Add API function Dart_ZoneAllocate

Add API function Dart_ZoneAllocate

This provides the embedder with the option for allocating temporary C
objects in the current ApiZone.

Zone allocation is especially useful when building a graph of
Dart_CObject structures for posting using Dart_PostCObject.

R=iposva@google.com, turnidge@google.com

BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=4348

[Ivan Posva, 2012-02-15 16:08:46]

LGTM, but please wait for Todd's feedback as well.

-Ivan

http://codereview.chromium.org/9347040/diff/1/runtime/vm/dart_api_state.h
File runtime/vm/dart_api_state.h (right):

http://codereview.chromium.org/9347040/diff/1/runtime/vm/dart_api_state.h#new...
runtime/vm/dart_api_state.h:540: ApiZone& zone() { return zone_; }
It should probably really stay as a ApiZone*. Maybe change the other place above
to return a pointer.

[Søren Gjesse, 2012-02-15 16:42:03]

http://codereview.chromium.org/9347040/diff/1/runtime/vm/dart_api_state.h
File runtime/vm/dart_api_state.h (right):

http://codereview.chromium.org/9347040/diff/1/runtime/vm/dart_api_state.h#new...
runtime/vm/dart_api_state.h:540: ApiZone& zone() { return zone_; }
On 2012/02/15 16:08:46, Ivan Posva wrote:
> It should probably really stay as a ApiZone*. Maybe change the other place
above
> to return a pointer.

Done.

[turnidge, 2012-02-16 17:54:55]

LGTM, with some comments below...

https://chromiumcodereview.appspot.com/9347040/diff/2002/runtime/include/dart...
File runtime/include/dart_api.h (right):

https://chromiumcodereview.appspot.com/9347040/diff/2002/runtime/include/dart...
runtime/include/dart_api.h:1833: DART_EXPORT uint8_t* Dart_ZoneAllocate(intptr_t
size);
I would rename this to Dart_ScopeAllocate and move the function up to the
"Scopes" section directly after Dart_ExitScope.

It is worth pointing out that the memory will be reclaimed on the next call to
Dart_ExitScope or when the native port handler exits.

https://chromiumcodereview.appspot.com/9347040/diff/2002/runtime/vm/dart_api_...
File runtime/vm/dart_api_state.h (right):

https://chromiumcodereview.appspot.com/9347040/diff/2002/runtime/vm/dart_api_...
runtime/vm/dart_api_state.h:365: ApiZone* zone() { return &zone_; }
This is better, thanks.

[Søren Gjesse, 2012-02-17 07:43:09]

Thanks for the review

http://codereview.chromium.org/9347040/diff/2002/runtime/include/dart_api.h
File runtime/include/dart_api.h (right):

http://codereview.chromium.org/9347040/diff/2002/runtime/include/dart_api.h#n...
runtime/include/dart_api.h:1833: DART_EXPORT uint8_t* Dart_ZoneAllocate(intptr_t
size);
On 2012/02/16 17:54:56, turnidge wrote:
> I would rename this to Dart_ScopeAllocate and move the function up to the
> "Scopes" section directly after Dart_ExitScope.
> 
> It is worth pointing out that the memory will be reclaimed on the next call to
> Dart_ExitScope or when the native port handler exits.

Done.

[turnidge, 2012-02-17 19:27:52]

https://chromiumcodereview.appspot.com/9347040/diff/9001/runtime/include/dart...
File runtime/include/dart_api.h (right):

https://chromiumcodereview.appspot.com/9347040/diff/9001/runtime/include/dart...
runtime/include/dart_api.h:677: * The Dart VM uses "zone allocation" for
temporary structures. Zones
We should probably change the word zone to scope in the comment as well.