From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-09-08T23:35:06+09:00
Subject: Re: sharing memory in ruby

On Thu, 8 Sep 2005, Masahiro TANAKA wrote:

> Hi,
>
>> Ara wrote:
>>    +  ary->ref = Qfalse;
>>
>> the 'ary->ref' means it will not be free'd...
>
> This is not what I have intended.
> 'ary->ref' is an object that is referred from NArray object
> so that the original String object is not garbage-collected.
> So here should be `ary->ref = str;'.

hi masa-

here's the result:

     jib:~/build/narray-0.5.7p2 > cat a.rb
     #
     # the narray lib below is patched with your suggested mod
     #
       require 'mmap'
       require './narray'

       data, format = './data', 'c*'
     #
     # create a file
     #
       open(data, 'w'){|f| f.write [42,0,0,42].flatten.pack(format)}
     #
     # map in in
     #
       mmap = Mmap::new 'data', 'rw', Mmap::MAP_SHARED
     #
     # modify mmap via mmap
     #
       na = NArray::str mmap.to_str, NArray::BYTE
       na[] = 42
     #
     # original backing file is changed
     #
       p IO::read(data).unpack(format)


     jib:~/build/narray-0.5.7p2 > ruby a.rb
     [42, 42, 42, 42]


looks good.  how would you feel about making a release with the patch?

it's inlined below.

cheers.

-a
-- 
===============================================================================
| email :: ara [dot] t [dot] howard [at] noaa [dot] gov
| phone :: 303.497.6469
| Your life dwells amoung the causes of death
| Like a lamp standing in a strong breeze.  --Nagarjuna
===============================================================================

--- narray.c.org	2004-10-15 20:57:34.000000000 -0600
+++ narray.c	2004-10-15 21:40:21.000000000 -0600
@@ -757,6 +757,54 @@


  /* singleton method: 
+   NArray.str( string, type, size1,size2,...,sizeN )
+*/
+static VALUE
+ na_s_str(int argc, VALUE *argv, VALUE klass)
+{
+  struct NARRAY *ary;
+  VALUE v;
+  VALUE str;
+  int i, type, len=1, str_len, *shape, rank=argc-2;
+
+  if (argc < 1)
+    rb_raise(rb_eArgError, "String Argument required");
+
+  if (argc < 2)
+    rb_raise(rb_eArgError, "Type and Size Arguments required");
+
+  type = na_get_typecode(argv[1]);
+
+  str = rb_funcall(argv[0], rb_intern("to_str"), 0);
+
+  str_len = RSTRING(str)->len;
+
+  if (argc == 2) {
+    rank  = 1;
+    shape = ALLOCA_N(int,rank);
+    if ( str_len % na_sizeof[type] != 0 )
+      rb_raise(rb_eArgError, "string size mismatch");
+    shape[0] = str_len / na_sizeof[type];
+  }
+  else {
+    shape = ALLOCA_N(int,rank);
+    for (i=0; i<rank; i++)
+      len *= shape[i] = NUM2INT(argv[i+2]);
+    len *= na_sizeof[type];
+    if ( len != str_len )
+      rb_raise(rb_eArgError, "size mismatch");
+  }
+ 
+  v = na_make_object( type, rank, shape, cNArray );
+  GetNArray(v,ary);
+  ary->ptr = RSTRING(str)->ptr;
+  ary->ref = str;
+
+  return v;
+}
+
+
+/* singleton method:
     NArray[object]
  */
  static VALUE
@@ -1189,6 +1237,7 @@
      rb_define_singleton_method(cNArray,"to_na",na_s_to_na,-1);
      rb_define_singleton_method(cNArray,"to_narray",na_s_to_na,-1);
      rb_define_singleton_method(cNArray,"[]",na_s_bracket,-1);
+    rb_define_singleton_method(cNArray,"str",na_s_str,-1);

      /* methods */
      rb_define_method(cNArray, "[]", na_aref,-1);