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authorvitalyisaev <vitalyisaev@yandex-team.com>2023-06-29 10:00:50 +0300
committervitalyisaev <vitalyisaev@yandex-team.com>2023-06-29 10:00:50 +0300
commit6ffe9e53658409f212834330e13564e4952558f6 (patch)
tree85b1e00183517648b228aafa7c8fb07f5276f419 /contrib/libs/llvm14/include/llvm/ADT/FunctionExtras.h
parent726057070f9c5a91fc10fde0d5024913d10f1ab9 (diff)
downloadydb-6ffe9e53658409f212834330e13564e4952558f6.tar.gz
YQ Connector: support managed ClickHouse
Со стороны dqrun можно обратиться к инстансу коннектора, который работает на streaming стенде, и извлечь данные из облачного CH.
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+#pragma once
+
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#endif
+
+//===- FunctionExtras.h - Function type erasure utilities -------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file provides a collection of function (or more generally, callable)
+/// type erasure utilities supplementing those provided by the standard library
+/// in `<function>`.
+///
+/// It provides `unique_function`, which works like `std::function` but supports
+/// move-only callable objects and const-qualification.
+///
+/// Future plans:
+/// - Add a `function` that provides ref-qualified support, which doesn't work
+/// with `std::function`.
+/// - Provide support for specifying multiple signatures to type erase callable
+/// objects with an overload set, such as those produced by generic lambdas.
+/// - Expand to include a copyable utility that directly replaces std::function
+/// but brings the above improvements.
+///
+/// Note that LLVM's utilities are greatly simplified by not supporting
+/// allocators.
+///
+/// If the standard library ever begins to provide comparable facilities we can
+/// consider switching to those.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_FUNCTIONEXTRAS_H
+#define LLVM_ADT_FUNCTIONEXTRAS_H
+
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/STLForwardCompat.h"
+#include "llvm/Support/MemAlloc.h"
+#include "llvm/Support/type_traits.h"
+#include <cstring>
+#include <memory>
+#include <type_traits>
+
+namespace llvm {
+
+/// unique_function is a type-erasing functor similar to std::function.
+///
+/// It can hold move-only function objects, like lambdas capturing unique_ptrs.
+/// Accordingly, it is movable but not copyable.
+///
+/// It supports const-qualification:
+/// - unique_function<int() const> has a const operator().
+/// It can only hold functions which themselves have a const operator().
+/// - unique_function<int()> has a non-const operator().
+/// It can hold functions with a non-const operator(), like mutable lambdas.
+template <typename FunctionT> class unique_function;
+
+namespace detail {
+
+template <typename T>
+using EnableIfTrivial =
+ std::enable_if_t<llvm::is_trivially_move_constructible<T>::value &&
+ std::is_trivially_destructible<T>::value>;
+template <typename CallableT, typename ThisT>
+using EnableUnlessSameType =
+ std::enable_if_t<!std::is_same<remove_cvref_t<CallableT>, ThisT>::value>;
+template <typename CallableT, typename Ret, typename... Params>
+using EnableIfCallable = std::enable_if_t<llvm::disjunction<
+ std::is_void<Ret>,
+ std::is_same<decltype(std::declval<CallableT>()(std::declval<Params>()...)),
+ Ret>,
+ std::is_same<const decltype(std::declval<CallableT>()(
+ std::declval<Params>()...)),
+ Ret>,
+ std::is_convertible<decltype(std::declval<CallableT>()(
+ std::declval<Params>()...)),
+ Ret>>::value>;
+
+template <typename ReturnT, typename... ParamTs> class UniqueFunctionBase {
+protected:
+ static constexpr size_t InlineStorageSize = sizeof(void *) * 3;
+
+ template <typename T, class = void>
+ struct IsSizeLessThanThresholdT : std::false_type {};
+
+ template <typename T>
+ struct IsSizeLessThanThresholdT<
+ T, std::enable_if_t<sizeof(T) <= 2 * sizeof(void *)>> : std::true_type {};
+
+ // Provide a type function to map parameters that won't observe extra copies
+ // or moves and which are small enough to likely pass in register to values
+ // and all other types to l-value reference types. We use this to compute the
+ // types used in our erased call utility to minimize copies and moves unless
+ // doing so would force things unnecessarily into memory.
+ //
+ // The heuristic used is related to common ABI register passing conventions.
+ // It doesn't have to be exact though, and in one way it is more strict
+ // because we want to still be able to observe either moves *or* copies.
+ template <typename T> struct AdjustedParamTBase {
+ static_assert(!std::is_reference<T>::value,
+ "references should be handled by template specialization");
+ using type = typename std::conditional<
+ llvm::is_trivially_copy_constructible<T>::value &&
+ llvm::is_trivially_move_constructible<T>::value &&
+ IsSizeLessThanThresholdT<T>::value,
+ T, T &>::type;
+ };
+
+ // This specialization ensures that 'AdjustedParam<V<T>&>' or
+ // 'AdjustedParam<V<T>&&>' does not trigger a compile-time error when 'T' is
+ // an incomplete type and V a templated type.
+ template <typename T> struct AdjustedParamTBase<T &> { using type = T &; };
+ template <typename T> struct AdjustedParamTBase<T &&> { using type = T &; };
+
+ template <typename T>
+ using AdjustedParamT = typename AdjustedParamTBase<T>::type;
+
+ // The type of the erased function pointer we use as a callback to dispatch to
+ // the stored callable when it is trivial to move and destroy.
+ using CallPtrT = ReturnT (*)(void *CallableAddr,
+ AdjustedParamT<ParamTs>... Params);
+ using MovePtrT = void (*)(void *LHSCallableAddr, void *RHSCallableAddr);
+ using DestroyPtrT = void (*)(void *CallableAddr);
+
+ /// A struct to hold a single trivial callback with sufficient alignment for
+ /// our bitpacking.
+ struct alignas(8) TrivialCallback {
+ CallPtrT CallPtr;
+ };
+
+ /// A struct we use to aggregate three callbacks when we need full set of
+ /// operations.
+ struct alignas(8) NonTrivialCallbacks {
+ CallPtrT CallPtr;
+ MovePtrT MovePtr;
+ DestroyPtrT DestroyPtr;
+ };
+
+ // Create a pointer union between either a pointer to a static trivial call
+ // pointer in a struct or a pointer to a static struct of the call, move, and
+ // destroy pointers.
+ using CallbackPointerUnionT =
+ PointerUnion<TrivialCallback *, NonTrivialCallbacks *>;
+
+ // The main storage buffer. This will either have a pointer to out-of-line
+ // storage or an inline buffer storing the callable.
+ union StorageUnionT {
+ // For out-of-line storage we keep a pointer to the underlying storage and
+ // the size. This is enough to deallocate the memory.
+ struct OutOfLineStorageT {
+ void *StoragePtr;
+ size_t Size;
+ size_t Alignment;
+ } OutOfLineStorage;
+ static_assert(
+ sizeof(OutOfLineStorageT) <= InlineStorageSize,
+ "Should always use all of the out-of-line storage for inline storage!");
+
+ // For in-line storage, we just provide an aligned character buffer. We
+ // provide three pointers worth of storage here.
+ // This is mutable as an inlined `const unique_function<void() const>` may
+ // still modify its own mutable members.
+ mutable
+ typename std::aligned_storage<InlineStorageSize, alignof(void *)>::type
+ InlineStorage;
+ } StorageUnion;
+
+ // A compressed pointer to either our dispatching callback or our table of
+ // dispatching callbacks and the flag for whether the callable itself is
+ // stored inline or not.
+ PointerIntPair<CallbackPointerUnionT, 1, bool> CallbackAndInlineFlag;
+
+ bool isInlineStorage() const { return CallbackAndInlineFlag.getInt(); }
+
+ bool isTrivialCallback() const {
+ return CallbackAndInlineFlag.getPointer().template is<TrivialCallback *>();
+ }
+
+ CallPtrT getTrivialCallback() const {
+ return CallbackAndInlineFlag.getPointer().template get<TrivialCallback *>()->CallPtr;
+ }
+
+ NonTrivialCallbacks *getNonTrivialCallbacks() const {
+ return CallbackAndInlineFlag.getPointer()
+ .template get<NonTrivialCallbacks *>();
+ }
+
+ CallPtrT getCallPtr() const {
+ return isTrivialCallback() ? getTrivialCallback()
+ : getNonTrivialCallbacks()->CallPtr;
+ }
+
+ // These three functions are only const in the narrow sense. They return
+ // mutable pointers to function state.
+ // This allows unique_function<T const>::operator() to be const, even if the
+ // underlying functor may be internally mutable.
+ //
+ // const callers must ensure they're only used in const-correct ways.
+ void *getCalleePtr() const {
+ return isInlineStorage() ? getInlineStorage() : getOutOfLineStorage();
+ }
+ void *getInlineStorage() const { return &StorageUnion.InlineStorage; }
+ void *getOutOfLineStorage() const {
+ return StorageUnion.OutOfLineStorage.StoragePtr;
+ }
+
+ size_t getOutOfLineStorageSize() const {
+ return StorageUnion.OutOfLineStorage.Size;
+ }
+ size_t getOutOfLineStorageAlignment() const {
+ return StorageUnion.OutOfLineStorage.Alignment;
+ }
+
+ void setOutOfLineStorage(void *Ptr, size_t Size, size_t Alignment) {
+ StorageUnion.OutOfLineStorage = {Ptr, Size, Alignment};
+ }
+
+ template <typename CalledAsT>
+ static ReturnT CallImpl(void *CallableAddr,
+ AdjustedParamT<ParamTs>... Params) {
+ auto &Func = *reinterpret_cast<CalledAsT *>(CallableAddr);
+ return Func(std::forward<ParamTs>(Params)...);
+ }
+
+ template <typename CallableT>
+ static void MoveImpl(void *LHSCallableAddr, void *RHSCallableAddr) noexcept {
+ new (LHSCallableAddr)
+ CallableT(std::move(*reinterpret_cast<CallableT *>(RHSCallableAddr)));
+ }
+
+ template <typename CallableT>
+ static void DestroyImpl(void *CallableAddr) noexcept {
+ reinterpret_cast<CallableT *>(CallableAddr)->~CallableT();
+ }
+
+ // The pointers to call/move/destroy functions are determined for each
+ // callable type (and called-as type, which determines the overload chosen).
+ // (definitions are out-of-line).
+
+ // By default, we need an object that contains all the different
+ // type erased behaviors needed. Create a static instance of the struct type
+ // here and each instance will contain a pointer to it.
+ // Wrap in a struct to avoid https://gcc.gnu.org/PR71954
+ template <typename CallableT, typename CalledAs, typename Enable = void>
+ struct CallbacksHolder {
+ static NonTrivialCallbacks Callbacks;
+ };
+ // See if we can create a trivial callback. We need the callable to be
+ // trivially moved and trivially destroyed so that we don't have to store
+ // type erased callbacks for those operations.
+ template <typename CallableT, typename CalledAs>
+ struct CallbacksHolder<CallableT, CalledAs, EnableIfTrivial<CallableT>> {
+ static TrivialCallback Callbacks;
+ };
+
+ // A simple tag type so the call-as type to be passed to the constructor.
+ template <typename T> struct CalledAs {};
+
+ // Essentially the "main" unique_function constructor, but subclasses
+ // provide the qualified type to be used for the call.
+ // (We always store a T, even if the call will use a pointer to const T).
+ template <typename CallableT, typename CalledAsT>
+ UniqueFunctionBase(CallableT Callable, CalledAs<CalledAsT>) {
+ bool IsInlineStorage = true;
+ void *CallableAddr = getInlineStorage();
+ if (sizeof(CallableT) > InlineStorageSize ||
+ alignof(CallableT) > alignof(decltype(StorageUnion.InlineStorage))) {
+ IsInlineStorage = false;
+ // Allocate out-of-line storage. FIXME: Use an explicit alignment
+ // parameter in C++17 mode.
+ auto Size = sizeof(CallableT);
+ auto Alignment = alignof(CallableT);
+ CallableAddr = allocate_buffer(Size, Alignment);
+ setOutOfLineStorage(CallableAddr, Size, Alignment);
+ }
+
+ // Now move into the storage.
+ new (CallableAddr) CallableT(std::move(Callable));
+ CallbackAndInlineFlag.setPointerAndInt(
+ &CallbacksHolder<CallableT, CalledAsT>::Callbacks, IsInlineStorage);
+ }
+
+ ~UniqueFunctionBase() {
+ if (!CallbackAndInlineFlag.getPointer())
+ return;
+
+ // Cache this value so we don't re-check it after type-erased operations.
+ bool IsInlineStorage = isInlineStorage();
+
+ if (!isTrivialCallback())
+ getNonTrivialCallbacks()->DestroyPtr(
+ IsInlineStorage ? getInlineStorage() : getOutOfLineStorage());
+
+ if (!IsInlineStorage)
+ deallocate_buffer(getOutOfLineStorage(), getOutOfLineStorageSize(),
+ getOutOfLineStorageAlignment());
+ }
+
+ UniqueFunctionBase(UniqueFunctionBase &&RHS) noexcept {
+ // Copy the callback and inline flag.
+ CallbackAndInlineFlag = RHS.CallbackAndInlineFlag;
+
+ // If the RHS is empty, just copying the above is sufficient.
+ if (!RHS)
+ return;
+
+ if (!isInlineStorage()) {
+ // The out-of-line case is easiest to move.
+ StorageUnion.OutOfLineStorage = RHS.StorageUnion.OutOfLineStorage;
+ } else if (isTrivialCallback()) {
+ // Move is trivial, just memcpy the bytes across.
+ memcpy(getInlineStorage(), RHS.getInlineStorage(), InlineStorageSize);
+ } else {
+ // Non-trivial move, so dispatch to a type-erased implementation.
+ getNonTrivialCallbacks()->MovePtr(getInlineStorage(),
+ RHS.getInlineStorage());
+ }
+
+ // Clear the old callback and inline flag to get back to as-if-null.
+ RHS.CallbackAndInlineFlag = {};
+
+#ifndef NDEBUG
+ // In debug builds, we also scribble across the rest of the storage.
+ memset(RHS.getInlineStorage(), 0xAD, InlineStorageSize);
+#endif
+ }
+
+ UniqueFunctionBase &operator=(UniqueFunctionBase &&RHS) noexcept {
+ if (this == &RHS)
+ return *this;
+
+ // Because we don't try to provide any exception safety guarantees we can
+ // implement move assignment very simply by first destroying the current
+ // object and then move-constructing over top of it.
+ this->~UniqueFunctionBase();
+ new (this) UniqueFunctionBase(std::move(RHS));
+ return *this;
+ }
+
+ UniqueFunctionBase() = default;
+
+public:
+ explicit operator bool() const {
+ return (bool)CallbackAndInlineFlag.getPointer();
+ }
+};
+
+template <typename R, typename... P>
+template <typename CallableT, typename CalledAsT, typename Enable>
+typename UniqueFunctionBase<R, P...>::NonTrivialCallbacks UniqueFunctionBase<
+ R, P...>::CallbacksHolder<CallableT, CalledAsT, Enable>::Callbacks = {
+ &CallImpl<CalledAsT>, &MoveImpl<CallableT>, &DestroyImpl<CallableT>};
+
+template <typename R, typename... P>
+template <typename CallableT, typename CalledAsT>
+typename UniqueFunctionBase<R, P...>::TrivialCallback
+ UniqueFunctionBase<R, P...>::CallbacksHolder<
+ CallableT, CalledAsT, EnableIfTrivial<CallableT>>::Callbacks{
+ &CallImpl<CalledAsT>};
+
+} // namespace detail
+
+template <typename R, typename... P>
+class unique_function<R(P...)> : public detail::UniqueFunctionBase<R, P...> {
+ using Base = detail::UniqueFunctionBase<R, P...>;
+
+public:
+ unique_function() = default;
+ unique_function(std::nullptr_t) {}
+ unique_function(unique_function &&) = default;
+ unique_function(const unique_function &) = delete;
+ unique_function &operator=(unique_function &&) = default;
+ unique_function &operator=(const unique_function &) = delete;
+
+ template <typename CallableT>
+ unique_function(
+ CallableT Callable,
+ detail::EnableUnlessSameType<CallableT, unique_function> * = nullptr,
+ detail::EnableIfCallable<CallableT, R, P...> * = nullptr)
+ : Base(std::forward<CallableT>(Callable),
+ typename Base::template CalledAs<CallableT>{}) {}
+
+ R operator()(P... Params) {
+ return this->getCallPtr()(this->getCalleePtr(), Params...);
+ }
+};
+
+template <typename R, typename... P>
+class unique_function<R(P...) const>
+ : public detail::UniqueFunctionBase<R, P...> {
+ using Base = detail::UniqueFunctionBase<R, P...>;
+
+public:
+ unique_function() = default;
+ unique_function(std::nullptr_t) {}
+ unique_function(unique_function &&) = default;
+ unique_function(const unique_function &) = delete;
+ unique_function &operator=(unique_function &&) = default;
+ unique_function &operator=(const unique_function &) = delete;
+
+ template <typename CallableT>
+ unique_function(
+ CallableT Callable,
+ detail::EnableUnlessSameType<CallableT, unique_function> * = nullptr,
+ detail::EnableIfCallable<const CallableT, R, P...> * = nullptr)
+ : Base(std::forward<CallableT>(Callable),
+ typename Base::template CalledAs<const CallableT>{}) {}
+
+ R operator()(P... Params) const {
+ return this->getCallPtr()(this->getCalleePtr(), Params...);
+ }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_ADT_FUNCTIONEXTRAS_H
+
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif