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

Summary:
This is towards upgrading to newer OpenNSA 6.5.21.

This diff will be landed after we have verified that OpenNSA 6.5.21 has not
regressed from OpenNSA 6.5.19 (HW test results)

sha256sum on the tarball, and use that in the manifest.

Reviewed By: jasmeetbagga

Differential Revision: D27470306

fbshipit-source-id: a56c1e012a790b0bc948a5804dd605cdf224916c

Reviewed By: yfeldblum

Differential Revision: D27461647

fbshipit-source-id: cf1f9747b535a9fb8c8aa851f2ce9cad8b9dce61

Summary: This is useful if your environment takes partial dumps of the process on crash - you can tell the process which does that to include the memory range of the flight recorder in what is dumped.

Differential Revision: D27206631

fbshipit-source-id: b3679004930486094e6030b5b39ee02d01bc7617

Summary:
jemalloc has background threads to purge unused pages, so stop purging
arenas used by idle threads since those arenas may be shared with active
threads which must page fault new pages in after the purge

Reviewed By: ot, davidtgoldblatt

Differential Revision: D26793042

fbshipit-source-id: 13617bfb0ace1c5b7aae52dfdc428b19ff99f7bf

Summary: This satisfies a new error in llvm11

Reviewed By: smeenai

Differential Revision: D27421459

fbshipit-source-id: 963d809a4f430a365223786ea7d2591fe239062f

Summary:
Enabling Velox/f4d getpdeps build on macOS, and adding the last
required dependency (libicu).

Reviewed By: amitkdutta

Differential Revision: D27316661

fbshipit-source-id: 60edf7d4a953a62f2b7b52d9b4f0827d12ac1367

Reviewed By: vitaut

Differential Revision: D27372973

fbshipit-source-id: fcbad2d9fceaecb4b02f5015a808f5744c7cb771

Summary: Add IOBuf multi create/destroy benchmark

Reviewed By: mokomull

Differential Revision: D27406019

fbshipit-source-id: 001cd92743892bb91111831044fc3a4d3b02aaf7

Summary: Rename, mark as kept, add a version taking an argument

Differential Revision: D27383132

fbshipit-source-id: 214af5b09e42159756e97b3b829ac9ecb237c17b

Summary: IOBuf allocate SharedInfo in the same allocation only if we do not cross into the next class size

Reviewed By: jrahman

Differential Revision: D27353914

fbshipit-source-id: 65be3641d7eaa0588bf26101ce02668fb827eee9

Summary:
`folly::observer::ReadMostlyAtomicObserver` docblock explains it well:
```
/**
 * A ReadMostlyAtomicObserver guarantees that reading is exactly one relaxed
 * atomic load. Like AtomicObserver, the value is cached using `std::atomic`.
 * However, there is no version check when reading which means that the
 * cached value may be out-of-date with the Observer value. The cached value
 * will be updated asynchronously in a background thread.
 *
 * Because there is no version check when reading, ReadMostlyAtomicObserver
 * does not capture observer dependencies when used from makeObserver. It is not
 * possible to create a dependent observer. Therefore, ReadMostlyAtomicObserver
 * models none of CopyConstructible, MoveConstructible, CopyAssignable, or
 * MoveAssignable. Dependent observers should be created using the underlying
 * observer.
 *
 * ReadMostlyAtomicObserver is ideal for fastest possible reads on a
 * trivially-copyable type when a slightly out-of-date value will suffice. It is
 * perfect for very frequent reads coupled with very infrequent writes.
 */
```
Other minor changes:
* Added `getUnderlyingObserver` to each of the special-purpose observers.
* Sprinkled `std::move` where neccessary.

Reviewed By: yfeldblum

Differential Revision: D27381490

fbshipit-source-id: fed039ae481af0c4e4148f80df03e30a125e333f

Summary:
This page says it can't be greater than 256:
https://docs.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-gethostname

POSIX one is equal to 255, so set it to 255.

Reviewed By: yfeldblum

Differential Revision: D27370716

fbshipit-source-id: 458ebc02d2914a0422862fafedd089e0c13c5e6d

Summary: Adding libicu manifest, which will be used by f4d/velox

Reviewed By: amitkdutta

Differential Revision: D25934666

fbshipit-source-id: 247d9961c90fcfc497498b556626e9ef1739b191

Summary: Alias `-h` to `--help` because we live in a society.

Reviewed By: yfeldblum

Differential Revision: D27370742

fbshipit-source-id: eb346546fe4066eef62313176ff7e47c20e507be

Summary: As titled. Convert float to int explicitly to get rid of compilation warning.

Reviewed By: therealgymmy

Differential Revision: D27364578

fbshipit-source-id: a5f53142be9ba64260e7028d29c89a857ed66770

Summary: `LLVM_COROUTINES` define indicates that LLVM compatible `<experimental/coroutine>` is available and we can enable coroutines for Clang on Windows.

Reviewed By: yfeldblum, WillerZ

Differential Revision: D26729942

fbshipit-source-id: 37999a9a727727aa9244e8d4d67f035fc311be50

Summary:
SharedMutex TSAN: call destroy only if the annotation was created

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D27379654

fbshipit-source-id: 90be62eb9e932c83e025a96dd36c4cba992e6267

Summary:
Add API equivalent to `std::optional::value_or`: https://en.cppreference.com/w/cpp/utility/optional/value_or

Returns the contained value if *this has a value, otherwise returns default_value.

  template< class U > constexpr T value_or( U&& default_value ) const&;

Equivalent to `bool(*this) ? **this : static_cast<T>(std::forward<U>(default_value))`

   template< class U > constexpr T value_or( U&& default_value ) &&;

Equivalent to `bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(default_value))`

Reviewed By: yfeldblum

Differential Revision: D27346319

fbshipit-source-id: 598b740cb9068cffb0cc0fbda3579e64fd125e8b

Summary: Even in debug mode, the branch can likely be coalesced with the actual condition if inlined.

Reviewed By: yfeldblum

Differential Revision: D27285173

fbshipit-source-id: 1662588f82d14a5ab2c9564bab5cec72981418ec

Summary:
Folly builds are broken in Legocastle MacOS because there's no Elf
support, but, since libdwarf is found (`-- Setting FOLLY_HAVE_DWARF: TRUE`),
folly tries to compile Dwarf symbolizer which depends on a few symbols from
Elf, which is not available, failing the compilation:

https://www.internalfb.com/intern/sandcastle/log/?instance_id=4503600026654665&step_id=4503603563228601&step_index=49&name=Build%20folly

Adding a check to make sure both Dwarf and Elf are available before compiling
Dwarf symbolizer.

See post for more details

https://fb.workplace.com/groups/fbcode/permalink/3847861398584004

Reviewed By: chadaustin

Differential Revision: D27328940

fbshipit-source-id: b06b852a8819275f63c57eb921562ecf37d0e63f

Reviewed By: yfeldblum

Differential Revision: D27261361

fbshipit-source-id: a3aa0b40d1a42313fbeeea5c8ca8f6d43dbc6bdf

Reviewed By: zertosh

Differential Revision: D27356622

fbshipit-source-id: f03ad23a2847b3cbaf61e16055393cbbfbc215ae

Summary: Add a test target to the eden_scm getdeps manifest and underlying Makefile

Reviewed By: markbt

Differential Revision: D27336805

fbshipit-source-id: 07ec4be1ff03c6a384451ce138d88938dd4bf86e

Summary: A note describing some ways compilers infer unlikeliness.

Reviewed By: iahs

Differential Revision: D27298067

fbshipit-source-id: c2e0409aa6f0e95f6e68724f56a0e53a47d9a19e

Summary: Posix does not require fsync to be provided, so define it as a local empty function when is it is not available

Reviewed By: yfeldblum

Differential Revision: D27243532

fbshipit-source-id: e7a9c31312e288458a9dc11736b238a378671caf

Reviewed By: yfeldblum

Differential Revision: D27260961

fbshipit-source-id: a2161e4e909531518f523fd611b109f7021ae258

Reviewed By: LeeHowes

Differential Revision: D27302462

fbshipit-source-id: 8af6a8106563ded80de8ece803589fa07cc59241

Reviewed By: yfeldblum

Differential Revision: D27260808

fbshipit-source-id: b15bcfea70f0ad5d92df3b1143ef417eb2b4adf9

Summary:
On some WIN32 platforms #defines `timezone` as such we get a compilation
error due to name collision.

To fix let's use a folly_ prefix on our polyfill.

Reviewed By: yfeldblum

Differential Revision: D27220643

fbshipit-source-id: ccd4fa971388d53b8c5e8fba9f217776573ea370

Summary: This diff added conversion from `IOBufQueue` and `QueueAppender` to `RWCursor`. It's safe to use `RWCursor` to mutate the their underlying `IOBuf` since the structure of `IOBuf` won't changed. It's worth noting appending data to `IOBufQueue` will invalidate RWCursor (just like iterator).

Reviewed By: yfeldblum

Differential Revision: D27257697

fbshipit-source-id: 17887d656a6095afe1c6882426457b9e75a66c84

Summary:
On glibc > 2.33 (e.g. on Fedora rawhide/35), `SIGSTKSZ` is no longer constant:
http://sourceware-org.1504.n7.nabble.com/PATCH-sysconf-Add-SC-MINSIGSTKSZ-SC-SIGSTKSZ-BZ-20305-td650948.html

Assume it's non-constant, and so:
- use `std::max` rather than `folly::constexpr_max` to compute the stack size
- cast both arguments to `size_t` since in the non-constant case we get a `long int` back
- use `std::unique_ptr<char[]>` and compute the size at the time of use rather than make it class-wide

Reviewed By: yfeldblum

Differential Revision: D27143320

fbshipit-source-id: 7dcdd7cf3d5e96db605266504f443cf2b48ba18c

Summary: Using folly::Function as node type for EventBaseAtomicNotificationQueue involves two mallocs (for creating the function and also to create the queue node). In this diff, I have created a class to hold the data required to send replies and using emplaceMessage to add to the queue.

Differential Revision: D26778920

fbshipit-source-id: 2dcf8395dc77db1d7c73d1d68c9a69e767191b95