rocksdb/table/cuckoo_table_builder.cc
Abhishek Madan eaaf1a6f05 Promote rocksdb.{deleted.keys,merge.operands} to main table properties (#4594)
Summary:
Since the number of range deletions are reported in
TableProperties, it is confusing to not report the number of merge
operands and point deletions as top-level properties; they are
accessible through the public API, but since they are not the "main"
properties, they do not appear in aggregated table properties, or the
string representation of table properties.

This change promotes those two property keys to
`rocksdb/table_properties.h`, adds corresponding uint64 members for
them, deprecates the old access methods `GetDeletedKeys()` and
`GetMergeOperands()` (though they are still usable for now), and removes
`InternalKeyPropertiesCollector`. The property key strings are the same
as before this change, so this should be able to read DBs written from older
versions (though I haven't tested this yet).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4594

Differential Revision: D12826893

Pulled By: abhimadan

fbshipit-source-id: 9e4e4fbdc5b0da161c89582566d184101ba8eb68
2018-10-30 15:34:27 -07:00

517 lines
20 KiB
C++

// 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).
#ifndef ROCKSDB_LITE
#include "table/cuckoo_table_builder.h"
#include <assert.h>
#include <algorithm>
#include <limits>
#include <string>
#include <vector>
#include "db/dbformat.h"
#include "rocksdb/env.h"
#include "rocksdb/table.h"
#include "table/block_builder.h"
#include "table/cuckoo_table_factory.h"
#include "table/format.h"
#include "table/meta_blocks.h"
#include "util/autovector.h"
#include "util/file_reader_writer.h"
#include "util/random.h"
#include "util/string_util.h"
namespace rocksdb {
const std::string CuckooTablePropertyNames::kEmptyKey =
"rocksdb.cuckoo.bucket.empty.key";
const std::string CuckooTablePropertyNames::kNumHashFunc =
"rocksdb.cuckoo.hash.num";
const std::string CuckooTablePropertyNames::kHashTableSize =
"rocksdb.cuckoo.hash.size";
const std::string CuckooTablePropertyNames::kValueLength =
"rocksdb.cuckoo.value.length";
const std::string CuckooTablePropertyNames::kIsLastLevel =
"rocksdb.cuckoo.file.islastlevel";
const std::string CuckooTablePropertyNames::kCuckooBlockSize =
"rocksdb.cuckoo.hash.cuckooblocksize";
const std::string CuckooTablePropertyNames::kIdentityAsFirstHash =
"rocksdb.cuckoo.hash.identityfirst";
const std::string CuckooTablePropertyNames::kUseModuleHash =
"rocksdb.cuckoo.hash.usemodule";
const std::string CuckooTablePropertyNames::kUserKeyLength =
"rocksdb.cuckoo.hash.userkeylength";
// Obtained by running echo rocksdb.table.cuckoo | sha1sum
extern const uint64_t kCuckooTableMagicNumber = 0x926789d0c5f17873ull;
CuckooTableBuilder::CuckooTableBuilder(
WritableFileWriter* file, double max_hash_table_ratio,
uint32_t max_num_hash_table, uint32_t max_search_depth,
const Comparator* user_comparator, uint32_t cuckoo_block_size,
bool use_module_hash, bool identity_as_first_hash,
uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t),
uint32_t column_family_id, const std::string& column_family_name)
: num_hash_func_(2),
file_(file),
max_hash_table_ratio_(max_hash_table_ratio),
max_num_hash_func_(max_num_hash_table),
max_search_depth_(max_search_depth),
cuckoo_block_size_(std::max(1U, cuckoo_block_size)),
hash_table_size_(use_module_hash ? 0 : 2),
is_last_level_file_(false),
has_seen_first_key_(false),
has_seen_first_value_(false),
key_size_(0),
value_size_(0),
num_entries_(0),
num_values_(0),
ucomp_(user_comparator),
use_module_hash_(use_module_hash),
identity_as_first_hash_(identity_as_first_hash),
get_slice_hash_(get_slice_hash),
closed_(false) {
// Data is in a huge block.
properties_.num_data_blocks = 1;
properties_.index_size = 0;
properties_.filter_size = 0;
properties_.column_family_id = column_family_id;
properties_.column_family_name = column_family_name;
}
void CuckooTableBuilder::Add(const Slice& key, const Slice& value) {
if (num_entries_ >= kMaxVectorIdx - 1) {
status_ = Status::NotSupported("Number of keys in a file must be < 2^32-1");
return;
}
ParsedInternalKey ikey;
if (!ParseInternalKey(key, &ikey)) {
status_ = Status::Corruption("Unable to parse key into inernal key.");
return;
}
if (ikey.type != kTypeDeletion && ikey.type != kTypeValue) {
status_ = Status::NotSupported("Unsupported key type " +
ToString(ikey.type));
return;
}
// Determine if we can ignore the sequence number and value type from
// internal keys by looking at sequence number from first key. We assume
// that if first key has a zero sequence number, then all the remaining
// keys will have zero seq. no.
if (!has_seen_first_key_) {
is_last_level_file_ = ikey.sequence == 0;
has_seen_first_key_ = true;
smallest_user_key_.assign(ikey.user_key.data(), ikey.user_key.size());
largest_user_key_.assign(ikey.user_key.data(), ikey.user_key.size());
key_size_ = is_last_level_file_ ? ikey.user_key.size() : key.size();
}
if (key_size_ != (is_last_level_file_ ? ikey.user_key.size() : key.size())) {
status_ = Status::NotSupported("all keys have to be the same size");
return;
}
if (ikey.type == kTypeValue) {
if (!has_seen_first_value_) {
has_seen_first_value_ = true;
value_size_ = value.size();
}
if (value_size_ != value.size()) {
status_ = Status::NotSupported("all values have to be the same size");
return;
}
if (is_last_level_file_) {
kvs_.append(ikey.user_key.data(), ikey.user_key.size());
} else {
kvs_.append(key.data(), key.size());
}
kvs_.append(value.data(), value.size());
++num_values_;
} else {
if (is_last_level_file_) {
deleted_keys_.append(ikey.user_key.data(), ikey.user_key.size());
} else {
deleted_keys_.append(key.data(), key.size());
}
}
++num_entries_;
// In order to fill the empty buckets in the hash table, we identify a
// key which is not used so far (unused_user_key). We determine this by
// maintaining smallest and largest keys inserted so far in bytewise order
// and use them to find a key outside this range in Finish() operation.
// Note that this strategy is independent of user comparator used here.
if (ikey.user_key.compare(smallest_user_key_) < 0) {
smallest_user_key_.assign(ikey.user_key.data(), ikey.user_key.size());
} else if (ikey.user_key.compare(largest_user_key_) > 0) {
largest_user_key_.assign(ikey.user_key.data(), ikey.user_key.size());
}
if (!use_module_hash_) {
if (hash_table_size_ < num_entries_ / max_hash_table_ratio_) {
hash_table_size_ *= 2;
}
}
}
bool CuckooTableBuilder::IsDeletedKey(uint64_t idx) const {
assert(closed_);
return idx >= num_values_;
}
Slice CuckooTableBuilder::GetKey(uint64_t idx) const {
assert(closed_);
if (IsDeletedKey(idx)) {
return Slice(&deleted_keys_[static_cast<size_t>((idx - num_values_) * key_size_)], static_cast<size_t>(key_size_));
}
return Slice(&kvs_[static_cast<size_t>(idx * (key_size_ + value_size_))], static_cast<size_t>(key_size_));
}
Slice CuckooTableBuilder::GetUserKey(uint64_t idx) const {
assert(closed_);
return is_last_level_file_ ? GetKey(idx) : ExtractUserKey(GetKey(idx));
}
Slice CuckooTableBuilder::GetValue(uint64_t idx) const {
assert(closed_);
if (IsDeletedKey(idx)) {
static std::string empty_value(static_cast<unsigned int>(value_size_), 'a');
return Slice(empty_value);
}
return Slice(&kvs_[static_cast<size_t>(idx * (key_size_ + value_size_) + key_size_)], static_cast<size_t>(value_size_));
}
Status CuckooTableBuilder::MakeHashTable(std::vector<CuckooBucket>* buckets) {
buckets->resize(static_cast<size_t>(hash_table_size_ + cuckoo_block_size_ - 1));
uint32_t make_space_for_key_call_id = 0;
for (uint32_t vector_idx = 0; vector_idx < num_entries_; vector_idx++) {
uint64_t bucket_id = 0;
bool bucket_found = false;
autovector<uint64_t> hash_vals;
Slice user_key = GetUserKey(vector_idx);
for (uint32_t hash_cnt = 0; hash_cnt < num_hash_func_ && !bucket_found;
++hash_cnt) {
uint64_t hash_val = CuckooHash(user_key, hash_cnt, use_module_hash_,
hash_table_size_, identity_as_first_hash_, get_slice_hash_);
// If there is a collision, check next cuckoo_block_size_ locations for
// empty locations. While checking, if we reach end of the hash table,
// stop searching and proceed for next hash function.
for (uint32_t block_idx = 0; block_idx < cuckoo_block_size_;
++block_idx, ++hash_val) {
if ((*buckets)[static_cast<size_t>(hash_val)].vector_idx == kMaxVectorIdx) {
bucket_id = hash_val;
bucket_found = true;
break;
} else {
if (ucomp_->Compare(user_key,
GetUserKey((*buckets)[static_cast<size_t>(hash_val)].vector_idx)) == 0) {
return Status::NotSupported("Same key is being inserted again.");
}
hash_vals.push_back(hash_val);
}
}
}
while (!bucket_found && !MakeSpaceForKey(hash_vals,
++make_space_for_key_call_id, buckets, &bucket_id)) {
// Rehash by increashing number of hash tables.
if (num_hash_func_ >= max_num_hash_func_) {
return Status::NotSupported("Too many collisions. Unable to hash.");
}
// We don't really need to rehash the entire table because old hashes are
// still valid and we only increased the number of hash functions.
uint64_t hash_val = CuckooHash(user_key, num_hash_func_, use_module_hash_,
hash_table_size_, identity_as_first_hash_, get_slice_hash_);
++num_hash_func_;
for (uint32_t block_idx = 0; block_idx < cuckoo_block_size_;
++block_idx, ++hash_val) {
if ((*buckets)[static_cast<size_t>(hash_val)].vector_idx == kMaxVectorIdx) {
bucket_found = true;
bucket_id = hash_val;
break;
} else {
hash_vals.push_back(hash_val);
}
}
}
(*buckets)[static_cast<size_t>(bucket_id)].vector_idx = vector_idx;
}
return Status::OK();
}
Status CuckooTableBuilder::Finish() {
assert(!closed_);
closed_ = true;
std::vector<CuckooBucket> buckets;
Status s;
std::string unused_bucket;
if (num_entries_ > 0) {
// Calculate the real hash size if module hash is enabled.
if (use_module_hash_) {
hash_table_size_ =
static_cast<uint64_t>(num_entries_ / max_hash_table_ratio_);
}
s = MakeHashTable(&buckets);
if (!s.ok()) {
return s;
}
// Determine unused_user_key to fill empty buckets.
std::string unused_user_key = smallest_user_key_;
int curr_pos = static_cast<int>(unused_user_key.size()) - 1;
while (curr_pos >= 0) {
--unused_user_key[curr_pos];
if (Slice(unused_user_key).compare(smallest_user_key_) < 0) {
break;
}
--curr_pos;
}
if (curr_pos < 0) {
// Try using the largest key to identify an unused key.
unused_user_key = largest_user_key_;
curr_pos = static_cast<int>(unused_user_key.size()) - 1;
while (curr_pos >= 0) {
++unused_user_key[curr_pos];
if (Slice(unused_user_key).compare(largest_user_key_) > 0) {
break;
}
--curr_pos;
}
}
if (curr_pos < 0) {
return Status::Corruption("Unable to find unused key");
}
if (is_last_level_file_) {
unused_bucket = unused_user_key;
} else {
ParsedInternalKey ikey(unused_user_key, 0, kTypeValue);
AppendInternalKey(&unused_bucket, ikey);
}
}
properties_.num_entries = num_entries_;
properties_.num_deletions = num_entries_ - num_values_;
properties_.fixed_key_len = key_size_;
properties_.user_collected_properties[
CuckooTablePropertyNames::kValueLength].assign(
reinterpret_cast<const char*>(&value_size_), sizeof(value_size_));
uint64_t bucket_size = key_size_ + value_size_;
unused_bucket.resize(static_cast<size_t>(bucket_size), 'a');
// Write the table.
uint32_t num_added = 0;
for (auto& bucket : buckets) {
if (bucket.vector_idx == kMaxVectorIdx) {
s = file_->Append(Slice(unused_bucket));
} else {
++num_added;
s = file_->Append(GetKey(bucket.vector_idx));
if (s.ok()) {
if (value_size_ > 0) {
s = file_->Append(GetValue(bucket.vector_idx));
}
}
}
if (!s.ok()) {
return s;
}
}
assert(num_added == NumEntries());
properties_.raw_key_size = num_added * properties_.fixed_key_len;
properties_.raw_value_size = num_added * value_size_;
uint64_t offset = buckets.size() * bucket_size;
properties_.data_size = offset;
unused_bucket.resize(static_cast<size_t>(properties_.fixed_key_len));
properties_.user_collected_properties[
CuckooTablePropertyNames::kEmptyKey] = unused_bucket;
properties_.user_collected_properties[
CuckooTablePropertyNames::kNumHashFunc].assign(
reinterpret_cast<char*>(&num_hash_func_), sizeof(num_hash_func_));
properties_.user_collected_properties[
CuckooTablePropertyNames::kHashTableSize].assign(
reinterpret_cast<const char*>(&hash_table_size_),
sizeof(hash_table_size_));
properties_.user_collected_properties[
CuckooTablePropertyNames::kIsLastLevel].assign(
reinterpret_cast<const char*>(&is_last_level_file_),
sizeof(is_last_level_file_));
properties_.user_collected_properties[
CuckooTablePropertyNames::kCuckooBlockSize].assign(
reinterpret_cast<const char*>(&cuckoo_block_size_),
sizeof(cuckoo_block_size_));
properties_.user_collected_properties[
CuckooTablePropertyNames::kIdentityAsFirstHash].assign(
reinterpret_cast<const char*>(&identity_as_first_hash_),
sizeof(identity_as_first_hash_));
properties_.user_collected_properties[
CuckooTablePropertyNames::kUseModuleHash].assign(
reinterpret_cast<const char*>(&use_module_hash_),
sizeof(use_module_hash_));
uint32_t user_key_len = static_cast<uint32_t>(smallest_user_key_.size());
properties_.user_collected_properties[
CuckooTablePropertyNames::kUserKeyLength].assign(
reinterpret_cast<const char*>(&user_key_len),
sizeof(user_key_len));
// Write meta blocks.
MetaIndexBuilder meta_index_builder;
PropertyBlockBuilder property_block_builder;
property_block_builder.AddTableProperty(properties_);
property_block_builder.Add(properties_.user_collected_properties);
Slice property_block = property_block_builder.Finish();
BlockHandle property_block_handle;
property_block_handle.set_offset(offset);
property_block_handle.set_size(property_block.size());
s = file_->Append(property_block);
offset += property_block.size();
if (!s.ok()) {
return s;
}
meta_index_builder.Add(kPropertiesBlock, property_block_handle);
Slice meta_index_block = meta_index_builder.Finish();
BlockHandle meta_index_block_handle;
meta_index_block_handle.set_offset(offset);
meta_index_block_handle.set_size(meta_index_block.size());
s = file_->Append(meta_index_block);
if (!s.ok()) {
return s;
}
Footer footer(kCuckooTableMagicNumber, 1);
footer.set_metaindex_handle(meta_index_block_handle);
footer.set_index_handle(BlockHandle::NullBlockHandle());
std::string footer_encoding;
footer.EncodeTo(&footer_encoding);
s = file_->Append(footer_encoding);
return s;
}
void CuckooTableBuilder::Abandon() {
assert(!closed_);
closed_ = true;
}
uint64_t CuckooTableBuilder::NumEntries() const {
return num_entries_;
}
uint64_t CuckooTableBuilder::FileSize() const {
if (closed_) {
return file_->GetFileSize();
} else if (num_entries_ == 0) {
return 0;
}
if (use_module_hash_) {
return static_cast<uint64_t>((key_size_ + value_size_) *
num_entries_ / max_hash_table_ratio_);
} else {
// Account for buckets being a power of two.
// As elements are added, file size remains constant for a while and
// doubles its size. Since compaction algorithm stops adding elements
// only after it exceeds the file limit, we account for the extra element
// being added here.
uint64_t expected_hash_table_size = hash_table_size_;
if (expected_hash_table_size < (num_entries_ + 1) / max_hash_table_ratio_) {
expected_hash_table_size *= 2;
}
return (key_size_ + value_size_) * expected_hash_table_size - 1;
}
}
// This method is invoked when there is no place to insert the target key.
// It searches for a set of elements that can be moved to accommodate target
// key. The search is a BFS graph traversal with first level (hash_vals)
// being all the buckets target key could go to.
// Then, from each node (curr_node), we find all the buckets that curr_node
// could go to. They form the children of curr_node in the tree.
// We continue the traversal until we find an empty bucket, in which case, we
// move all elements along the path from first level to this empty bucket, to
// make space for target key which is inserted at first level (*bucket_id).
// If tree depth exceedes max depth, we return false indicating failure.
bool CuckooTableBuilder::MakeSpaceForKey(
const autovector<uint64_t>& hash_vals,
const uint32_t make_space_for_key_call_id,
std::vector<CuckooBucket>* buckets, uint64_t* bucket_id) {
struct CuckooNode {
uint64_t bucket_id;
uint32_t depth;
uint32_t parent_pos;
CuckooNode(uint64_t _bucket_id, uint32_t _depth, int _parent_pos)
: bucket_id(_bucket_id), depth(_depth), parent_pos(_parent_pos) {}
};
// This is BFS search tree that is stored simply as a vector.
// Each node stores the index of parent node in the vector.
std::vector<CuckooNode> tree;
// We want to identify already visited buckets in the current method call so
// that we don't add same buckets again for exploration in the tree.
// We do this by maintaining a count of current method call in
// make_space_for_key_call_id, which acts as a unique id for this invocation
// of the method. We store this number into the nodes that we explore in
// current method call.
// It is unlikely for the increment operation to overflow because the maximum
// no. of times this will be called is <= max_num_hash_func_ + num_entries_.
for (uint32_t hash_cnt = 0; hash_cnt < num_hash_func_; ++hash_cnt) {
uint64_t bid = hash_vals[hash_cnt];
(*buckets)[static_cast<size_t>(bid)].make_space_for_key_call_id = make_space_for_key_call_id;
tree.push_back(CuckooNode(bid, 0, 0));
}
bool null_found = false;
uint32_t curr_pos = 0;
while (!null_found && curr_pos < tree.size()) {
CuckooNode& curr_node = tree[curr_pos];
uint32_t curr_depth = curr_node.depth;
if (curr_depth >= max_search_depth_) {
break;
}
CuckooBucket& curr_bucket = (*buckets)[static_cast<size_t>(curr_node.bucket_id)];
for (uint32_t hash_cnt = 0;
hash_cnt < num_hash_func_ && !null_found; ++hash_cnt) {
uint64_t child_bucket_id = CuckooHash(GetUserKey(curr_bucket.vector_idx),
hash_cnt, use_module_hash_, hash_table_size_, identity_as_first_hash_,
get_slice_hash_);
// Iterate inside Cuckoo Block.
for (uint32_t block_idx = 0; block_idx < cuckoo_block_size_;
++block_idx, ++child_bucket_id) {
if ((*buckets)[static_cast<size_t>(child_bucket_id)].make_space_for_key_call_id ==
make_space_for_key_call_id) {
continue;
}
(*buckets)[static_cast<size_t>(child_bucket_id)].make_space_for_key_call_id =
make_space_for_key_call_id;
tree.push_back(CuckooNode(child_bucket_id, curr_depth + 1,
curr_pos));
if ((*buckets)[static_cast<size_t>(child_bucket_id)].vector_idx == kMaxVectorIdx) {
null_found = true;
break;
}
}
}
++curr_pos;
}
if (null_found) {
// There is an empty node in tree.back(). Now, traverse the path from this
// empty node to top of the tree and at every node in the path, replace
// child with the parent. Stop when first level is reached in the tree
// (happens when 0 <= bucket_to_replace_pos < num_hash_func_) and return
// this location in first level for target key to be inserted.
uint32_t bucket_to_replace_pos = static_cast<uint32_t>(tree.size()) - 1;
while (bucket_to_replace_pos >= num_hash_func_) {
CuckooNode& curr_node = tree[bucket_to_replace_pos];
(*buckets)[static_cast<size_t>(curr_node.bucket_id)] =
(*buckets)[static_cast<size_t>(tree[curr_node.parent_pos].bucket_id)];
bucket_to_replace_pos = curr_node.parent_pos;
}
*bucket_id = tree[bucket_to_replace_pos].bucket_id;
}
return null_found;
}
} // namespace rocksdb
#endif // ROCKSDB_LITE