Summary:
`folly::AtomicBitSet<N>` used `N` to denote the number of blocks
(32-bit or 64-bit each) instead of number of bits as used by
`std::bitset`. This confusion of unit led to unintentional allocation
of extra storage in many cases.

A simple fix would be to make `N` denote number of bits. However,
changing meaning of `N`could lead to silent breakage of code during
run time for some users who used `N` to denote number of blocks.

Therefore, to make the new meaning of `N` more explicit,
`AtomicBitSet` is renamed to `ConcurrentBitSet` & `N` now denotes the
number of bits.

Reviewed By: al13n321

Differential Revision: D18866751

fbshipit-source-id: 17741646862776e1a080eaac7877f495bb56b656

Differential Revision: D19001755

fbshipit-source-id: bda1a278017059e83c9a529aac7b429f074e42c1

Summary: We should be able to associate rootId with the TID the request is running on.

Reviewed By: yfeldblum

Differential Revision: D18918492

fbshipit-source-id: 539cd78729b438928a9a4b0c93e8e17295b642d5

Summary:
What:
exposed an API `folly::RequestContext::getRootsFromAllThreads` that reports all "root" RequestContexts for all threads in the process.
(where "root" is defined as the original RequestContext created for the request but which might have been overridden with `ShallowCopyRequestContextScopeGuard)`

Reviewed By: andriigrynenko

Differential Revision: D18849187

fbshipit-source-id: f3c67becf1e38fb8d2198c81ed0ce77bac860d63

Summary:
Fixing couple more failures in folly when compiling wasm:
1) making posix_memalign used instead of memalign (wasi-libc has memlaign as legacy P123789170)
2) disabling clearenv() that is using environ, which wasi-libc has off by ```#ifdef _GNU_SOURCE```, not sure why, but it's already off for linux and we won't use it our wasm code either.

Reviewed By: shodoco

Differential Revision: D18944271

fbshipit-source-id: ffa838591ada1248fdb8ae24f7eac45896a311e2

Summary:
This is intentionally not hidden in `folly/compression/Zstd.cpp`, so that it
can be used by other Zstd users as well.

Reviewed By: bimbashrestha

Differential Revision: D18890515

fbshipit-source-id: e87eb6acd03f4b4d5f68201ef924984047d0160e

Summary:
This reduces contention on the synchronized stack in the
`CompressionContextPool`, as well as potentially helping cache locality under
heavy compression workloads.

I have plans to make a singleton of this, and to use it in `folly::io::Codec`
and some other places, so they all use the same contexts.

Reviewed By: bimbashrestha

Differential Revision: D18863824

fbshipit-source-id: 63c2f3dd0abe0aa4c88350767e9e77acb763c9a5

Summary: `F14Vector{Map,Set}` have specified iteration order: inverse insertion order. When serialized, however, the order does not round-trip (in fact, it flips). This diff introduces an extension point to specify the iteration order for serialization, and it specializes it for F14 to make the iteration order round-trip.

Reviewed By: vitaut

Differential Revision: D17108774

fbshipit-source-id: 466b746baacff861242729bfa62447c138094cee

Reviewed By: yfeldblum

Differential Revision: D18926899

fbshipit-source-id: d16c1b5b54a75fe70514f25b648de70ae66b6415

Summary: [Folly] Define support macro in all branches v.s. as a fallback for style.

Differential Revision: D18900489

fbshipit-source-id: 9f9cb3c70889c8d6800070221bd8fe9ce091745c

Summary: Stub interface for logging functions to integrate with the GlobalExecutor and Futures.

Reviewed By: andriigrynenko

Differential Revision: D18229089

fbshipit-source-id: ad57de08a8bd6a80e2d0af9a9792de86a8267176

Summary:
This should fix the Travis CI builds. It adds rust toolchain support inside docker and sets the required THRIFT env variable.
Pull Request resolved: https://github.com/facebookexperimental/rust-shed/pull/3

Reviewed By: krallin

Differential Revision: D18905608

Pulled By: lukaspiatkowski

fbshipit-source-id: 5db1eff6f215a6617d8acaa0c99a62d45225956b

Summary: [Folly] Helper variable templates for tuple applicability traits: `is_applicable_v`, `is_applicable_r_v`, `is_nothrow_applicable_v`, `is_nothrow_applicable_r_v`.

Reviewed By: lewissbaker

Differential Revision: D18746853

fbshipit-source-id: 9d01b24030f95ab5b4963660dc4ef471b5e0ad02

Summary: Add support for io_uring based EventBase backend

Reviewed By: kevin-vigor

Differential Revision: D18682173

fbshipit-source-id: d6e02879e2b493680caaa3097d75970d0b5d7d07

Summary: Helps test resumption failure/success in other tests that use AsyncSSLSocketTest classes.

Reviewed By: mingtaoy

Differential Revision: D18561383

fbshipit-source-id: 29852ede80ecd59f662f536368ce2efe7d26745d

Summary: This fixes a timing issue that has been observed in rare cases under very heavy load.

Differential Revision: D18875069

fbshipit-source-id: cd47abfbd01c10e2568693f876dd3e6c2cb3bb24

Summary: Add support for setting a zerocopy enable function

Reviewed By: kevin-vigor

Differential Revision: D18579527

fbshipit-source-id: dc3ab7bb13b26528bc964c7eb616517e444487a4

Summary: To enable building with -Werror,-Wundef.

Reviewed By: guangyfb

Differential Revision: D18850905

fbshipit-source-id: 95555781fec991eac119c95a6a6cd7751b5ba742

Summary:
When compiling each file individually, bring the includes
closer as they are referenced (e.g., rely less on transitive includes
and include what you use)

Reviewed By: bithree

Differential Revision: D18864197

fbshipit-source-id: 24adef418fd2eb944aa283a55411ec5a7c6f549b

Summary: Currently if compiler decides to inline fiber function, we'll end up allocating variables on fiber stack even though we use `runInMainContext`.

Reviewed By: andriigrynenko

Differential Revision: D18842065

fbshipit-source-id: 847c4f95c44ef49f5c7537af878ca8340f2b7b16

Summary:
Update the getdeps builders to save all command output to a log file in the
build directory.  This makes it easier to go back after the fact and look at
the config options selected by the build run.

Reviewed By: wez

Differential Revision: D18777059

fbshipit-source-id: 86d3ffa48ec992fe90c59a3835e18f08310ed88c

Summary: Add check for `__cpp_lib_atomic_is_always_lock_free` for using `is_always_lock_free`.

Reviewed By: davidtgoldblatt

Differential Revision: D18827013

fbshipit-source-id: 796d1ce3c279a807198897c092464dc3aff734e3

Summary: `folly/portability/Config.h` serves this purpose now. Clean up references

Reviewed By: Orvid

Differential Revision: D18800127

fbshipit-source-id: 8e1300af74d63f028b83f5e2d8963a674e77e573

Reviewed By: mitrandir77

Differential Revision: D18850917

fbshipit-source-id: f211dfbfadf4b5b0cb372cf8aeb9a232c4b3a739

Summary:
Pull Request resolved: https://github.com/facebook/folly/pull/1273

[Folly] Skip some `is_constexpr_default_constructible` tests under gcc7.

In gcc7 specifically, i.e. not gcc6 and not gcc8, some of the expectations fail. The compiler is wrong and this affects the outcome of `is_constexpr_default_constructible`, but this is mostly harmless as far as existing uses go. Fix the tests by skipping them when using gcc7.

Reviewed By: vitaut

Differential Revision: D18820312

fbshipit-source-id: a2d0d53ed2716fffba7840e2b167e9ad4ac012ff

Summary: [Folly] Add `kGnuc` C++ constant representing `__GNUC__` preprocessor constant.

Reviewed By: vitaut

Differential Revision: D18827910

fbshipit-source-id: 43e07e12017df1e7cf4d6a5747e7a85d8a7616f3

Summary: This is the expected design of the class, so suppress the warning using `FOLLY_MSVC_DISABLE_WARNING` instead of fixing the issue.

Reviewed By: Orvid

Differential Revision: D18733718

fbshipit-source-id: ff9368a9ce31ad11e5992d65f0b5b26b2859ff02

Reviewed By: ikostia

Differential Revision: D18814410

fbshipit-source-id: 889306e51c03a29c2b72e34b7dc60db21f11ff97

Summary:
D15485589 updated folly to depend on fmt.  This updates the installed
`folly-config.cmake` file to correctly find the `fmt` dependency, so that
downstream projects that depend on folly still work correctly.

Reviewed By: vitaut

Differential Revision: D18822127

fbshipit-source-id: 970751c7252bf62173d2d26cdc76e46fc08618ba

Summary: This is implicitly used, so explicitly include the file

Reviewed By: Orvid

Differential Revision: D18800769

fbshipit-source-id: 18e1dd06213927370e6a6620863cd68b1d675a14

Summary:
[Folly] Let `ElfFile` open functions take a single builder-style composite `Options` argument v.s. taking a sequence of individual arguments one for each option.

Right now there is only one option but it is possible to add more in the future.

While here, rename and invert `readOnly` to `writable`.

Reviewed By: vitaut

Differential Revision: D18740699

fbshipit-source-id: 6fb016f731bf46a1b4ac6b2efcea739f6261818a

Summary: Shared-ptr, which should be explicitly joined and waits for all other instances to be destroyed.

Reviewed By: spalamarchuk

Differential Revision: D18696536

fbshipit-source-id: 9d7b0b960a00095be7df033680c7a116c358637c

Summary: [Folly] Implement `co_invoke` as a generic CPO with customizations found via ADL.

Reviewed By: lewissbaker

Differential Revision: D18753006

fbshipit-source-id: 16239f0bd6140f56bd23effbf092f2b8279c1350

Summary:
Use the new recvmsg api on the client to receive a packet
from AsyncUDPSocket

Reviewed By: mjoras

Differential Revision: D18797963

fbshipit-source-id: 319d5c41f3a868e7b78947fdbcf2c411b6d7fbf0

Summary:
Add a mode to read callback which only notifies but does not call getReadBuffer.

This also adds a readmsg api for notification callbacks to invoke

This is useful for callbacks that want to perform their own logic of reading from the socket, for example
a callback might want to perform multiple read calls per callback to save on CPU of epoll

Differential Revision: D18797964

fbshipit-source-id: 86bf1553078a20ea16f56f0c404887fca5050065

Summary: Add support for multiple EventBase backends

Reviewed By: simpkins, mjoras

Differential Revision: D16157574

fbshipit-source-id: 915c3f08cac5673b5c4ca52a661b41b8a228df75

Summary: Mark the header as it is not a header provided by folly

Reviewed By: yfeldblum

Differential Revision: D18800770

fbshipit-source-id: 95c9dcdeb6f4b745f0bce859e4d9669c009c353a

Summary:
This diff introduces the following changes:

- EliasFano encoding populates all skip pointers between last value and the universeUpperBound.

Reviewed By: ot, philippv

Differential Revision: D18734361

fbshipit-source-id: 2451614ff99dca22f0247cb572542f8cadc97b6f

Summary: The projects have been moved to a "shed/" subdirectory, so the root Cargo.toml with workspace has to be adjusted to that move.

Reviewed By: farnz

Differential Revision: D18807189

fbshipit-source-id: 0fd66fa7edd38ab4fdf905872f38fac57ae0230e

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