template <typename Export, typename Import>class ObjectLinker
Defined at line 218 of file ../../src/ui/scenic/lib/utils/object_linker.h
Allows direct linking of peer objects, regardless of which session(s) they
exist in. Once the objects are linked, they have direct references to each
other.
This linking is accomplished via lookup between pairable kernel objects.
zx::eventpair objects are a natural fit for this purpose and are commonly
used.
To create a Link, provide a handle to one half of a pairable kernel object
(zx::object_traits:supports_duplication is true) to the |CreateExport| or
|CreateImport| methods. It can be connected with its peer by providing a
concrete object to link along with callbacks for both successful and
unsuccessful resolution. Import and Export should be copy constructable as
they might be relinked.
When the other half of the kernel object is registered with the
ObjectLinker, and Initialize() is called on the corresponding Link, the
provided resolution callbacks in both Links will be fired. The callback
associated with the Export will always fire first.
If either Link endpoint is destroyed, this will cause the provided
disconnection callback on its peer endpoint to be fired. If the peer
endpoint has not been provided any callbacks yet via Initialize(), the
disconnection callback will be fired later when Initialize() is first called
on it.
Attempts to register either half of the kernel object multiple times, even
through cloned handles, will result in an error.
TODO(https://fxbug.dev/42098134): Allow multiple Imports.
Thread-safety: this class is thread-safe. Links may be created and used on multiple threads.
Links must be destroyed before their dispatcher is destroyed (i.e. the default dispatcher when
the Link is created).
Public Methods
std::shared_ptr<ObjectLinker<Export, Import>> New ()Defined at line 304 of file ../../src/ui/scenic/lib/utils/object_linker.h
void ~ObjectLinker<Export, Import> ()Defined at line 307 of file ../../src/ui/scenic/lib/utils/object_linker.h
template <typename T, typename = std::enable_if_t<zx::object_traits<T>::has_peer_handle>>ExportLink CreateExport (Export export_obj, T token, ErrorReporter * error_reporter)Creates an outgoing cross-session ExportLink between two objects,
which can be used to initiate and close the connection between them.
The ObjectLinker uses the provided |token| to locate the paired ImportLink.
|token| must reference a pairable kernel object type such as |zx::channel| or |zx::eventpair|.
|token| may not reference a kernel object that is in use by this ObjectLinker.
If a link cannot be created, |error_reporter| will be used to flag an error.
The objects are linked as soon as the |Initialize()| method is called on
the links for both objects.
Defined at line 321 of file ../../src/ui/scenic/lib/utils/object_linker.h
template <typename T, typename = std::enable_if_t<zx::object_traits<T>::has_peer_handle>>ImportLink CreateImport (Import import_obj, T token, ErrorReporter * error_reporter)Creates an incoming cross-session ImportLink between two objects,
which can be used to initiate and close the connection between them.
The ObjectLinker uses the provided |token| to locate the paired ExportLink.
|token| must reference a pairable kernel object type such as |zx::channel| or |zx::eventpair|.
|token| may not reference a kernel object that is in use by this ObjectLinker.
If a link cannot be created, |error_reporter| will be used to flag an error.
The objects are linked as soon as the |Initialize()| method is called on
the links for both objects.
Defined at line 340 of file ../../src/ui/scenic/lib/utils/object_linker.h