New Interprocess version

[SVN r38272]

example/doc_managed_allocation_command.cpp

@@ -0,0 +1,87 @@
+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga 2006-2007. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying file
+// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/interprocess for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+//[doc_managed_allocation_command
+#include <boost/interprocess/managed_shared_memory.hpp>
+#include <cassert>
+
+int main()
+{
+   using namespace boost::interprocess;
+
+   //Managed memory segment that allocates portions of a shared memory
+   //segment with the default management algorithm
+   shared_memory_object::remove("MyManagedShm");
+
+   try{
+      managed_shared_memory managed_shm(create_only, "MyManagedShm", 10000*sizeof(std::size_t));
+
+      //Allocate at least 100 bytes, 1000 bytes if possible
+      std::size_t received_size, min_size = 100, preferred_size = 1000;
+      std::size_t *ptr = managed_shm.allocation_command<std::size_t>
+         (allocate_new, min_size, preferred_size, received_size).first;
+
+      //Received size must be bigger than min_size
+      assert(received_size >= min_size);
+
+      //Get free memory
+      std::size_t free_memory_after_allocation = managed_shm.get_free_memory();
+
+      //Now write the data
+      for(std::size_t i = 0; i < received_size; ++i) ptr[i] = i;
+
+      //Now try to triplicate the buffer. We won't admit an expansion
+      //lower to the double of the original buffer.
+      //This "should" be successful since no other class is allocating
+      //memory from the segment
+      std::size_t expanded_size;
+      std::pair<std::size_t *, bool> ret = managed_shm.allocation_command
+         (expand_fwd, received_size*2, received_size*3, expanded_size, ptr);
+
+      //Check invariants
+      assert(ret.second == true);
+      assert(ret.first == ptr);
+      assert(expanded_size >= received_size*2);
+
+      //Get free memory and compare
+      std::size_t free_memory_after_expansion = managed_shm.get_free_memory();
+      assert(free_memory_after_expansion < free_memory_after_allocation);
+
+      //Write new values
+      for(std::size_t i = received_size; i < expanded_size; ++i)  ptr[i] = i;
+
+      //Try to shrink approximately to min_size, but the new size
+      //should be smaller than min_size*2.
+      //This "should" be successful since no other class is allocating
+      //memory from the segment
+      std::size_t shrunk_size;
+      ret = managed_shm.allocation_command
+         (shrink_in_place, min_size*2, min_size, shrunk_size, ptr);
+
+      //Check invariants
+      assert(ret.second == true);
+      assert(ret.first == ptr);
+      assert(shrunk_size <= min_size*2);
+      assert(shrunk_size >= min_size);
+
+      //Get free memory and compare
+      std::size_t free_memory_after_shrinking = managed_shm.get_free_memory();
+      assert(free_memory_after_shrinking > free_memory_after_expansion);
+
+      //Deallocate the buffer
+      managed_shm.deallocate(ptr);
+   }
+   catch(...){
+      shared_memory_object::remove("MyManagedShm");
+      throw;
+   }
+   shared_memory_object::remove("MyManagedShm");
+   return 0;
+}
+//]