1 files changed, 98 insertions, 0 deletions
diff --git a/TAO/tao/MMAP_Allocator.cpp b/TAO/tao/MMAP_Allocator.cpp
new file mode 100644
index 00000000000..a77884aa272
--- /dev/null
+++ b/TAO/tao/MMAP_Allocator.cpp
@@ -0,0 +1,98 @@
+// $Id$
+
+#include "tao/MMAP_Allocator.h"
+
+#if TAO_HAS_SENDFILE == 1
+
+#include "ace/Mem_Map.h"
+#include "ace/Default_Constants.h"
+
+
+TAO_BEGIN_VERSIONED_NAMESPACE_DECL
+
+namespace
+{
+  // Default size mmap()ed memory pool will be the sum of the control
+  // block size and the default CDR buffer chosen by the user.  The
+  // final size may be rounded up by the allocator to be aligned on
+  // the appropriate boundary/page.
+  //
+  // @@ This type really should be ACE_LOFF_T but ACE's mmap()-based
+  //    classes currently do not handle large file offsets.
+  //        -Ossama
+  off_t const the_default_buf_size =
+    sizeof (ACE_Control_Block) + ACE_DEFAULT_CDR_BUFSIZE;
+
+  ACE_MMAP_Memory_Pool_Options const the_pool_options (
+    ACE_DEFAULT_BASE_ADDR,
+    ACE_MMAP_Memory_Pool_Options::ALWAYS_FIXED,
+    0, // No need to sync
+    the_default_buf_size,
+    MAP_SHARED, // Written data must be reflected in the backing store
+                // file in order for sendfile() to be able to read it.
+    1,
+    0,
+    /* 0 */ ACE_DEFAULT_FILE_PERMS,
+    true); // Generate for each mmap an unqiue pool
+}
+
+
+// Ideally we should open the backing store with shm_open() so that we
+// can avoid creating an on-disk backing store.  An on-disk backing
+// store could potentially cause sendfile() to block on disk I/O,
+// which is undesirable.  Unfortunately, ACE_Mem_Map currently
+// provides no way to configure which "open" function to use,
+// i.e. open(2) or shm_open(3).  Alternatively we could shm_open() the
+// backing store file beforehand.  Unfortunately,
+// ACE_{Lite_}MMAP_Memory_Pool currently doesn't provide a means to
+// pass the file descriptor for the desired backing store to the
+// underlying ACE_Mem_Map object.
+//
+// It may be tempting to mmap() /dev/zero.  That would certainly
+// provide the desired transient "scratch space" memory that we can
+// write and read to and from, respectively.  Unfortunately, the data
+// in /dev/zero-based memory mapped buffer can only be read through
+// the buffer itself, not through the file descriptor (e.g. using
+// read(2)) for the open()ed /dev/zero device.  Reading through the
+// /dev/zero file descriptor simply returns zero, as /dev/zero was
+// designed to do.  So unfortunate. :)
+TAO_MMAP_Allocator::TAO_MMAP_Allocator (void)
+  : TAO_MMAP_Allocator_Base ((char const *) 0 /* pool name */,
+                             0,  // No need to explicitly name the lock.
+                             &the_pool_options)
+{
+}
+
+TAO_MMAP_Allocator::~TAO_MMAP_Allocator (void)
+{
+}
+
+// @@ Should be const but underlying allocator methods are not!
+ACE_HANDLE
+TAO_MMAP_Allocator::handle (void)
+{
+  return this->alloc ().memory_pool ().mmap ().handle ();
+}
+
+// @@ Should be const but underlying allocator methods are not!
+off_t
+TAO_MMAP_Allocator::offset (void * p)
+{
+  ACE_Mem_Map const & m = this->alloc ().memory_pool ().mmap ();
+
+  ptrdiff_t const off  = reinterpret_cast<ptrdiff_t> (p);
+  ptrdiff_t const base = reinterpret_cast<ptrdiff_t> (m.addr ());
+  ptrdiff_t const end  = base + m.size ();
+
+  // Check if p is in the range of the mmap pool, if not we return -1
+  if (off < base || off > end)
+    return -1;
+
+  off_t const the_offset = static_cast<off_t> (off - base);
+
+  return (the_offset < 0 ? static_cast<off_t> (-1) : the_offset);
+}
+
+TAO_END_VERSIONED_NAMESPACE_DECL
+
+#endif  /* TAO_HAS_SENDFILE==1 */