Summary:
It's not safe to expect that the executor is alive after a task is added to the queue (this task could be holding the last KeepAlive and when finished - it may unblock the executor shutdown).
The fix is to hold a KeepAlive if some operation has to be done after adding to the queue. However it's safe to avoid this in a case where executor thread count will never drop below 1 (otherwise not having active threads may result in a deadlock) and we already have the maximum number of threads running. This optimization should help avoid grabbing the KeepAlive on the fast path.

Differential Revision: D27584518

fbshipit-source-id: e1242e3f4c40cee4f7e0c6dfca39abe6d17415f1

Summary:
as titled, an ugly hack to support LABEL attribute for 1.7.0 which didn't exist.

getting rid of it now since oss support upgraded to 1.7.1

Differential Revision: D27536730

fbshipit-source-id: 58653e71cbf20a1cda0b7414f66b5f0014d89b84

Summary:
Addresses - at least partly - issue https://github.com/facebook/folly/issues/1550

We'd like to limit our exposure to additional libraries. Fmt is a new dependency. It doesn't look like we need it in actuality; gating the include based on whether the file exists or not makes it possible for clients (specifically React Native for Windows) to not need to fork Folly.

Pull Request resolved: https://github.com/facebook/folly/pull/1551

Reviewed By: yfeldblum

Differential Revision: D27531237

Pulled By: Orvid

fbshipit-source-id: 340a7ff49be81872aaf23044945a1e8ecd157546

Summary:
This can be used to avoid noisy logging if the process is in the middle of a crash: symbolizing the stack trace can take a long time, so we can end up interleaving the crash report with unrelated logs.

In particular, we can use this to guard monitoring code that is more likely to trip while the process is crashing (for example stall detectors).

Reviewed By: yfeldblum, philippv, luciang

Differential Revision: D27663380

fbshipit-source-id: e3bb40292c3c57579b3eb172847ca089b0f9b07a

Summary: They are observed to trigger pathological behavior.

Differential Revision: D27659117

fbshipit-source-id: 5e4e770e61ffde02075364f2247614cf5bbcf8ce

Reviewed By: Mizuchi

Differential Revision: D27559375

fbshipit-source-id: aad3cc1a5bef017a52d2530068ca18be2eb50cd1

Summary: as title, marking this import as manual will make it so autodeps won't double list it in the TARGETS file.

Reviewed By: yfeldblum, luciang

Differential Revision: D27418310

fbshipit-source-id: 0c32ff1ad0ad7997a83b050f7fe3cdc522f582cc

Summary: Allow callers to `IOBuf::takeOwnership()` to specify valid data in the middle of the underlying buffer.

Reviewed By: yfeldblum

Differential Revision: D27583632

fbshipit-source-id: 4651dec5e53c5eea341b2b4ad3782adfbe7ff779

Summary:
There appear always to be problems with `extern template struct`. In this case, some compilers either not emitting or dropping thread-local wrapper functions.

```
stderr: Undefined symbols for architecture x86_64:
  "thread-local wrapper routine for folly::AccessSpreader<std::__1::atomic>::cpuCache", referenced from:
      folly::AccessSpreader<std::__1::atomic>::cachedCurrent(unsigned long) in CacheLocality.cpp.o
  "thread-local wrapper routine for folly::SequentialThreadId<std::__1::atomic>::currentId", referenced from:
      folly::SequentialThreadId<std::__1::atomic>::get() in CacheLocality.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```

Reviewed By: Mizuchi

Differential Revision: D27579816

fbshipit-source-id: b539816fb1f62d9e50e22d6cbc3c91a0d82ac629

Summary: Extract its content to an outline function and pass it the template immediates it needs.

Reviewed By: Mizuchi

Differential Revision: D27579474

fbshipit-source-id: 193c769d83f886b4fefea4a34118c44f7da08bd1

Summary: Adds a portability header for later ease of use when deciding to include external_deps libunwind in TARGETS files

Reviewed By: yfeldblum

Differential Revision: D27416623

fbshipit-source-id: fc42f010302b8caa280fdf5cbdf013ed1b23af04

Summary: Required for msvc 32-bit builds - the result of `to_ascii_port_clzll` is used in an arithmetic expression.

Reviewed By: SarahDesouky, Orvid

Differential Revision: D27585004

fbshipit-source-id: b84b5b6d6fe417f3c6adafcaf826505275aa827c

Reviewed By: yfeldblum

Differential Revision: D27575037

fbshipit-source-id: fa5817ee3fe1eca99e83f26a13e43ec4a4a6e7cf

Reviewed By: yfeldblum

Differential Revision: D27253836

fbshipit-source-id: a72531e0deca9f0f6582339d483ed56f2eb37d87

Summary: Add a CHECK() to the IOBuf constructor to ensure the underlying buffer does not include any bytes that have been poisoned by AddressSanitizer.

Reviewed By: yfeldblum

Differential Revision: D25627483

fbshipit-source-id: 5bca59e545c32ba7b61430d7cd4787712eecb204

Reviewed By: Orvid

Differential Revision: D27559344

fbshipit-source-id: cf90be5a19da87bffe72fb6646296dd46889bc90

Summary:
Close-on-exec is an important feature to avoid leaking file descriptors to spawned processes.

This diff adds `File::dupCloseOnExec()` function which is equivalent to `File::dup` function, but sets close-on-exec flag where supported (i. e. everywhere except Windows).

Practically most users want to have `closeOnExec = true` by default, but we need to preserve backwards compatibility, thus this diff leaves `dup` function as is.

Reviewed By: yfeldblum

Differential Revision: D27495214

fbshipit-source-id: 540deb2bc6c8fec626a0120bc20c345950dc8af7

Reviewed By: Orvid

Differential Revision: D27555992

fbshipit-source-id: d68dc183f7c7b7c64975ede21e6f3018575fb7c9

Reviewed By: Orvid

Differential Revision: D27537202

fbshipit-source-id: d1aa8ad81f3749129dd6f1795e788a0e55d9f06a

Summary: Between gnu and msvc compilers, the builtins and intrinsics `__builtin_clzll` and `__lzcnt64` have different return types. They are wrapped in a portability function in `to_ascii` which currently forces a return type, which return type could trip implicit-conversion warnings. Avoid forcing the return type to avoid tripping implicit-conversion warnings.

Reviewed By: luciang

Differential Revision: D27535348

fbshipit-source-id: 3339d5d04e095f936c18d2b39ac1fb4b32f8a810

Summary: The ambiguity is that the name appears as both `folly::to_ascii_size` and `folly::detail::to_ascii_size`, so that anything which imports both `folly` and `folly::detail` or which is within `folly::detail` may, depending on the particular compiler, find an unqualified call ambiguous.

Differential Revision: D27535255

fbshipit-source-id: 05db44e6b153d75b691d67c878785cab1655051d

Summary: SingletonRelaxedCounter is templated over tag types, but this leads to heavy monomorphization. extract the common code.

Reviewed By: aary

Differential Revision: D27383671

fbshipit-source-id: e419579e4d9ab84b5107670bd1e94e1768dcebf4

Summary: No strict need for them to be functions.

Differential Revision: D27484949

fbshipit-source-id: f0fbc91aa9940720bbd3b685b730acc314bf122d

Reviewed By: philippv

Differential Revision: D27535007

fbshipit-source-id: 384235553b18320fa9728740f7f1b83b4c8b0a1a

Reviewed By: WillerZ

Differential Revision: D27489039

fbshipit-source-id: 5d397a24fcb165b7ea25e32f0c81435bce474b04

Summary:
Win32 does not support weak symbols.  This means the linker will fail due to the unresolved symbol `__asan_region_is_poisoned` when ASAN is not available.
Use `FOLLY_CREATE_EXTERN_ACCESSOR` macro when filtering for ASAN availability in `SanitizeAddress.cpp` to ensure the symbol `__asan_region_is_poisoned` is referenced only when ASAN is available.

Reviewed By: yfeldblum, luciang

Differential Revision: D27278826

fbshipit-source-id: 3c8efbfc687295c2fa70e3712402fd8dfe81bc45

Summary:
NestedCommandLineApp works by performing two passes over the argument vector:

1. Treat the entire argv as a single command, ignoring subcommands. Consume all options that "match" a global flag here.

2. Find the first positional argument in argv and treat it as a subcommand, then re-parse everything after it as options to the subcommand.

This allows constructs like `cli subcommand --subcommand-flag --global-flag`. However, as a side effect, if `subcommand-flag` happens to be even a prefix of a global flag name, boost "helpfully" matches it with the global flag in the first pass so that the subcommand never even sees it.

Fixing the issue of a subcommand flag conflicting with a global flag would break backwards compatibility; however, we can at least add an option to disable prefix matching so that there would need to be an exact flag name collision for this scenario to occur. It may be possible to extend NestedCommandLineApp in the future to detect flag collisions as well, instead of silently associating arguments with the wrong flag.

Reviewed By: yfeldblum

Differential Revision: D27419341

fbshipit-source-id: 941c0769e16d40c87f96620155f0ab09927cef3d

Summary:
If zero copy starts out enabled on a unencrypted connection, disable
it when the SSL handshake begins. Otherwise, AsyncSocket will receive send
notifications for buffers that it did not pre-register.

Reviewed By: yfeldblum

Differential Revision: D27145232

fbshipit-source-id: f07d006d095e1e6839eb2f4adb07d7c284786572

Summary: A mechanism to make it easier conditionally to access possibly-defined names, which can be a bit tricky especially without `if constexpr`.

Reviewed By: luciang

Differential Revision: D27434753

fbshipit-source-id: 4c9aaebe89b354aa94f4f370c8fbdc8456b0e7f7

Summary:
On darwin with Xcode, deleter for a shared_ptr is passed by copying the whole lambda, causing issues when building PrimaryPtr.

In this diff we try to work around this problem by putting the last promise value on the heap while sharing the control block with the shared_ptr exposed to user.

Reviewed By: yfeldblum

Differential Revision: D27354087

fbshipit-source-id: 9cb23912c9f1058505f3c20384eb998233eba2da

Summary:

Pull Request resolved: https://github.com/facebook/folly/pull/1553

Differential Revision: D27504501

Pulled By: yfeldblum

fbshipit-source-id: 291036c64050896d3873271722c84380fd2b3ec7
Co-authored-by: Zhiwei Chen <condy0919@gmail.com>

Summary: Let the `to_ascii` functions take and check the out range, not just the out begin. Add overloads which take arrays.

Reviewed By: WillerZ

Differential Revision: D27484478

fbshipit-source-id: 56a9ba1465204b58d9df018bdae707d39ef6525d

Summary:
Before this patch, it relies on the c++17 guaranteed copy elision, since `SemaphoreBase::Waiter` is NOT copy constructible due to `std::atomic<intptr_t>`.

This patch makes it compile even using `-std=c++14`.

Pull Request resolved: https://github.com/facebook/folly/pull/1554

Differential Revision: D27505938

Pulled By: yfeldblum

fbshipit-source-id: 6c26f82f77a24236a1233cff7921cd6b9f53bd09

Reviewed By: yfeldblum

Differential Revision: D27461546

fbshipit-source-id: 500ecd312b0b0ba15db7f373a3b6c7d633802846

Summary:
Tpx works well for all OSS jobs, we should migrate to Tpx instead of
relying testpilot.

Reviewed By: marcelogomez

Differential Revision: D27396539

fbshipit-source-id: dd1994be0eb3b4396764c1f3e68ddd6763b60139

Reviewed By: yfeldblum

Differential Revision: D27461452

fbshipit-source-id: 3e46ba71b10aea10d6006c3c6f145377ce6687da

Reviewed By: yfeldblum

Differential Revision: D27461464

fbshipit-source-id: 53facc1cc42f60ffa3083c12c32352bb78b16280

Summary: Persuade the compiler to emit a tail call in the `SingletonRelaxedCounter` inline slow path.

Differential Revision: D27383131

fbshipit-source-id: 6f58b1eb23477c00221515d7d6e55a91668f7c84

Summary:
C++17 permits use of `std::unique_lock` instead of `folly::SpinLockGuard`; just use that.

C++11 permits use of `std::unique_lock<SpinLock>`.

Differential Revision: D27390136

fbshipit-source-id: bcc34a043644289523ddfdfbf47a260c133db186

Summary: Avoids warnings with -Wterminate.

Reviewed By: yfeldblum

Differential Revision: D27452798

fbshipit-source-id: 129b66179c5ff9bbf3f8fe791224cd925a3b33f3