[simix] Make Mutex a C++ class (kind-of)

[simgrid.git] / src / mc / AddressSpace.hpp

diff --git a/src/mc/AddressSpace.hpp b/src/mc/AddressSpace.hpp
index 75fbcae..c3d1e70 100644 (file)
--- a/src/mc/AddressSpace.hpp
+++ b/src/mc/AddressSpace.hpp
@@ -10,8 +10,12 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <cstring>
 #include <type_traits>
 
+#include <string>
+#include <vector>
+
 #include "src/mc/mc_forward.hpp"
 #include "src/mc/RemotePtr.hpp"
 
@@ -20,7 +24,7 @@ namespace mc {
 
 /** Process index used when no process is available
  *
- *  The expected behaviour is that if a process index is needed it will fail.
+ *  The expected behavior is that if a process index is needed it will fail.
  * */
 const int ProcessIndexMissing = -1;
 
@@ -91,15 +95,49 @@ public:
   static constexpr ReadOptions lazy() { return ReadOptions(1); }
 };
 
-/** A value read from another process */
+/** HACK, A value from another process
+ *
+ *  This represents a value from another process:
+ *
+ *  * constructor/destructor are disabled;
+ *
+ *  * raw memory copy (std::memcpy) is used to copy Remote<T>;
+ *
+ *  * raw memory comparison is used to compare them;
+ *
+ *  * when T is a trivial type, Remote is convertible to a T.
+ *
+ *  We currently only handle the case where the type has the same layout
+ *  in the current process and in the target process: we don't handle
+ *  cross-architecture (such as 32-bit/64-bit access).
+ */
 template<class T>
-class Remote {
+union Remote {
 private:
-  char buffer[sizeof(T)];
+  T buffer;
 public:
-  void*       data() { return buffer; }
-  const void* data() const { return buffer; }
-  constexpr std::size_t size() const { return sizeof(T); }
+  Remote() {}
+  ~Remote() {}
+  Remote(Remote const& that)
+  {
+    std::memcpy(&buffer, &that.buffer, sizeof(buffer));
+  }
+  Remote& operator=(Remote const& that)
+  {
+    std::memcpy(&buffer, &that.buffer, sizeof(buffer));
+    return *this;
+  }
+  T*       getBuffer() { return &buffer; }
+  const T* getBuffer() const { return &buffer; }
+  std::size_t getBufferSize() const { return sizeof(T); }
+  operator T() const {
+    static_assert(std::is_trivial<T>::value, "Cannot convert non trivial type");
+    return buffer;
+  }
+  void clear()
+  {
+    std::memset(static_cast<void*>(&buffer), 0, sizeof(T));
+  }
 };
 
 /** A given state of a given process (abstract base class)
@@ -133,25 +171,35 @@ public:
 
   /** Read a given data structure from the address space */
   template<class T> inline
-  void read(T *buffer, RemotePtr<T> ptr, int process_index = ProcessIndexAny)
+  void read(T *buffer, RemotePtr<T> ptr, int process_index = ProcessIndexAny) const
   {
     this->read_bytes(buffer, sizeof(T), ptr, process_index);
   }
 
   template<class T> inline
-  void read(Remote<T>& buffer, RemotePtr<T> ptr, int process_index = ProcessIndexAny)
+  void read(Remote<T>& buffer, RemotePtr<T> ptr, int process_index = ProcessIndexAny) const
   {
-    this->read_bytes(buffer.data(), sizeof(T), ptr, process_index);
+    this->read_bytes(buffer.getBuffer(), sizeof(T), ptr, process_index);
   }
 
   /** Read a given data structure from the address space */
   template<class T> inline
-  T read(RemotePtr<T> ptr, int process_index = ProcessIndexMissing)
+  Remote<T> read(RemotePtr<T> ptr, int process_index = ProcessIndexMissing) const
   {
-    static_assert(std::is_trivial<T>::value, "Cannot read a non-trivial type");
-    T res;
-    return *(T*)this->read_bytes(&res, sizeof(T), ptr, process_index);
+    Remote<T> res;
+    this->read_bytes(&res, sizeof(T), ptr, process_index);
+    return res;
   }
+
+  std::string read_string(RemotePtr<char> address, std::size_t len) const
+  {
+    // TODO, use std::vector with .data() in C++17 to avoid useless copies
+    std::vector<char> buffer(len);
+    buffer[len] = '\0';
+    this->read_bytes(buffer.data(), len, address);
+    return std::string(buffer.data(), buffer.size());
+  }
+
 };
 
 }