builder;

  friend Builder;

  BlockPrefixIndex(const SliceTransform* internal_prefix_extractor,

                   uint32_t num_buckets,

                   uint32_t* buckets,

                   uint32_t num_block_array_buffer_entries,

                   uint32_t* block_array_buffer)

      : internal_prefix_extractor_(internal_prefix_extractor),

        num_buckets_(num_buckets),

        num_block_array_buffer_entries_(num_block_array_buffer_entries),

        buckets_(buckets),

        block_array_buffer_(block_array_buffer) {}

  const SliceTransform* internal_prefix_extractor_;

  uint32_t num_buckets_;

  uint32_t num_block_array_buffer_entries_;

  uint32_t* buckets_;

  uint32_t* block_array_buffer_;

};

}  // namespace rocksdb

#endif // ROCKSDB_TABLE_BLOCK_PREFIX_INDEX_H