Summary:
Add a `install_fb_python_executable()` function to `FBPythonBinary.cmake` for
helping to install python executables generated with
`add_fb_python_executable()`.  This primarily helps by automatically looking
up the correct output file to install from the generated targets.

Reviewed By: wez

Differential Revision: D18774539

fbshipit-source-id: 4b397580d72ac448f21d1db6d2cdd653cf3635df

Reviewed By: yfeldblum

Differential Revision: D18780743

fbshipit-source-id: 5b26163f5dabcb14fd9ad7b4d9489d3ca1f6df0d

Summary:
Add hazard-pointer-based implementation to allow concurrent reading during updates. This is done by using lightweight concurrent structures protected by hazard pointers instead of sequential structures protected by read locks.

The implementation is gated by a gflag that is off by default.

Reviewed By: davidtgoldblatt

Differential Revision: D18622072

fbshipit-source-id: 120ba14a7a559883e64a3fdf81b35a26315312c1

Summary:
It's impossible for a consumer of a released version of
rocksdb to do anything about this except not use it, and this particular
version of rocksdb ships with a number of shadow warnings.

Disable warning to error promotion.

See also: https://twitter.com/pcwalton/status/1201679307552083968

Reviewed By: chadaustin

Differential Revision: D18785637

fbshipit-source-id: 1db2b00b3c397d6c0b8f05b9d1c658877685c961

Summary:
I tried building on a fresh docker image ubuntu:16.04, the current setup doesn't work because libunwind-dev is missing. Adding this fixed the problem for me.
Pull Request resolved: https://github.com/facebook/folly/pull/1268

Reviewed By: Orvid

Differential Revision: D18759832

Pulled By: yfeldblum

fbshipit-source-id: 8a861844e0b4687bf0107553274322954fdc1c00

Summary: Similar to other sanitizer macros add one for memory sanitizer.

Reviewed By: pixelb

Differential Revision: D18662903

fbshipit-source-id: aa62dfedbfd1b174403af451e14ace9896b26466

Summary: As per title

Reviewed By: MohamedBassem

Differential Revision: D18781525

fbshipit-source-id: a23d8207bd3776b55ba42ec87598a0a9375848aa

Summary:
When assigning a function whose return type is marked `nodiscard` to a `Function<void(Args...)>`, the fact that we are internally explicitly casting the result of the function call to `void` hides the `nodiscard` warning.

For instance:

```
struct [[nodiscard]] DoNotIgnore {};
Function<void()> fn = [] { return DoNotIgnore{}; };
```

emits no warnings, and when `fn()` is invoked, the `DoNotIgnore` struct gets silently ignored.

This diff causes the warning to be emitted.

It is only enabled on compilers that support `if constexpr`. It could be supported on more compilers at the cost of one or more of the following:

* extra template instantiations
* an additional function dispatch
* SFINAE
* Spamming out 4 more specializations of the `FunctionTraits` template.

Reviewed By: yfeldblum

Differential Revision: D18668177

fbshipit-source-id: 0a2cd1366855a0582ab27bb157998d3a4bf4e5a0

Summary: Provides a way to transition to folly::AsyncSSLSocket for applications that manage their own SSL_CTX

Reviewed By: yfeldblum

Differential Revision: D18625198

fbshipit-source-id: cae8c531203134bbb27b648f3f92a6794b14ea3c

Summary:
OpenBCM libraries are stored with git LFS. As a result, fetcher fetches LFS pointers and not the contents. Use git-lfs to pull the real contents before copying to install dir using NoopBuilder.
In future, if more builders require git-lfs, we would consider installing
git-lfs as part of the sandcastle infra as against repeating similar
 logic for each builder that requires git-lfs.

Reviewed By: wez

Differential Revision: D18759806

fbshipit-source-id: f988a0460107bc0685e7aba107daba9ed88f71e7

Summary:
As titled. This is needed by OpenBCM, and in future, possibly by other
manifests as well.

Reviewed By: wez

Differential Revision: D18759807

fbshipit-source-id: d445dfa382cea4bf96443ab9889926a4abbf0757

Summary:
The previous approach (D16760775) reserved space for inlined function info in each `SymbolizedFrame`.

```
struct SymbolizedFrame {
  Dwarf::LocationInfo location;
  Dwarf::LocationInfo inlineLocations[Dwarf::kMaxLocationInfoPerFrame];
  ...
```

That increased the size of `SymbolizedFrame` and `FrameArray` and lead to stack overflow in some already deep stacks.
```
template <size_t N>
struct FrameArray {
  FrameArray() {}

  size_t frameCount = 0;
  uintptr_t addresses[N];
  SymbolizedFrame frames[N];
};
```

To avoid allocate more space on stack, changed to use extra frames to store inline calls:
- Usually the callers allocate `FrameArray<100>` frames, but the stack trace is usually smaller than 100
- Use the unused slots to fill in inlined function info:
 -- each function gets at most `kMaxLocationInfoPerFrame` (currently 3) inlined entries
 -- when the available buffer fills up no more inlined functions are filled in.

To find the inline calling stack, we need first need to find the subprogram Debug Info Entry (with tag DW_TAG_subprogram) with the given address, then recursively find all the inline subroutines (with tag DW_TAG_inlined_subroutine) in the call stack. Sadly debug info has no index we can use for jump, and a linear search over debug info entries (and their attributes) is needed during the process, which would cause performance regression.

```
buck run mode/opt folly/experimental/symbolizer/test:dwarf_benchmark -- --benchmark

============================================================================
folly/experimental/symbolizer/test/DwarfBenchmark.cpprelative  time/iter  iters/s
============================================================================
DwarfFindAddressFast                                         4.03us  248.36K
DwarfFindAddressFull                                         4.03us  248.18K
DwarfFindAddressFullWithInline                             293.23us    3.41K
============================================================================
```

Reviewed By: luciang

Differential Revision: D17586385

fbshipit-source-id: 1b84b3f3a576573ce24092b433a501a3bdf76be0

Summary: users may need AsyncUDPSocket to send back datagram to clients.

Reviewed By: yfeldblum

Differential Revision: D18764100

fbshipit-source-id: 7ab7cce5711f47db92f43a68b94568729d5746d0

Summary: Workaround for something that looks like a compiler bug

Reviewed By: kevin-vigor

Differential Revision: D18700404

fbshipit-source-id: 6d9c9a40e9e468ee910c5456bcbfdf02c1b1c59a

Summary:
This is the header which provides `_mm_set1_epi8`
(https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_set1_epi8).

Although this header is transitively found via other headers (which is why this
isn't a build failure), without this explicit include IWYU's heursitics around
template functions wrongly assume that this header should be provided by
downstream includers of this header.

Reviewed By: yfeldblum

Differential Revision: D18753275

fbshipit-source-id: 7d6ee934542867f2d1e84d40397f48ea8146facc

Summary:
localPush invoked in recycleIndex can end up looping more than once if it has to retry the update of head. When that happens, the onRecycle call will be made again which will call destructor on the object again if eagerRecycle is true.

Fixed it by making sure only the 1st pass of the loop will call onRecycle.

(Note: this ignores all push blocking failures!)

Reviewed By: nbronson

Differential Revision: D18752349

fbshipit-source-id: 27dcb5c7840f724bbd39f4dc0176e21095a22284

Summary: For this iterator to satisfy the `input_or_output_iterator` concept in range-v3, it must also satisfy the `semiregular` concept, which requires a default constructor.

Reviewed By: yfeldblum

Differential Revision: D18689298

fbshipit-source-id: a38cde0041ceba1aac79128d428df05ee0f00ab4

Summary:
This is an update to the fbcode_builder codebase to allow setting up the python virtualenv with python dependencies installed. I've included wheel and cython (with a pinned version to 0.28.6 which is the only version that works with thriftpy3 at the moment, due to https://github.com/cython/cython/issues/2985) as standard packages since these are required by some of our top-level dependencies (folly and thrift)

As far as I know, there are no other projects that use PYTHON_VENV at the moment except LogDevice so the impact should be minimal.

Reviewed By: lucaspmelo

Differential Revision: D18758383

fbshipit-source-id: 264941311c5e3a19dc4ef2bb78c9a1baa34dfd8c

Summary: As titled

Differential Revision: D18726457

fbshipit-source-id: 717a6cda4a78e1b246f20328df1f01b78560cac5

Summary: [Folly] More direct overload resolution control in `folly::coro::concat`. Just name the type directly rather than using SFINAE, when the SFINAE would just name the type directly in a more roundabout way.

Differential Revision: D18746633

fbshipit-source-id: 6da909834b511426b1cf7bbda0fd7643b5761f14

Summary:
This diff addresses a collection of issues with our thrift-py3 build story in open source.
- Cython 0.29 bug https://github.com/cython/cython/issues/2985 prevents us from loading the generated binary python extensions. I've tested 0.28.6 and it works perfectly.
- Adds ssl to the extensions (since we need SSLContext in get_client, we must have access to the module)
- No need to special case folly_pic. There is really no easy way to get the python bindings to work without using shared library libfolly.so. So, In our build (logdevice) we will build folly as a shared library, this also reduces the complexity everywhere.
- We also need iobuf as extension for thrift to work, added that to setup.py
- Refactored some of the CMake code that had hardcoded file names to use globbing to future-proof this as much as possible.
- Moved `python/lang/cast.pxd` to match the python module name `folly.cast`, so now it lives in `python/cast.pxd`. This simplifies the globbing as well.
- Moved `setup.py` to live in the `/python` directory.
- Added `*.py` in setup.py to pickup any raw python code (including `__init__.py`)

Reviewed By: yfeldblum

Differential Revision: D18685009

fbshipit-source-id: 749b30942a3e5e9e314b5248cc0aa90c6ac1581f

Summary: This is another step of moving the python extensions for folly that are currently defined in thrift's codebase. Another step for getting us closer on unblocking LogDevice to use the python3 thrift client in open-source.

Reviewed By: yfeldblum, vitaut

Differential Revision: D16221352

fbshipit-source-id: bc24fce073d67397f20f28f79c68512444704402

Reviewed By: farnz

Differential Revision: D18726052

fbshipit-source-id: 4f18430342ab6fd4fc82cc7d03e21f3e50e0ce25

Summary: [Folly] Avoid linear recursion in `folly::coro::concat`.

Reviewed By: kirkshoop

Differential Revision: D18746601

fbshipit-source-id: a383715bfc47ae8c0d4baad8799e98699c7cc14f

Summary: [Folly] Remove remnants of replacing `std::string` with the implementation of `folly::fbstring`.

Reviewed By: luciang

Differential Revision: D18738367

fbshipit-source-id: b57d38100c9da38c6351145979ac6d2f677ba817

Summary: [Folly] No unnecessary SFINAE in `ElfFile::at` - just use an explicit `static_assert` directly, rather than relying on overload resolution failure for the same goal.

Reviewed By: luciang

Differential Revision: D18746254

fbshipit-source-id: 4bb209bf3f563f2425e4532f6553e66856cb9bbb

Summary: [Folly] `try_call_once`, a nothrow variant of `call_once`. Takes a `noexcept` function which returns `bool`; the function returning `false` indicates failure and that the `once_flag` is not to be marked as as set, while the function returning `true` indicates success and that the `once_flag` is to be marked as set.

Reviewed By: andriigrynenko, luciang

Differential Revision: D18742590

fbshipit-source-id: 3b3a6fab9a328f7540cc6fee1452a0f1367b6e0f

Summary: [Folly] Let `test_once` be `noexcept` since it is required not to fail.

Reviewed By: andriigrynenko, luciang

Differential Revision: D18742588

fbshipit-source-id: fda78057d10fca1521ee6335f7c7758d05c43b88

Summary: [Folly] Hide some test helper functions to permit some tests to be linked together into the same binary, if desired.

Differential Revision: D18746529

fbshipit-source-id: 9829eb1227cb348f65734ceb670c85508577763d

Summary:
[Folly] Mark most `ElfFile` members as `noexcept`.

Since they may be used in signal handlers, they are required not to throw exceptions. Mark it so.

Reviewed By: luciang

Differential Revision: D18743292

fbshipit-source-id: 95fb2a20511ca4cc7c0e832c1b20b8324ca7d0af

Summary: The cargo builder will be used to verify if an opensource Rust project passes Cargo build, test and (optionally) documentation build.

Reviewed By: markbt

Differential Revision: D18636934

fbshipit-source-id: e982e6a017eb32913e2994e7457c8add2e9d6b95

Summary: The `accumulate` algorithm will behave similarly to `std::accumulate`, but instead returns a `Task` of the accumulated result from the values in the `AsyncGenerator`

Reviewed By: kirkshoop

Differential Revision: D18714284

fbshipit-source-id: 66625cd1347d767467d98a421b78b6f45d70260c

Summary: [Folly] Check prev thread-id in `EventBase::loopBody` to enforce that it is not called concurrently.

Reviewed By: andriigrynenko

Differential Revision: D18722163

fbshipit-source-id: 01e18758e4d517011697e025519c84e29ca96636

Summary: The `concat` algorithm will concatenate a series of streams known at compile time into a single stream of the same type.

Reviewed By: kirkshoop

Differential Revision: D18695001

fbshipit-source-id: 2da7f53cbc835333ffd9551ceae1aa5db085936d

Summary: This hadn't been updated since we moved to openssl 1.1

Reviewed By: knekritz

Differential Revision: D18668447

fbshipit-source-id: 26d58ef759fccf7e97c4d127b747b093077f6e59

Summary:
[Folly] Use `relaxed` order for `EventBase::loopThread_` consistently. There is only one location which uses a different memory order.

Atomic operations on this location do not guard any other locations, so non-`relaxed` memory orders are not required.

Reviewed By: andriigrynenko

Differential Revision: D18722614

fbshipit-source-id: b73b61e4845c34c58e9f4adbeb368c815b375d38

Summary: `folly::Function` has this explicit bool conversion operator and it makes sense to also have it for `SharedProxy`.

Reviewed By: yfeldblum, ericniebler

Differential Revision: D18504667

fbshipit-source-id: 32fede326c7a3eebd340dea9d118714a0cdfa5c0

Summary: collectAny had this overload, it was missed when collectAnySemiFuture was added.

Reviewed By: mpark

Differential Revision: D18689251

fbshipit-source-id: 1fccd6eca9d4afde46a173842641f14aff78aada

Summary: Make sure that fiber stack overflow is immediatelly discoverable from the crash stack trace, not just from the error log.

Reviewed By: spalamarchuk

Differential Revision: D18702739

fbshipit-source-id: c0a05081e67b12c94b20a929b2d10396bc1b6949

Summary: [Folly] Make `Function` shared proxy empty when constructed with an empty `Function`, just like it would be when constructed with `nullptr`.

Reviewed By: ericniebler, vitaut

Differential Revision: D18518858

fbshipit-source-id: fdad5b4cd30a1fda5465dae80054c5c74837faa9