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// 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/file_indexer.h"
#include <algorithm>
#include <functional>
#include "db/version_edit.h"
#include "rocksdb/comparator.h"
namespace ROCKSDB_NAMESPACE {
FileIndexer::FileIndexer(const Comparator* ucmp)
: num_levels_(0), ucmp_(ucmp), level_rb_(nullptr) {}
size_t FileIndexer::NumLevelIndex() const { return next_level_index_.size(); }
size_t FileIndexer::LevelIndexSize(size_t level) const {
if (level >= next_level_index_.size()) {
return 0;
}
return next_level_index_[level].num_index;
}
void FileIndexer::GetNextLevelIndex(const size_t level, const size_t file_index,
const int cmp_smallest,
const int cmp_largest, int32_t* left_bound,
int32_t* right_bound) const {
assert(level > 0);
// Last level, no hint
if (level == num_levels_ - 1) {
*left_bound = 0;
*right_bound = -1;
return;
}
assert(level < num_levels_ - 1);
assert(static_cast<int32_t>(file_index) <= level_rb_[level]);
const IndexUnit* index_units = next_level_index_[level].index_units;
const auto& index = index_units[file_index];
if (cmp_smallest < 0) {
*left_bound = (level > 0 && file_index > 0)
? index_units[file_index - 1].largest_lb
: 0;
*right_bound = index.smallest_rb;
} else if (cmp_smallest == 0) {
*left_bound = index.smallest_lb;
*right_bound = index.smallest_rb;
} else if (cmp_smallest > 0 && cmp_largest < 0) {
*left_bound = index.smallest_lb;
*right_bound = index.largest_rb;
} else if (cmp_largest == 0) {
*left_bound = index.largest_lb;
*right_bound = index.largest_rb;
} else if (cmp_largest > 0) {
*left_bound = index.largest_lb;
*right_bound = level_rb_[level + 1];
} else {
assert(false);
}
assert(*left_bound >= 0);
assert(*left_bound <= *right_bound + 1);
assert(*right_bound <= level_rb_[level + 1]);
}
void FileIndexer::UpdateIndex(Arena* arena, const size_t num_levels,
std::vector<FileMetaData*>* const files) {
if (files == nullptr) {
return;
}
if (num_levels == 0) { // uint_32 0-1 would cause bad behavior
num_levels_ = num_levels;
return;
}
assert(level_rb_ == nullptr); // level_rb_ should be init here
num_levels_ = num_levels;
next_level_index_.resize(num_levels);
char* mem = arena->AllocateAligned(num_levels_ * sizeof(int32_t));
level_rb_ = new (mem) int32_t[num_levels_];
for (size_t i = 0; i < num_levels_; i++) {
level_rb_[i] = -1;
}
// L1 - Ln-1
for (size_t level = 1; level < num_levels_ - 1; ++level) {
const auto& upper_files = files[level];
const int32_t upper_size = static_cast<int32_t>(upper_files.size());
const auto& lower_files = files[level + 1];
level_rb_[level] = static_cast<int32_t>(upper_files.size()) - 1;
if (upper_size == 0) {
continue;
}
IndexLevel& index_level = next_level_index_[level];
index_level.num_index = upper_size;
mem = arena->AllocateAligned(upper_size * sizeof(IndexUnit));
index_level.index_units = new (mem) IndexUnit[upper_size];
CalculateLB(
upper_files, lower_files, &index_level,
[this](const FileMetaData* a, const FileMetaData* b) -> int {
return ucmp_->CompareWithoutTimestamp(a->smallest.user_key(),
b->largest.user_key());
},
[](IndexUnit* index, int32_t f_idx) { index->smallest_lb = f_idx; });
CalculateLB(
upper_files, lower_files, &index_level,
[this](const FileMetaData* a, const FileMetaData* b) -> int {
return ucmp_->CompareWithoutTimestamp(a->largest.user_key(),
b->largest.user_key());
},
[](IndexUnit* index, int32_t f_idx) { index->largest_lb = f_idx; });
CalculateRB(
upper_files, lower_files, &index_level,
[this](const FileMetaData* a, const FileMetaData* b) -> int {
return ucmp_->CompareWithoutTimestamp(a->smallest.user_key(),
b->smallest.user_key());
},
[](IndexUnit* index, int32_t f_idx) { index->smallest_rb = f_idx; });
CalculateRB(
upper_files, lower_files, &index_level,
[this](const FileMetaData* a, const FileMetaData* b) -> int {
return ucmp_->CompareWithoutTimestamp(a->largest.user_key(),
b->smallest.user_key());
},
[](IndexUnit* index, int32_t f_idx) { index->largest_rb = f_idx; });
}
level_rb_[num_levels_ - 1] =
static_cast<int32_t>(files[num_levels_ - 1].size()) - 1;
}
void FileIndexer::CalculateLB(
const std::vector<FileMetaData*>& upper_files,
const std::vector<FileMetaData*>& lower_files, IndexLevel* index_level,
std::function<int(const FileMetaData*, const FileMetaData*)> cmp_op,
std::function<void(IndexUnit*, int32_t)> set_index) {
const int32_t upper_size = static_cast<int32_t>(upper_files.size());
const int32_t lower_size = static_cast<int32_t>(lower_files.size());
int32_t upper_idx = 0;
int32_t lower_idx = 0;
IndexUnit* index = index_level->index_units;
while (upper_idx < upper_size && lower_idx < lower_size) {
int cmp = cmp_op(upper_files[upper_idx], lower_files[lower_idx]);
if (cmp == 0) {
set_index(&index[upper_idx], lower_idx);
++upper_idx;
} else if (cmp > 0) {
// Lower level's file (largest) is smaller, a key won't hit in that
// file. Move to next lower file
++lower_idx;
} else {
// Lower level's file becomes larger, update the index, and
// move to the next upper file
set_index(&index[upper_idx], lower_idx);
++upper_idx;
}
}
while (upper_idx < upper_size) {
// Lower files are exhausted, that means the remaining upper files are
// greater than any lower files. Set the index to be the lower level size.
set_index(&index[upper_idx], lower_size);
++upper_idx;
}
}
void FileIndexer::CalculateRB(
const std::vector<FileMetaData*>& upper_files,
const std::vector<FileMetaData*>& lower_files, IndexLevel* index_level,
std::function<int(const FileMetaData*, const FileMetaData*)> cmp_op,
std::function<void(IndexUnit*, int32_t)> set_index) {
const int32_t upper_size = static_cast<int32_t>(upper_files.size());
const int32_t lower_size = static_cast<int32_t>(lower_files.size());
int32_t upper_idx = upper_size - 1;
int32_t lower_idx = lower_size - 1;
IndexUnit* index = index_level->index_units;
while (upper_idx >= 0 && lower_idx >= 0) {
int cmp = cmp_op(upper_files[upper_idx], lower_files[lower_idx]);
if (cmp == 0) {
set_index(&index[upper_idx], lower_idx);
--upper_idx;
} else if (cmp < 0) {
// Lower level's file (smallest) is larger, a key won't hit in that
// file. Move to next lower file.
--lower_idx;
} else {
// Lower level's file becomes smaller, update the index, and move to
// the next the upper file
set_index(&index[upper_idx], lower_idx);
--upper_idx;
}
}
while (upper_idx >= 0) {
// Lower files are exhausted, that means the remaining upper files are
// smaller than any lower files. Set it to -1.
set_index(&index[upper_idx], -1);
--upper_idx;
}
}
} // namespace ROCKSDB_NAMESPACE
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