ffe1e4b820
Summary: The old block-based filter has been deprecated for years, but this makes that more clear by marking the functions specific to it and logging a warning when the feature is used. It is deprecated because of performance. In that old design, you have to binary search through the full SST index before a bloom filter query, which is much more expensive than a bloom query itself. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9403 Test Plan: Used db_bench with and without -use_block_based_filter, running at the same time TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom,readrandom -num=10000000 -duration=20 -disable_wal=1 -write_buffer_size=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 No significant difference in construction time but 3x slower readrandom with -use_block_based_filter: readrandom : 100.517 micros/op 9948 ops/sec; 1.1 MB/s vs. readrandom : 33.368 micros/op 29968 ops/sec; 3.3 MB/s Also saw deprecation message (just once) in LOG only with -use_block_based_filter Reviewed By: ajkr Differential Revision: D33673202 Pulled By: pdillinger fbshipit-source-id: 99f6f0eff619408d9e5f7ef546954ed0be6c7a5b
1615 lines
60 KiB
C++
1615 lines
60 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "rocksdb/filter_policy.h"
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#include <array>
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#include <deque>
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#include <limits>
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#include <memory>
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#include "cache/cache_entry_roles.h"
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#include "cache/cache_reservation_manager.h"
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#include "logging/logging.h"
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#include "rocksdb/slice.h"
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#include "table/block_based/block_based_filter_block.h"
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#include "table/block_based/block_based_table_reader.h"
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#include "table/block_based/filter_policy_internal.h"
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#include "table/block_based/full_filter_block.h"
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#include "third-party/folly/folly/ConstexprMath.h"
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#include "util/bloom_impl.h"
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#include "util/coding.h"
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#include "util/hash.h"
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#include "util/ribbon_config.h"
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#include "util/ribbon_impl.h"
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namespace ROCKSDB_NAMESPACE {
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namespace {
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// Metadata trailer size for built-in filters. (This is separate from
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// block-based table block trailer.)
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//
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// Originally this was 1 byte for num_probes and 4 bytes for number of
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// cache lines in the Bloom filter, but now the first trailer byte is
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// usually an implementation marker and remaining 4 bytes have various
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// meanings.
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static constexpr uint32_t kMetadataLen = 5;
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Slice FinishAlwaysFalse(std::unique_ptr<const char[]>* /*buf*/) {
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// Missing metadata, treated as zero entries
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return Slice(nullptr, 0);
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}
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// Base class for filter builders using the XXH3 preview hash,
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// also known as Hash64 or GetSliceHash64.
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class XXPH3FilterBitsBuilder : public BuiltinFilterBitsBuilder {
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public:
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explicit XXPH3FilterBitsBuilder(
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std::atomic<int64_t>* aggregate_rounding_balance,
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std::shared_ptr<CacheReservationManager> cache_res_mgr)
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: aggregate_rounding_balance_(aggregate_rounding_balance),
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cache_res_mgr_(cache_res_mgr) {}
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~XXPH3FilterBitsBuilder() override {}
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virtual void AddKey(const Slice& key) override {
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uint64_t hash = GetSliceHash64(key);
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// Especially with prefixes, it is common to have repetition,
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// though only adjacent repetition, which we want to immediately
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// recognize and collapse for estimating true filter space
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// requirements.
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if (hash_entries_.empty() || hash != hash_entries_.back()) {
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hash_entries_.push_back(hash);
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if (cache_res_mgr_ &&
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// Traditional rounding to whole bucket size
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((hash_entries_.size() % kUint64tHashEntryCacheResBucketSize) ==
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kUint64tHashEntryCacheResBucketSize / 2)) {
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hash_entry_cache_res_bucket_handles_.emplace_back(nullptr);
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Status s =
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cache_res_mgr_
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->MakeCacheReservation<CacheEntryRole::kFilterConstruction>(
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kUint64tHashEntryCacheResBucketSize * sizeof(hash),
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&hash_entry_cache_res_bucket_handles_.back());
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s.PermitUncheckedError();
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}
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}
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}
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virtual size_t EstimateEntriesAdded() override {
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return hash_entries_.size();
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}
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protected:
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static constexpr uint32_t kMetadataLen = 5;
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// Number of hash entries to accumulate before charging their memory usage to
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// the cache when cache reservation is available
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static const std::size_t kUint64tHashEntryCacheResBucketSize =
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CacheReservationManager::GetDummyEntrySize() / sizeof(uint64_t);
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// For delegating between XXPH3FilterBitsBuilders
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void SwapEntriesWith(XXPH3FilterBitsBuilder* other) {
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std::swap(hash_entries_, other->hash_entries_);
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if (cache_res_mgr_) {
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std::swap(hash_entry_cache_res_bucket_handles_,
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other->hash_entry_cache_res_bucket_handles_);
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}
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}
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virtual size_t RoundDownUsableSpace(size_t available_size) = 0;
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// To choose size using malloc_usable_size, we have to actually allocate.
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size_t AllocateMaybeRounding(size_t target_len_with_metadata,
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size_t num_entries,
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std::unique_ptr<char[]>* buf) {
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// Return value set to a default; overwritten in some cases
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size_t rv = target_len_with_metadata;
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#ifdef ROCKSDB_MALLOC_USABLE_SIZE
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if (aggregate_rounding_balance_ != nullptr) {
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// Do optimize_filters_for_memory, using malloc_usable_size.
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// Approach: try to keep FP rate balance better than or on
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// target (negative aggregate_rounding_balance_). We can then select a
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// lower bound filter size (within reasonable limits) that gets us as
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// close to on target as possible. We request allocation for that filter
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// size and use malloc_usable_size to "round up" to the actual
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// allocation size.
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// Although it can be considered bad practice to use malloc_usable_size
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// to access an object beyond its original size, this approach should be
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// quite general: working for all allocators that properly support
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// malloc_usable_size.
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// Race condition on balance is OK because it can only cause temporary
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// skew in rounding up vs. rounding down, as long as updates are atomic
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// and relative.
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int64_t balance = aggregate_rounding_balance_->load();
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double target_fp_rate =
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EstimatedFpRate(num_entries, target_len_with_metadata);
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double rv_fp_rate = target_fp_rate;
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if (balance < 0) {
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// See formula for BloomFilterPolicy::aggregate_rounding_balance_
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double for_balance_fp_rate =
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-balance / double{0x100000000} + target_fp_rate;
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// To simplify, we just try a few modified smaller sizes. This also
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// caps how much we vary filter size vs. target, to avoid outlier
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// behavior from excessive variance.
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size_t target_len = target_len_with_metadata - kMetadataLen;
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assert(target_len < target_len_with_metadata); // check underflow
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for (uint64_t maybe_len_rough :
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{uint64_t{3} * target_len / 4, uint64_t{13} * target_len / 16,
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uint64_t{7} * target_len / 8, uint64_t{15} * target_len / 16}) {
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size_t maybe_len_with_metadata =
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RoundDownUsableSpace(maybe_len_rough + kMetadataLen);
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double maybe_fp_rate =
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EstimatedFpRate(num_entries, maybe_len_with_metadata);
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if (maybe_fp_rate <= for_balance_fp_rate) {
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rv = maybe_len_with_metadata;
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rv_fp_rate = maybe_fp_rate;
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break;
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}
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}
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}
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// Filter blocks are loaded into block cache with their block trailer.
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// We need to make sure that's accounted for in choosing a
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// fragmentation-friendly size.
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const size_t kExtraPadding = BlockBasedTable::kBlockTrailerSize;
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size_t requested = rv + kExtraPadding;
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// Allocate and get usable size
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buf->reset(new char[requested]);
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size_t usable = malloc_usable_size(buf->get());
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if (usable - usable / 4 > requested) {
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// Ratio greater than 4/3 is too much for utilizing, if it's
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// not a buggy or mislinked malloc_usable_size implementation.
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// Non-linearity of FP rates with bits/key means rapidly
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// diminishing returns in overall accuracy for additional
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// storage on disk.
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// Nothing to do, except assert that the result is accurate about
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// the usable size. (Assignment never used.)
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assert(((*buf)[usable - 1] = 'x'));
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} else if (usable > requested) {
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rv = RoundDownUsableSpace(usable - kExtraPadding);
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assert(rv <= usable - kExtraPadding);
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rv_fp_rate = EstimatedFpRate(num_entries, rv);
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} else {
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// Too small means bad malloc_usable_size
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assert(usable == requested);
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}
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memset(buf->get(), 0, rv);
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// Update balance
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int64_t diff = static_cast<int64_t>((rv_fp_rate - target_fp_rate) *
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double{0x100000000});
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*aggregate_rounding_balance_ += diff;
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} else {
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buf->reset(new char[rv]());
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}
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#else
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(void)num_entries;
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buf->reset(new char[rv]());
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#endif // ROCKSDB_MALLOC_USABLE_SIZE
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return rv;
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}
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// A deque avoids unnecessary copying of already-saved values
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// and has near-minimal peak memory use.
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std::deque<uint64_t> hash_entries_;
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// See BloomFilterPolicy::aggregate_rounding_balance_. If nullptr,
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// always "round up" like historic behavior.
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std::atomic<int64_t>* aggregate_rounding_balance_;
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// For reserving memory used in (new) Bloom and Ribbon Filter construction
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std::shared_ptr<CacheReservationManager> cache_res_mgr_;
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// For managing cache reservation for buckets of hash entry in (new) Bloom and
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// Ribbon Filter construction
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std::deque<std::unique_ptr<
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CacheReservationHandle<CacheEntryRole::kFilterConstruction>>>
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hash_entry_cache_res_bucket_handles_;
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// For managing cache reservation for final filter in (new) Bloom and Ribbon
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// Filter construction
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std::deque<std::unique_ptr<
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CacheReservationHandle<CacheEntryRole::kFilterConstruction>>>
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final_filter_cache_res_handles_;
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};
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// #################### FastLocalBloom implementation ################## //
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// ############## also known as format_version=5 Bloom filter ########## //
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// See description in FastLocalBloomImpl
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class FastLocalBloomBitsBuilder : public XXPH3FilterBitsBuilder {
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public:
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// Non-null aggregate_rounding_balance implies optimize_filters_for_memory
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explicit FastLocalBloomBitsBuilder(
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const int millibits_per_key,
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std::atomic<int64_t>* aggregate_rounding_balance,
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std::shared_ptr<CacheReservationManager> cache_res_mgr)
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: XXPH3FilterBitsBuilder(aggregate_rounding_balance, cache_res_mgr),
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millibits_per_key_(millibits_per_key) {
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assert(millibits_per_key >= 1000);
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}
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// No Copy allowed
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FastLocalBloomBitsBuilder(const FastLocalBloomBitsBuilder&) = delete;
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void operator=(const FastLocalBloomBitsBuilder&) = delete;
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~FastLocalBloomBitsBuilder() override {}
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virtual Slice Finish(std::unique_ptr<const char[]>* buf) override {
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size_t num_entries = hash_entries_.size();
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size_t len_with_metadata = CalculateSpace(num_entries);
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std::unique_ptr<char[]> mutable_buf;
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len_with_metadata =
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AllocateMaybeRounding(len_with_metadata, num_entries, &mutable_buf);
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// Cache reservation for mutable_buf
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if (cache_res_mgr_) {
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std::unique_ptr<
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CacheReservationHandle<CacheEntryRole::kFilterConstruction>>
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final_filter_cache_res_handle;
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Status s =
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cache_res_mgr_
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->MakeCacheReservation<CacheEntryRole::kFilterConstruction>(
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len_with_metadata * sizeof(char),
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&final_filter_cache_res_handle);
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final_filter_cache_res_handles_.push_back(
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std::move(final_filter_cache_res_handle));
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s.PermitUncheckedError();
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}
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assert(mutable_buf);
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assert(len_with_metadata >= kMetadataLen);
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// Max size supported by implementation
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assert(len_with_metadata <= 0xffffffffU);
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// Compute num_probes after any rounding / adjustments
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int num_probes = GetNumProbes(num_entries, len_with_metadata);
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uint32_t len = static_cast<uint32_t>(len_with_metadata - kMetadataLen);
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if (len > 0) {
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AddAllEntries(mutable_buf.get(), len, num_probes);
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}
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assert(hash_entries_.empty());
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// Release cache for hash entries
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hash_entry_cache_res_bucket_handles_.clear();
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// See BloomFilterPolicy::GetBloomBitsReader re: metadata
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// -1 = Marker for newer Bloom implementations
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mutable_buf[len] = static_cast<char>(-1);
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// 0 = Marker for this sub-implementation
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mutable_buf[len + 1] = static_cast<char>(0);
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// num_probes (and 0 in upper bits for 64-byte block size)
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mutable_buf[len + 2] = static_cast<char>(num_probes);
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// rest of metadata stays zero
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Slice rv(mutable_buf.get(), len_with_metadata);
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*buf = std::move(mutable_buf);
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return rv;
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}
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size_t ApproximateNumEntries(size_t bytes) override {
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size_t bytes_no_meta =
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bytes >= kMetadataLen ? RoundDownUsableSpace(bytes) - kMetadataLen : 0;
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return static_cast<size_t>(uint64_t{8000} * bytes_no_meta /
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millibits_per_key_);
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}
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size_t CalculateSpace(size_t num_entries) override {
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// If not for cache line blocks in the filter, what would the target
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// length in bytes be?
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size_t raw_target_len = static_cast<size_t>(
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(uint64_t{num_entries} * millibits_per_key_ + 7999) / 8000);
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if (raw_target_len >= size_t{0xffffffc0}) {
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// Max supported for this data structure implementation
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raw_target_len = size_t{0xffffffc0};
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}
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// Round up to nearest multiple of 64 (block size). This adjustment is
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// used for target FP rate only so that we don't receive complaints about
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// lower FP rate vs. historic Bloom filter behavior.
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return ((raw_target_len + 63) & ~size_t{63}) + kMetadataLen;
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}
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double EstimatedFpRate(size_t keys, size_t len_with_metadata) override {
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int num_probes = GetNumProbes(keys, len_with_metadata);
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return FastLocalBloomImpl::EstimatedFpRate(
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keys, len_with_metadata - kMetadataLen, num_probes, /*hash bits*/ 64);
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}
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protected:
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size_t RoundDownUsableSpace(size_t available_size) override {
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size_t rv = available_size - kMetadataLen;
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if (rv >= size_t{0xffffffc0}) {
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// Max supported for this data structure implementation
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rv = size_t{0xffffffc0};
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}
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// round down to multiple of 64 (block size)
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rv &= ~size_t{63};
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return rv + kMetadataLen;
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}
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private:
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// Compute num_probes after any rounding / adjustments
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int GetNumProbes(size_t keys, size_t len_with_metadata) {
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uint64_t millibits = uint64_t{len_with_metadata - kMetadataLen} * 8000;
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int actual_millibits_per_key =
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static_cast<int>(millibits / std::max(keys, size_t{1}));
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// BEGIN XXX/TODO(peterd): preserving old/default behavior for now to
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// minimize unit test churn. Remove this some time.
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if (!aggregate_rounding_balance_) {
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actual_millibits_per_key = millibits_per_key_;
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}
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// END XXX/TODO
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return FastLocalBloomImpl::ChooseNumProbes(actual_millibits_per_key);
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}
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void AddAllEntries(char* data, uint32_t len, int num_probes) {
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// Simple version without prefetching:
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//
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// for (auto h : hash_entries_) {
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// FastLocalBloomImpl::AddHash(Lower32of64(h), Upper32of64(h), len,
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// num_probes, data);
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// }
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const size_t num_entries = hash_entries_.size();
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constexpr size_t kBufferMask = 7;
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static_assert(((kBufferMask + 1) & kBufferMask) == 0,
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"Must be power of 2 minus 1");
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std::array<uint32_t, kBufferMask + 1> hashes;
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std::array<uint32_t, kBufferMask + 1> byte_offsets;
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// Prime the buffer
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size_t i = 0;
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for (; i <= kBufferMask && i < num_entries; ++i) {
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uint64_t h = hash_entries_.front();
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hash_entries_.pop_front();
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FastLocalBloomImpl::PrepareHash(Lower32of64(h), len, data,
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/*out*/ &byte_offsets[i]);
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hashes[i] = Upper32of64(h);
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}
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// Process and buffer
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for (; i < num_entries; ++i) {
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uint32_t& hash_ref = hashes[i & kBufferMask];
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uint32_t& byte_offset_ref = byte_offsets[i & kBufferMask];
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// Process (add)
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FastLocalBloomImpl::AddHashPrepared(hash_ref, num_probes,
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data + byte_offset_ref);
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// And buffer
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uint64_t h = hash_entries_.front();
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hash_entries_.pop_front();
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FastLocalBloomImpl::PrepareHash(Lower32of64(h), len, data,
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/*out*/ &byte_offset_ref);
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hash_ref = Upper32of64(h);
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}
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// Finish processing
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for (i = 0; i <= kBufferMask && i < num_entries; ++i) {
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FastLocalBloomImpl::AddHashPrepared(hashes[i], num_probes,
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data + byte_offsets[i]);
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}
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}
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// Target allocation per added key, in thousandths of a bit.
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int millibits_per_key_;
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};
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// See description in FastLocalBloomImpl
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class FastLocalBloomBitsReader : public FilterBitsReader {
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public:
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FastLocalBloomBitsReader(const char* data, int num_probes, uint32_t len_bytes)
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: data_(data), num_probes_(num_probes), len_bytes_(len_bytes) {}
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// No Copy allowed
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FastLocalBloomBitsReader(const FastLocalBloomBitsReader&) = delete;
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void operator=(const FastLocalBloomBitsReader&) = delete;
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~FastLocalBloomBitsReader() override {}
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bool MayMatch(const Slice& key) override {
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uint64_t h = GetSliceHash64(key);
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uint32_t byte_offset;
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FastLocalBloomImpl::PrepareHash(Lower32of64(h), len_bytes_, data_,
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/*out*/ &byte_offset);
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return FastLocalBloomImpl::HashMayMatchPrepared(Upper32of64(h), num_probes_,
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data_ + byte_offset);
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}
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virtual void MayMatch(int num_keys, Slice** keys, bool* may_match) override {
|
|
std::array<uint32_t, MultiGetContext::MAX_BATCH_SIZE> hashes;
|
|
std::array<uint32_t, MultiGetContext::MAX_BATCH_SIZE> byte_offsets;
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
uint64_t h = GetSliceHash64(*keys[i]);
|
|
FastLocalBloomImpl::PrepareHash(Lower32of64(h), len_bytes_, data_,
|
|
/*out*/ &byte_offsets[i]);
|
|
hashes[i] = Upper32of64(h);
|
|
}
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
may_match[i] = FastLocalBloomImpl::HashMayMatchPrepared(
|
|
hashes[i], num_probes_, data_ + byte_offsets[i]);
|
|
}
|
|
}
|
|
|
|
private:
|
|
const char* data_;
|
|
const int num_probes_;
|
|
const uint32_t len_bytes_;
|
|
};
|
|
|
|
// ##################### Ribbon filter implementation ################### //
|
|
|
|
// Implements concept RehasherTypesAndSettings in ribbon_impl.h
|
|
struct Standard128RibbonRehasherTypesAndSettings {
|
|
// These are schema-critical. Any change almost certainly changes
|
|
// underlying data.
|
|
static constexpr bool kIsFilter = true;
|
|
static constexpr bool kHomogeneous = false;
|
|
static constexpr bool kFirstCoeffAlwaysOne = true;
|
|
static constexpr bool kUseSmash = false;
|
|
using CoeffRow = ROCKSDB_NAMESPACE::Unsigned128;
|
|
using Hash = uint64_t;
|
|
using Seed = uint32_t;
|
|
// Changing these doesn't necessarily change underlying data,
|
|
// but might affect supported scalability of those dimensions.
|
|
using Index = uint32_t;
|
|
using ResultRow = uint32_t;
|
|
// Save a conditional in Ribbon queries
|
|
static constexpr bool kAllowZeroStarts = false;
|
|
};
|
|
|
|
using Standard128RibbonTypesAndSettings =
|
|
ribbon::StandardRehasherAdapter<Standard128RibbonRehasherTypesAndSettings>;
|
|
|
|
class Standard128RibbonBitsBuilder : public XXPH3FilterBitsBuilder {
|
|
public:
|
|
explicit Standard128RibbonBitsBuilder(
|
|
double desired_one_in_fp_rate, int bloom_millibits_per_key,
|
|
std::atomic<int64_t>* aggregate_rounding_balance,
|
|
std::shared_ptr<CacheReservationManager> cache_res_mgr, Logger* info_log)
|
|
: XXPH3FilterBitsBuilder(aggregate_rounding_balance, cache_res_mgr),
|
|
desired_one_in_fp_rate_(desired_one_in_fp_rate),
|
|
info_log_(info_log),
|
|
bloom_fallback_(bloom_millibits_per_key, aggregate_rounding_balance,
|
|
cache_res_mgr) {
|
|
assert(desired_one_in_fp_rate >= 1.0);
|
|
}
|
|
|
|
// No Copy allowed
|
|
Standard128RibbonBitsBuilder(const Standard128RibbonBitsBuilder&) = delete;
|
|
void operator=(const Standard128RibbonBitsBuilder&) = delete;
|
|
|
|
~Standard128RibbonBitsBuilder() override {}
|
|
|
|
virtual Slice Finish(std::unique_ptr<const char[]>* buf) override {
|
|
if (hash_entries_.size() > kMaxRibbonEntries) {
|
|
ROCKS_LOG_WARN(info_log_, "Too many keys for Ribbon filter: %llu",
|
|
static_cast<unsigned long long>(hash_entries_.size()));
|
|
SwapEntriesWith(&bloom_fallback_);
|
|
assert(hash_entries_.empty());
|
|
return bloom_fallback_.Finish(buf);
|
|
}
|
|
if (hash_entries_.size() == 0) {
|
|
// Save a conditional in Ribbon queries by using alternate reader
|
|
// for zero entries added.
|
|
return FinishAlwaysFalse(buf);
|
|
}
|
|
uint32_t num_entries = static_cast<uint32_t>(hash_entries_.size());
|
|
uint32_t num_slots;
|
|
size_t len_with_metadata;
|
|
|
|
CalculateSpaceAndSlots(num_entries, &len_with_metadata, &num_slots);
|
|
|
|
// Bloom fall-back indicator
|
|
if (num_slots == 0) {
|
|
SwapEntriesWith(&bloom_fallback_);
|
|
assert(hash_entries_.empty());
|
|
return bloom_fallback_.Finish(buf);
|
|
}
|
|
|
|
uint32_t entropy = 0;
|
|
if (!hash_entries_.empty()) {
|
|
entropy = Lower32of64(hash_entries_.front());
|
|
}
|
|
|
|
BandingType banding;
|
|
std::size_t bytes_banding = ribbon::StandardBanding<
|
|
Standard128RibbonTypesAndSettings>::EstimateMemoryUsage(num_slots);
|
|
Status status_banding_cache_res = Status::OK();
|
|
|
|
// Cache reservation for banding
|
|
std::unique_ptr<CacheReservationHandle<CacheEntryRole::kFilterConstruction>>
|
|
banding_res_handle;
|
|
if (cache_res_mgr_) {
|
|
status_banding_cache_res =
|
|
cache_res_mgr_
|
|
->MakeCacheReservation<CacheEntryRole::kFilterConstruction>(
|
|
bytes_banding, &banding_res_handle);
|
|
}
|
|
|
|
if (status_banding_cache_res.IsIncomplete()) {
|
|
ROCKS_LOG_WARN(info_log_,
|
|
"Cache reservation for Ribbon filter banding failed due "
|
|
"to cache full");
|
|
SwapEntriesWith(&bloom_fallback_);
|
|
assert(hash_entries_.empty());
|
|
// Release cache for banding since the banding won't be allocated
|
|
banding_res_handle.reset();
|
|
return bloom_fallback_.Finish(buf);
|
|
}
|
|
|
|
bool success = banding.ResetAndFindSeedToSolve(
|
|
num_slots, hash_entries_.begin(), hash_entries_.end(),
|
|
/*starting seed*/ entropy & 255, /*seed mask*/ 255);
|
|
if (!success) {
|
|
ROCKS_LOG_WARN(info_log_,
|
|
"Too many re-seeds (256) for Ribbon filter, %llu / %llu",
|
|
static_cast<unsigned long long>(hash_entries_.size()),
|
|
static_cast<unsigned long long>(num_slots));
|
|
SwapEntriesWith(&bloom_fallback_);
|
|
assert(hash_entries_.empty());
|
|
return bloom_fallback_.Finish(buf);
|
|
}
|
|
hash_entries_.clear();
|
|
// Release cache for hash entries
|
|
hash_entry_cache_res_bucket_handles_.clear();
|
|
|
|
uint32_t seed = banding.GetOrdinalSeed();
|
|
assert(seed < 256);
|
|
|
|
std::unique_ptr<char[]> mutable_buf;
|
|
len_with_metadata =
|
|
AllocateMaybeRounding(len_with_metadata, num_entries, &mutable_buf);
|
|
// Cache reservation for mutable_buf
|
|
if (cache_res_mgr_) {
|
|
std::unique_ptr<
|
|
CacheReservationHandle<CacheEntryRole::kFilterConstruction>>
|
|
final_filter_cache_res_handle;
|
|
Status s =
|
|
cache_res_mgr_
|
|
->MakeCacheReservation<CacheEntryRole::kFilterConstruction>(
|
|
len_with_metadata * sizeof(char),
|
|
&final_filter_cache_res_handle);
|
|
final_filter_cache_res_handles_.push_back(
|
|
std::move(final_filter_cache_res_handle));
|
|
s.PermitUncheckedError();
|
|
}
|
|
|
|
SolnType soln(mutable_buf.get(), len_with_metadata);
|
|
soln.BackSubstFrom(banding);
|
|
uint32_t num_blocks = soln.GetNumBlocks();
|
|
// This should be guaranteed:
|
|
// num_entries < 2^30
|
|
// => (overhead_factor < 2.0)
|
|
// num_entries * overhead_factor == num_slots < 2^31
|
|
// => (num_blocks = num_slots / 128)
|
|
// num_blocks < 2^24
|
|
assert(num_blocks < 0x1000000U);
|
|
|
|
// See BloomFilterPolicy::GetBloomBitsReader re: metadata
|
|
// -2 = Marker for Standard128 Ribbon
|
|
mutable_buf[len_with_metadata - 5] = static_cast<char>(-2);
|
|
// Hash seed
|
|
mutable_buf[len_with_metadata - 4] = static_cast<char>(seed);
|
|
// Number of blocks, in 24 bits
|
|
// (Along with bytes, we can derive other settings)
|
|
mutable_buf[len_with_metadata - 3] = static_cast<char>(num_blocks & 255);
|
|
mutable_buf[len_with_metadata - 2] =
|
|
static_cast<char>((num_blocks >> 8) & 255);
|
|
mutable_buf[len_with_metadata - 1] =
|
|
static_cast<char>((num_blocks >> 16) & 255);
|
|
|
|
Slice rv(mutable_buf.get(), len_with_metadata);
|
|
*buf = std::move(mutable_buf);
|
|
return rv;
|
|
}
|
|
|
|
// Setting num_slots to 0 means "fall back on Bloom filter."
|
|
// And note this implementation does not support num_entries or num_slots
|
|
// beyond uint32_t; see kMaxRibbonEntries.
|
|
void CalculateSpaceAndSlots(size_t num_entries,
|
|
size_t* target_len_with_metadata,
|
|
uint32_t* num_slots) {
|
|
if (num_entries > kMaxRibbonEntries) {
|
|
// More entries than supported by this Ribbon
|
|
*num_slots = 0; // use Bloom
|
|
*target_len_with_metadata = bloom_fallback_.CalculateSpace(num_entries);
|
|
return;
|
|
}
|
|
uint32_t entropy = 0;
|
|
if (!hash_entries_.empty()) {
|
|
entropy = Upper32of64(hash_entries_.front());
|
|
}
|
|
|
|
*num_slots = NumEntriesToNumSlots(static_cast<uint32_t>(num_entries));
|
|
*target_len_with_metadata =
|
|
SolnType::GetBytesForOneInFpRate(*num_slots, desired_one_in_fp_rate_,
|
|
/*rounding*/ entropy) +
|
|
kMetadataLen;
|
|
|
|
// Consider possible Bloom fallback for small filters
|
|
if (*num_slots < 1024) {
|
|
size_t bloom = bloom_fallback_.CalculateSpace(num_entries);
|
|
if (bloom < *target_len_with_metadata) {
|
|
*num_slots = 0; // use Bloom
|
|
*target_len_with_metadata = bloom;
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
size_t CalculateSpace(size_t num_entries) override {
|
|
if (num_entries == 0) {
|
|
// See FinishAlwaysFalse
|
|
return 0;
|
|
}
|
|
size_t target_len_with_metadata;
|
|
uint32_t num_slots;
|
|
CalculateSpaceAndSlots(num_entries, &target_len_with_metadata, &num_slots);
|
|
(void)num_slots;
|
|
return target_len_with_metadata;
|
|
}
|
|
|
|
// This is a somewhat ugly but reasonably fast and reasonably accurate
|
|
// reversal of CalculateSpace.
|
|
size_t ApproximateNumEntries(size_t bytes) override {
|
|
size_t len_no_metadata =
|
|
RoundDownUsableSpace(std::max(bytes, size_t{kMetadataLen})) -
|
|
kMetadataLen;
|
|
|
|
if (!(desired_one_in_fp_rate_ > 1.0)) {
|
|
// Effectively asking for 100% FP rate, or NaN etc.
|
|
// Note that NaN is neither < 1.0 nor > 1.0
|
|
return kMaxRibbonEntries;
|
|
}
|
|
|
|
// Find a slight under-estimate for actual average bits per slot
|
|
double min_real_bits_per_slot;
|
|
if (desired_one_in_fp_rate_ >= 1.0 + std::numeric_limits<uint32_t>::max()) {
|
|
// Max of 32 solution columns (result bits)
|
|
min_real_bits_per_slot = 32.0;
|
|
} else {
|
|
// Account for mix of b and b+1 solution columns being slightly
|
|
// suboptimal vs. ideal log2(1/fp_rate) bits.
|
|
uint32_t rounded = static_cast<uint32_t>(desired_one_in_fp_rate_);
|
|
int upper_bits_per_key = 1 + FloorLog2(rounded);
|
|
double fp_rate_for_upper = std::pow(2.0, -upper_bits_per_key);
|
|
double portion_lower =
|
|
(1.0 / desired_one_in_fp_rate_ - fp_rate_for_upper) /
|
|
fp_rate_for_upper;
|
|
min_real_bits_per_slot = upper_bits_per_key - portion_lower;
|
|
assert(min_real_bits_per_slot > 0.0);
|
|
assert(min_real_bits_per_slot <= 32.0);
|
|
}
|
|
|
|
// An overestimate, but this should only be O(1) slots away from truth.
|
|
double max_slots = len_no_metadata * 8.0 / min_real_bits_per_slot;
|
|
|
|
// Let's not bother accounting for overflow to Bloom filter
|
|
// (Includes NaN case)
|
|
if (!(max_slots < ConfigHelper::GetNumSlots(kMaxRibbonEntries))) {
|
|
return kMaxRibbonEntries;
|
|
}
|
|
|
|
// Set up for short iteration
|
|
uint32_t slots = static_cast<uint32_t>(max_slots);
|
|
slots = SolnType::RoundUpNumSlots(slots);
|
|
|
|
// Assert that we have a valid upper bound on slots
|
|
assert(SolnType::GetBytesForOneInFpRate(
|
|
SolnType::RoundUpNumSlots(slots + 1), desired_one_in_fp_rate_,
|
|
/*rounding*/ 0) > len_no_metadata);
|
|
|
|
// Iterate up to a few times to rather precisely account for small effects
|
|
for (int i = 0; slots > 0; ++i) {
|
|
size_t reqd_bytes =
|
|
SolnType::GetBytesForOneInFpRate(slots, desired_one_in_fp_rate_,
|
|
/*rounding*/ 0);
|
|
if (reqd_bytes <= len_no_metadata) {
|
|
break; // done
|
|
}
|
|
if (i >= 2) {
|
|
// should have been enough iterations
|
|
assert(false);
|
|
break;
|
|
}
|
|
slots = SolnType::RoundDownNumSlots(slots - 1);
|
|
}
|
|
|
|
uint32_t num_entries = ConfigHelper::GetNumToAdd(slots);
|
|
|
|
// Consider possible Bloom fallback for small filters
|
|
if (slots < 1024) {
|
|
size_t bloom = bloom_fallback_.ApproximateNumEntries(bytes);
|
|
if (bloom > num_entries) {
|
|
return bloom;
|
|
} else {
|
|
return num_entries;
|
|
}
|
|
} else {
|
|
return std::min(num_entries, kMaxRibbonEntries);
|
|
}
|
|
}
|
|
|
|
double EstimatedFpRate(size_t num_entries,
|
|
size_t len_with_metadata) override {
|
|
if (num_entries > kMaxRibbonEntries) {
|
|
// More entries than supported by this Ribbon
|
|
return bloom_fallback_.EstimatedFpRate(num_entries, len_with_metadata);
|
|
}
|
|
uint32_t num_slots =
|
|
NumEntriesToNumSlots(static_cast<uint32_t>(num_entries));
|
|
SolnType fake_soln(nullptr, len_with_metadata);
|
|
fake_soln.ConfigureForNumSlots(num_slots);
|
|
return fake_soln.ExpectedFpRate();
|
|
}
|
|
|
|
protected:
|
|
size_t RoundDownUsableSpace(size_t available_size) override {
|
|
size_t rv = available_size - kMetadataLen;
|
|
|
|
// round down to multiple of 16 (segment size)
|
|
rv &= ~size_t{15};
|
|
|
|
return rv + kMetadataLen;
|
|
}
|
|
|
|
private:
|
|
using TS = Standard128RibbonTypesAndSettings;
|
|
using SolnType = ribbon::SerializableInterleavedSolution<TS>;
|
|
using BandingType = ribbon::StandardBanding<TS>;
|
|
using ConfigHelper = ribbon::BandingConfigHelper1TS<ribbon::kOneIn20, TS>;
|
|
|
|
static uint32_t NumEntriesToNumSlots(uint32_t num_entries) {
|
|
uint32_t num_slots1 = ConfigHelper::GetNumSlots(num_entries);
|
|
return SolnType::RoundUpNumSlots(num_slots1);
|
|
}
|
|
|
|
// Approximate num_entries to ensure number of bytes fits in 32 bits, which
|
|
// is not an inherent limitation but does ensure somewhat graceful Bloom
|
|
// fallback for crazy high number of entries, since the Bloom implementation
|
|
// does not support number of bytes bigger than fits in 32 bits. This is
|
|
// within an order of magnitude of implementation limit on num_slots
|
|
// fitting in 32 bits, and even closer for num_blocks fitting in 24 bits
|
|
// (for filter metadata).
|
|
static constexpr uint32_t kMaxRibbonEntries = 950000000; // ~ 1 billion
|
|
|
|
// A desired value for 1/fp_rate. For example, 100 -> 1% fp rate.
|
|
double desired_one_in_fp_rate_;
|
|
|
|
// For warnings, or can be nullptr
|
|
Logger* info_log_;
|
|
|
|
// For falling back on Bloom filter in some exceptional cases and
|
|
// very small filter cases
|
|
FastLocalBloomBitsBuilder bloom_fallback_;
|
|
};
|
|
|
|
// for the linker, at least with DEBUG_LEVEL=2
|
|
constexpr uint32_t Standard128RibbonBitsBuilder::kMaxRibbonEntries;
|
|
|
|
class Standard128RibbonBitsReader : public FilterBitsReader {
|
|
public:
|
|
Standard128RibbonBitsReader(const char* data, size_t len_bytes,
|
|
uint32_t num_blocks, uint32_t seed)
|
|
: soln_(const_cast<char*>(data), len_bytes) {
|
|
soln_.ConfigureForNumBlocks(num_blocks);
|
|
hasher_.SetOrdinalSeed(seed);
|
|
}
|
|
|
|
// No Copy allowed
|
|
Standard128RibbonBitsReader(const Standard128RibbonBitsReader&) = delete;
|
|
void operator=(const Standard128RibbonBitsReader&) = delete;
|
|
|
|
~Standard128RibbonBitsReader() override {}
|
|
|
|
bool MayMatch(const Slice& key) override {
|
|
uint64_t h = GetSliceHash64(key);
|
|
return soln_.FilterQuery(h, hasher_);
|
|
}
|
|
|
|
virtual void MayMatch(int num_keys, Slice** keys, bool* may_match) override {
|
|
struct SavedData {
|
|
uint64_t seeded_hash;
|
|
uint32_t segment_num;
|
|
uint32_t num_columns;
|
|
uint32_t start_bits;
|
|
};
|
|
std::array<SavedData, MultiGetContext::MAX_BATCH_SIZE> saved;
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
ribbon::InterleavedPrepareQuery(
|
|
GetSliceHash64(*keys[i]), hasher_, soln_, &saved[i].seeded_hash,
|
|
&saved[i].segment_num, &saved[i].num_columns, &saved[i].start_bits);
|
|
}
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
may_match[i] = ribbon::InterleavedFilterQuery(
|
|
saved[i].seeded_hash, saved[i].segment_num, saved[i].num_columns,
|
|
saved[i].start_bits, hasher_, soln_);
|
|
}
|
|
}
|
|
|
|
private:
|
|
using TS = Standard128RibbonTypesAndSettings;
|
|
ribbon::SerializableInterleavedSolution<TS> soln_;
|
|
ribbon::StandardHasher<TS> hasher_;
|
|
};
|
|
|
|
// ##################### Legacy Bloom implementation ################### //
|
|
|
|
using LegacyBloomImpl = LegacyLocalityBloomImpl</*ExtraRotates*/ false>;
|
|
|
|
class LegacyBloomBitsBuilder : public BuiltinFilterBitsBuilder {
|
|
public:
|
|
explicit LegacyBloomBitsBuilder(const int bits_per_key, Logger* info_log);
|
|
|
|
// No Copy allowed
|
|
LegacyBloomBitsBuilder(const LegacyBloomBitsBuilder&) = delete;
|
|
void operator=(const LegacyBloomBitsBuilder&) = delete;
|
|
|
|
~LegacyBloomBitsBuilder() override;
|
|
|
|
void AddKey(const Slice& key) override;
|
|
|
|
virtual size_t EstimateEntriesAdded() override {
|
|
return hash_entries_.size();
|
|
}
|
|
|
|
Slice Finish(std::unique_ptr<const char[]>* buf) override;
|
|
|
|
size_t CalculateSpace(size_t num_entries) override {
|
|
uint32_t dont_care1;
|
|
uint32_t dont_care2;
|
|
return CalculateSpace(num_entries, &dont_care1, &dont_care2);
|
|
}
|
|
|
|
double EstimatedFpRate(size_t keys, size_t bytes) override {
|
|
return LegacyBloomImpl::EstimatedFpRate(keys, bytes - kMetadataLen,
|
|
num_probes_);
|
|
}
|
|
|
|
size_t ApproximateNumEntries(size_t bytes) override;
|
|
|
|
private:
|
|
int bits_per_key_;
|
|
int num_probes_;
|
|
std::vector<uint32_t> hash_entries_;
|
|
Logger* info_log_;
|
|
|
|
// Get totalbits that optimized for cpu cache line
|
|
uint32_t GetTotalBitsForLocality(uint32_t total_bits);
|
|
|
|
// Reserve space for new filter
|
|
char* ReserveSpace(size_t num_entries, uint32_t* total_bits,
|
|
uint32_t* num_lines);
|
|
|
|
// Implementation-specific variant of public CalculateSpace
|
|
uint32_t CalculateSpace(size_t num_entries, uint32_t* total_bits,
|
|
uint32_t* num_lines);
|
|
|
|
// Assuming single threaded access to this function.
|
|
void AddHash(uint32_t h, char* data, uint32_t num_lines, uint32_t total_bits);
|
|
};
|
|
|
|
LegacyBloomBitsBuilder::LegacyBloomBitsBuilder(const int bits_per_key,
|
|
Logger* info_log)
|
|
: bits_per_key_(bits_per_key),
|
|
num_probes_(LegacyNoLocalityBloomImpl::ChooseNumProbes(bits_per_key_)),
|
|
info_log_(info_log) {
|
|
assert(bits_per_key_);
|
|
}
|
|
|
|
LegacyBloomBitsBuilder::~LegacyBloomBitsBuilder() {}
|
|
|
|
void LegacyBloomBitsBuilder::AddKey(const Slice& key) {
|
|
uint32_t hash = BloomHash(key);
|
|
if (hash_entries_.size() == 0 || hash != hash_entries_.back()) {
|
|
hash_entries_.push_back(hash);
|
|
}
|
|
}
|
|
|
|
Slice LegacyBloomBitsBuilder::Finish(std::unique_ptr<const char[]>* buf) {
|
|
uint32_t total_bits, num_lines;
|
|
size_t num_entries = hash_entries_.size();
|
|
char* data =
|
|
ReserveSpace(static_cast<int>(num_entries), &total_bits, &num_lines);
|
|
assert(data);
|
|
|
|
if (total_bits != 0 && num_lines != 0) {
|
|
for (auto h : hash_entries_) {
|
|
AddHash(h, data, num_lines, total_bits);
|
|
}
|
|
|
|
// Check for excessive entries for 32-bit hash function
|
|
if (num_entries >= /* minimum of 3 million */ 3000000U) {
|
|
// More specifically, we can detect that the 32-bit hash function
|
|
// is causing significant increase in FP rate by comparing current
|
|
// estimated FP rate to what we would get with a normal number of
|
|
// keys at same memory ratio.
|
|
double est_fp_rate = LegacyBloomImpl::EstimatedFpRate(
|
|
num_entries, total_bits / 8, num_probes_);
|
|
double vs_fp_rate = LegacyBloomImpl::EstimatedFpRate(
|
|
1U << 16, (1U << 16) * bits_per_key_ / 8, num_probes_);
|
|
|
|
if (est_fp_rate >= 1.50 * vs_fp_rate) {
|
|
// For more details, see
|
|
// https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter
|
|
ROCKS_LOG_WARN(
|
|
info_log_,
|
|
"Using legacy SST/BBT Bloom filter with excessive key count "
|
|
"(%.1fM @ %dbpk), causing estimated %.1fx higher filter FP rate. "
|
|
"Consider using new Bloom with format_version>=5, smaller SST "
|
|
"file size, or partitioned filters.",
|
|
num_entries / 1000000.0, bits_per_key_, est_fp_rate / vs_fp_rate);
|
|
}
|
|
}
|
|
}
|
|
// See BloomFilterPolicy::GetFilterBitsReader for metadata
|
|
data[total_bits / 8] = static_cast<char>(num_probes_);
|
|
EncodeFixed32(data + total_bits / 8 + 1, static_cast<uint32_t>(num_lines));
|
|
|
|
const char* const_data = data;
|
|
buf->reset(const_data);
|
|
hash_entries_.clear();
|
|
|
|
return Slice(data, total_bits / 8 + kMetadataLen);
|
|
}
|
|
|
|
size_t LegacyBloomBitsBuilder::ApproximateNumEntries(size_t bytes) {
|
|
assert(bits_per_key_);
|
|
assert(bytes > 0);
|
|
|
|
uint64_t total_bits_tmp = bytes * 8;
|
|
// total bits, including temporary computations, cannot exceed 2^32
|
|
// for compatibility
|
|
total_bits_tmp = std::min(total_bits_tmp, uint64_t{0xffff0000});
|
|
|
|
uint32_t high = static_cast<uint32_t>(total_bits_tmp) /
|
|
static_cast<uint32_t>(bits_per_key_) +
|
|
1;
|
|
uint32_t low = 1;
|
|
uint32_t n = high;
|
|
for (; n >= low; n--) {
|
|
if (CalculateSpace(n) <= bytes) {
|
|
break;
|
|
}
|
|
}
|
|
return n;
|
|
}
|
|
|
|
uint32_t LegacyBloomBitsBuilder::GetTotalBitsForLocality(uint32_t total_bits) {
|
|
uint32_t num_lines =
|
|
(total_bits + CACHE_LINE_SIZE * 8 - 1) / (CACHE_LINE_SIZE * 8);
|
|
|
|
// Make num_lines an odd number to make sure more bits are involved
|
|
// when determining which block.
|
|
if (num_lines % 2 == 0) {
|
|
num_lines++;
|
|
}
|
|
return num_lines * (CACHE_LINE_SIZE * 8);
|
|
}
|
|
|
|
uint32_t LegacyBloomBitsBuilder::CalculateSpace(size_t num_entries,
|
|
uint32_t* total_bits,
|
|
uint32_t* num_lines) {
|
|
assert(bits_per_key_);
|
|
if (num_entries != 0) {
|
|
size_t total_bits_tmp = num_entries * bits_per_key_;
|
|
// total bits, including temporary computations, cannot exceed 2^32
|
|
// for compatibility
|
|
total_bits_tmp = std::min(total_bits_tmp, size_t{0xffff0000});
|
|
|
|
*total_bits =
|
|
GetTotalBitsForLocality(static_cast<uint32_t>(total_bits_tmp));
|
|
*num_lines = *total_bits / (CACHE_LINE_SIZE * 8);
|
|
assert(*total_bits > 0 && *total_bits % 8 == 0);
|
|
} else {
|
|
// filter is empty, just leave space for metadata
|
|
*total_bits = 0;
|
|
*num_lines = 0;
|
|
}
|
|
|
|
// Reserve space for Filter
|
|
uint32_t sz = *total_bits / 8;
|
|
sz += kMetadataLen; // 4 bytes for num_lines, 1 byte for num_probes
|
|
return sz;
|
|
}
|
|
|
|
char* LegacyBloomBitsBuilder::ReserveSpace(size_t num_entries,
|
|
uint32_t* total_bits,
|
|
uint32_t* num_lines) {
|
|
uint32_t sz = CalculateSpace(num_entries, total_bits, num_lines);
|
|
char* data = new char[sz];
|
|
memset(data, 0, sz);
|
|
return data;
|
|
}
|
|
|
|
inline void LegacyBloomBitsBuilder::AddHash(uint32_t h, char* data,
|
|
uint32_t num_lines,
|
|
uint32_t total_bits) {
|
|
#ifdef NDEBUG
|
|
static_cast<void>(total_bits);
|
|
#endif
|
|
assert(num_lines > 0 && total_bits > 0);
|
|
|
|
LegacyBloomImpl::AddHash(h, num_lines, num_probes_, data,
|
|
folly::constexpr_log2(CACHE_LINE_SIZE));
|
|
}
|
|
|
|
class LegacyBloomBitsReader : public FilterBitsReader {
|
|
public:
|
|
LegacyBloomBitsReader(const char* data, int num_probes, uint32_t num_lines,
|
|
uint32_t log2_cache_line_size)
|
|
: data_(data),
|
|
num_probes_(num_probes),
|
|
num_lines_(num_lines),
|
|
log2_cache_line_size_(log2_cache_line_size) {}
|
|
|
|
// No Copy allowed
|
|
LegacyBloomBitsReader(const LegacyBloomBitsReader&) = delete;
|
|
void operator=(const LegacyBloomBitsReader&) = delete;
|
|
|
|
~LegacyBloomBitsReader() override {}
|
|
|
|
// "contents" contains the data built by a preceding call to
|
|
// FilterBitsBuilder::Finish. MayMatch must return true if the key was
|
|
// passed to FilterBitsBuilder::AddKey. This method may return true or false
|
|
// if the key was not on the list, but it should aim to return false with a
|
|
// high probability.
|
|
bool MayMatch(const Slice& key) override {
|
|
uint32_t hash = BloomHash(key);
|
|
uint32_t byte_offset;
|
|
LegacyBloomImpl::PrepareHashMayMatch(
|
|
hash, num_lines_, data_, /*out*/ &byte_offset, log2_cache_line_size_);
|
|
return LegacyBloomImpl::HashMayMatchPrepared(
|
|
hash, num_probes_, data_ + byte_offset, log2_cache_line_size_);
|
|
}
|
|
|
|
virtual void MayMatch(int num_keys, Slice** keys, bool* may_match) override {
|
|
std::array<uint32_t, MultiGetContext::MAX_BATCH_SIZE> hashes;
|
|
std::array<uint32_t, MultiGetContext::MAX_BATCH_SIZE> byte_offsets;
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
hashes[i] = BloomHash(*keys[i]);
|
|
LegacyBloomImpl::PrepareHashMayMatch(hashes[i], num_lines_, data_,
|
|
/*out*/ &byte_offsets[i],
|
|
log2_cache_line_size_);
|
|
}
|
|
for (int i = 0; i < num_keys; ++i) {
|
|
may_match[i] = LegacyBloomImpl::HashMayMatchPrepared(
|
|
hashes[i], num_probes_, data_ + byte_offsets[i],
|
|
log2_cache_line_size_);
|
|
}
|
|
}
|
|
|
|
private:
|
|
const char* data_;
|
|
const int num_probes_;
|
|
const uint32_t num_lines_;
|
|
const uint32_t log2_cache_line_size_;
|
|
};
|
|
|
|
class AlwaysTrueFilter : public FilterBitsReader {
|
|
public:
|
|
bool MayMatch(const Slice&) override { return true; }
|
|
using FilterBitsReader::MayMatch; // inherit overload
|
|
};
|
|
|
|
class AlwaysFalseFilter : public FilterBitsReader {
|
|
public:
|
|
bool MayMatch(const Slice&) override { return false; }
|
|
using FilterBitsReader::MayMatch; // inherit overload
|
|
};
|
|
|
|
} // namespace
|
|
|
|
const std::vector<BloomFilterPolicy::Mode> BloomFilterPolicy::kAllFixedImpls = {
|
|
kLegacyBloom,
|
|
kDeprecatedBlock,
|
|
kFastLocalBloom,
|
|
kStandard128Ribbon,
|
|
};
|
|
|
|
const std::vector<BloomFilterPolicy::Mode> BloomFilterPolicy::kAllUserModes = {
|
|
kDeprecatedBlock,
|
|
kAutoBloom,
|
|
kStandard128Ribbon,
|
|
};
|
|
|
|
BloomFilterPolicy::BloomFilterPolicy(double bits_per_key, Mode mode)
|
|
: mode_(mode), warned_(false), aggregate_rounding_balance_(0) {
|
|
// Sanitize bits_per_key
|
|
if (bits_per_key < 1.0) {
|
|
bits_per_key = 1.0;
|
|
} else if (!(bits_per_key < 100.0)) { // including NaN
|
|
bits_per_key = 100.0;
|
|
}
|
|
|
|
// Includes a nudge toward rounding up, to ensure on all platforms
|
|
// that doubles specified with three decimal digits after the decimal
|
|
// point are interpreted accurately.
|
|
millibits_per_key_ = static_cast<int>(bits_per_key * 1000.0 + 0.500001);
|
|
|
|
// For now configure Ribbon filter to match Bloom FP rate and save
|
|
// memory. (Ribbon bits per key will be ~30% less than Bloom bits per key
|
|
// for same FP rate.)
|
|
desired_one_in_fp_rate_ =
|
|
1.0 / BloomMath::CacheLocalFpRate(
|
|
bits_per_key,
|
|
FastLocalBloomImpl::ChooseNumProbes(millibits_per_key_),
|
|
/*cache_line_bits*/ 512);
|
|
|
|
// For better or worse, this is a rounding up of a nudged rounding up,
|
|
// e.g. 7.4999999999999 will round up to 8, but that provides more
|
|
// predictability against small arithmetic errors in floating point.
|
|
whole_bits_per_key_ = (millibits_per_key_ + 500) / 1000;
|
|
}
|
|
|
|
BloomFilterPolicy::~BloomFilterPolicy() {}
|
|
|
|
const char* BuiltinFilterPolicy::Name() const {
|
|
return "rocksdb.BuiltinBloomFilter";
|
|
}
|
|
|
|
void BloomFilterPolicy::CreateFilter(const Slice* keys, int n,
|
|
std::string* dst) const {
|
|
// We should ideally only be using this deprecated interface for
|
|
// appropriately constructed BloomFilterPolicy
|
|
assert(mode_ == kDeprecatedBlock);
|
|
|
|
// Compute bloom filter size (in both bits and bytes)
|
|
uint32_t bits = static_cast<uint32_t>(n * whole_bits_per_key_);
|
|
|
|
// For small n, we can see a very high false positive rate. Fix it
|
|
// by enforcing a minimum bloom filter length.
|
|
if (bits < 64) bits = 64;
|
|
|
|
uint32_t bytes = (bits + 7) / 8;
|
|
bits = bytes * 8;
|
|
|
|
int num_probes =
|
|
LegacyNoLocalityBloomImpl::ChooseNumProbes(whole_bits_per_key_);
|
|
|
|
const size_t init_size = dst->size();
|
|
dst->resize(init_size + bytes, 0);
|
|
dst->push_back(static_cast<char>(num_probes)); // Remember # of probes
|
|
char* array = &(*dst)[init_size];
|
|
for (int i = 0; i < n; i++) {
|
|
LegacyNoLocalityBloomImpl::AddHash(BloomHash(keys[i]), bits, num_probes,
|
|
array);
|
|
}
|
|
}
|
|
|
|
bool BuiltinFilterPolicy::KeyMayMatch(const Slice& key,
|
|
const Slice& bloom_filter) const {
|
|
const size_t len = bloom_filter.size();
|
|
if (len < 2 || len > 0xffffffffU) {
|
|
return false;
|
|
}
|
|
|
|
const char* array = bloom_filter.data();
|
|
const uint32_t bits = static_cast<uint32_t>(len - 1) * 8;
|
|
|
|
// Use the encoded k so that we can read filters generated by
|
|
// bloom filters created using different parameters.
|
|
const int k = static_cast<uint8_t>(array[len - 1]);
|
|
if (k > 30) {
|
|
// Reserved for potentially new encodings for short bloom filters.
|
|
// Consider it a match.
|
|
return true;
|
|
}
|
|
// NB: using stored k not num_probes for whole_bits_per_key_
|
|
return LegacyNoLocalityBloomImpl::HashMayMatch(BloomHash(key), bits, k,
|
|
array);
|
|
}
|
|
|
|
FilterBitsBuilder* BuiltinFilterPolicy::GetFilterBitsBuilder() const {
|
|
// This code path should no longer be used, for the built-in
|
|
// BloomFilterPolicy. Internal to RocksDB and outside
|
|
// BloomFilterPolicy, only get a FilterBitsBuilder with
|
|
// BloomFilterPolicy::GetBuilderFromContext(), which will call
|
|
// BloomFilterPolicy::GetBuilderWithContext(). RocksDB users have
|
|
// been warned (HISTORY.md) that they can no longer call this on
|
|
// the built-in BloomFilterPolicy (unlikely).
|
|
assert(false);
|
|
return GetBuilderWithContext(FilterBuildingContext(BlockBasedTableOptions()));
|
|
}
|
|
|
|
FilterBitsBuilder* BloomFilterPolicy::GetBuilderWithContext(
|
|
const FilterBuildingContext& context) const {
|
|
Mode cur = mode_;
|
|
bool offm = context.table_options.optimize_filters_for_memory;
|
|
bool reserve_filter_construction_mem =
|
|
(context.table_options.reserve_table_builder_memory &&
|
|
context.table_options.block_cache);
|
|
std::shared_ptr<CacheReservationManager> cache_res_mgr;
|
|
if (reserve_filter_construction_mem) {
|
|
cache_res_mgr = std::make_shared<CacheReservationManager>(
|
|
context.table_options.block_cache);
|
|
}
|
|
// Unusual code construction so that we can have just
|
|
// one exhaustive switch without (risky) recursion
|
|
for (int i = 0; i < 2; ++i) {
|
|
switch (cur) {
|
|
case kAutoBloom:
|
|
if (context.table_options.format_version < 5) {
|
|
cur = kLegacyBloom;
|
|
} else {
|
|
cur = kFastLocalBloom;
|
|
}
|
|
break;
|
|
case kDeprecatedBlock:
|
|
if (context.info_log && !warned_.load(std::memory_order_relaxed)) {
|
|
warned_ = true;
|
|
ROCKS_LOG_WARN(context.info_log,
|
|
"Using deprecated block-based Bloom filter is "
|
|
"inefficient (%d bits per key).",
|
|
whole_bits_per_key_);
|
|
}
|
|
return nullptr;
|
|
case kFastLocalBloom:
|
|
return new FastLocalBloomBitsBuilder(
|
|
millibits_per_key_, offm ? &aggregate_rounding_balance_ : nullptr,
|
|
cache_res_mgr);
|
|
case kLegacyBloom:
|
|
if (whole_bits_per_key_ >= 14 && context.info_log &&
|
|
!warned_.load(std::memory_order_relaxed)) {
|
|
warned_ = true;
|
|
const char* adjective;
|
|
if (whole_bits_per_key_ >= 20) {
|
|
adjective = "Dramatic";
|
|
} else {
|
|
adjective = "Significant";
|
|
}
|
|
// For more details, see
|
|
// https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter
|
|
ROCKS_LOG_WARN(
|
|
context.info_log,
|
|
"Using legacy Bloom filter with high (%d) bits/key. "
|
|
"%s filter space and/or accuracy improvement is available "
|
|
"with format_version>=5.",
|
|
whole_bits_per_key_, adjective);
|
|
}
|
|
return new LegacyBloomBitsBuilder(whole_bits_per_key_,
|
|
context.info_log);
|
|
case kStandard128Ribbon:
|
|
return new Standard128RibbonBitsBuilder(
|
|
desired_one_in_fp_rate_, millibits_per_key_,
|
|
offm ? &aggregate_rounding_balance_ : nullptr, cache_res_mgr,
|
|
context.info_log);
|
|
}
|
|
}
|
|
assert(false);
|
|
return nullptr; // something legal
|
|
}
|
|
|
|
FilterBitsBuilder* BloomFilterPolicy::GetBuilderFromContext(
|
|
const FilterBuildingContext& context) {
|
|
if (context.table_options.filter_policy) {
|
|
return context.table_options.filter_policy->GetBuilderWithContext(context);
|
|
} else {
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
// Read metadata to determine what kind of FilterBitsReader is needed
|
|
// and return a new one.
|
|
FilterBitsReader* BuiltinFilterPolicy::GetFilterBitsReader(
|
|
const Slice& contents) const {
|
|
uint32_t len_with_meta = static_cast<uint32_t>(contents.size());
|
|
if (len_with_meta <= kMetadataLen) {
|
|
// filter is empty or broken. Treat like zero keys added.
|
|
return new AlwaysFalseFilter();
|
|
}
|
|
|
|
// Legacy Bloom filter data:
|
|
// 0 +-----------------------------------+
|
|
// | Raw Bloom filter data |
|
|
// | ... |
|
|
// len +-----------------------------------+
|
|
// | byte for num_probes or |
|
|
// | marker for new implementations |
|
|
// len+1 +-----------------------------------+
|
|
// | four bytes for number of cache |
|
|
// | lines |
|
|
// len_with_meta +-----------------------------------+
|
|
|
|
int8_t raw_num_probes =
|
|
static_cast<int8_t>(contents.data()[len_with_meta - kMetadataLen]);
|
|
// NB: *num_probes > 30 and < 128 probably have not been used, because of
|
|
// BloomFilterPolicy::initialize, unless directly calling
|
|
// LegacyBloomBitsBuilder as an API, but we are leaving those cases in
|
|
// limbo with LegacyBloomBitsReader for now.
|
|
|
|
if (raw_num_probes < 1) {
|
|
// Note: < 0 (or unsigned > 127) indicate special new implementations
|
|
// (or reserved for future use)
|
|
switch (raw_num_probes) {
|
|
case 0:
|
|
// Treat as zero probes (always FP)
|
|
return new AlwaysTrueFilter();
|
|
case -1:
|
|
// Marker for newer Bloom implementations
|
|
return GetBloomBitsReader(contents);
|
|
case -2:
|
|
// Marker for Ribbon implementations
|
|
return GetRibbonBitsReader(contents);
|
|
default:
|
|
// Reserved (treat as zero probes, always FP, for now)
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
}
|
|
// else attempt decode for LegacyBloomBitsReader
|
|
|
|
int num_probes = raw_num_probes;
|
|
assert(num_probes >= 1);
|
|
assert(num_probes <= 127);
|
|
|
|
uint32_t len = len_with_meta - kMetadataLen;
|
|
assert(len > 0);
|
|
|
|
uint32_t num_lines = DecodeFixed32(contents.data() + len_with_meta - 4);
|
|
uint32_t log2_cache_line_size;
|
|
|
|
if (num_lines * CACHE_LINE_SIZE == len) {
|
|
// Common case
|
|
log2_cache_line_size = folly::constexpr_log2(CACHE_LINE_SIZE);
|
|
} else if (num_lines == 0 || len % num_lines != 0) {
|
|
// Invalid (no solution to num_lines * x == len)
|
|
// Treat as zero probes (always FP) for now.
|
|
return new AlwaysTrueFilter();
|
|
} else {
|
|
// Determine the non-native cache line size (from another system)
|
|
log2_cache_line_size = 0;
|
|
while ((num_lines << log2_cache_line_size) < len) {
|
|
++log2_cache_line_size;
|
|
}
|
|
if ((num_lines << log2_cache_line_size) != len) {
|
|
// Invalid (block size not a power of two)
|
|
// Treat as zero probes (always FP) for now.
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
}
|
|
// if not early return
|
|
return new LegacyBloomBitsReader(contents.data(), num_probes, num_lines,
|
|
log2_cache_line_size);
|
|
}
|
|
|
|
FilterBitsReader* BuiltinFilterPolicy::GetRibbonBitsReader(
|
|
const Slice& contents) const {
|
|
uint32_t len_with_meta = static_cast<uint32_t>(contents.size());
|
|
uint32_t len = len_with_meta - kMetadataLen;
|
|
|
|
assert(len > 0); // precondition
|
|
|
|
uint32_t seed = static_cast<uint8_t>(contents.data()[len + 1]);
|
|
uint32_t num_blocks = static_cast<uint8_t>(contents.data()[len + 2]);
|
|
num_blocks |= static_cast<uint8_t>(contents.data()[len + 3]) << 8;
|
|
num_blocks |= static_cast<uint8_t>(contents.data()[len + 4]) << 16;
|
|
if (num_blocks < 2) {
|
|
// Not supported
|
|
// num_blocks == 1 is not used because num_starts == 1 is problematic
|
|
// for the hashing scheme. num_blocks == 0 is unused because there's
|
|
// already a concise encoding of an "always false" filter.
|
|
// Return something safe:
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
return new Standard128RibbonBitsReader(contents.data(), len, num_blocks,
|
|
seed);
|
|
}
|
|
|
|
// For newer Bloom filter implementations
|
|
FilterBitsReader* BuiltinFilterPolicy::GetBloomBitsReader(
|
|
const Slice& contents) const {
|
|
uint32_t len_with_meta = static_cast<uint32_t>(contents.size());
|
|
uint32_t len = len_with_meta - kMetadataLen;
|
|
|
|
assert(len > 0); // precondition
|
|
|
|
// New Bloom filter data:
|
|
// 0 +-----------------------------------+
|
|
// | Raw Bloom filter data |
|
|
// | ... |
|
|
// len +-----------------------------------+
|
|
// | char{-1} byte -> new Bloom filter |
|
|
// len+1 +-----------------------------------+
|
|
// | byte for subimplementation |
|
|
// | 0: FastLocalBloom |
|
|
// | other: reserved |
|
|
// len+2 +-----------------------------------+
|
|
// | byte for block_and_probes |
|
|
// | 0 in top 3 bits -> 6 -> 64-byte |
|
|
// | reserved: |
|
|
// | 1 in top 3 bits -> 7 -> 128-byte|
|
|
// | 2 in top 3 bits -> 8 -> 256-byte|
|
|
// | ... |
|
|
// | num_probes in bottom 5 bits, |
|
|
// | except 0 and 31 reserved |
|
|
// len+3 +-----------------------------------+
|
|
// | two bytes reserved |
|
|
// | possibly for hash seed |
|
|
// len_with_meta +-----------------------------------+
|
|
|
|
// Read more metadata (see above)
|
|
char sub_impl_val = contents.data()[len_with_meta - 4];
|
|
char block_and_probes = contents.data()[len_with_meta - 3];
|
|
int log2_block_bytes = ((block_and_probes >> 5) & 7) + 6;
|
|
|
|
int num_probes = (block_and_probes & 31);
|
|
if (num_probes < 1 || num_probes > 30) {
|
|
// Reserved / future safe
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
|
|
uint16_t rest = DecodeFixed16(contents.data() + len_with_meta - 2);
|
|
if (rest != 0) {
|
|
// Reserved, possibly for hash seed
|
|
// Future safe
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
|
|
if (sub_impl_val == 0) { // FastLocalBloom
|
|
if (log2_block_bytes == 6) { // Only block size supported for now
|
|
return new FastLocalBloomBitsReader(contents.data(), num_probes, len);
|
|
}
|
|
}
|
|
// otherwise
|
|
// Reserved / future safe
|
|
return new AlwaysTrueFilter();
|
|
}
|
|
|
|
const FilterPolicy* NewBloomFilterPolicy(double bits_per_key,
|
|
bool use_block_based_builder) {
|
|
BloomFilterPolicy::Mode m;
|
|
if (use_block_based_builder) {
|
|
m = BloomFilterPolicy::kDeprecatedBlock;
|
|
} else {
|
|
m = BloomFilterPolicy::kAutoBloom;
|
|
}
|
|
assert(std::find(BloomFilterPolicy::kAllUserModes.begin(),
|
|
BloomFilterPolicy::kAllUserModes.end(),
|
|
m) != BloomFilterPolicy::kAllUserModes.end());
|
|
return new BloomFilterPolicy(bits_per_key, m);
|
|
}
|
|
|
|
// Chooses between two filter policies based on LSM level, but
|
|
// only for Level and Universal compaction styles. Flush is treated
|
|
// as level -1. Policy b is considered fallback / primary policy.
|
|
LevelThresholdFilterPolicy::LevelThresholdFilterPolicy(
|
|
std::unique_ptr<const FilterPolicy>&& a,
|
|
std::unique_ptr<const FilterPolicy>&& b, int starting_level_for_b)
|
|
: policy_a_(std::move(a)),
|
|
policy_b_(std::move(b)),
|
|
starting_level_for_b_(starting_level_for_b) {
|
|
// Don't use this wrapper class if you were going to set to -1
|
|
assert(starting_level_for_b_ >= 0);
|
|
}
|
|
|
|
// Deprecated block-based filter only
|
|
void LevelThresholdFilterPolicy::CreateFilter(const Slice* keys, int n,
|
|
std::string* dst) const {
|
|
policy_b_->CreateFilter(keys, n, dst);
|
|
}
|
|
|
|
FilterBitsBuilder* LevelThresholdFilterPolicy::GetBuilderWithContext(
|
|
const FilterBuildingContext& context) const {
|
|
switch (context.compaction_style) {
|
|
case kCompactionStyleLevel:
|
|
case kCompactionStyleUniversal: {
|
|
int levelish;
|
|
if (context.reason == TableFileCreationReason::kFlush) {
|
|
// Treat flush as level -1
|
|
assert(context.level_at_creation == 0);
|
|
levelish = -1;
|
|
} else if (context.level_at_creation == -1) {
|
|
// Unknown level
|
|
// Policy b considered fallback / primary
|
|
return policy_b_->GetBuilderWithContext(context);
|
|
} else {
|
|
levelish = context.level_at_creation;
|
|
}
|
|
if (levelish >= starting_level_for_b_) {
|
|
return policy_b_->GetBuilderWithContext(context);
|
|
} else {
|
|
return policy_a_->GetBuilderWithContext(context);
|
|
}
|
|
}
|
|
case kCompactionStyleFIFO:
|
|
case kCompactionStyleNone:
|
|
break;
|
|
}
|
|
// Policy b considered fallback / primary
|
|
return policy_b_->GetBuilderWithContext(context);
|
|
}
|
|
|
|
const FilterPolicy* NewRibbonFilterPolicy(double bloom_equivalent_bits_per_key,
|
|
int bloom_before_level) {
|
|
std::unique_ptr<const FilterPolicy> ribbon_only{new BloomFilterPolicy(
|
|
bloom_equivalent_bits_per_key, BloomFilterPolicy::kStandard128Ribbon)};
|
|
if (bloom_before_level > -1) {
|
|
// Could also use Bloom policy
|
|
std::unique_ptr<const FilterPolicy> bloom_only{new BloomFilterPolicy(
|
|
bloom_equivalent_bits_per_key, BloomFilterPolicy::kFastLocalBloom)};
|
|
return new LevelThresholdFilterPolicy(
|
|
std::move(bloom_only), std::move(ribbon_only), bloom_before_level);
|
|
} else {
|
|
return ribbon_only.release();
|
|
}
|
|
}
|
|
|
|
FilterBuildingContext::FilterBuildingContext(
|
|
const BlockBasedTableOptions& _table_options)
|
|
: table_options(_table_options) {}
|
|
|
|
FilterPolicy::~FilterPolicy() { }
|
|
|
|
Status FilterPolicy::CreateFromString(
|
|
const ConfigOptions& /*options*/, const std::string& value,
|
|
std::shared_ptr<const FilterPolicy>* policy) {
|
|
const std::string kBloomName = "bloomfilter:";
|
|
const std::string kExpRibbonName = "experimental_ribbon:";
|
|
const std::string kRibbonName = "ribbonfilter:";
|
|
if (value == kNullptrString || value == "rocksdb.BuiltinBloomFilter") {
|
|
policy->reset();
|
|
#ifndef ROCKSDB_LITE
|
|
} else if (value.compare(0, kBloomName.size(), kBloomName) == 0) {
|
|
size_t pos = value.find(':', kBloomName.size());
|
|
if (pos == std::string::npos) {
|
|
return Status::InvalidArgument(
|
|
"Invalid filter policy config, missing bits_per_key");
|
|
} else {
|
|
double bits_per_key = ParseDouble(
|
|
trim(value.substr(kBloomName.size(), pos - kBloomName.size())));
|
|
bool use_block_based_builder =
|
|
ParseBoolean("use_block_based_builder", trim(value.substr(pos + 1)));
|
|
policy->reset(
|
|
NewBloomFilterPolicy(bits_per_key, use_block_based_builder));
|
|
}
|
|
} else if (value.compare(0, kExpRibbonName.size(), kExpRibbonName) == 0) {
|
|
double bloom_equivalent_bits_per_key =
|
|
ParseDouble(trim(value.substr(kExpRibbonName.size())));
|
|
policy->reset(
|
|
NewExperimentalRibbonFilterPolicy(bloom_equivalent_bits_per_key));
|
|
} else if (value.compare(0, kRibbonName.size(), kRibbonName) == 0) {
|
|
size_t pos = value.find(':', kRibbonName.size());
|
|
int bloom_before_level;
|
|
if (pos == std::string::npos) {
|
|
pos = value.size();
|
|
bloom_before_level = 0;
|
|
} else {
|
|
bloom_before_level = ParseInt(trim(value.substr(pos + 1)));
|
|
}
|
|
double bloom_equivalent_bits_per_key =
|
|
ParseDouble(trim(value.substr(kRibbonName.size(), pos)));
|
|
policy->reset(NewRibbonFilterPolicy(bloom_equivalent_bits_per_key,
|
|
bloom_before_level));
|
|
} else {
|
|
return Status::NotFound("Invalid filter policy name ", value);
|
|
#else
|
|
} else {
|
|
return Status::NotSupported("Cannot load filter policy in LITE mode ",
|
|
value);
|
|
#endif // ROCKSDB_LITE
|
|
}
|
|
return Status::OK();
|
|
}
|
|
} // namespace ROCKSDB_NAMESPACE
|