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5cd0576ffe
rocksdb/table/plain_table_reader.cc
Lei Jin 5665e5e285 introduce ImmutableOptions 
Summary:
As a preparation to support updating some options dynamically, I'd like
to first introduce ImmutableOptions, which is a subset of Options that
cannot be changed during the course of a DB lifetime without restart.

ColumnFamily will keep both Options and ImmutableOptions. Any component
below ColumnFamily should only take ImmutableOptions in their
constructor. Other options should be taken from APIs, which will be
allowed to adjust dynamically.

I am yet to make changes to memtable and other related classes to take
ImmutableOptions in their ctor. That can be done in a seprate diff as
this one is already pretty big.

Test Plan: make all check

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D22545
2014-09-04 16:18:36 -07:00

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// 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.
#ifndef ROCKSDB_LITE
#include "table/plain_table_reader.h"
#include <string>
#include <vector>
#include "db/dbformat.h"
#include "rocksdb/cache.h"
#include "rocksdb/comparator.h"
#include "rocksdb/env.h"
#include "rocksdb/filter_policy.h"
#include "rocksdb/options.h"
#include "rocksdb/statistics.h"
#include "table/block.h"
#include "table/bloom_block.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "table/meta_blocks.h"
#include "table/two_level_iterator.h"
#include "table/plain_table_factory.h"
#include "table/plain_table_key_coding.h"
#include "util/arena.h"
#include "util/coding.h"
#include "util/dynamic_bloom.h"
#include "util/hash.h"
#include "util/histogram.h"
#include "util/murmurhash.h"
#include "util/perf_context_imp.h"
#include "util/stop_watch.h"
namespace rocksdb {
namespace {
// Safely getting a uint32_t element from a char array, where, starting from
// `base`, every 4 bytes are considered as an fixed 32 bit integer.
inline uint32_t GetFixed32Element(const char* base, size_t offset) {
return DecodeFixed32(base + offset * sizeof(uint32_t));
}
} // namespace
// Iterator to iterate IndexedTable
class PlainTableIterator : public Iterator {
public:
explicit PlainTableIterator(PlainTableReader* table, bool use_prefix_seek);
~PlainTableIterator();
bool Valid() const;
void SeekToFirst();
void SeekToLast();
void Seek(const Slice& target);
void Next();
void Prev();
Slice key() const;
Slice value() const;
Status status() const;
private:
PlainTableReader* table_;
PlainTableKeyDecoder decoder_;
bool use_prefix_seek_;
uint32_t offset_;
uint32_t next_offset_;
Slice key_;
Slice value_;
Status status_;
// No copying allowed
PlainTableIterator(const PlainTableIterator&) = delete;
void operator=(const Iterator&) = delete;
};
extern const uint64_t kPlainTableMagicNumber;
PlainTableReader::PlainTableReader(const ImmutableCFOptions& ioptions,
unique_ptr<RandomAccessFile>&& file,
const EnvOptions& storage_options,
const InternalKeyComparator& icomparator,
EncodingType encoding_type,
uint64_t file_size,
const TableProperties* table_properties)
: internal_comparator_(icomparator),
encoding_type_(encoding_type),
full_scan_mode_(false),
data_end_offset_(table_properties->data_size),
user_key_len_(table_properties->fixed_key_len),
prefix_extractor_(ioptions.prefix_extractor),
enable_bloom_(false),
bloom_(6, nullptr),
ioptions_(ioptions),
file_(std::move(file)),
file_size_(file_size),
table_properties_(nullptr) {}
PlainTableReader::~PlainTableReader() {
}
Status PlainTableReader::Open(const ImmutableCFOptions& ioptions,
const EnvOptions& env_options,
const InternalKeyComparator& internal_comparator,
unique_ptr<RandomAccessFile>&& file,
uint64_t file_size,
unique_ptr<TableReader>* table_reader,
const int bloom_bits_per_key,
double hash_table_ratio, size_t index_sparseness,
size_t huge_page_tlb_size, bool full_scan_mode) {
assert(ioptions.allow_mmap_reads);
if (file_size > PlainTableIndex::kMaxFileSize) {
return Status::NotSupported("File is too large for PlainTableReader!");
}
TableProperties* props = nullptr;
auto s = ReadTableProperties(file.get(), file_size, kPlainTableMagicNumber,
ioptions.env, ioptions.info_log, &props);
if (!s.ok()) {
return s;
}
assert(hash_table_ratio >= 0.0);
auto& user_props = props->user_collected_properties;
auto prefix_extractor_in_file =
user_props.find(PlainTablePropertyNames::kPrefixExtractorName);
if (!full_scan_mode && prefix_extractor_in_file != user_props.end()) {
if (!ioptions.prefix_extractor) {
return Status::InvalidArgument(
"Prefix extractor is missing when opening a PlainTable built "
"using a prefix extractor");
} else if (prefix_extractor_in_file->second.compare(
ioptions.prefix_extractor->Name()) != 0) {
return Status::InvalidArgument(
"Prefix extractor given doesn't match the one used to build "
"PlainTable");
}
}
EncodingType encoding_type = kPlain;
auto encoding_type_prop =
user_props.find(PlainTablePropertyNames::kEncodingType);
if (encoding_type_prop != user_props.end()) {
encoding_type = static_cast<EncodingType>(
DecodeFixed32(encoding_type_prop->second.c_str()));
}
std::unique_ptr<PlainTableReader> new_reader(new PlainTableReader(
ioptions, std::move(file), env_options, internal_comparator,
encoding_type, file_size, props));
s = new_reader->MmapDataFile();
if (!s.ok()) {
return s;
}
if (!full_scan_mode) {
s = new_reader->PopulateIndex(props, bloom_bits_per_key, hash_table_ratio,
index_sparseness, huge_page_tlb_size);
if (!s.ok()) {
return s;
}
} else {
// Flag to indicate it is a full scan mode so that none of the indexes
// can be used.
new_reader->full_scan_mode_ = true;
}
*table_reader = std::move(new_reader);
return s;
}
void PlainTableReader::SetupForCompaction() {
}
Iterator* PlainTableReader::NewIterator(const ReadOptions& options,
Arena* arena) {
if (options.total_order_seek && !IsTotalOrderMode()) {
return NewErrorIterator(
Status::InvalidArgument("total_order_seek not supported"), arena);
}
if (arena == nullptr) {
return new PlainTableIterator(this, prefix_extractor_ != nullptr);
} else {
auto mem = arena->AllocateAligned(sizeof(PlainTableIterator));
return new (mem) PlainTableIterator(this, prefix_extractor_ != nullptr);
}
}
Status PlainTableReader::PopulateIndexRecordList(
PlainTableIndexBuilder* index_builder, vector<uint32_t>* prefix_hashes) {
Slice prev_key_prefix_slice;
uint32_t pos = data_start_offset_;
bool is_first_record = true;
Slice key_prefix_slice;
PlainTableKeyDecoder decoder(encoding_type_, user_key_len_,
ioptions_.prefix_extractor);
while (pos < data_end_offset_) {
uint32_t key_offset = pos;
ParsedInternalKey key;
Slice value_slice;
bool seekable = false;
Status s = Next(&decoder, &pos, &key, nullptr, &value_slice, &seekable);
if (!s.ok()) {
return s;
}
key_prefix_slice = GetPrefix(key);
if (enable_bloom_) {
bloom_.AddHash(GetSliceHash(key.user_key));
} else {
if (is_first_record || prev_key_prefix_slice != key_prefix_slice) {
if (!is_first_record) {
prefix_hashes->push_back(GetSliceHash(prev_key_prefix_slice));
}
prev_key_prefix_slice = key_prefix_slice;
}
}
index_builder->AddKeyPrefix(GetPrefix(key), key_offset);
if (!seekable && is_first_record) {
return Status::Corruption("Key for a prefix is not seekable");
}
is_first_record = false;
}
prefix_hashes->push_back(GetSliceHash(key_prefix_slice));
auto s = index_.InitFromRawData(index_builder->Finish());
return s;
}
void PlainTableReader::AllocateAndFillBloom(int bloom_bits_per_key,
int num_prefixes,
size_t huge_page_tlb_size,
vector<uint32_t>* prefix_hashes) {
if (!IsTotalOrderMode()) {
uint32_t bloom_total_bits = num_prefixes * bloom_bits_per_key;
if (bloom_total_bits > 0) {
enable_bloom_ = true;
bloom_.SetTotalBits(&arena_, bloom_total_bits, ioptions_.bloom_locality,
huge_page_tlb_size, ioptions_.info_log);
FillBloom(prefix_hashes);
}
}
}
void PlainTableReader::FillBloom(vector<uint32_t>* prefix_hashes) {
assert(bloom_.IsInitialized());
for (auto prefix_hash : *prefix_hashes) {
bloom_.AddHash(prefix_hash);
}
}
Status PlainTableReader::MmapDataFile() {
// Get mmapped memory to file_data_.
return file_->Read(0, file_size_, &file_data_, nullptr);
}
Status PlainTableReader::PopulateIndex(TableProperties* props,
int bloom_bits_per_key,
double hash_table_ratio,
size_t index_sparseness,
size_t huge_page_tlb_size) {
assert(props != nullptr);
table_properties_.reset(props);
BlockContents bloom_block_contents;
auto s = ReadMetaBlock(file_.get(), file_size_, kPlainTableMagicNumber,
ioptions_.env, BloomBlockBuilder::kBloomBlock,
&bloom_block_contents);
bool index_in_file = s.ok();
BlockContents index_block_contents;
s = ReadMetaBlock(file_.get(), file_size_, kPlainTableMagicNumber,
ioptions_.env, PlainTableIndexBuilder::kPlainTableIndexBlock,
&index_block_contents);
index_in_file &= s.ok();
Slice* bloom_block;
if (index_in_file) {
bloom_block = &bloom_block_contents.data;
} else {
bloom_block = nullptr;
}
// index_in_file == true only if there are kBloomBlock and
// kPlainTableIndexBlock
// in file
Slice* index_block;
if (index_in_file) {
index_block = &index_block_contents.data;
} else {
index_block = nullptr;
}
if ((ioptions_.prefix_extractor == nullptr) &&
(hash_table_ratio != 0)) {
// ioptions.prefix_extractor is requried for a hash-based look-up.
return Status::NotSupported(
"PlainTable requires a prefix extractor enable prefix hash mode.");
}
// First, read the whole file, for every kIndexIntervalForSamePrefixKeys rows
// for a prefix (starting from the first one), generate a record of (hash,
// offset) and append it to IndexRecordList, which is a data structure created
// to store them.
if (!index_in_file) {
// Allocate bloom filter here for total order mode.
if (IsTotalOrderMode()) {
uint32_t num_bloom_bits =
table_properties_->num_entries * bloom_bits_per_key;
if (num_bloom_bits > 0) {
enable_bloom_ = true;
bloom_.SetTotalBits(&arena_, num_bloom_bits, ioptions_.bloom_locality,
huge_page_tlb_size, ioptions_.info_log);
}
}
} else {
enable_bloom_ = true;
auto num_blocks_property = props->user_collected_properties.find(
PlainTablePropertyNames::kNumBloomBlocks);
uint32_t num_blocks = 0;
if (num_blocks_property != props->user_collected_properties.end()) {
Slice temp_slice(num_blocks_property->second);
if (!GetVarint32(&temp_slice, &num_blocks)) {
num_blocks = 0;
}
}
// cast away const qualifier, because bloom_ won't be changed
bloom_.SetRawData(
const_cast<unsigned char*>(
reinterpret_cast<const unsigned char*>(bloom_block->data())),
bloom_block->size() * 8, num_blocks);
}
PlainTableIndexBuilder index_builder(&arena_, ioptions_, index_sparseness,
hash_table_ratio, huge_page_tlb_size);
std::vector<uint32_t> prefix_hashes;
if (!index_in_file) {
Status s = PopulateIndexRecordList(&index_builder, &prefix_hashes);
if (!s.ok()) {
return s;
}
} else {
Status s = index_.InitFromRawData(*index_block);
if (!s.ok()) {
return s;
}
}
if (!index_in_file) {
// Calculated bloom filter size and allocate memory for
// bloom filter based on the number of prefixes, then fill it.
AllocateAndFillBloom(bloom_bits_per_key, index_.GetNumPrefixes(),
huge_page_tlb_size, &prefix_hashes);
}
// Fill two table properties.
if (!index_in_file) {
props->user_collected_properties["plain_table_hash_table_size"] =
std::to_string(index_.GetIndexSize() * PlainTableIndex::kOffsetLen);
props->user_collected_properties["plain_table_sub_index_size"] =
std::to_string(index_.GetSubIndexSize());
} else {
props->user_collected_properties["plain_table_hash_table_size"] =
std::to_string(0);
props->user_collected_properties["plain_table_sub_index_size"] =
std::to_string(0);
}
return Status::OK();
}
Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
uint32_t prefix_hash, bool& prefix_matched,
uint32_t* offset) const {
prefix_matched = false;
uint32_t prefix_index_offset;
auto res = index_.GetOffset(prefix_hash, &prefix_index_offset);
if (res == PlainTableIndex::kNoPrefixForBucket) {
*offset = data_end_offset_;
return Status::OK();
} else if (res == PlainTableIndex::kDirectToFile) {
*offset = prefix_index_offset;
return Status::OK();
}
// point to sub-index, need to do a binary search
uint32_t upper_bound;
const char* base_ptr =
index_.GetSubIndexBasePtrAndUpperBound(prefix_index_offset, &upper_bound);
uint32_t low = 0;
uint32_t high = upper_bound;
ParsedInternalKey mid_key;
ParsedInternalKey parsed_target;
if (!ParseInternalKey(target, &parsed_target)) {
return Status::Corruption(Slice());
}
// The key is between [low, high). Do a binary search between it.
while (high - low > 1) {
uint32_t mid = (high + low) / 2;
uint32_t file_offset = GetFixed32Element(base_ptr, mid);
size_t tmp;
Status s = PlainTableKeyDecoder(encoding_type_, user_key_len_,
ioptions_.prefix_extractor)
.NextKey(file_data_.data() + file_offset,
file_data_.data() + data_end_offset_, &mid_key,
nullptr, &tmp);
if (!s.ok()) {
return s;
}
int cmp_result = internal_comparator_.Compare(mid_key, parsed_target);
if (cmp_result < 0) {
low = mid;
} else {
if (cmp_result == 0) {
// Happen to have found the exact key or target is smaller than the
// first key after base_offset.
prefix_matched = true;
*offset = file_offset;
return Status::OK();
} else {
high = mid;
}
}
}
// Both of the key at the position low or low+1 could share the same
// prefix as target. We need to rule out one of them to avoid to go
// to the wrong prefix.
ParsedInternalKey low_key;
size_t tmp;
uint32_t low_key_offset = GetFixed32Element(base_ptr, low);
Status s = PlainTableKeyDecoder(encoding_type_, user_key_len_,
ioptions_.prefix_extractor)
.NextKey(file_data_.data() + low_key_offset,
file_data_.data() + data_end_offset_, &low_key,
nullptr, &tmp);
if (!s.ok()) {
return s;
}
if (GetPrefix(low_key) == prefix) {
prefix_matched = true;
*offset = low_key_offset;
} else if (low + 1 < upper_bound) {
// There is possible a next prefix, return it
prefix_matched = false;
*offset = GetFixed32Element(base_ptr, low + 1);
} else {
// target is larger than a key of the last prefix in this bucket
// but with a different prefix. Key does not exist.
*offset = data_end_offset_;
}
return Status::OK();
}
bool PlainTableReader::MatchBloom(uint32_t hash) const {
return !enable_bloom_ || bloom_.MayContainHash(hash);
}
Status PlainTableReader::Next(PlainTableKeyDecoder* decoder, uint32_t* offset,
ParsedInternalKey* parsed_key,
Slice* internal_key, Slice* value,
bool* seekable) const {
if (*offset == data_end_offset_) {
*offset = data_end_offset_;
return Status::OK();
}
if (*offset > data_end_offset_) {
return Status::Corruption("Offset is out of file size");
}
const char* start = file_data_.data() + *offset;
size_t bytes_for_key;
Status s =
decoder->NextKey(start, file_data_.data() + data_end_offset_, parsed_key,
internal_key, &bytes_for_key, seekable);
if (!s.ok()) {
return s;
}
uint32_t value_size;
const char* value_ptr = GetVarint32Ptr(
start + bytes_for_key, file_data_.data() + data_end_offset_, &value_size);
if (value_ptr == nullptr) {
return Status::Corruption(
"Unexpected EOF when reading the next value's size.");
}
*offset = *offset + (value_ptr - start) + value_size;
if (*offset > data_end_offset_) {
return Status::Corruption("Unexpected EOF when reading the next value. ");
}
*value = Slice(value_ptr, value_size);
return Status::OK();
}
void PlainTableReader::Prepare(const Slice& target) {
if (enable_bloom_) {
uint32_t prefix_hash = GetSliceHash(GetPrefix(target));
bloom_.Prefetch(prefix_hash);
}
}
Status PlainTableReader::Get(const ReadOptions& ro, const Slice& target,
void* arg,
bool (*saver)(void*, const ParsedInternalKey&,
const Slice&),
void (*mark_key_may_exist)(void*)) {
// Check bloom filter first.
Slice prefix_slice;
uint32_t prefix_hash;
if (IsTotalOrderMode()) {
if (full_scan_mode_) {
status_ =
Status::InvalidArgument("Get() is not allowed in full scan mode.");
}
// Match whole user key for bloom filter check.
if (!MatchBloom(GetSliceHash(GetUserKey(target)))) {
return Status::OK();
}
// in total order mode, there is only one bucket 0, and we always use empty
// prefix.
prefix_slice = Slice();
prefix_hash = 0;
} else {
prefix_slice = GetPrefix(target);
prefix_hash = GetSliceHash(prefix_slice);
if (!MatchBloom(prefix_hash)) {
return Status::OK();
}
}
uint32_t offset;
bool prefix_match;
Status s =
GetOffset(target, prefix_slice, prefix_hash, prefix_match, &offset);
if (!s.ok()) {
return s;
}
ParsedInternalKey found_key;
ParsedInternalKey parsed_target;
if (!ParseInternalKey(target, &parsed_target)) {
return Status::Corruption(Slice());
}
Slice found_value;
PlainTableKeyDecoder decoder(encoding_type_, user_key_len_,
ioptions_.prefix_extractor);
while (offset < data_end_offset_) {
Status s = Next(&decoder, &offset, &found_key, nullptr, &found_value);
if (!s.ok()) {
return s;
}
if (!prefix_match) {
// Need to verify prefix for the first key found if it is not yet
// checked.
if (GetPrefix(found_key) != prefix_slice) {
return Status::OK();
}
prefix_match = true;
}
if (internal_comparator_.Compare(found_key, parsed_target) >= 0) {
if (!(*saver)(arg, found_key, found_value)) {
break;
}
}
}
return Status::OK();
}
uint64_t PlainTableReader::ApproximateOffsetOf(const Slice& key) {
return 0;
}
PlainTableIterator::PlainTableIterator(PlainTableReader* table,
bool use_prefix_seek)
: table_(table),
decoder_(table_->encoding_type_, table_->user_key_len_,
table_->prefix_extractor_),
use_prefix_seek_(use_prefix_seek) {
next_offset_ = offset_ = table_->data_end_offset_;
}
PlainTableIterator::~PlainTableIterator() {
}
bool PlainTableIterator::Valid() const {
return offset_ < table_->data_end_offset_
&& offset_ >= table_->data_start_offset_;
}
void PlainTableIterator::SeekToFirst() {
next_offset_ = table_->data_start_offset_;
if (next_offset_ >= table_->data_end_offset_) {
next_offset_ = offset_ = table_->data_end_offset_;
} else {
Next();
}
}
void PlainTableIterator::SeekToLast() {
assert(false);
status_ = Status::NotSupported("SeekToLast() is not supported in PlainTable");
}
void PlainTableIterator::Seek(const Slice& target) {
// If the user doesn't set prefix seek option and we are not able to do a
// total Seek(). assert failure.
if (!use_prefix_seek_) {
if (table_->full_scan_mode_) {
status_ =
Status::InvalidArgument("Seek() is not allowed in full scan mode.");
offset_ = next_offset_ = table_->data_end_offset_;
return;
} else if (table_->GetIndexSize() > 1) {
assert(false);
status_ = Status::NotSupported(
"PlainTable cannot issue non-prefix seek unless in total order "
"mode.");
offset_ = next_offset_ = table_->data_end_offset_;
return;
}
}
Slice prefix_slice = table_->GetPrefix(target);
uint32_t prefix_hash = 0;
// Bloom filter is ignored in total-order mode.
if (!table_->IsTotalOrderMode()) {
prefix_hash = GetSliceHash(prefix_slice);
if (!table_->MatchBloom(prefix_hash)) {
offset_ = next_offset_ = table_->data_end_offset_;
return;
}
}
bool prefix_match;
status_ = table_->GetOffset(target, prefix_slice, prefix_hash, prefix_match,
&next_offset_);
if (!status_.ok()) {
offset_ = next_offset_ = table_->data_end_offset_;
return;
}
if (next_offset_ < table_-> data_end_offset_) {
for (Next(); status_.ok() && Valid(); Next()) {
if (!prefix_match) {
// Need to verify the first key's prefix
if (table_->GetPrefix(key()) != prefix_slice) {
offset_ = next_offset_ = table_->data_end_offset_;
break;
}
prefix_match = true;
}
if (table_->internal_comparator_.Compare(key(), target) >= 0) {
break;
}
}
} else {
offset_ = table_->data_end_offset_;
}
}
void PlainTableIterator::Next() {
offset_ = next_offset_;
if (offset_ < table_->data_end_offset_) {
Slice tmp_slice;
ParsedInternalKey parsed_key;
status_ =
table_->Next(&decoder_, &next_offset_, &parsed_key, &key_, &value_);
if (!status_.ok()) {
offset_ = next_offset_ = table_->data_end_offset_;
}
}
}
void PlainTableIterator::Prev() {
assert(false);
}
Slice PlainTableIterator::key() const {
assert(Valid());
return key_;
}
Slice PlainTableIterator::value() const {
assert(Valid());
return value_;
}
Status PlainTableIterator::status() const {
return status_;
}
} // namespace rocksdb
#endif // ROCKSDB_LITE
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