--- /dev/null
+// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#include <atomic>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "rocksdb/filter_policy.h"
+#include "rocksdb/table.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class Slice;
+
+// Exposes any extra information needed for testing built-in
+// FilterBitsBuilders
+class BuiltinFilterBitsBuilder : public FilterBitsBuilder {
+ public:
+ // Calculate number of bytes needed for a new filter, including
+ // metadata. Passing the result to CalculateNumEntry should
+ // return >= the num_entry passed in.
+ virtual uint32_t CalculateSpace(const int num_entry) = 0;
+
+ // Returns an estimate of the FP rate of the returned filter if
+ // `keys` keys are added and the filter returned by Finish is `bytes`
+ // bytes.
+ virtual double EstimatedFpRate(size_t keys, size_t bytes) = 0;
+};
+
+// RocksDB built-in filter policy for Bloom or Bloom-like filters.
+// This class is considered internal API and subject to change.
+// See NewBloomFilterPolicy.
+class BloomFilterPolicy : public FilterPolicy {
+ public:
+ // An internal marker for operating modes of BloomFilterPolicy, in terms
+ // of selecting an implementation. This makes it easier for tests to track
+ // or to walk over the built-in set of Bloom filter implementations. The
+ // only variance in BloomFilterPolicy by mode/implementation is in
+ // GetFilterBitsBuilder(), so an enum is practical here vs. subclasses.
+ //
+ // This enum is essentially the union of all the different kinds of return
+ // value from GetFilterBitsBuilder, or "underlying implementation", and
+ // higher-level modes that choose an underlying implementation based on
+ // context information.
+ enum Mode {
+ // Legacy implementation of Bloom filter for full and partitioned filters.
+ // Set to 0 in case of value confusion with bool use_block_based_builder
+ // NOTE: TESTING ONLY as this mode does not use best compatible
+ // implementation
+ kLegacyBloom = 0,
+ // Deprecated block-based Bloom filter implementation.
+ // Set to 1 in case of value confusion with bool use_block_based_builder
+ // NOTE: DEPRECATED but user exposed
+ kDeprecatedBlock = 1,
+ // A fast, cache-local Bloom filter implementation. See description in
+ // FastLocalBloomImpl.
+ // NOTE: TESTING ONLY as this mode does not check format_version
+ kFastLocalBloom = 2,
+ // Automatically choose from the above (except kDeprecatedBlock) based on
+ // context at build time, including compatibility with format_version.
+ // NOTE: This is currently the only recommended mode that is user exposed.
+ kAuto = 100,
+ };
+ // All the different underlying implementations that a BloomFilterPolicy
+ // might use, as a mode that says "always use this implementation."
+ // Only appropriate for unit tests.
+ static const std::vector<Mode> kAllFixedImpls;
+
+ // All the different modes of BloomFilterPolicy that are exposed from
+ // user APIs. Only appropriate for higher-level unit tests. Integration
+ // tests should prefer using NewBloomFilterPolicy (user-exposed).
+ static const std::vector<Mode> kAllUserModes;
+
+ explicit BloomFilterPolicy(double bits_per_key, Mode mode);
+
+ ~BloomFilterPolicy() override;
+
+ const char* Name() const override;
+
+ // Deprecated block-based filter only
+ void CreateFilter(const Slice* keys, int n, std::string* dst) const override;
+
+ // Deprecated block-based filter only
+ bool KeyMayMatch(const Slice& key, const Slice& bloom_filter) const override;
+
+ FilterBitsBuilder* GetFilterBitsBuilder() const override;
+
+ // To use this function, call GetBuilderFromContext().
+ //
+ // Neither the context nor any objects therein should be saved beyond
+ // the call to this function, unless it's shared_ptr.
+ FilterBitsBuilder* GetBuilderWithContext(
+ const FilterBuildingContext&) const override;
+
+ // Returns a new FilterBitsBuilder from the filter_policy in
+ // table_options of a context, or nullptr if not applicable.
+ // (An internal convenience function to save boilerplate.)
+ static FilterBitsBuilder* GetBuilderFromContext(const FilterBuildingContext&);
+
+ // Read metadata to determine what kind of FilterBitsReader is needed
+ // and return a new one. This must successfully process any filter data
+ // generated by a built-in FilterBitsBuilder, regardless of the impl
+ // chosen for this BloomFilterPolicy. Not compatible with CreateFilter.
+ FilterBitsReader* GetFilterBitsReader(const Slice& contents) const override;
+
+ // Essentially for testing only: configured millibits/key
+ int GetMillibitsPerKey() const { return millibits_per_key_; }
+ // Essentially for testing only: legacy whole bits/key
+ int GetWholeBitsPerKey() const { return whole_bits_per_key_; }
+
+ private:
+ // Newer filters support fractional bits per key. For predictable behavior
+ // of 0.001-precision values across floating point implementations, we
+ // round to thousandths of a bit (on average) per key.
+ int millibits_per_key_;
+
+ // Older filters round to whole number bits per key. (There *should* be no
+ // compatibility issue with fractional bits per key, but preserving old
+ // behavior with format_version < 5 just in case.)
+ int whole_bits_per_key_;
+
+ // Selected mode (a specific implementation or way of selecting an
+ // implementation) for building new SST filters.
+ Mode mode_;
+
+ // Whether relevant warnings have been logged already. (Remember so we
+ // only report once per BloomFilterPolicy instance, to keep the noise down.)
+ mutable std::atomic<bool> warned_;
+
+ // For newer Bloom filter implementation(s)
+ FilterBitsReader* GetBloomBitsReader(const Slice& contents) const;
+};
+
+} // namespace ROCKSDB_NAMESPACE
projects / ceph.git / blobdiff