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184 lines
7.0 KiB
184 lines
7.0 KiB
1 year ago
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// 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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//
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// A filter block is stored near the end of a Table file. It contains
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// filters (e.g., bloom filters) for all data blocks in the table combined
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// into a single filter block.
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#pragma once
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include "rocksdb/options.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/slice_transform.h"
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#include "rocksdb/table.h"
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#include "table/format.h"
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#include "table/multiget_context.h"
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#include "trace_replay/block_cache_tracer.h"
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#include "util/hash.h"
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namespace ROCKSDB_NAMESPACE {
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const uint64_t kNotValid = ULLONG_MAX;
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class FilterPolicy;
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class GetContext;
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using MultiGetRange = MultiGetContext::Range;
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// A FilterBlockBuilder is used to construct all of the filters for a
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// particular Table. It generates a single string which is stored as
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// a special block in the Table, or partitioned into smaller filters.
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//
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// The sequence of calls to FilterBlockBuilder must match the regexp:
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// Add* Finish
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class FilterBlockBuilder {
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public:
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explicit FilterBlockBuilder() {}
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// No copying allowed
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FilterBlockBuilder(const FilterBlockBuilder&) = delete;
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void operator=(const FilterBlockBuilder&) = delete;
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virtual ~FilterBlockBuilder() {}
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virtual void Add(
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const Slice& key_without_ts) = 0; // Add a key to current filter
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virtual bool IsEmpty() const = 0; // Empty == none added
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// For reporting stats on how many entries the builder considered unique
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virtual size_t EstimateEntriesAdded() = 0;
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Slice Finish() { // Generate Filter
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const BlockHandle empty_handle;
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Status dont_care_status;
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auto ret = Finish(empty_handle, &dont_care_status);
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assert(dont_care_status.ok());
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return ret;
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}
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// If filter_data is not nullptr, Finish() may transfer ownership of
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// underlying filter data to the caller, so that it can be freed as soon as
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// possible. BlockBasedFilterBlock will ignore this parameter.
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//
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virtual Slice Finish(
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const BlockHandle& tmp /* only used in PartitionedFilterBlock as
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last_partition_block_handle */
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,
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Status* status, std::unique_ptr<const char[]>* filter_data = nullptr) = 0;
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// This is called when finishes using the FilterBitsBuilder
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// in order to release memory usage and cache charge
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// associated with it timely
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virtual void ResetFilterBitsBuilder() {}
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// To optionally post-verify the filter returned from
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// FilterBlockBuilder::Finish.
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// Return Status::OK() if skipped.
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virtual Status MaybePostVerifyFilter(const Slice& /* filter_content */) {
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return Status::OK();
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}
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};
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// A FilterBlockReader is used to parse filter from SST table.
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// KeyMayMatch and PrefixMayMatch would trigger filter checking
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//
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// BlockBased/Full FilterBlock would be called in the same way.
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class FilterBlockReader {
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public:
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FilterBlockReader() = default;
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virtual ~FilterBlockReader() = default;
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FilterBlockReader(const FilterBlockReader&) = delete;
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FilterBlockReader& operator=(const FilterBlockReader&) = delete;
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/**
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* If no_io is set, then it returns true if it cannot answer the query without
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* reading data from disk. This is used in PartitionedFilterBlockReader to
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* avoid reading partitions that are not in block cache already
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*
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* Normally filters are built on only the user keys and the InternalKey is not
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* needed for a query. The index in PartitionedFilterBlockReader however is
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* built upon InternalKey and must be provided via const_ikey_ptr when running
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* queries.
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*/
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virtual bool KeyMayMatch(const Slice& key, const bool no_io,
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const Slice* const const_ikey_ptr,
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GetContext* get_context,
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BlockCacheLookupContext* lookup_context,
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const ReadOptions& read_options) = 0;
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virtual void KeysMayMatch(MultiGetRange* range, const bool no_io,
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BlockCacheLookupContext* lookup_context,
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const ReadOptions& read_options) {
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for (auto iter = range->begin(); iter != range->end(); ++iter) {
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const Slice ukey_without_ts = iter->ukey_without_ts;
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const Slice ikey = iter->ikey;
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GetContext* const get_context = iter->get_context;
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if (!KeyMayMatch(ukey_without_ts, no_io, &ikey, get_context,
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lookup_context, read_options)) {
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range->SkipKey(iter);
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}
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}
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}
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/**
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* no_io and const_ikey_ptr here means the same as in KeyMayMatch
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*/
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virtual bool PrefixMayMatch(const Slice& prefix, const bool no_io,
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const Slice* const const_ikey_ptr,
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GetContext* get_context,
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BlockCacheLookupContext* lookup_context,
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const ReadOptions& read_options) = 0;
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virtual void PrefixesMayMatch(MultiGetRange* range,
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const SliceTransform* prefix_extractor,
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const bool no_io,
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BlockCacheLookupContext* lookup_context,
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const ReadOptions& read_options) {
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for (auto iter = range->begin(); iter != range->end(); ++iter) {
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const Slice ukey_without_ts = iter->ukey_without_ts;
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const Slice ikey = iter->ikey;
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GetContext* const get_context = iter->get_context;
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if (prefix_extractor->InDomain(ukey_without_ts) &&
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!PrefixMayMatch(prefix_extractor->Transform(ukey_without_ts), no_io,
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&ikey, get_context, lookup_context, read_options)) {
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range->SkipKey(iter);
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}
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}
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}
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virtual size_t ApproximateMemoryUsage() const = 0;
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// convert this object to a human readable form
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virtual std::string ToString() const {
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std::string error_msg("Unsupported filter \n");
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return error_msg;
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}
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virtual Status CacheDependencies(
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const ReadOptions& /*ro*/, bool /*pin*/,
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FilePrefetchBuffer* /* tail_prefetch_buffer */) {
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return Status::OK();
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}
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virtual bool RangeMayExist(const Slice* /*iterate_upper_bound*/,
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const Slice& user_key_without_ts,
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const SliceTransform* prefix_extractor,
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const Comparator* /*comparator*/,
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const Slice* const const_ikey_ptr,
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bool* filter_checked, bool need_upper_bound_check,
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bool no_io,
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BlockCacheLookupContext* lookup_context,
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const ReadOptions& read_options) = 0;
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};
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} // namespace ROCKSDB_NAMESPACE
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