1 /* Copyright (c) 2008-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #ifndef SIMGRID_MC_REMOTE_PTR_HPP
7 #define SIMGRID_MC_REMOTE_PTR_HPP
9 #include "src/kernel/actor/ActorImpl.hpp"
11 namespace simgrid::mc {
13 /** HACK, A value from another process
15 * This represents a value from another process:
17 * * constructor/destructor are disabled;
19 * * raw memory copy (std::memcpy) is used to copy Remote<T>;
21 * * when T is a trivial type, Remote is convertible to a T.
23 * We currently only handle the case where the type has the same layout
24 * in the current process and in the target process: we don't handle
25 * cross-architecture (such as 32-bit/64-bit access).
27 template <class T> class Remote {
29 typename std::aligned_storage_t<sizeof(T), alignof(T)> buffer;
33 explicit Remote(T const& p) { std::memcpy(&buffer, &p, sizeof buffer); }
35 T* get_buffer() { return reinterpret_cast<T*>(&buffer); }
36 const T* get_buffer() const { return reinterpret_cast<const T*>(&buffer); }
37 std::size_t get_buffer_size() const { return sizeof(T); }
40 static_assert(std::is_trivial<T>::value, "Cannot convert non trivial type");
43 void clear() { std::memset(&buffer, 0, sizeof buffer); }
46 /** Pointer to a remote address-space (process, snapshot)
48 * With this we can clearly identify the expected type of an address in the
49 * remote process while avoiding to use native local pointers.
51 * Some operators (+/-) assume use the size of the underlying element. This
52 * only works if the target applications is using the same target: it won't
53 * work for example, when inspecting a 32 bit application from a 64 bit
56 * We do not actually store the target address space because we can
57 * always detect it in context. This way `RemotePtr` is as efficient
60 template <class T> class RemotePtr {
61 std::uint64_t address_ = 0;
64 RemotePtr() = default;
65 explicit RemotePtr(std::nullptr_t) {}
66 explicit RemotePtr(std::uint64_t address) : address_(address) {}
67 explicit RemotePtr(T* address) : address_((std::uintptr_t)address) {}
68 explicit RemotePtr(Remote<T*> p) : address_((std::uintptr_t)*p.get_buffer()) {}
69 std::uint64_t address() const { return address_; }
71 /** Turn into a local pointer
73 (if the remote process is not, in fact, remote) */
74 T* local() const { return (T*)address_; }
76 operator bool() const { return address_; }
77 bool operator!() const { return not address_; }
78 operator RemotePtr<void>() const { return RemotePtr<void>(address_); }
79 RemotePtr<T>& operator=(std::nullptr_t)
84 RemotePtr<T> operator+(std::uint64_t n) const { return RemotePtr<T>(address_ + n * sizeof(T)); }
85 RemotePtr<T> operator-(std::uint64_t n) const { return RemotePtr<T>(address_ - n * sizeof(T)); }
86 RemotePtr<T>& operator+=(std::uint64_t n)
88 address_ += n * sizeof(T);
91 RemotePtr<T>& operator-=(std::uint64_t n)
93 address_ -= n * sizeof(T);
98 template <class X, class Y> bool operator<(RemotePtr<X> const& x, RemotePtr<Y> const& y)
100 return x.address() < y.address();
103 template <class X, class Y> bool operator>(RemotePtr<X> const& x, RemotePtr<Y> const& y)
105 return x.address() > y.address();
108 template <class X, class Y> bool operator>=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
110 return x.address() >= y.address();
113 template <class X, class Y> bool operator<=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
115 return x.address() <= y.address();
118 template <class X, class Y> bool operator==(RemotePtr<X> const& x, RemotePtr<Y> const& y)
120 return x.address() == y.address();
123 template <class X, class Y> bool operator!=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
125 return x.address() != y.address();
128 template <class T> inline RemotePtr<T> remote(T* p)
130 return RemotePtr<T>(p);
133 template <class T = void> inline RemotePtr<T> remote(uint64_t p)
135 return RemotePtr<T>(p);
137 } // namespace simgrid::mc