leveldb::FilterBlockReader Class Reference

#include <filter_block.h>

Collaboration diagram for leveldb::FilterBlockReader:

Public Member Functions
	FilterBlockReader (const FilterPolicy *policy, const Slice &contents)
bool	KeyMayMatch (uint64_t block_offset, const Slice &key)

Private Attributes
const FilterPolicy *	policy_
const char *	data_
const char *	offset_
size_t	num_
size_t	base_lg_

Detailed Description

Definition at line 52 of file filter_block.h.

Constructor & Destructor Documentation

FilterBlockReader()

leveldb::FilterBlockReader::FilterBlockReader	(	const FilterPolicy *	policy,
		const Slice &	contents
	)

Definition at line 78 of file filter_block.cc.

    : policy_(policy),
      data_(NULL),
      offset_(NULL),
      num_(0),
      base_lg_(0) {
  size_t n = contents.size();
  if (n < 5) return;  // 1 byte for base_lg_ and 4 for start of offset array
  base_lg_ = contents[n-1];
  uint32_t last_word = DecodeFixed32(contents.data() + n - 5);
  if (last_word > n - 5) return;
  data_ = contents.data();
  offset_ = data_ + last_word;
  num_ = (n - 5 - last_word) / 4;
}

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Member Function Documentation

KeyMayMatch()

bool leveldb::FilterBlockReader::KeyMayMatch	(	uint64_t	block_offset,
		const Slice &	key
	)

Definition at line 95 of file filter_block.cc.

                                                                           {
  uint64_t index = block_offset >> base_lg_;
  if (index < num_) {
    uint32_t start = DecodeFixed32(offset_ + index*4);
    uint32_t limit = DecodeFixed32(offset_ + index*4 + 4);
    if (start <= limit && limit <= static_cast<size_t>(offset_ - data_)) {
      Slice filter = Slice(data_ + start, limit - start);
      return policy_->KeyMayMatch(key, filter);
    } else if (start == limit) {
      // Empty filters do not match any keys
      return false;
    }
  }
  return true;  // Errors are treated as potential matches
}

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Member Data Documentation

base_lg_

size_t leveldb::FilterBlockReader::base_lg_

private

Definition at line 63 of file filter_block.h.

data_

const char* leveldb::FilterBlockReader::data_

private

Definition at line 60 of file filter_block.h.

num_

size_t leveldb::FilterBlockReader::num_

private

Definition at line 62 of file filter_block.h.

offset_

const char* leveldb::FilterBlockReader::offset_

private

Definition at line 61 of file filter_block.h.

policy_

const FilterPolicy* leveldb::FilterBlockReader::policy_

private

Definition at line 59 of file filter_block.h.

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The documentation for this class was generated from the following files:

• table/filter_block.h
• table/filter_block.cc