This adjusts the use of Dispatch to build on Windows. Windows does not
provide `stdout_fileno` and `stderr_fileno`. However, it is possible to
use `fileno` to get the associated fileno from the descriptor.
Dispatch on Windows does not deal with fd's but rather with handles.
Convert the file descriptor to a handle and pass that off to dispatch.
The handle is a non-owning reference, and should not be closed.
Fortunately, dispatch does not close the handle when the DispatchIO is
closed.
Specifically, we care that all outstanding **writes** are finished
before we call the close handler, because otherwise we may (a) send
corrupted output during shutdown, or (b) drop notifications and replies
sent during the shutdown process. The former is a potential issue for
clients that are not robust about parse failures, and the latter is an
issue for reproducibility and robustness during testing/debugging - in
particular, we have some integration tests that send data without
waiting for individual replies and they need to finish outstanding
replies before exiting.
rdar://60159448
Since the connection and message handler have a reciprocal need to know
about each other, move the closeHandler so that it has the opportunity
to call a method on the message handler if desired.
We will be able to split the LSP modules off later. These LSP modules
will provide the ability to write custom LSP servers and clients in
Swift. The sourcekit-lsp repository will build on top of this new
package to provide an LSP implementation that creates a language server
for Swift and C-based-languages.
This code was doing a sync dispatch to a queue it was already running
on. Instead, go through the same path as other close calls. This would
hang, or if you're lucky crash when dispatch detects the issue.
We implicitly close the connection when the input file descriptor is
closed, or if it has an error. But we also close things down explicitly
when we see the exit notification. We need to protect against a race
triggering us to call the close handler multiple times. This was
resulting in `sourcekit-lsp` racing to call `exit(0)`, which triggered a
double-free and abort on Linux.
When testing the sourcekit-lsp binary, it is handy to be able to force
requests to be handled synchronously. This only affects the protocol
layer, not the implementation. This option is hidden from the help text
and should only be used for testing/debugging.
