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74 lines
1.9 KiB
C++
74 lines
1.9 KiB
C++
#pragma once
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#include <memory>
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#include <Common/LRUCache.h>
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#include <Common/ProfileEvents.h>
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#include <Common/SipHash.h>
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#include <Interpreters/AggregationCommon.h>
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#include <DataStreams/MarkInCompressedFile.h>
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namespace ProfileEvents
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{
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extern const Event MarkCacheHits;
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extern const Event MarkCacheMisses;
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}
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namespace DB
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{
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/// Estimate of number of bytes in cache for marks.
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struct MarksWeightFunction
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{
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/// We spent additional bytes on key in hashmap, linked lists, shared pointers, etc ...
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static constexpr size_t MARK_CACHE_OVERHEAD = 128;
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size_t operator()(const MarksInCompressedFile & marks) const
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{
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return marks.size() * sizeof(MarkInCompressedFile) + MARK_CACHE_OVERHEAD;
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}
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};
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/** Cache of 'marks' for StorageMergeTree.
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* Marks is an index structure that addresses ranges in column file, corresponding to ranges of primary key.
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*/
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class MarkCache : public LRUCache<UInt128, MarksInCompressedFile, UInt128TrivialHash, MarksWeightFunction>
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{
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private:
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using Base = LRUCache<UInt128, MarksInCompressedFile, UInt128TrivialHash, MarksWeightFunction>;
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public:
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MarkCache(size_t max_size_in_bytes)
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: Base(max_size_in_bytes) {}
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/// Calculate key from path to file and offset.
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static UInt128 hash(const String & path_to_file)
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{
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UInt128 key;
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SipHash hash;
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hash.update(path_to_file.data(), path_to_file.size() + 1);
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hash.get128(key.low, key.high);
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return key;
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}
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template <typename LoadFunc>
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MappedPtr getOrSet(const Key & key, LoadFunc && load)
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{
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auto result = Base::getOrSet(key, load);
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if (result.second)
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ProfileEvents::increment(ProfileEvents::MarkCacheMisses);
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else
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ProfileEvents::increment(ProfileEvents::MarkCacheHits);
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return result.first;
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}
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};
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using MarkCachePtr = std::shared_ptr<MarkCache>;
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}
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