//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#include "table/meta_blocks.h"

#include <map>

#include <string>

#include "block_fetcher.h"

#include "db/table_properties_collector.h"

#include "file/random_access_file_reader.h"

#include "logging/logging.h"

#include "rocksdb/options.h"

#include "rocksdb/table.h"

#include "rocksdb/table_properties.h"

#include "table/block_based/block.h"

#include "table/block_based/reader_common.h"

#include "table/format.h"

#include "table/internal_iterator.h"

#include "table/persistent_cache_helper.h"

#include "table/sst_file_writer_collectors.h"

#include "table/table_properties_internal.h"

#include "test_util/sync_point.h"

#include "util/coding.h"

namespace ROCKSDB_NAMESPACE {

const std::string kPropertiesBlockName = "rocksdb.properties";

// NB: only used with format_version >= 6

const std::string kIndexBlockName = "rocksdb.index";

const std::string kCompressionDictBlockName = "rocksdb.compression_dict";

const std::string kRangeDelBlockName = "rocksdb.range_del";

MetaIndexBuilder::MetaIndexBuilder()

    : meta_index_block_(new BlockBuilder(1 /* restart interval */)) {}

void MetaIndexBuilder::Add(const std::string& key, const BlockHandle& handle) {

  std::string handle_encoding;

  handle.EncodeTo(&handle_encoding);

  meta_block_handles_.insert({key, handle_encoding});

}

Slice MetaIndexBuilder::Finish() {

  for (const auto& metablock : meta_block_handles_) {

    meta_index_block_->Add(metablock.first, metablock.second);

  }

  return meta_index_block_->Finish();

}

// Property block will be read sequentially and cached in a heap located

// object, so there's no need for restart points. Thus we set the restart

// interval to infinity to save space.

PropertyBlockBuilder::PropertyBlockBuilder()

    : properties_block_(new BlockBuilder(

          std::numeric_limits<int32_t>::max() /* restart interval */)) {}

void PropertyBlockBuilder::Add(const std::string& name,

                               const std::string& val) {

  assert(props_.find(name) == props_.end());

  props_.insert({name, val});

}

void PropertyBlockBuilder::Add(const std::string& name, uint64_t val) {

  std::string dst;

  PutVarint64(&dst, val);

  Add(name, dst);

}

void PropertyBlockBuilder::Add(

    const UserCollectedProperties& user_collected_properties) {

  for (const auto& prop : user_collected_properties) {

    Add(prop.first, prop.second);

  }

}

void PropertyBlockBuilder::AddTableProperty(const TableProperties& props) {

  TEST_SYNC_POINT_CALLBACK("PropertyBlockBuilder::AddTableProperty:Start",

                           const_cast<TableProperties*>(&props));

  Add(TablePropertiesNames::kOriginalFileNumber, props.orig_file_number);

  Add(TablePropertiesNames::kRawKeySize, props.raw_key_size);

  Add(TablePropertiesNames::kRawValueSize, props.raw_value_size);

  Add(TablePropertiesNames::kDataSize, props.data_size);

  Add(TablePropertiesNames::kIndexSize, props.index_size);

  if (props.index_partitions != 0) {

    Add(TablePropertiesNames::kIndexPartitions, props.index_partitions);

    Add(TablePropertiesNames::kTopLevelIndexSize, props.top_level_index_size);

  }

  Add(TablePropertiesNames::kIndexKeyIsUserKey, props.index_key_is_user_key);

  Add(TablePropertiesNames::kIndexValueIsDeltaEncoded,

      props.index_value_is_delta_encoded);

  Add(TablePropertiesNames::kNumEntries, props.num_entries);

  Add(TablePropertiesNames::kNumFilterEntries, props.num_filter_entries);

  Add(TablePropertiesNames::kDeletedKeys, props.num_deletions);

  Add(TablePropertiesNames::kMergeOperands, props.num_merge_operands);

  Add(TablePropertiesNames::kNumRangeDeletions, props.num_range_deletions);

  Add(TablePropertiesNames::kNumDataBlocks, props.num_data_blocks);

  Add(TablePropertiesNames::kNumUniformBlocks, props.num_uniform_blocks);

  Add(TablePropertiesNames::kFilterSize, props.filter_size);

  Add(TablePropertiesNames::kFormatVersion, props.format_version);

  Add(TablePropertiesNames::kFixedKeyLen, props.fixed_key_len);

  Add(TablePropertiesNames::kColumnFamilyId, props.column_family_id);

  Add(TablePropertiesNames::kCreationTime, props.creation_time);

  Add(TablePropertiesNames::kOldestKeyTime, props.oldest_key_time);

  Add(TablePropertiesNames::kNewestKeyTime, props.newest_key_time);

  if (props.file_creation_time > 0) {

    Add(TablePropertiesNames::kFileCreationTime, props.file_creation_time);

  }

  if (props.slow_compression_estimated_data_size > 0) {

    Add(TablePropertiesNames::kSlowCompressionEstimatedDataSize,

        props.slow_compression_estimated_data_size);

  }

  if (props.fast_compression_estimated_data_size > 0) {

    Add(TablePropertiesNames::kFastCompressionEstimatedDataSize,

        props.fast_compression_estimated_data_size);

  }

  Add(TablePropertiesNames::kTailStartOffset, props.tail_start_offset);

  if (props.user_defined_timestamps_persisted == 0) {

    Add(TablePropertiesNames::kUserDefinedTimestampsPersisted,

        props.user_defined_timestamps_persisted);

  }

  if (!props.db_id.empty()) {

    Add(TablePropertiesNames::kDbId, props.db_id);

  }

  if (!props.db_session_id.empty()) {

    Add(TablePropertiesNames::kDbSessionId, props.db_session_id);

  }

  if (!props.db_host_id.empty()) {

    Add(TablePropertiesNames::kDbHostId, props.db_host_id);

  }

  if (!props.filter_policy_name.empty()) {

    Add(TablePropertiesNames::kFilterPolicy, props.filter_policy_name);

  }

  if (!props.comparator_name.empty()) {

    Add(TablePropertiesNames::kComparator, props.comparator_name);

  }

  if (!props.merge_operator_name.empty()) {

    Add(TablePropertiesNames::kMergeOperator, props.merge_operator_name);

  }

  if (!props.prefix_extractor_name.empty()) {

    Add(TablePropertiesNames::kPrefixExtractorName,

        props.prefix_extractor_name);

  }

  if (!props.property_collectors_names.empty()) {

    Add(TablePropertiesNames::kPropertyCollectors,

        props.property_collectors_names);

  }

  if (!props.column_family_name.empty()) {

    Add(TablePropertiesNames::kColumnFamilyName, props.column_family_name);

  }

  if (!props.compression_name.empty()) {

    Add(TablePropertiesNames::kCompression, props.compression_name);

  }

  if (!props.compression_options.empty()) {

    Add(TablePropertiesNames::kCompressionOptions, props.compression_options);

  }

  if (!props.seqno_to_time_mapping.empty()) {

    Add(TablePropertiesNames::kSequenceNumberTimeMapping,

        props.seqno_to_time_mapping);

  }

  if (props.key_largest_seqno != UINT64_MAX) {

    Add(TablePropertiesNames::kKeyLargestSeqno, props.key_largest_seqno);

  }

  if (props.key_smallest_seqno != UINT64_MAX) {

    Add(TablePropertiesNames::kKeySmallestSeqno, props.key_smallest_seqno);

  }

  if (props.data_block_restart_interval > 0) {

    Add(TablePropertiesNames::kDataBlockRestartInterval,

        props.data_block_restart_interval);

  }

  if (props.index_block_restart_interval > 0) {

    Add(TablePropertiesNames::kIndexBlockRestartInterval,

        props.index_block_restart_interval);

  }

  if (props.separate_key_value_in_data_block > 0) {

    Add(TablePropertiesNames::kSeparateKeyValueInDataBlock,

        props.separate_key_value_in_data_block);

  }

}

Slice PropertyBlockBuilder::Finish() {

  for (const auto& prop : props_) {

    assert(last_prop_added_to_block_.empty() ||

           comparator_->Compare(prop.first, last_prop_added_to_block_) > 0);

    properties_block_->Add(prop.first, prop.second);

#ifndef NDEBUG

    last_prop_added_to_block_ = prop.first;

#endif /* !NDEBUG */

  }

  return properties_block_->Finish();

}

void LogPropertiesCollectionError(Logger* info_log, const std::string& method,

                                  const std::string& name) {

  assert(method == "Add" || method == "Finish");

  std::string msg =

      "Encountered error when calling TablePropertiesCollector::" + method +

      "() with collector name: " + name;

  ROCKS_LOG_ERROR(info_log, "%s", msg.c_str());

}

bool NotifyCollectTableCollectorsOnAdd(

    const Slice& key, const Slice& value, uint64_t file_size,

    const std::vector<std::unique_ptr<InternalTblPropColl>>& collectors,

    Logger* info_log) {

  bool all_succeeded = true;

  for (auto& collector : collectors) {

    Status s = collector->InternalAdd(key, value, file_size);

    all_succeeded = all_succeeded && s.ok();

    if (!s.ok()) {

      LogPropertiesCollectionError(info_log, "Add" /* method */,

                                   collector->Name());

    }

  }

  return all_succeeded;

}

void NotifyCollectTableCollectorsOnBlockAdd(

    const std::vector<std::unique_ptr<InternalTblPropColl>>& collectors,

    const uint64_t block_uncomp_bytes,

    const uint64_t block_compressed_bytes_fast,

    const uint64_t block_compressed_bytes_slow) {

  for (auto& collector : collectors) {

    collector->BlockAdd(block_uncomp_bytes, block_compressed_bytes_fast,

                        block_compressed_bytes_slow);

  }

}

bool NotifyCollectTableCollectorsOnFinish(

    const std::vector<std::unique_ptr<InternalTblPropColl>>& collectors,

    Logger* info_log, PropertyBlockBuilder* builder,

    UserCollectedProperties& user_collected_properties,

    UserCollectedProperties& readable_properties) {

  bool all_succeeded = true;

  for (auto& collector : collectors) {

    UserCollectedProperties user_properties;

    Status s = collector->Finish(&user_properties);

    if (s.ok()) {

      for (const auto& prop : collector->GetReadableProperties()) {

        readable_properties.insert(prop);

      }

#ifndef NDEBUG

      // Check different user properties collectors are not adding properties of

      // the same name.

      for (const auto& pair : user_properties) {

        assert(user_collected_properties.find(pair.first) ==

               user_collected_properties.end());

      }

#endif /* !NDEBUG */

      user_collected_properties.merge(user_properties);

    } else {

      LogPropertiesCollectionError(info_log, "Finish" /* method */,

                                   collector->Name());

      if (all_succeeded) {

        all_succeeded = false;

      }

    }

  }

  builder->Add(user_collected_properties);

  return all_succeeded;

}

Status ParsePropertiesBlock(

    const ImmutableOptions& ioptions, uint64_t offset, Block& properties_block,

    std::unique_ptr<TableProperties>& new_table_properties) {

  std::unique_ptr<MetaBlockIter> iter(properties_block.NewMetaIterator());

  //  All pre-defined properties of type uint64_t

  std::unordered_map<std::string, uint64_t*> predefined_uint64_properties = {

      {TablePropertiesNames::kOriginalFileNumber,

       &new_table_properties->orig_file_number},

      {TablePropertiesNames::kDataSize, &new_table_properties->data_size},

      {TablePropertiesNames::kIndexSize, &new_table_properties->index_size},

      {TablePropertiesNames::kIndexPartitions,

       &new_table_properties->index_partitions},

      {TablePropertiesNames::kTopLevelIndexSize,

       &new_table_properties->top_level_index_size},

      {TablePropertiesNames::kIndexKeyIsUserKey,

       &new_table_properties->index_key_is_user_key},

      {TablePropertiesNames::kIndexValueIsDeltaEncoded,

       &new_table_properties->index_value_is_delta_encoded},

      {TablePropertiesNames::kFilterSize, &new_table_properties->filter_size},

      {TablePropertiesNames::kRawKeySize, &new_table_properties->raw_key_size},

      {TablePropertiesNames::kRawValueSize,

       &new_table_properties->raw_value_size},

      {TablePropertiesNames::kNumDataBlocks,

       &new_table_properties->num_data_blocks},

      {TablePropertiesNames::kNumUniformBlocks,

       &new_table_properties->num_uniform_blocks},

      {TablePropertiesNames::kNumEntries, &new_table_properties->num_entries},

      {TablePropertiesNames::kNumFilterEntries,

       &new_table_properties->num_filter_entries},

      {TablePropertiesNames::kDeletedKeys,

       &new_table_properties->num_deletions},

      {TablePropertiesNames::kMergeOperands,

       &new_table_properties->num_merge_operands},

      {TablePropertiesNames::kNumRangeDeletions,

       &new_table_properties->num_range_deletions},

      {TablePropertiesNames::kFormatVersion,

       &new_table_properties->format_version},

      {TablePropertiesNames::kFixedKeyLen,

       &new_table_properties->fixed_key_len},

      {TablePropertiesNames::kColumnFamilyId,

       &new_table_properties->column_family_id},

      {TablePropertiesNames::kCreationTime,

       &new_table_properties->creation_time},

      {TablePropertiesNames::kOldestKeyTime,

       &new_table_properties->oldest_key_time},

      {TablePropertiesNames::kNewestKeyTime,

       &new_table_properties->newest_key_time},

      {TablePropertiesNames::kFileCreationTime,

       &new_table_properties->file_creation_time},

      {TablePropertiesNames::kSlowCompressionEstimatedDataSize,

       &new_table_properties->slow_compression_estimated_data_size},

      {TablePropertiesNames::kFastCompressionEstimatedDataSize,

       &new_table_properties->fast_compression_estimated_data_size},

      {TablePropertiesNames::kTailStartOffset,

       &new_table_properties->tail_start_offset},

      {TablePropertiesNames::kUserDefinedTimestampsPersisted,

       &new_table_properties->user_defined_timestamps_persisted},

      {TablePropertiesNames::kKeyLargestSeqno,

       &new_table_properties->key_largest_seqno},

      {TablePropertiesNames::kKeySmallestSeqno,

       &new_table_properties->key_smallest_seqno},

      {TablePropertiesNames::kDataBlockRestartInterval,

       &new_table_properties->data_block_restart_interval},

      {TablePropertiesNames::kIndexBlockRestartInterval,

       &new_table_properties->index_block_restart_interval},

      {TablePropertiesNames::kSeparateKeyValueInDataBlock,

       &new_table_properties->separate_key_value_in_data_block},

  };

  Status s;

  std::string last_key;

  for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {

    s = iter->status();

    if (!s.ok()) {

      break;

    }

    auto key = iter->key().ToString();

    // properties block should be strictly sorted with no duplicate key.

    if (!last_key.empty() &&

        BytewiseComparator()->Compare(key, last_key) <= 0) {

      s = Status::Corruption("properties unsorted");

      break;

    }

    last_key = key;

    auto raw_val = iter->value();

    auto pos = predefined_uint64_properties.find(key);

    if (key == ExternalSstFilePropertyNames::kGlobalSeqno) {

      new_table_properties->external_sst_file_global_seqno_offset =

          offset + iter->ValueOffset();

    }

    if (pos != predefined_uint64_properties.end()) {

      if (key == TablePropertiesNames::kDeletedKeys ||

          key == TablePropertiesNames::kMergeOperands) {

        // Insert in user-collected properties for API backwards compatibility

        new_table_properties->user_collected_properties.insert(

            {key, raw_val.ToString()});

      }

      // handle predefined rocksdb properties

      uint64_t val;

      if (!GetVarint64(&raw_val, &val)) {

        // skip malformed value

        auto error_msg =

            "Detect malformed value in properties meta-block:"

            "\tkey: " +

            key + "\tval: " + raw_val.ToString();

        ROCKS_LOG_ERROR(ioptions.logger, "%s", error_msg.c_str());

        continue;

      }

      *(pos->second) = val;

    } else if (key == TablePropertiesNames::kDbId) {

      new_table_properties->db_id = raw_val.ToString();

    } else if (key == TablePropertiesNames::kDbSessionId) {

      new_table_properties->db_session_id = raw_val.ToString();

    } else if (key == TablePropertiesNames::kDbHostId) {

      new_table_properties->db_host_id = raw_val.ToString();

    } else if (key == TablePropertiesNames::kFilterPolicy) {

      new_table_properties->filter_policy_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kColumnFamilyName) {

      new_table_properties->column_family_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kComparator) {

      new_table_properties->comparator_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kMergeOperator) {

      new_table_properties->merge_operator_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kPrefixExtractorName) {

      new_table_properties->prefix_extractor_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kPropertyCollectors) {

      new_table_properties->property_collectors_names = raw_val.ToString();

    } else if (key == TablePropertiesNames::kCompression) {

      new_table_properties->compression_name = raw_val.ToString();

    } else if (key == TablePropertiesNames::kCompressionOptions) {

      new_table_properties->compression_options = raw_val.ToString();

    } else if (key == TablePropertiesNames::kSequenceNumberTimeMapping) {

      new_table_properties->seqno_to_time_mapping = raw_val.ToString();

    } else {

      // handle user-collected properties

      new_table_properties->user_collected_properties.insert(

          {key, raw_val.ToString()});

    }

  }

  return s;

}

// FIXME: should be a parameter for reading table properties to use persistent

// cache?

Status ReadTablePropertiesHelper(

    const ReadOptions& ro, const BlockHandle& handle,

    RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,

    const Footer& footer, const ImmutableOptions& ioptions,

    std::unique_ptr<TableProperties>* table_properties,

    MemoryAllocator* memory_allocator) {

  assert(table_properties);

  Status s;

  bool retry = false;

  while (true) {

    BlockContents block_contents;

    size_t len = handle.size() + footer.GetBlockTrailerSize();

    // If this is an external SST file ingested with write_global_seqno set to

    // true, then we expect the checksum mismatch because checksum was written

    // by SstFileWriter, but its global seqno in the properties block may have

    // been changed during ingestion. For this reason, we initially read

    // and process without checksum verification, then later try checksum

    // verification so that if it fails, we can copy to a temporary buffer with

    // global seqno set to its original value, i.e. 0, and attempt checksum

    // verification again.

    if (!retry) {

      ReadOptions modified_ro = ro;

      modified_ro.verify_checksums = false;

      BlockFetcher block_fetcher(

          file, prefetch_buffer, footer, modified_ro, handle, &block_contents,

          ioptions, false /* decompress */, false /*maybe_compressed*/,

          BlockType::kProperties, nullptr /*decompressor*/,

          PersistentCacheOptions::kEmpty, memory_allocator);

      s = block_fetcher.ReadBlockContents();

      if (!s.ok()) {

        return s;

      }

      assert(block_fetcher.GetBlockSizeWithTrailer() == len);

      TEST_SYNC_POINT_CALLBACK("ReadTablePropertiesHelper:0",

                               &block_contents.data);

    } else {

      assert(s.IsCorruption());

      // If retrying, use a stronger file system read to check and correct

      // data corruption

      IOOptions opts;

      IODebugContext dbg;

      if (PrepareIOFromReadOptions(ro, ioptions.clock, opts, &dbg) !=

          IOStatus::OK()) {

        return s;

      }

      opts.verify_and_reconstruct_read = true;

      std::unique_ptr<char[]> data(new char[len]);

      Slice result;

      IOStatus io_s = file->Read(opts, handle.offset(), len, &result,

                                 data.get(), nullptr, &dbg);

      RecordTick(ioptions.stats, FILE_READ_CORRUPTION_RETRY_COUNT);

      if (!io_s.ok()) {

        ROCKS_LOG_INFO(ioptions.info_log,

                       "Reading properties block failed - %s",

                       io_s.ToString().c_str());

        // Return the original corruption error as that's more serious

        return s;

      }

      if (result.size() < len) {

        return Status::Corruption("Reading properties block failed - " +

                                  std::to_string(result.size()) +

                                  " bytes read");

      }

      RecordTick(ioptions.stats, FILE_READ_CORRUPTION_RETRY_SUCCESS_COUNT);

      block_contents = BlockContents(std::move(data), handle.size());

    }

    uint64_t block_size = block_contents.data.size();

    Block properties_block(std::move(block_contents));

    std::unique_ptr<TableProperties> new_table_properties{new TableProperties};

    s = ParsePropertiesBlock(ioptions, handle.offset(), properties_block,

                             new_table_properties);

    // Modified version of BlockFetcher checksum verification

    // (See write_global_seqno comment above)

    if (s.ok() && footer.GetBlockTrailerSize() > 0) {

      s = VerifyBlockChecksum(footer, properties_block.data(), block_size,

                              file->file_name(), handle.offset(),

                              BlockType::kProperties);

      if (s.IsCorruption()) {

        if (new_table_properties->external_sst_file_global_seqno_offset != 0) {

          std::string tmp_buf(properties_block.data(), len);

          uint64_t global_seqno_offset =

              new_table_properties->external_sst_file_global_seqno_offset -

              handle.offset();

          EncodeFixed64(&tmp_buf[static_cast<size_t>(global_seqno_offset)], 0);

          s = VerifyBlockChecksum(footer, tmp_buf.data(), block_size,

                                  file->file_name(), handle.offset(),

                                  BlockType::kProperties);

        }

      }

    }

    // If we detected a corruption and the file system supports verification

    // and reconstruction, retry the read

    if (s.IsCorruption() && !retry &&

        CheckFSFeatureSupport(ioptions.fs.get(),

                              FSSupportedOps::kVerifyAndReconstructRead)) {

      retry = true;

    } else {

      if (s.ok()) {

        *table_properties = std::move(new_table_properties);

      }

      break;

    }

  }

  return s;

}

Status ReadTableProperties(RandomAccessFileReader* file, uint64_t file_size,

                           uint64_t table_magic_number,

                           const ImmutableOptions& ioptions,

                           const ReadOptions& read_options,

                           std::unique_ptr<TableProperties>* properties,

                           MemoryAllocator* memory_allocator,

                           FilePrefetchBuffer* prefetch_buffer) {

  BlockHandle block_handle;

  Footer footer;

  Status s =

      FindMetaBlockInFile(file, file_size, table_magic_number, ioptions,

                          read_options, kPropertiesBlockName, &block_handle,

                          memory_allocator, prefetch_buffer, &footer);

  if (!s.ok()) {

    return s;

  }

  if (!block_handle.IsNull()) {

    s = ReadTablePropertiesHelper(read_options, block_handle, file,

                                  prefetch_buffer, footer, ioptions, properties,

                                  memory_allocator);

  } else {

    s = Status::NotFound();

  }

  return s;

}

Status FindOptionalMetaBlock(InternalIterator* meta_index_iter,

                             const std::string& meta_block_name,

                             BlockHandle* block_handle) {

  assert(block_handle != nullptr);

  meta_index_iter->Seek(meta_block_name);

  if (meta_index_iter->status().ok()) {

    if (meta_index_iter->Valid() && meta_index_iter->key() == meta_block_name) {

      Slice v = meta_index_iter->value();

      return block_handle->DecodeFrom(&v);

    }

  }

  // else

  *block_handle = BlockHandle::NullBlockHandle();

  return meta_index_iter->status();

}

Status FindMetaBlock(InternalIterator* meta_index_iter,

                     const std::string& meta_block_name,

                     BlockHandle* block_handle) {

  Status s =

      FindOptionalMetaBlock(meta_index_iter, meta_block_name, block_handle);

  if (s.ok() && block_handle->IsNull()) {

    return Status::Corruption("Cannot find the meta block", meta_block_name);

  } else {

    return s;

  }

}

Status ReadMetaIndexBlockInFile(RandomAccessFileReader* file,

                                uint64_t file_size, uint64_t table_magic_number,

                                const ImmutableOptions& ioptions,

                                const ReadOptions& read_options,

                                BlockContents* metaindex_contents,

                                MemoryAllocator* memory_allocator,

                                FilePrefetchBuffer* prefetch_buffer,

                                Footer* footer_out) {

  Footer footer;

  IOOptions opts;

  IODebugContext dbg;

  Status s;

  s = file->PrepareIOOptions(read_options, opts, &dbg);

  if (!s.ok()) {

    return s;

  }

  s = ReadFooterFromFile(opts, file, *ioptions.fs, prefetch_buffer, file_size,

                         &footer, table_magic_number, ioptions.stats);

  if (!s.ok()) {

    return s;

  }

  if (footer_out) {

    *footer_out = footer;

  }

  auto metaindex_handle = footer.metaindex_handle();

  return BlockFetcher(file, prefetch_buffer, footer, read_options,

                      metaindex_handle, metaindex_contents, ioptions,

                      false /* do decompression */, false /*maybe_compressed*/,

                      BlockType::kMetaIndex, nullptr /*decompressor*/,

                      PersistentCacheOptions::kEmpty, memory_allocator)

      .ReadBlockContents();

}

Status FindMetaBlockInFile(

    RandomAccessFileReader* file, uint64_t file_size,

    uint64_t table_magic_number, const ImmutableOptions& ioptions,

    const ReadOptions& read_options, const std::string& meta_block_name,

    BlockHandle* block_handle, MemoryAllocator* memory_allocator,

    FilePrefetchBuffer* prefetch_buffer, Footer* footer_out) {

  BlockContents metaindex_contents;

  auto s = ReadMetaIndexBlockInFile(

      file, file_size, table_magic_number, ioptions, read_options,

      &metaindex_contents, memory_allocator, prefetch_buffer, footer_out);

  if (!s.ok()) {

    return s;

  }

  // meta blocks are never compressed. Need to add uncompress logic if we are to

  // compress it.

  Block metaindex_block(std::move(metaindex_contents));

  std::unique_ptr<InternalIterator> meta_iter;

  meta_iter.reset(metaindex_block.NewMetaIterator());

  return FindMetaBlock(meta_iter.get(), meta_block_name, block_handle);

}

Status ReadMetaBlock(RandomAccessFileReader* file,

                     FilePrefetchBuffer* prefetch_buffer, uint64_t file_size,

                     uint64_t table_magic_number,

                     const ImmutableOptions& ioptions,

                     const ReadOptions& read_options,

                     const std::string& meta_block_name, BlockType block_type,

                     BlockContents* contents,

                     MemoryAllocator* memory_allocator) {

  // TableProperties requires special handling because of checksum issues.

  // Call ReadTableProperties instead for that case.

  assert(block_type != BlockType::kProperties);

  BlockHandle block_handle;

  Footer footer;

  Status status =

      FindMetaBlockInFile(file, file_size, table_magic_number, ioptions,

                          read_options, meta_block_name, &block_handle,

                          memory_allocator, prefetch_buffer, &footer);

  if (!status.ok()) {

    return status;

  }

  return BlockFetcher(file, prefetch_buffer, footer, read_options, block_handle,

                      contents, ioptions, false /* decompress */,

                      false /*maybe_compressed*/, block_type,

                      nullptr /*decompressor*/, PersistentCacheOptions::kEmpty,

                      memory_allocator)

      .ReadBlockContents();

}

}  // namespace ROCKSDB_NAMESPACE