This is a helper that creates a promise, then a future and immediately
resolves the promise, this will let the future be dispatched as usual,
from a clean main loop context.
Coverity reports that eina_safepointer_get returns a NULL promise here
(checked 20 out of 21 times). As eina_safepointer_get can return NULL,
we should check the validity of 'promise' here before trying to
derefernce it later.
Fixes Coverity CID1356625
@fix
Signed-off-by: Chris Michael <cp.michael@samsung.com>
Cancelling a promise will fulfill it but won't actually free the memory. This
memory is under custody of the owner, who must either call value_set or
error_set to finish it.
Now when dealing with pointer types, we will not get pointer to
pointer semantics in callbacks and eina_promise_owner_value_set
for Eina_Promise.
It will work as expected:
Eina_Promise_Owner* promise = eina_promise_add();
void* p = malloc(sizeof(T));
eina_promise_owner_value_set(promise, p, &free);
The call to eina_promise_then steals the first ref'count, so it is
possible that the promise is freed after the eina_promise_then,
so we need to eina_promise_ref before eina_promise_then.
We do properly unref promise while calling all the then callback. There
is no need to check it a second time (which actually lead to a 100%
bad access).
T3759
Eina_Error is not passed by pointer anymore, which could cause invalid
pointer access in promise compositions (all and race).
Also added Eina_Promise* to prototypes.
Added eina_promise_race function that composes multiple
promise objects into a new promise which is fulfilled
when one of the promises are fulfilled, or fails
when one of the promises have failed.
Add a way for users of the promise owner to get notified when a
promise progress is registered. Also added a convenience composition
function that creates a promise which is fulfilled when another
promise has a progress notification.
Fix value_set and error_set signatures which were receiving a
owner. They actually receive the promise and not the owner, this
caused wrong access to memory and were not visible by warnings because
the functions are casted.
This problem caused errors in which it seemed that promise had
actually error'ed when questioned it.
Add a promise object that will allows Eolian interface to include promises
as a way to have asynchronous value return and composibility.
To understand better, let see the coming usage in a .eo file:
class Foo {
methods {
bar {
params {
@inout promise: Promise<int>;
}
}
}
}
Which will create the following API interface:
void foo_bar(Eo* obj, Eina_Promise** promise);
and the equivalent declaration for implementation.
However, the API function will instantiate the Promise for the user
and the implementer of the class automatically. So the user of this
function will treat it as a @out parameter, while the developer of the
function will treat it like a @inout parameter.
So, the user will use this function like this:
Eina_Promise* promise; // No need to instantiate
foo_bar(obj, &promise);
eina_promise_then(promise, callback);
Signed-off-by: Cedric Bail <cedric@osg.samsung.com>