Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: e90f899882e41a77d0baaa336e347b4e19da3f2f
https://github.com/WebKit/WebKit/commit/e90f899882e41a77d0baaa336e347b4e19da3f2f
Author: Alex Christensen <[email protected]>
Date: 2024-05-20 (Mon, 20 May 2024)
Changed paths:
A Source/WebKit/Platform/CoroutineUtilities.h
M Source/WebKit/Platform/IPC/Connection.h
M Source/WebKit/UIProcess/WebPageProxy.cpp
M Source/WebKit/UIProcess/WebPageProxy.h
M Source/WebKit/WebKit.xcodeproj/project.pbxproj
M Tools/TestWebKitAPI/cocoa/HTTPServer.h
Log Message:
-----------
Begin using C++ coroutines for WebPageProxy::decidePolicyForNavigationAction
https://bugs.webkit.org/show_bug.cgi?id=267827
Reviewed by Abrar Rahman Protyasha.
WebKit has a long history with C++ and asynchrony. Deciding whether to proceed
with
a navigation has always had the ability to be done asynchronously. Before
C++11, we
made our own object that contained state and context for a call to indicate
continuation.
With https://commits.webkit.org/193766@main we finished the transition from
this object,
WebCore::PolicyCallback, to C++ lambdas.
Since then, a large and growing amount of our code has developed the ability to
do things
asynchronously using WTF::CompletionHandler, a std::function-like object that
contains
state and context to use when continuing. Also since then, C++ has added
coroutine support
in C++20, including the co_await keyword. This has the potential to allow us
to more elegantly
write code that does many things asynchronously.
WebPageProxy::decidePolicyForNavigationAction has a growing amount of
complexity, with
deeply nested lambdas and many functions calling another function to continue
the logic,
trying to break up the logic. With site isolation, I've needed to add many
things to this
already complex area of the code, and more are needed still. I've had
difficulty passing
parameters from one end of the flow to the other, through the many nested
lambdas. This
has led me to do introduce things like ProvisionalPageProxy's
needsCookieAccessAddedInNetworkProcess,
where I set a bool early in the flow and query the bool much later in the flow.
This needs
a better solution.
In order to begin using C++ coroutines, we need a way to get into a coroutine
from a function
with a CompletionHandler parameter, and we also need a way to get from a
coroutine to a function
with a CompletionHandler parameter and await its result. For these two
operations, I introduce
CoroutineCaller and AwaitableTaskWithCompletionHandler. Task is the object
that an asynchronous
coroutine returns. Lazy<T> is what a coroutine returns for its resulting T to
be awaitable,
analogous to a CompletionHandler<void(T)> which is called with the resulting T.
These primitives are used to make WebPageProxy::decidePolicyForNavigationAction
an asynchronous
coroutine. The introduction of this new technology in such a small scope makes
it look like
most of the code is just the CoroutineCaller/AwaitableTaskWithCompletionHandler
borders to call
to and from existing code, but as coroutine adoption increases we will see
simpler and simpler
code, where we can easily and elegantly add new steps in the logic flow by just
awaiting another
asynchronous step or calling a synchronous step directly.
* Source/WebKit/Platform/CoroutineUtilities.h: Added.
(WebKit::CoroutineHandle::CoroutineHandle):
(WebKit::CoroutineHandle::operator=):
(WebKit::CoroutineHandle::~CoroutineHandle):
(WebKit::CoroutineHandle::handle const):
(WebKit::Lazy::PromiseBase::initial_suspend):
(WebKit::Lazy::PromiseBase::unhandled_exception):
(WebKit::Lazy::PromiseBase::setHandle):
(WebKit::Lazy::PromiseBase::handle):
(WebKit::Lazy::Promise<void>::get_return_object):
(WebKit::Lazy::Promise<void>::return_void):
(WebKit::Lazy::Promise<void>::result):
(WebKit::Lazy::Awaitable::Awaitable):
(WebKit::Lazy::Awaitable::await_ready const):
(WebKit::Lazy::Awaitable::await_suspend):
(WebKit::Lazy::Awaitable::await_resume):
(WebKit::Lazy::Lazy):
(WebKit::Lazy::operator co_await const):
(WebKit::Task::promise_type::get_return_object):
(WebKit::Task::promise_type::initial_suspend):
(WebKit::Task::promise_type::unhandled_exception):
(WebKit::Task::promise_type::return_void):
(WebKit::CoroutineCaller::setCoroutine):
(WebKit::callCoroutine):
(WebKit::AwaitableTaskWithCompletionHandler::AwaitableTaskWithCompletionHandler):
(WebKit::AwaitableTaskWithCompletionHandler::await_ready):
(WebKit::AwaitableTaskWithCompletionHandler::await_suspend):
(WebKit::AwaitableTaskWithCompletionHandler::await_resume):
* Source/WebKit/Platform/IPC/Connection.h:
* Source/WebKit/UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::decidePolicyForNavigationAction):
(WebKit::WebPageProxy::awaitableDecidePolicyForNavigationAction):
(WebKit::WebPageProxy::continueDecidePolicyForNavigationAction):
* Source/WebKit/UIProcess/WebPageProxy.h:
* Source/WebKit/WebKit.xcodeproj/project.pbxproj:
Canonical link: https://commits.webkit.org/278995@main
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