Summary:
Adds the ability to request cancellation of the folly::coro::UnboundedQueue's
dequeue() operation by injecting a CancellationToken using co_withCancellation().

Most of the work for supporting this was implemented in the change to
Semaphore::co_wait() to support cancellation.

This diff just adds some tests for cancellation of UnboundedQueue::dequeue()
and provides a more efficient code-path for the cancellation-case that does
not involve throwing an exception.

Reviewed By: yfeldblum

Differential Revision: D21555325

fbshipit-source-id: 7fbae8aa426b40bbea4d0d6dec85df4bad813733

Summary:
The `Semaphore::co_await()` method now response to requests for cancellation
communicated through the awaiting context's CancellationToken.

This allows interrupting a wait-operation if the result is no longer required,
in which case the co_wait() task completes with the OperationCancelled exception.

Reviewed By: yfeldblum

Differential Revision: D21655946

fbshipit-source-id: 8c7f862580ddebd2b4d3eb3cc3ab5e01ad5ee289

Summary:
Now use an intrusive list structure to store the list of waiters waiting
for the semaphore to be signalled.

This is primarily motivated by the need to support efficient cancellation,
which requires the ability to efficiently remove a specific element from
the waiter list without having to scan the list like we would for the
existing `std::deque`-based list storage.

Another beneift of this change is that it now eliminates memory allocations
that were previously required by the std::deque container.

The `Semaphore::future_wait()` implementation should now also have one fewer
allocations as the allocation of the Baton and the Baton::Waiter are now fused.

Reviewed By: yfeldblum

Differential Revision: D21692257

fbshipit-source-id: 9beff176b250ae3f37df9e2138f93b15d2607353

Summary: These only had a 1 month expiration after D21271202.

Reviewed By: xybu, mingtaoy

Differential Revision: D21765601

fbshipit-source-id: 18b9f400e96b2ba39df650db9e6627f1cf917250

Summary:
If inline functions are enabled, actual frames used can be larger than the
address count.

Reviewed By: luciang

Differential Revision: D21371112

fbshipit-source-id: c1e602b62b6af427f11701bf25894a99f554ec47

Summary:
Baton is the primitive that allows fibers to block. The goal of this diff is to provide an `Async` interface to blocking calls that operate on Batons.

Overloading `await` directly was one option, however, there are 3 blocking baton APIs (wait, try_wait_for and try_wait_until). Morover these APIs can accept arguments (something async::await doesn't do so far)

So, this diff adds a bunch of wrappers that return Async<> results that must be 'awaited' on. This keeps static-analysis happy, and performs the onFiber check.

Reviewed By: yfeldblum

Differential Revision: D21667887

fbshipit-source-id: 774c19d223ebb0932c043e4c09635c5e85cc8241

Summary:
Fix race condition between releaseRefClearDelete and releaseRefDeleteOnly by fixing handling in releaseRefClearDelete of the case where the clear count is 1 and the delete count is > 1.

The correct behavior of releaseRefClearDelete when delete count > 1 is to release the clear count first and then release the delete count, instead of releasing the two counts in one step.

The following sequence of events demonstrates the problem in the absence of the fix:
- clear count == 1 and delete count == 2
- Thread 1 calls releaseRefClearDeleteCount
- Thread 2 calls releaseRefDeleteOnly
- Thread 1 atomically decrements the counts to 0 and 1
- Thread 2 atomically decrements the delete count to 0
- Thread 2 deletes the RequestData object
- Thread 1 call to onClear accesses deleted object

Reviewed By: yfeldblum, davidtgoldblatt

Differential Revision: D21705266

fbshipit-source-id: 8ec2151c4e98968beaef7e9ccec0a786ca5ae267

Summary: This diff factors out some of the logic needed in the stacked diff D21628842. We want `RocketClientChannel::sendRequestResponse` to work without a fiber if the caller is not already on a fiber, which means we cannot only use `Baton::TimeoutHandler` for the request's timeout callback.

Reviewed By: iahs

Differential Revision: D21628871

fbshipit-source-id: 2e739f205fcb0a255108fa88f94107378a1bab49

Summary:
In order to use the Python 3 streaming thrift client on platforms that
don't support coroutines, conditionally define anything that depends
on coroutines.

Reviewed By: yfeldblum

Differential Revision: D21692900

fbshipit-source-id: 9f26d598097181ae43d1ff377a22b1c2f789321e

Summary: Add missing includes of `folly/synchronization/Baton.h`.

Differential Revision: D21716396

fbshipit-source-id: 8c8fb818f3083b4fe04fd1c62923d7ba698dcedd

Summary: Add AsyncUDPSocket::maxReadsPerEvent_ support

Reviewed By: yfeldblum

Differential Revision: D21509991

fbshipit-source-id: 5c4f939c1cfdda8711864df3b5f5c58439f8d7bf

Summary: [Folly] Compare `exception_wrapper::class_name()` to `demangle(typeid(...))` in tests v.s. comparing it to string literals since the actual result of `...::class_name()` depends on the platform and whether `libiberty-dev` is available.

Differential Revision: D21711569

fbshipit-source-id: b2289d89923d6775c7e806eff9c3732ad37a0218

Summary: [Folly] Prefer `EndsWith` matcher in `exception_wrapper` test so that, in case of failure, the non-matching input will be shown.

Differential Revision: D21708674

fbshipit-source-id: 022f7d64a030417b80b8796ae3d78534295509fc

Summary: [Folly] Comments in `folly/synchronization/Lock.h`.

Differential Revision: D21689050

fbshipit-source-id: 65ffa2cf9bf3afe8740ae0c4a0d529c706397dae

Summary: [Folly] Extract utf-16 surrogate-pair helpers from `folly/json.cpp` into `folly/Unicode.h`.

Reviewed By: luciang

Differential Revision: D21634400

fbshipit-source-id: 64d15e79fe19cce5f5c9c38837d4663209b5f888

Summary: Add tracing to SemiFuture destruction that is potentially work-dropping.

Reviewed By: yfeldblum

Differential Revision: D21671142

fbshipit-source-id: 8e3e733d9a0845b00fe7ccf465e9c817a10fee59

Summary:
Now that we've deployed the new eden build with globfiles
support, we can enable the use of eden prefetch in the getdeps
build when running inside an EdenFS mount on Windows.

Reviewed By: fanzeyi

Differential Revision: D21692689

fbshipit-source-id: b42e778901976cf0385ec31056c227b2049162dc

Summary:
`folly::expected_detail::Promise<Value, Error>` won't build with exceptions
turned off (e.g. by passing `-fno-exceptions` on Clang's command line) because
its `unhandled_exception()` says `throw;`.  This diff replaces the `throw;`
with a call to `folly::rethrow_current_exception();`.

Reviewed By: yfeldblum

Differential Revision: D21682605

fbshipit-source-id: 294752590d54b0671395982ccdeb0386a742c01e

Summary: [Folly] Use `RequestToken` in `RequestEventBase` to speed up lookup.

Reviewed By: zhxchen17

Differential Revision: D21529465

fbshipit-source-id: eaaef7b48be2c5a8d76fb5f4a5293f7db7e68bed

Summary: [Folly] Fix technical typo in checking hw checksum support, but which makes no practical difference.

Differential Revision: D21689112

fbshipit-source-id: 8ad71d20a561f4bbf5c413ce94e7bec227d9d940

Reviewed By: yfeldblum

Differential Revision: D21666740

fbshipit-source-id: 96975e777df0745f343c5b722f1d8c05bb8ac32e

Summary: [Folly] Tweak `BlockingContext` in various ways.

Differential Revision: D21657789

fbshipit-source-id: 4b03b3b43dddc0e9011a7594001994f2594a1a5b

Summary:
[Folly] Lock utilities: `upgrade_lock`, `transition_to_shared_lock`, `transition_to_upgrade_lock`, `transition_to_unique_lock`, `try_transition_to_unique_lock`.

Note: `std::shared_mutex` does not have an upgrade state or any atomic transitions; there is no `std::upgrade_lock`; and `std::shared_lock` does not have a constructor from `std::unique_lock`.

Reviewed By: simpkins, nbronson

Differential Revision: D15532568

fbshipit-source-id: d32f387b26b57539857922c3090dc75ffcaaa538

Summary:
Migration from Future-returning executor-erasing collectX forms to
SemiFuture-returning forms, that are less risky in particular with coroutines.

Earlier changes added collectXSemiFuture and collectXUnsafe as a migration
path. We then migrated collectX callsites to collectXSemiFuture or
collectXUnsafe and switched the implementation of collectX to the SemiFuture
form.

This diff removes collectXSemiFuture completely.

Reviewed By: yfeldblum, mpark

Differential Revision: D21631886

fbshipit-source-id: c7b296d51f30c8b51ab0c7d06b1ce62c8cdd28d5

Summary:
`folly::detail::OptionalPromise<Value>` won't build with exceptions turned off
(e.g. by passing `-fno-exceptions` on Clang's command line) because its
`unhandled_exception()` says `throw;`.  This diff replaces the `throw;` with a
call to `folly::rethrow_current_exception();`.

Reviewed By: yfeldblum

Differential Revision: D21655976

fbshipit-source-id: 5f431372f2494a09f98e3b8c36a94e8475efff29

Summary:
This fails to build on win32 platform with:
```
xplat\folly\portability\pthread.cpp(142): error C2664: 'HANDLE CreateThread(LPSECURITY_ATTRIBUTES,SIZE_T,LPTHREAD_START_ROUTINE,LPVOID,DWORD,LPDWORD)': cannot convert argument 3 from 'DWORD (__cdecl *)(void *)' to 'LPTHREAD_START_ROUTINE'
```

This seems to fix it.

Reviewed By: Orvid

Differential Revision: D21623386

fbshipit-source-id: 1b18a74bd71ffc75f34a92074e07f3d69742c07d

Summary: [Folly] Small simplification of `AsyncSocket` read loop.

Differential Revision: D21514325

fbshipit-source-id: 0af27205b4aa2807a800430e8a2b3dea36356970

Summary: Add io_uring_submit_and_wait call

Reviewed By: yfeldblum

Differential Revision: D21653382

fbshipit-source-id: 945aa877a30b3c6431089a113ece5999d1217eb4

Reviewed By: yfeldblum, luciang

Differential Revision: D21656746

fbshipit-source-id: 5e19d72ccd524926c698b8814cc6c8f2c6133565

Summary: fsync the temp file

Reviewed By: yfeldblum, kevin-vigor

Differential Revision: D21668049

fbshipit-source-id: 85825f81dfbe10a452f7f946133bb3d8993850f8

Summary: [Folly] `rethrow_current_exception`, a `-fno-exceptions` compatibility wrapper for `throw;`.

Reviewed By: ispeters

Differential Revision: D21656269

fbshipit-source-id: 8f37fe71c6255162b8f05268cae04ac5927013d7

Summary:
gcc-6.5 on OS X <= 10.6 complains about the `\r` when this code path
is enabled. I don't think we officially support `__i386__`, but I want to
backport the patch from zstd. https://github.com/facebook/zstd/pull/1418

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum, Orvid

Differential Revision: D13104652

fbshipit-source-id: 737a68253c7d90c3a1cc026069b048551cb5ced9

Summary:
If an error is thrown when formating arguments for a log message, use
`folly::exceptionStr()` to format the exception instead of just `ex.what()`.

I changed all of the tests that verify the results of these strings to use a
regular expression, as `folly::exceptionStr()` produces different results in
different platforms, and does not always demangle type names.

I also included a minor change to increase a timeout in
AsyncFileWriterTest.cpp, as I saw this timeout fail spuriously once in my
testing.

Reviewed By: yfeldblum

Differential Revision: D21635680

fbshipit-source-id: 749ef48deb59af1f2faef0158e0291838e09fc38

Summary:
Fix the issue that there may be other tags like DW_TAG_lexical_block between DW_TAG_subprogram and DW_TAG_inlined_subroutine.

Also increase the maximum inline location info per frame since previous value 3 is too small.

Refactors the code to set file and line for inline functions.

Reviewed By: luciang

Differential Revision: D21250080

fbshipit-source-id: f52dc74ee5c144aa26723546b48486f8a5250f19

Summary: Fix uninitialized maxSubmit_, maxGet_ member variables

Reviewed By: danobi

Differential Revision: D21645171

fbshipit-source-id: 094ba7b045010954fdebc249318191f956f5b7b2

Summary:
This updates the logging code so that it is possible to include `folly/xlog.h`
and write log statements in code that is compiled with `-fno-exceptions`

The code for parsing log configuration strings does still use exceptions in
some of its config parsing logic.  It shouldn't be too difficult to disable
that in a subsequent diff, but for now this change at least makes it possible
for calling code to write log messages.

Reviewed By: yfeldblum

Differential Revision: D21630914

fbshipit-source-id: ce9ed422f40066e57433a85182e1a8fc6d8628db

Summary:
This fixes a race condition detected by ThreadSanitizer.

The thread list is protected by a mutex, but individual structs in the list are not protected, leading to racy access to two of their fields. This diff makes the fields atomic.

Reviewed By: yfeldblum

Differential Revision: D21484748

fbshipit-source-id: a981419f47a2aebaf1d40b23e9c4967cf2104aaa

Summary: Remove PollIoBackend inline submit

Reviewed By: danobi

Differential Revision: D21625033

fbshipit-source-id: 02ee55e64a2538c6a2392ea70912f4ae9b642963

Summary:
The current stack trace formatting is based on repeated string appends with newlines. This change adds more control so that we can produce file and line information only, without unnecessary newlines.

New format:
  ./folly/experimental/symbolizer/Symbolizer.h:77
  ./folly/experimental/symbolizer/test/StackTraceTest.cpp:209
  ./folly/experimental/symbolizer/test/StackTraceTest.cpp:213
  ./folly/experimental/symbolizer/test/StackTraceTest.cpp:258

Reviewed By: yfeldblum

Differential Revision: D21562670

fbshipit-source-id: 7d05605cbda686e2f1c87577647c7ab7581f8580

Summary:
adds ensureCleanupAfterTask()

takes a SemiFuture<T> task and a SemiFuture<Unit> cleanup.

returns a SemiFuture<T>

always starts cleanup after task completes. stores the result of the task and replays it after the cleanup completes.

cleanup is not allowed to fail.

Reviewed By: yfeldblum, andriigrynenko

Differential Revision: D21481825

fbshipit-source-id: 901a91c25f7b2b4fa794a590a5433e0fad27d168