Summary:
- Reads are never executed if canceled before ready-to run.
In practice, we finalize cancelled reads eagerly and out-of-order.
- Cancelled reads don't prevent prior updates from being elided, as they don't
actually depend on the result of the update.
- Updates are downgraded from WantDiagnostics::Yes to WantDiagnostics::Auto when
cancelled, which allows them to be elided when all dependent reads are
cancelled and there are subsequent writes. (e.g. when the queue is backed up
with cancelled requests).
The queue operations aren't optimal (we scan the whole queue for cancelled
tasks every time the scheduler runs, and check cancellation twice in the end).
However I believe these costs are still trivial in practice (compared to any
AST operation) and the logic can be cleanly separated from the rest of the
scheduler.
Reviewers: ilya-biryukov
Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits
Differential Revision: https://reviews.llvm.org/D54746
llvm-svn: 347450
Summary:
Task is no longer exposed:
- task cancellation is hidden as a std::function
- task creation returns the new context directly
- checking is via free function only, with no way to avoid the context lookup
The implementation is essentially the same, but a bit terser as it's hidden.
isCancelled() is now safe to use outside any task (it returns false).
This will leave us free to sprinkle cancellation in e.g. TUScheduler without
needing elaborate test setup, and lets callers that don't cancel "just work".
Updated the docs to describe the new expected use pattern.
One thing I noticed: there's nothing async-specific about the cancellation.
Async tasks can be cancelled from any thread (typically the one that created
them), sync tasks can be cancelled from any *other* thread in the same way.
So the docs now refer to "long-running" tasks instead of async ones.
Updated usage in code complete, without any structural changes.
I didn't update all the names of the helpers in ClangdLSPServer (these will
likely be moved to JSONRPCDispatcher anyway).
Reviewers: ilya-biryukov, kadircet
Subscribers: ioeric, MaskRay, jkorous, arphaman, jfb, cfe-commits
Differential Revision: https://reviews.llvm.org/D51996
llvm-svn: 342130
Sam McCall