[mc] Don't expose the Type in Buffer

diff --git a/src/mc/RegionSnapshot.cpp b/src/mc/RegionSnapshot.cpp
index 8bf91df..bfcc7ba 100644 (file)
--- a/src/mc/RegionSnapshot.cpp
+++ b/src/mc/RegionSnapshot.cpp
@@ -43,10 +43,10 @@ Buffer::Buffer(std::size_t size, Type type) : size_(size), type_(type)
 {
   switch(type_) {
   case Type::Malloc:
-    data_ = malloc(size_);
+    data_ = ::malloc(size_);
     break;
   case Type::Mmap:
-    data_ = mmap(nullptr, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
+    data_ = ::mmap(nullptr, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
     if (data_ == MAP_FAILED) {
       data_ = nullptr;
       size_ = 0;
@@ -81,16 +81,14 @@ RegionSnapshot dense_region(
   RegionType region_type,
   void *start_addr, void* permanent_addr, size_t size)
 {
-  simgrid::mc::Buffer::Type buffer_type;
+  // When KSM support is enables, we allocate memory using mmap:
+  // * we don't want to madvise bits of the heap;
+  // * mmap gives data aligned on page boundaries which is merge friendly.
+  simgrid::mc::Buffer data;
   if (_sg_mc_ksm)
-    // We use mmap to allocate the memory in order to madvise it.
-    // We don't want to madvise the main heap.
-    // Moreover we get aligned pgaes which is merge-friendly.
-    buffer_type = simgrid::mc::Buffer::Type::Mmap;
+    data = Buffer::mmap(size);
   else
-    buffer_type = simgrid::mc::Buffer::Type::Malloc;
-
-  simgrid::mc::Buffer data(size, buffer_type);
+    data = Buffer::malloc(size);
 
   mc_model_checker->process().read_bytes(data.get(), size,
     remote(permanent_addr),
@@ -98,7 +96,7 @@ RegionSnapshot dense_region(
 
   if (_sg_mc_ksm)
     // Mark the region as mergeable *after* we have written into it.
-    // There no point to let KSM do the hard work before that.
+    // Trying to merge them before is useless/counterproductive.
     madvise(data.get(), size, MADV_MERGEABLE);
 
   simgrid::mc::RegionSnapshot region(

diff --git a/src/mc/RegionSnapshot.hpp b/src/mc/RegionSnapshot.hpp
index 0214d89..9707681 100644 (file)
--- a/src/mc/RegionSnapshot.hpp
+++ b/src/mc/RegionSnapshot.hpp
@@ -38,23 +38,32 @@ enum class StorageType {
 };
 
 class Buffer {
-public:
+private:
   enum class Type {
     Malloc,
     Mmap
   };
-private:
   void* data_ = nullptr;
   std::size_t size_;
   Type type_ = Type::Malloc;
-public:
-  Buffer() {}
+private:
   Buffer(std::size_t size, Type type = Type::Malloc);
   Buffer(void* data, std::size_t size, Type type = Type::Malloc) :
     data_(data), size_(size), type_(type) {}
+public:
+  Buffer() {}
   void clear() noexcept;
   ~Buffer() noexcept { clear(); }
 
+  static Buffer malloc(std::size_t size)
+  {
+    return Buffer(size, Type::Malloc);
+  }
+  static Buffer mmap(std::size_t size)
+  {
+    return Buffer(size, Type::Mmap);
+  }
+
   // No copy
   Buffer(Buffer const& buffer) = delete;
   Buffer& operator=(Buffer const& buffer) = delete;
@@ -82,7 +91,6 @@ public:
   void* get()              { return data_; }
   const void* get()  const { return data_; }
   std::size_t size() const { return size_; }
-  Type type()        const { return type_; }
 };
 
 /** A copy/snapshot of a given memory region