Added CPP wrapper for PPB_TCPServerSocket_Private.

ppapi/cpp/private/tcp_server_socket_private.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_CPP_PRIVATE_TCP_SERVER_SOCKET_PRIVATE_H_
+#define PPAPI_CPP_PRIVATE_TCP_SERVER_SOCKET_PRIVATE_H_
+
+#include "ppapi/c/pp_stdint.h"
+#include "ppapi/c/private/ppb_tcp_server_socket_private.h"
+#include "ppapi/cpp/resource.h"
+
+namespace pp {
+
+class CompletionCallback;
+class InstanceHandle;
+
+class TCPServerSocketPrivate : public Resource {
+ public:
+  explicit TCPServerSocketPrivate(const InstanceHandle& instance);
+
+  // Returns true if the required interface is available.
+  static bool IsAvailable();

[brettw, 2012/03/05 18:30:50]

We don't normally add this type of function for resources.

Yuzhu: do you know why we have this for The TCPSocketPrivate? Are you OK
removing it for both places?

[yzshen1, 2012/03/05 18:53:13]

It is used to ease Pepper Flash developing: 
Usually, we put new features using an interface into Pepper Flash, and we want
it to still work on older browsers that don't support the interface, e.g.,
beta/stable channel. Because we don't want to maintain several Pepper Flash
branches.

We could use GetBrowserInterface() to check as well. But IsAvailable() seems
easier. The user don't need to deal with interface names directly.


On 2012/03/05 18:30:50, brettw wrote:

[brettw, 2012/03/05 21:30:42]

I guess I'd say we shouldn't bother with this function unless we need it for
something. The way it's "supposed" to work is that the constructor just returns
an is_null() resource if it's not available. So unless we need this for a
convenience at a higher level, just skip it.

[yzshen1, 2012/03/05 22:49:27]

Resource creation could fail because of other reasons than interface not
available. So it still seems different.

We have 7 wrapper classes that have IsAvailable. If we remove them, Trung will
probably be affected (when the next time he updates PPAPI in Flash). So I cc-ed
him.

On 2012/03/05 21:30:42, brettw wrote:

[ygorshenin1, 2012/03/06 11:37:52]

IsAvailable is deleted.

On 2012/03/05 22:49:27, yzshen1 wrote:

[viettrungluu, 2012/03/06 18:31:49]

I stipulate that if it's at all plausible that the browser not provide a given
interface, then the C++ wrapper should have an IsAvailable() method.

By the time you get to resource creation, it's typically very late in the game.
Plugin UI, etc. needs to reflect the lack of availability of certain features
much earlier.

[ygorshenin1, 2012/03/07 11:17:29]

OK, I restored this method.

On 2012/03/06 18:31:49, viettrungluu wrote:

+
+  int32_t Listen(const PP_NetAddress_Private* addr,
+                 int32_t backlog,
+                 const CompletionCallback& callback);
+  int32_t Accept(PP_Resource* socket,

[yzshen1, 2012/03/05 18:53:13]

- How about returning a cpp wrapper object?
int32_t Accept(TCPSocketPrivate* socket, ...);

- Comment about how long the caller should keep this output parameter alive.

[ygorshenin1, 2012/03/06 11:37:52]

- This is possible, but will greatly complicate this wrapper, because in this
case wrapper'll have internal state: completion callback and pointer (or
pointer-to-pointer) to TCPSocketPrivate. Also, we should make
TCPSocketPrivate::TCPSocketPrivate(PP_Resource) private and make
TCPServerSocketPrivate a friend... I thought due to implementation complexity we
should not do that. For user it is very easy to wrap raw PP_Resource into
TCPSocketPrivate wrapper.

- What do you mean by saying "keep this output parameter alive"?

On 2012/03/05 18:53:13, yzshen1 wrote:

[yzshen1, 2012/03/06 19:08:41]

Please be noted that there is not a proper constructor of TCPSocketPrivate to
wrap this returned PP_Resource at the moment.

What we need here is a
TCPSocketPrivate(PASSREF, PP_Resource).
And there isn't one yet.

Unless you want the user to do:
- TCPSocketPrivate socket(the_output_pp_resource);
- Explicitly release the ref of the_output_resource.

It is very likely the user will do the wrong thing and leak reference.

I am fine with the current approach, if you insist. But you need the add new
constructor and have very clear comments about how to wrap the returned
resource.
If PP_OK_COMPLETIONPENDING is returned, the memory pointed to by this output
parameter should stay valid until
- the callback is called, or
- StopListening() is called.
Right?

[ygorshenin1, 2012/03/07 11:17:29]

Thanks for explaining, Done.

+                 const CompletionCallback& callback);
+  void StopListening();
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_PRIVATE_TCP_SERVER_SOCKET_PRIVATE_H_