1 /* Copyright (c) 2008-2019. 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/simix/smx_private.hpp"
10 #include <type_traits>
15 /** HACK, A value from another process
17 * This represents a value from another process:
19 * * constructor/destructor are disabled;
21 * * raw memory copy (std::memcpy) is used to copy Remote<T>;
23 * * when T is a trivial type, Remote is convertible to a T.
25 * We currently only handle the case where the type has the same layout
26 * in the current process and in the target process: we don't handle
27 * cross-architecture (such as 32-bit/64-bit access).
29 template <class T> class Remote {
31 typename std::aligned_storage<sizeof(T), alignof(T)>::type buffer;
35 Remote(T const& p) { std::memcpy(&buffer, &p, sizeof buffer); }
37 T* getBuffer() { return reinterpret_cast<T*>(&buffer); }
38 const T* getBuffer() const { return reinterpret_cast<const T*>(&buffer); }
39 std::size_t getBufferSize() const { return sizeof(T); }
42 static_assert(std::is_trivial<T>::value, "Cannot convert non trivial type");
45 void clear() { std::memset(&buffer, 0, sizeof buffer); }
48 /** Pointer to a remote address-space (process, snapshot)
50 * With this we can clearly identify the expected type of an address in the
51 * remote process while avoiding to use native local pointers.
53 * Some operators (+/-) assume use the size of the underlying element. This
54 * only works if the target applications is using the same target: it won't
55 * work for example, when inspecting a 32 bit application from a 64 bit
58 * We do not actually store the target address space because we can
59 * always detect it in context. This way `RemotePtr` is as efficient
62 template <class T> class RemotePtr {
63 std::uint64_t address_;
66 RemotePtr() : address_(0) {}
67 explicit RemotePtr(std::nullptr_t) : address_(0) {}
68 explicit RemotePtr(std::uint64_t address) : address_(address) {}
69 explicit RemotePtr(T* address) : address_((std::uintptr_t)address) {}
70 explicit RemotePtr(Remote<T*> p) : address_((std::uintptr_t)*p.getBuffer()) {}
71 std::uint64_t address() const { return address_; }
73 /** Turn into a local pointer
75 (if the remote process is not, in fact, remote) */
76 T* local() const { return (T*)address_; }
78 operator bool() const { return address_; }
79 bool operator!() const { return not address_; }
80 operator RemotePtr<void>() const { return RemotePtr<void>(address_); }
81 RemotePtr<T>& operator=(std::nullptr_t)
86 RemotePtr<T> operator+(std::uint64_t n) const { return RemotePtr<T>(address_ + n * sizeof(T)); }
87 RemotePtr<T> operator-(std::uint64_t n) const { return RemotePtr<T>(address_ - n * sizeof(T)); }
88 RemotePtr<T>& operator+=(std::uint64_t n)
90 address_ += n * sizeof(T);
93 RemotePtr<T>& operator-=(std::uint64_t n)
95 address_ -= n * sizeof(T);
100 template <class X, class Y> bool operator<(RemotePtr<X> const& x, RemotePtr<Y> const& y)
102 return x.address() < y.address();
105 template <class X, class Y> bool operator>(RemotePtr<X> const& x, RemotePtr<Y> const& y)
107 return x.address() > y.address();
110 template <class X, class Y> bool operator>=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
112 return x.address() >= y.address();
115 template <class X, class Y> bool operator<=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
117 return x.address() <= y.address();
120 template <class X, class Y> bool operator==(RemotePtr<X> const& x, RemotePtr<Y> const& y)
122 return x.address() == y.address();
125 template <class X, class Y> bool operator!=(RemotePtr<X> const& x, RemotePtr<Y> const& y)
127 return x.address() != y.address();
130 template <class T> inline RemotePtr<T> remote(T* p)
132 return RemotePtr<T>(p);
135 template <class T = void> inline RemotePtr<T> remote(uint64_t p)
137 return RemotePtr<T>(p);