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cdb11f5ce6
Summary: More code leading up to dynamic HCC. * Small enhancements to cache_bench * Extra assertion in Unref * Improve a CAS loop in ChargeUsageMaybeEvictStrict * Put load factor constants in appropriate class * Move `standalone` field to HyperClockTable::HandleImpl because it can be encoded differently in the upcoming dynamic HCC. * Add a typed version of MemMapping to simplify some future code. Pull Request resolved: https://github.com/facebook/rocksdb/pull/11670 Test Plan: existing tests, unit test added for TypedMemMapping Reviewed By: jowlyzhang Differential Revision: D48056464 Pulled By: pdillinger fbshipit-source-id: 186b7d3105c5d6d2eb6a592369bc10a97ee14a15
91 lines
2.6 KiB
C++
91 lines
2.6 KiB
C++
// Copyright (c) Meta Platforms, Inc. and affiliates.
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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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#pragma once
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#ifdef OS_WIN
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#include "port/win/port_win.h"
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// ^^^ For proper/safe inclusion of windows.h. Must come first.
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#include <memoryapi.h>
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#else
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#include <sys/mman.h>
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#endif // OS_WIN
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#include <cstdint>
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#include <utility>
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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// An RAII wrapper for mmaped memory
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class MemMapping {
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public:
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static constexpr bool kHugePageSupported =
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#if defined(MAP_HUGETLB) || defined(FILE_MAP_LARGE_PAGES)
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true;
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#else
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false;
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#endif
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// Allocate memory requesting to be backed by huge pages
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static MemMapping AllocateHuge(size_t length);
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// Allocate memory that is only lazily mapped to resident memory and
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// guaranteed to be zero-initialized. Note that some platforms like
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// Linux allow memory over-commit, where only the used portion of memory
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// matters, while other platforms require enough swap space (page file) to
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// back the full mapping.
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static MemMapping AllocateLazyZeroed(size_t length);
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// No copies
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MemMapping(const MemMapping&) = delete;
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MemMapping& operator=(const MemMapping&) = delete;
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// Move
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MemMapping(MemMapping&&) noexcept;
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MemMapping& operator=(MemMapping&&) noexcept;
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// Releases the mapping
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~MemMapping();
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inline void* Get() const { return addr_; }
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inline size_t Length() const { return length_; }
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private:
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MemMapping() {}
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// The mapped memory, or nullptr on failure / not supported
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void* addr_ = nullptr;
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// The known usable number of bytes starting at that address
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size_t length_ = 0;
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#ifdef OS_WIN
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HANDLE page_file_handle_ = NULL;
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#endif // OS_WIN
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static MemMapping AllocateAnonymous(size_t length, bool huge);
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};
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// Simple MemMapping wrapper that presents the memory as an array of T.
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// For example,
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// TypedMemMapping<uint64_t> arr = MemMapping::AllocateLazyZeroed(num_bytes);
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template <typename T>
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class TypedMemMapping : public MemMapping {
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public:
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/*implicit*/ TypedMemMapping(MemMapping&& v) noexcept
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: MemMapping(std::move(v)) {}
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TypedMemMapping& operator=(MemMapping&& v) noexcept {
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MemMapping& base = *this;
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base = std::move(v);
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}
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inline T* Get() const { return static_cast<T*>(MemMapping::Get()); }
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inline size_t Count() const { return MemMapping::Length() / sizeof(T); }
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inline T& operator[](size_t index) const { return Get()[index]; }
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};
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} // namespace ROCKSDB_NAMESPACE
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