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Followup code refactor on plain table

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Summary:
Fixed most comments in https://reviews.facebook.net/D15429.
Still have some remaining comments left.

Test Plan: make all check

Reviewers: sdong, haobo

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15885
This commit is contained in:
Kai Liu
2014-02-13 15:27:59 -08:00
parent 85c0545fac
commit b2e7ee8b41
4 changed files with 139 additions and 131 deletions
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181
table/plain_table_reader.cc
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@@ -5,6 +5,7 @@
#include "table/plain_table_reader.h"
#include <string>
#include <vector>
#include "db/dbformat.h"
@@ -35,7 +36,7 @@ namespace rocksdb {
namespace {
inline uint32_t GetSliceHash(Slice const& s) {
inline uint32_t GetSliceHash(const Slice& s) {
return Hash(s.data(), s.size(), 397) ;
}
@@ -43,6 +44,12 @@ inline uint32_t GetBucketIdFromHash(uint32_t hash, uint32_t num_buckets) {
return hash % num_buckets;
}
// 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
@@ -84,13 +91,14 @@ class PlainTableIterator : public Iterator {
};
extern const uint64_t kPlainTableMagicNumber;
PlainTableReader::PlainTableReader(const EnvOptions& storage_options,
const InternalKeyComparator& icomparator,
uint64_t file_size, int bloom_bits_per_key,
double hash_table_ratio,
size_t index_sparseness,
const TableProperties* table_properties)
: soptions_(storage_options),
PlainTableReader::PlainTableReader(
const Options& options, unique_ptr<RandomAccessFile>&& file,
const EnvOptions& storage_options, const InternalKeyComparator& icomparator,
uint64_t file_size, int bloom_bits_per_key, double hash_table_ratio,
size_t index_sparseness, const TableProperties* table_properties)
: options_(options),
soptions_(storage_options),
file_(std::move(file)),
internal_comparator_(icomparator),
file_size_(file_size),
kHashTableRatio(hash_table_ratio),
@@ -98,12 +106,11 @@ PlainTableReader::PlainTableReader(const EnvOptions& storage_options,
kIndexIntervalForSamePrefixKeys(index_sparseness),
table_properties_(table_properties),
data_end_offset_(table_properties_->data_size),
user_key_len_(table_properties->fixed_key_len) {}
user_key_len_(table_properties->fixed_key_len) {
assert(kHashTableRatio >= 0.0);
}
PlainTableReader::~PlainTableReader() {
delete[] hash_table_;
delete[] sub_index_;
delete bloom_;
}
Status PlainTableReader::Open(
@@ -126,10 +133,8 @@ Status PlainTableReader::Open(
}
std::unique_ptr<PlainTableReader> new_reader(new PlainTableReader(
soptions, internal_comparator, file_size, bloom_bits_per_key,
hash_table_ratio, index_sparseness, props));
new_reader->file_ = std::move(file);
new_reader->options_ = options;
options, std::move(file), soptions, internal_comparator, file_size,
bloom_bits_per_key, hash_table_ratio, index_sparseness, props));
// -- Populate Index
s = new_reader->PopulateIndex();
@@ -198,6 +203,9 @@ class PlainTableReader::IndexRecordList {
return result;
}
// Each group in `groups_` contains fix-sized records (determined by
// kNumRecordsPerGroup). Which can help us minimize the cost if resizing
// occurs.
const size_t kNumRecordsPerGroup;
IndexRecord* current_group_;
// List of arrays allocated
@@ -206,12 +214,11 @@ class PlainTableReader::IndexRecordList {
};
Status PlainTableReader::PopulateIndexRecordList(IndexRecordList* record_list,
int* num_prefixes,
DynamicBloom* bloom_) const {
int* num_prefixes) const {
Slice prev_key_prefix_slice;
uint32_t prev_key_prefix_hash = 0;
uint32_t pos = data_start_offset_;
int key_index_within_prefix = 0;
int num_keys_per_prefix = 0;
bool is_first_record = true;
HistogramImpl keys_per_prefix_hist;
// Need map to be ordered to make sure sub indexes generated
@@ -222,7 +229,7 @@ Status PlainTableReader::PopulateIndexRecordList(IndexRecordList* record_list,
uint32_t key_offset = pos;
ParsedInternalKey key;
Slice value_slice;
Status s = Next(pos, &key, &value_slice, &pos);
Status s = Next(&pos, &key, &value_slice);
if (!s.ok()) {
return s;
}
@@ -235,22 +242,22 @@ Status PlainTableReader::PopulateIndexRecordList(IndexRecordList* record_list,
if (is_first_record || prev_key_prefix_slice != key_prefix_slice) {
++(*num_prefixes);
if (!is_first_record) {
keys_per_prefix_hist.Add(key_index_within_prefix);
keys_per_prefix_hist.Add(num_keys_per_prefix);
}
key_index_within_prefix = 0;
num_keys_per_prefix = 0;
prev_key_prefix_slice = key_prefix_slice;
prev_key_prefix_hash = GetSliceHash(key_prefix_slice);
}
if (kIndexIntervalForSamePrefixKeys == 0 ||
key_index_within_prefix++ % kIndexIntervalForSamePrefixKeys == 0) {
num_keys_per_prefix++ % kIndexIntervalForSamePrefixKeys == 0) {
// Add an index key for every kIndexIntervalForSamePrefixKeys keys
record_list->AddRecord(prev_key_prefix_hash, key_offset);
}
is_first_record = false;
}
keys_per_prefix_hist.Add(key_index_within_prefix);
keys_per_prefix_hist.Add(num_keys_per_prefix);
Log(options_.info_log, "Number of Keys per prefix Histogram: %s",
keys_per_prefix_hist.ToString().c_str());
@@ -258,36 +265,35 @@ Status PlainTableReader::PopulateIndexRecordList(IndexRecordList* record_list,
}
void PlainTableReader::AllocateIndexAndBloom(int num_prefixes) {
delete[] hash_table_;
index_.reset();
if (options_.prefix_extractor != nullptr) {
uint32_t bloom_total_bits = num_prefixes * kBloomBitsPerKey;
if (bloom_total_bits > 0) {
bloom_ = new DynamicBloom(bloom_total_bits);
bloom_.reset(new DynamicBloom(bloom_total_bits));
}
}
if (options_.prefix_extractor == nullptr || kHashTableRatio <= 0) {
// Fall back to pure binary search if the user fails to specify a prefix
// extractor.
hash_table_size_ = 1;
index_size_ = 1;
} else {
double hash_table_size_multipier = 1.0 / kHashTableRatio;
hash_table_size_ = num_prefixes * hash_table_size_multipier + 1;
index_size_ = num_prefixes * hash_table_size_multipier + 1;
}
hash_table_ = new uint32_t[hash_table_size_];
index_.reset(new uint32_t[index_size_]);
}
size_t PlainTableReader::BucketizeIndexesAndFillBloom(
IndexRecordList& record_list, int num_prefixes,
std::vector<IndexRecord*>* hash_to_offsets,
IndexRecordList* record_list, std::vector<IndexRecord*>* hash_to_offsets,
std::vector<uint32_t>* bucket_count) {
size_t sub_index_size_needed = 0;
bool first = true;
uint32_t prev_hash = 0;
size_t num_records = record_list.GetNumRecords();
size_t num_records = record_list->GetNumRecords();
for (size_t i = 0; i < num_records; i++) {
IndexRecord* index_record = record_list.At(i);
IndexRecord* index_record = record_list->At(i);
uint32_t cur_hash = index_record->hash;
if (first || prev_hash != cur_hash) {
prev_hash = cur_hash;
@@ -296,7 +302,7 @@ size_t PlainTableReader::BucketizeIndexesAndFillBloom(
bloom_->AddHash(cur_hash);
}
}
uint32_t bucket = GetBucketIdFromHash(cur_hash, hash_table_size_);
uint32_t bucket = GetBucketIdFromHash(cur_hash, index_size_);
IndexRecord* prev_bucket_head = (*hash_to_offsets)[bucket];
index_record->next = prev_bucket_head;
(*hash_to_offsets)[bucket] = index_record;
@@ -326,27 +332,24 @@ void PlainTableReader::FillIndexes(
size_t buffer_size = 8 * 8;
size_t buffer_used = 0;
sub_index_size_needed += buffer_size;
sub_index_ = new char[sub_index_size_needed];
sub_index_.reset(new char[sub_index_size_needed]);
size_t sub_index_offset = 0;
char* prev_ptr;
char* cur_ptr;
uint32_t* sub_index_ptr;
for (int i = 0; i < hash_table_size_; i++) {
for (int i = 0; i < index_size_; i++) {
uint32_t num_keys_for_bucket = bucket_count[i];
switch (num_keys_for_bucket) {
case 0:
// No key for bucket
hash_table_[i] = data_end_offset_;
index_[i] = data_end_offset_;
break;
case 1:
// point directly to the file offset
hash_table_[i] = hash_to_offsets[i]->offset;
index_[i] = hash_to_offsets[i]->offset;
break;
default:
// point to second level indexes.
hash_table_[i] = sub_index_offset | kSubIndexMask;
prev_ptr = sub_index_ + sub_index_offset;
cur_ptr = EncodeVarint32(prev_ptr, num_keys_for_bucket);
index_[i] = sub_index_offset | kSubIndexMask;
char* prev_ptr = &sub_index_[sub_index_offset];
char* cur_ptr = EncodeVarint32(prev_ptr, num_keys_for_bucket);
sub_index_offset += (cur_ptr - prev_ptr);
if (cur_ptr - prev_ptr > 2
|| (cur_ptr - prev_ptr == 2 && num_keys_for_bucket <= 127)) {
@@ -359,17 +362,16 @@ void PlainTableReader::FillIndexes(
sub_index_size_needed += buffer_size;
buffer_size *= 2;
char* new_sub_index = new char[sub_index_size_needed];
memcpy(new_sub_index, sub_index_, sub_index_offset);
delete[] sub_index_;
sub_index_ = new_sub_index;
memcpy(new_sub_index, sub_index_.get(), sub_index_offset);
sub_index_.reset(new_sub_index);
}
}
sub_index_ptr = (uint32_t*) (sub_index_ + sub_index_offset);
char* sub_index_pos = &sub_index_[sub_index_offset];
IndexRecord* record = hash_to_offsets[i];
int j;
for (j = num_keys_for_bucket - 1; j >= 0 && record;
j--, record = record->next) {
sub_index_ptr[j] = record->offset;
EncodeFixed32(sub_index_pos + j * sizeof(uint32_t), record->offset);
}
assert(j == -1 && record == nullptr);
sub_index_offset += kOffsetLen * num_keys_for_bucket;
@@ -378,7 +380,7 @@ void PlainTableReader::FillIndexes(
}
Log(options_.info_log, "hash table size: %d, suffix_map length %zu",
hash_table_size_, sub_index_size_needed);
index_size_, sub_index_size_needed);
}
Status PlainTableReader::PopulateIndex() {
@@ -405,11 +407,11 @@ Status PlainTableReader::PopulateIndex() {
if (IsTotalOrderMode()) {
uint32_t num_bloom_bits = table_properties_->num_entries * kBloomBitsPerKey;
if (num_bloom_bits > 0) {
bloom_ = new DynamicBloom(num_bloom_bits);
bloom_.reset(new DynamicBloom(num_bloom_bits));
}
}
s = PopulateIndexRecordList(&record_list, &num_prefixes, bloom_);
s = PopulateIndexRecordList(&record_list, &num_prefixes);
if (!s.ok()) {
return s;
}
@@ -419,10 +421,10 @@ Status PlainTableReader::PopulateIndex() {
// Bucketize all the index records to a temp data structure, in which for
// each bucket, we generate a linked list of IndexRecord, in reversed order.
std::vector<IndexRecord*> hash_to_offsets(hash_table_size_, nullptr);
std::vector<uint32_t> bucket_count(hash_table_size_, 0);
std::vector<IndexRecord*> hash_to_offsets(index_size_, nullptr);
std::vector<uint32_t> bucket_count(index_size_, 0);
size_t sub_index_size_needed = BucketizeIndexesAndFillBloom(
record_list, num_prefixes, &hash_to_offsets, &bucket_count);
&record_list, &hash_to_offsets, &bucket_count);
// From the temp data structure, populate indexes.
FillIndexes(sub_index_size_needed, hash_to_offsets, bucket_count);
@@ -431,16 +433,16 @@ Status PlainTableReader::PopulateIndex() {
Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
uint32_t prefix_hash, bool& prefix_matched,
uint32_t* ret_offset) const {
uint32_t* offset) const {
prefix_matched = false;
int bucket = GetBucketIdFromHash(prefix_hash, hash_table_size_);
uint32_t bucket_value = hash_table_[bucket];
int bucket = GetBucketIdFromHash(prefix_hash, index_size_);
uint32_t bucket_value = index_[bucket];
if (bucket_value == data_end_offset_) {
*ret_offset = data_end_offset_;
*offset = data_end_offset_;
return Status::OK();
} else if ((bucket_value & kSubIndexMask) == 0) {
// point directly to the file
*ret_offset = bucket_value;
*offset = bucket_value;
return Status::OK();
}
@@ -448,11 +450,9 @@ Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
uint32_t low = 0;
uint64_t prefix_index_offset = bucket_value ^ kSubIndexMask;
const char* index_ptr = sub_index_ + prefix_index_offset;
const char* index_ptr = &sub_index_[prefix_index_offset];
uint32_t upper_bound = 0;
const uint32_t* base_ptr = (const uint32_t*) GetVarint32Ptr(index_ptr,
index_ptr + 4,
&upper_bound);
const char* base_ptr = GetVarint32Ptr(index_ptr, index_ptr + 4, &upper_bound);
uint32_t high = upper_bound;
ParsedInternalKey mid_key;
ParsedInternalKey parsed_target;
@@ -463,7 +463,7 @@ Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
// 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 = base_ptr[mid];
uint32_t file_offset = GetFixed32Element(base_ptr, mid);
size_t tmp;
Status s = ReadKey(file_data_.data() + file_offset, &mid_key, &tmp);
if (!s.ok()) {
@@ -477,7 +477,7 @@ Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
// Happen to have found the exact key or target is smaller than the
// first key after base_offset.
prefix_matched = true;
*ret_offset = file_offset;
*offset = file_offset;
return Status::OK();
} else {
high = mid;
@@ -489,19 +489,19 @@ Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
// to the wrong prefix.
ParsedInternalKey low_key;
size_t tmp;
uint32_t low_key_offset = base_ptr[low];
uint32_t low_key_offset = GetFixed32Element(base_ptr, low);
Status s = ReadKey(file_data_.data() + low_key_offset, &low_key, &tmp);
if (GetPrefix(low_key) == prefix) {
prefix_matched = true;
*ret_offset = low_key_offset;
*offset = low_key_offset;
} else if (low + 1 < upper_bound) {
// There is possible a next prefix, return it
prefix_matched = false;
*ret_offset = base_ptr[low + 1];
*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.
*ret_offset = data_end_offset_;
*offset = data_end_offset_;
}
return Status::OK();
}
@@ -514,23 +514,23 @@ Slice PlainTableReader::GetPrefix(const ParsedInternalKey& target) const {
return GetPrefixFromUserKey(target.user_key);
}
Status PlainTableReader::ReadKey(const char* row_ptr, ParsedInternalKey* key,
Status PlainTableReader::ReadKey(const char* start, ParsedInternalKey* key,
size_t* bytes_read) const {
const char* key_ptr = nullptr;
*bytes_read = 0;
size_t user_key_size = 0;
if (IsFixedLength()) {
user_key_size = user_key_len_;
key_ptr = row_ptr;
key_ptr = start;
} else {
uint32_t tmp_size = 0;
key_ptr = GetVarint32Ptr(row_ptr, file_data_.data() + data_end_offset_,
&tmp_size);
key_ptr =
GetVarint32Ptr(start, file_data_.data() + data_end_offset_, &tmp_size);
if (key_ptr == nullptr) {
return Status::Corruption("Unable to read the next key");
}
user_key_size = (size_t)tmp_size;
*bytes_read = key_ptr - row_ptr;
*bytes_read = key_ptr - start;
}
if (key_ptr + user_key_size + 1 >= file_data_.data() + data_end_offset_) {
return Status::Corruption("Unable to read the next key");
@@ -543,7 +543,7 @@ Status PlainTableReader::ReadKey(const char* row_ptr, ParsedInternalKey* key,
key->type = kTypeValue;
*bytes_read += user_key_size + 1;
} else {
if (row_ptr + user_key_size + 8 >= file_data_.data() + data_end_offset_) {
if (start + user_key_size + 8 >= file_data_.data() + data_end_offset_) {
return Status::Corruption("Unable to read the next key");
}
if (!ParseInternalKey(Slice(key_ptr, user_key_size + 8), key)) {
@@ -555,29 +555,28 @@ Status PlainTableReader::ReadKey(const char* row_ptr, ParsedInternalKey* key,
return Status::OK();
}
Status PlainTableReader::Next(uint32_t offset, ParsedInternalKey* key,
Slice* value, uint32_t* next_offset) const {
if (offset == data_end_offset_) {
*next_offset = data_end_offset_;
Status PlainTableReader::Next(uint32_t* offset, ParsedInternalKey* key,
Slice* value) const {
if (*offset == data_end_offset_) {
*offset = data_end_offset_;
return Status::OK();
}
if (offset > data_end_offset_) {
if (*offset > data_end_offset_) {
return Status::Corruption("Offset is out of file size");
}
const char* row_ptr = file_data_.data() + offset;
const char* start = file_data_.data() + *offset;
size_t bytes_for_key;
Status s = ReadKey(row_ptr, key, &bytes_for_key);
Status s = ReadKey(start, key, &bytes_for_key);
uint32_t value_size;
const char* value_ptr = GetVarint32Ptr(row_ptr + bytes_for_key,
file_data_.data() + data_end_offset_,
&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("Error reading value length.");
}
*next_offset = offset + (value_ptr - row_ptr) + value_size;
if (*next_offset > data_end_offset_) {
*offset = *offset + (value_ptr - start) + value_size;
if (*offset > data_end_offset_) {
return Status::Corruption("Reach end of file when reading value");
}
*value = Slice(value_ptr, value_size);
@@ -624,7 +623,7 @@ Status PlainTableReader::Get(const ReadOptions& ro, const Slice& target,
Slice found_value;
while (offset < data_end_offset_) {
Status s = Next(offset, &found_key, &found_value, &offset);
Status s = Next(&offset, &found_key, &found_value);
if (!s.ok()) {
return s;
}
@@ -680,7 +679,7 @@ void PlainTableIterator::SeekToLast() {
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_ && table_->hash_table_size_ > 1) {
if (!use_prefix_seek_ && table_->index_size_ > 1) {
assert(false);
status_ = Status::NotSupported(
"PlainTable cannot issue non-prefix seek unless in total order mode.");
@@ -736,7 +735,7 @@ void PlainTableIterator::Next() {
if (offset_ < table_->data_end_offset_) {
Slice tmp_slice;
ParsedInternalKey parsed_key;
status_ = table_->Next(next_offset_, &parsed_key, &value_, &next_offset_);
status_ = table_->Next(&next_offset_, &parsed_key, &value_);
if (status_.ok()) {
// Make a copy in this case. TODO optimize.
tmp_str_.clear();