Summary:
Instead of passing Context explicitly around, we now have a thread-local
Context object `Context::current()` which is an implicit argument to
every function.
Most manipulation of this should use the WithContextValue helper, which
augments the current Context to add a single KV pair, and restores the
old context on destruction.
Advantages are:
- less boilerplate in functions that just propagate contexts
- reading most code doesn't require understanding context at all, and
using context as values in fewer places still
- fewer options to pass the "wrong" context when it changes within a
scope (e.g. when using Span)
- contexts pass through interfaces we can't modify, such as VFS
- propagating contexts across threads was slightly tricky (e.g.
copy vs move, no move-init in lambdas), and is now encapsulated in
the threadpool
Disadvantages are all the usual TLS stuff - hidden magic, and
potential for higher memory usage on threads that don't use the
context. (In practice, it's just one pointer)
Reviewers: ilya-biryukov
Subscribers: klimek, jkorous-apple, ioeric, cfe-commits
Differential Revision: https://reviews.llvm.org/D42517
llvm-svn: 323872
Summary:
This is probably the right behavior for distributed tracers, and makes unpaired
begin-end events impossible without requiring Spans to be bound to a thread.
The API is conceptually clean but syntactically awkward. As discussed offline,
this is basically a naming problem and will go away if (when) we use TLS to
store the current context.
The apparently-unrelated change to onScopeExit are because its move semantics
broken if Func is POD-like since r322838. This is true of function pointers,
and the lambda I use here that captures two pointers only.
I've raised this issue on llvm-dev and will revert this part if we fix it in
some other way.
Reviewers: ilya-biryukov
Subscribers: klimek, jkorous-apple, ioeric, cfe-commits
Differential Revision: https://reviews.llvm.org/D42499
llvm-svn: 323511
Summary:
It will be used to pass around things like Logger and Tracer throughout
clangd classes.
Reviewers: sammccall, ioeric, hokein, bkramer
Reviewed By: sammccall
Subscribers: klimek, bkramer, mgorny, cfe-commits
Differential Revision: https://reviews.llvm.org/D40485
llvm-svn: 320468
Sam McCall