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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
#pragma once
#include <boost/intrusive_ptr.hpp>
#include <boost/smart_ptr/intrusive_ref_counter.hpp>
#include <seastar/core/smp.hh>
#include <seastar/core/future.hh>
#include <seastar/core/sharded.hh>
namespace crimson {
/**
* local_shared_foreign_ptr
*
* See seastar/include/seastar/core/sharded.hh:foreign_ptr
*
* seastar::foreign_ptr wraps a smart ptr by proxying the copy() and destructor
* operations back to the original core. This works well except that copy()
* requires a cross-core call. We need a smart_ptr which allows cross-core
* caching of (for example) OSDMaps, but we want to avoid the overhead inherent
* in incrementing the source smart_ptr on every copy. Thus,
* local_shared_foreign_ptr maintains a core-local foreign_ptr back to the
* original core instance with core-local ref counting.
*/
template <typename PtrType>
class local_shared_foreign_ptr {
using element_type = typename std::pointer_traits<PtrType>::element_type;
using pointer = element_type*;
seastar::lw_shared_ptr<seastar::foreign_ptr<PtrType>> ptr;
/// Wraps a pointer object and remembers the current core.
local_shared_foreign_ptr(seastar::foreign_ptr<PtrType> &&fptr)
: ptr(fptr ? seastar::make_lw_shared(std::move(fptr)) : nullptr) {
assert(!ptr || (ptr && *ptr));
}
template <typename T>
friend local_shared_foreign_ptr<T> make_local_shared_foreign(
seastar::foreign_ptr<T> &&);
public:
/// Constructs a null local_shared_foreign_ptr<>.
local_shared_foreign_ptr() = default;
/// Constructs a null local_shared_foreign_ptr<>.
local_shared_foreign_ptr(std::nullptr_t) : local_shared_foreign_ptr() {}
/// Moves a local_shared_foreign_ptr<> to another object.
local_shared_foreign_ptr(local_shared_foreign_ptr&& other) = default;
/// Copies a local_shared_foreign_ptr<>
local_shared_foreign_ptr(const local_shared_foreign_ptr &other) = default;
/// Releases reference to ptr eventually releasing the contained foreign_ptr
~local_shared_foreign_ptr() = default;
/// Creates a copy of this foreign ptr. Only works if the stored ptr is copyable.
seastar::future<seastar::foreign_ptr<PtrType>> get_foreign() const noexcept {
assert(!ptr || (ptr && *ptr));
return ptr ? ptr->copy() :
seastar::make_ready_future<seastar::foreign_ptr<PtrType>>(nullptr);
}
/// Accesses the wrapped object.
element_type& operator*() const noexcept {
assert(ptr && *ptr);
return **ptr;
}
/// Accesses the wrapped object.
element_type* operator->() const noexcept {
assert(ptr && *ptr);
return &**ptr;
}
/// Access the raw pointer to the wrapped object.
pointer get() const noexcept {
assert(!ptr || (ptr && *ptr));
return ptr ? ptr->get() : nullptr;
}
/// Return the owner-shard of the contained foreign_ptr.
unsigned get_owner_shard() const noexcept {
assert(!ptr || (ptr && *ptr));
return ptr ? ptr->get_owner_shard() : seastar::this_shard_id();
}
/// Checks whether the wrapped pointer is non-null.
operator bool() const noexcept {
assert(!ptr || (ptr && *ptr));
return static_cast<bool>(ptr);
}
/// Move-assigns a \c local_shared_foreign_ptr<>.
local_shared_foreign_ptr& operator=(local_shared_foreign_ptr&& other) noexcept {
ptr = std::move(other.ptr);
return *this;
}
/// Copy-assigns a \c local_shared_foreign_ptr<>.
local_shared_foreign_ptr& operator=(const local_shared_foreign_ptr& other) noexcept {
ptr = other.ptr;
return *this;
}
/// Reset the containing ptr
void reset() noexcept {
assert(!ptr || (ptr && *ptr));
ptr = nullptr;
}
};
/// Wraps a smart_ptr T in a local_shared_foreign_ptr<>.
template <typename T>
local_shared_foreign_ptr<T> make_local_shared_foreign(
seastar::foreign_ptr<T> &&ptr) {
return local_shared_foreign_ptr<T>(std::move(ptr));
}
/// Wraps ptr in a local_shared_foreign_ptr<>.
template <typename T>
local_shared_foreign_ptr<T> make_local_shared_foreign(T &&ptr) {
return make_local_shared_foreign<T>(
ptr ? seastar::make_foreign(std::forward<T>(ptr)) : nullptr);
}
template <typename T, typename U>
inline bool operator==(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() == y.get();
}
template <typename T>
inline bool operator==(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() == nullptr;
}
template <typename T>
inline bool operator==(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr == y.get();
}
template <typename T, typename U>
inline bool operator!=(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() != y.get();
}
template <typename T>
inline bool operator!=(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() != nullptr;
}
template <typename T>
inline bool operator!=(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr != y.get();
}
template <typename T, typename U>
inline bool operator<(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() < y.get();
}
template <typename T>
inline bool operator<(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() < nullptr;
}
template <typename T>
inline bool operator<(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr < y.get();
}
template <typename T, typename U>
inline bool operator<=(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() <= y.get();
}
template <typename T>
inline bool operator<=(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() <= nullptr;
}
template <typename T>
inline bool operator<=(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr <= y.get();
}
template <typename T, typename U>
inline bool operator>(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() > y.get();
}
template <typename T>
inline bool operator>(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() > nullptr;
}
template <typename T>
inline bool operator>(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr > y.get();
}
template <typename T, typename U>
inline bool operator>=(const local_shared_foreign_ptr<T> &x,
const local_shared_foreign_ptr<U> &y) {
return x.get() >= y.get();
}
template <typename T>
inline bool operator>=(const local_shared_foreign_ptr<T> &x, std::nullptr_t) {
return x.get() >= nullptr;
}
template <typename T>
inline bool operator>=(std::nullptr_t, const local_shared_foreign_ptr<T>& y) {
return nullptr >= y.get();
}
}
namespace std {
template <typename T>
struct hash<crimson::local_shared_foreign_ptr<T>>
: private hash<typename std::pointer_traits<T>::element_type *> {
size_t operator()(const crimson::local_shared_foreign_ptr<T>& p) const {
return hash<typename std::pointer_traits<T>::element_type *>::operator()(p.get());
}
};
}
namespace seastar {
template<typename T>
struct is_smart_ptr<crimson::local_shared_foreign_ptr<T>> : std::true_type {};
}
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