This reverts commit fb32de9e97.
Remove the secondary synchronization point as noted by Adrian. This is
technically only to make the builders happier about tests and should not
be needed. This also pushes the condition variable setting to after the
watch is actually established (which was the source of the original race
condition, but would normally succeed as the thread shouldn't get put to
sleep immediately on the trigger of the condition variable).
This also was pretested on the chromium builders:
https://ci.chromium.org/ui/p/chromium/builders/try/win_upload_clang/1612/overview.
This reverts commit 76f1baa787.
Also reverts 2 follow-ups:
1. Revert "DirectoryWatcher: also wait for the notifier thread"
This reverts commit 527a1821e6.
2. Revert "DirectoryWatcher: close a possible window of race on Windows"
This reverts commit a6948da86a.
Makes tests hang, see comments on https://reviews.llvm.org/D88666
The initial scan occurring before the watcher is ready allows a race
condition where a change occurs before the initial scan completes.
Ensure that we wait for the watcher to begin executing the initial scan.
Addresses some feedback from Adrian McCarthy in post-commit review.
Ultimately the DirectoryWatcher is not ready until the notifier thread
is also active. Failure to wait for the notifier thread may result in
loss of events. While this is not catastrophic in practice, the tests
are sensitive to this as depending on the thread scheduler, the thread
may fail to being execution before the operations are completed by the
fixture. Running this in a tight loop shows no regressions locally as
previously, but this failure mode was been sighted once on a builder.
This reverts commit 0ec1cf13f2.
Restore the implementation with some minor tweaks:
- Use std::unique_ptr for the path instead of std::vector
* Stylistic improvement as the buffer is already heap allocated, this
just makes it clearer.
- Correct the notification buffer allocation size
* Memory usage fix: we were allocating 4x the computed size
- Correct the passing of the buffer size to RDC
* Memory usage fix: we were reporting 1/4th of the size
- Convert the operation event to auto-reset
* Bug Fix: we never reset the event
- Remove `FILE_NOTIFY_CHANGE_LAST_ACCESS` from RDC events
* Memory usage fix: we never needed this notification
- Fold events for the notification action
* Stylistic improvement to be clear how the events map
- Update comment
* Stylistic improvement to be clear what the RAII controls
- Fix the race condition that was uncovered previously
* We would return from the construction before the watcher thread
began execution. The test would then proceed to begin execution,
and we would miss the initial notifications. We now ensure that the
watcher thread is initialized before we return. This ensures that
we do not miss the initial notifications.
Running the test on a SSD was able to uncover the access pattern. This
now seems to pass reliably where it was previously flaky locally.
We determined that the MSVC implementation of std::aligned* isn't suited
to our needs. It doesn't support 16 byte alignment or higher, and it
doesn't really guarantee 8 byte alignment. See
https://github.com/microsoft/STL/issues/1533
Also reverts "ADT: Change AlignedCharArrayUnion to an alias of std::aligned_union_t, NFC"
Also reverts "ADT: Remove AlignedCharArrayUnion, NFC" to bring back
AlignedCharArrayUnion.
This reverts commit 4d8bf870a8.
This reverts commit d10f9863a5.
This reverts commit 4b5dc150b9.
Prepare to delete `AlignedCharArrayUnion` by migrating its users over to
`std::aligned_union_t`.
I will delete `AlignedCharArrayUnion` and its tests in a follow-up
commit so that it's easier to revert in isolation in case some
downstream wants to keep using it.
Differential Revision: https://reviews.llvm.org/D92516
This implements the directory watcher on Windows. It does the most
naive thing for simplicity. ReadDirectoryChangesW is used to monitor
the changes. However, in order to support interruption, we must use
overlapped IO, which allows us to use the blocking, synchronous
mechanism. We create a thread to post the notification to the consumer
to allow the monitoring to continue. The two threads communicate via a
locked queue.
Differential Revision: https://reviews.llvm.org/D88666
Reviewed By: Adrian McCarthy
The FSEvents APIs are available on iOS6+: however, the DirectoryWatcher
code isn't wired up to really use FSEvents on embedded platforms.
I've duplicated code from DirectoryWatcher-not-implemented.cpp here and
used TargetConditionals instead of adding cmakery to check try_compile;
I couldn't get that to work properly.
I observed two bugs in the DirectoryWatcher on macOS
1. We were calling FSEventStreamStop and FSEventStreamInvalidate before
we called FSEventStreamStart and FSEventStreamSetDispatchQueue, if the
DirectoryWatcher was destroyed before the initial async work was done.
This violates the requirements of the FSEvents API.
2. Calls to Receiver could race between the initial work and the
invalidation during destruction.
The second issue is easier to see when using TSan.
Differential Revision: https://reviews.llvm.org/D74371
rdar://59215667
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
Differential revision: https://reviews.llvm.org/D66259
llvm-svn: 368942
r367979 changed DirectoryWatcher::Create to return an llvm::Expected.
Adjust the Windows stub accordingly.
(upstreamed from github.com/apple/swift-clang)
llvm-svn: 368762
This is just a code skeleton for DirectoryWatcher-windows.cpp so the
build on Windows stops breaking.
(upstreamed from github.com/apple/swift-clang)
llvm-svn: 368761
I also have replaced all the instances of
"auto DW = DirectoryWatcher::create" with
llvm::Expected<std::unique_ptr<DirectoryWatcher>> DW = DirectoryWatcher::create
to make it more clear that DirectoryWatcher::create is returning an Expected.
I've also allowed for logAllUnhandledErrors to consume errors in the case were
DirectoryWatcher::create produces them.
Differential Revision: https://reviews.llvm.org/D65829
llvm-svn: 368108
Add a missing semicolon after an assert. Remove the period from the
assert message while I'm here, because we don't usually have those.
llvm-svn: 367984
Prior to this patch Unix style errno error reporting from the inotify layer was
used by DirectoryWatcher::create to simply return a nullptr on error. This
would generally be ok, except that in LLVM we have much more robust error
reporting through the facilities of llvm::Expected.
The other critical thing I stumbled across was that the unit tests for
DirectoryWatcher were not failing abruptly when inotify_init() was reporting an
error, but would continue with the testing and eventually hit a deadlock in a
pathological machine state (ie in the unit test, the return nullptr on ::create
was ignored).
Generally this pathological state never happens on any build bot, so it is
totally understandable that it was overlooked, but on a Linux desktop running
a dubious desktop environment (which I will not name) there is a chance that
said desktop environment could use up enough inotify instances to exceed the
user's limit. These are the conditions that led me to hit the deadlock I am
addressing in this patch with more robust error handling.
With the new llvm::Expected error handling when your system runs out of inotify
instances for your user, the unit test will be forced to handle the error or
crash and report the issue to the user instead of weirdly deadlocking on a
condition variable wait.
Differential Revision: https://reviews.llvm.org/D65704
llvm-svn: 367979
Apparently kernel support for IN_EXCL_UNLINK in inotify_add_watch() doesn't imply it's defined in sys/inotify.h.
https://bugs.llvm.org/show_bug.cgi?id=42824
llvm-svn: 367906
As discussed in D65249, don't use AlignedCharArray or std::aligned_storage. Just use alignas(X) char Buf[Size];. This will allow me to remove AlignedCharArray entirely, and works on the current minimum version of Visual Studio.
llvm-svn: 367274
This reverts commit f561227d13.
- DirectoryWatcher
- Fix the build for platforms that don't have DW implementated.
- Fix the threading dependencies (thanks to compnerd).
llvm-svn: 365954
Asynchronously monitors specified directory for changes and passes notifications to provided callback.
Dependency for index-while-building.
Differential Revision: https://reviews.llvm.org/D58418
llvm-svn: 365574
Saleem Abdulrasool