Summary:
This code is new in 9.3.0, introduced upstream with:
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ed920373
Unless we qualify folly::reduce() we get the clash
in P127472223 when running the test plan.

Reviewed By: meyering

Differential Revision: D20461173

fbshipit-source-id: 41b21e9215571da2cbd2ef7f817e2d9999083033

Summary: [Folly] `FOLLY_SSSE`, for testing compiler mode support for SSSE3 intrinsics.

Reviewed By: markisaa

Differential Revision: D20414435

fbshipit-source-id: 077a78f880ea8dce44f1aced38a6cca08cdd1f65

Summary: [Folly] Move remove_reference_wrapper to coro traits, since this is not a language-level trait and is there to be used in the coro library.

Reviewed By: iahs

Differential Revision: D20301017

fbshipit-source-id: aa78488cc5138e6ade9dcbc99ec1b75b65c74c78

Differential Revision:
D20443631

Original commit changeset: 03e8210a64a3

fbshipit-source-id: 42621768beab530619aba877015dd48d509bc62b

Summary:
`unsigned int` is a more typical definition of the mode_t type on Linux systems, which is what this is trying to emulate.

Also guard by checking that HAVE_MODE_T isn't already define to allow clients to suppress its definition in cases where other client-used libraries (e.g. wxWindows) have their own definition which may conflict.
Pull Request resolved: https://github.com/facebook/folly/pull/1335

Reviewed By: yfeldblum

Differential Revision: D20408879

Pulled By: scramsby

fbshipit-source-id: 511484f6513501bf595ccb9cdfb893c9d5761320

Summary:
Compiling with gcc 10.0.1 and -std=gnu++2a, we have the following errors:
```
folly/FBString.h:1013:33: error: no type named 'reference' in 'class std::allocator<char>'
 1013 |   typedef typename A::reference reference;
      |                                 ^~~~~~~~~
folly/FBString.h:1014:39: error: no type named 'const_reference' in 'class std::allocator<char>'
 1014 |   typedef typename A::const_reference const_reference;
```
This is due to the fact many members in `std::allocator` have been remove in C++20: https://en.cppreference.com/w/cpp/memory/allocator

We also have this one due to the new way C++ resolves the comparison operators:
```
folly/dynamic-inl.h:854:20: error: ambiguous overload for 'operator!=' (operand types are 'folly::dynamic::const_item_iterator' and 'folly::dynamic::const_item_iterator')
  854 |   return find(key) != items().end() ? 1u : 0u;
      |          ~~~~~~~~~ ^~ ~~~~~~~~~~~~~
      |              |                   |
      |              |                   folly::dynamic::const_item_iterator
      |              folly::dynamic::const_item_iterator
In file included from folly/dynamic-inl.h:25,
                 from folly/dynamic.h:796,
                 from folly/dynamic.cpp:17:
folly/detail/Iterators.h:80:8: note: candidate: 'bool folly::detail::IteratorFacade<D, V, Tag>::operator==(const D&) const [with D = folly::dynamic::const_item_iterator; V = const std::pair<const folly::dynamic, folly::dynamic>; Tag = std::f
orward_iterator_tag]' (reversed)
   80 |   bool operator==(D const& rhs) const {
      |        ^~~~~~~~
folly/detail/Iterators.h:98:3: note: candidate: 'typename std::enable_if<std::is_convertible<D, D2>::value, bool>::type folly::detail::IteratorFacade<D, V, Tag>::operator==(const D2&) const [with D2 = folly::dynamic::const_item_iterator; D =
 folly::dynamic::const_item_iterator; V = const std::pair<const folly::dynamic, folly::dynamic>; Tag = std::forward_iterator_tag; typename std::enable_if<std::is_convertible<D, D2>::value, bool>::type = bool]' (reversed)
   98 |   operator==(D2 const& rhs) const {
      |   ^~~~~~~~
folly/detail/Iterators.h:84:8: note: candidate: 'bool folly::detail::IteratorFacade<D, V, Tag>::operator!=(const D&) const [with D = folly::dynamic::const_item_iterator; V = const std::pair<const folly::dynamic, folly::dynamic>; Tag = std::f
orward_iterator_tag]'
   84 |   bool operator!=(D const& rhs) const {
      |        ^~~~~~~~
folly/detail/Iterators.h:103:8: note: candidate: 'bool folly::detail::IteratorFacade<D, V, Tag>::operator!=(const D2&) const [with D2 = folly::dynamic::const_item_iterator; D = folly::dynamic::const_item_iterator; V = const std::pair<const f
olly::dynamic, folly::dynamic>; Tag = std::forward_iterator_tag]'
  103 |   bool operator!=(D2 const& rhs) const {
      |        ^~~~~~~~
```
Pull Request resolved: https://github.com/facebook/folly/pull/1329

Reviewed By: ot, igorsugak

Differential Revision: D20443631

Pulled By: yfeldblum

fbshipit-source-id: 03e8210a64a3eeaefb6f14afaddf45be882e3ba6

Summary: Both operators use their own copy of the container (eg line 104), so mutating it should be ok

Reviewed By: ot

Differential Revision: D19170228

fbshipit-source-id: a53094bdbd3fb7b5028cf7ed4e0b073dd919b2d7

Summary:
[Folly] Add `#include <bit>` in `folly/lang/Bits.h` when that header, which is introduced in C++20, is available.

Fixes https://github.com/facebook/folly/issues/1333.
Closes https://github.com/facebook/folly/pull/1334.

Reviewed By: luciang, markisaa

Differential Revision: D20369239

fbshipit-source-id: fee8682c23107a1da17c35abf5a9e16bb5177cdd

Summary: When n = 1, `oneIn` is always true. This can be used to avoid generating a random number.

Reviewed By: yfeldblum

Differential Revision: D20267645

fbshipit-source-id: 0c0bde1e80389f11ffdb0ad0f0de053d47b9f760

Summary:
Next OpenNSA release with increased stack size (needed for FBOSS) is available.
Start linking with it.

Differential Revision: D20062997

fbshipit-source-id: 9938270c322087ac3990861aa1ddd3b9ea1148ac

Summary: Add UDP GRO support

Reviewed By: mjoras

Differential Revision: D20347326

fbshipit-source-id: be3c31f070c4f2c1ef84f9e2df60f49a5fcabd93

Summary: Move `toStdString` to `FBString.h` because it's fbstring-related and remove the dependency between `String.h` and `FBString.h`. This is possible because the only other use of fbstring in `String.h` is removed in previous diff.

Reviewed By: yfeldblum

Differential Revision: D20195591

fbshipit-source-id: b5ff7c918669e063e24bf91155a2496f82d7e975

Summary: Add ThreadWheelTimekeeperHighRes class

Reviewed By: LeeHowes

Differential Revision: D20355093

fbshipit-source-id: b76563a3706d7732b490a88096fed484954820e5

Summary: It looks like that test file was deleted, but it was still referenced in a CMakeLists.txt file.

Reviewed By: yfeldblum, Gownta

Differential Revision: D20365343

fbshipit-source-id: 40792bb9c526e1aef48062b0e560646bdcf201b8

Summary:
Add support for onClear() callback function to RequestData. The callback is to be executed on the last clearing of RequestData. This typically happens upon the destruction of the last RequestContext that contains the RequestData or due to explicit calls to RequestContext::clearContextData that remove the RequestData from the RequestContext.

The onClear() callback is executed exactly once. If there are no calls to clearContextData, then onClear is executed upon the destruction of the last RequestContext that refers to the RequestData. If there are calls to clearContextData, then onClear is executed upon the removal of the last reference to the RequestData from a RequestContext.

RequestData::hasCallback() applies only to onSet() and onUnset() which may be called multiple times, whereas onClear() is called exactly once.

If a class derived from RequestData overrides onClear and either or both of onSet and onUnset, then care must be taken that the callbacks are mutually safe, as it is possible for the execution of onClear to be concurrent with executions of onSet and onUnset.

Motivation: Some uses of RequestContext::clearContextData expect the immediate destruction of associated RequestData. The hazard pointer-based implementation of RequestContext guarantees only that all associated RequestData is destroyed before the completion of the destructor of the RequestContext. This callback provides users of RequestContext more control of the timing of executing actions related to clearing the data. The addition of this capability is intended to provide a tool to eliminate differences in timing of executing actions between the two implementations of RequestContext (hazard pointer-based vs. read lock-based).

Also, fixes a minor bug in request_context_test, where the key "test2" was used in two tests (setIfAbsentTest and deadlockTest) without being cleared, which generated a warning when the tests were run in the same process.

Reviewed By: davidtgoldblatt

Differential Revision: D20332008

fbshipit-source-id: c9cefffb28c8da098e97f851f31d29a1bf704061

Summary:
Clean the sigar build dependency completely under:
- fbcode/fbzmq/public_tld/build/...
- fbcode/openr/public_tld/build/...

Delete files:
- fbcode/opensource/fbcode_builder/manifests/sigar
- fbcode/opensource/fbcode_builder/specs/sigar.py

Reviewed By: steven1327

Differential Revision: D20376067

fbshipit-source-id: 3321a14df2551525acee605028ef06a04cda7c6a

Summary: This is mainly used for logging, and we can elide an unnecessary copy in some cases.

Reviewed By: mingtaoy

Differential Revision: D20402430

fbshipit-source-id: 79b73792a69cf2817ffb88b07d9973139c3c67bb

Summary: Split WTCallback cod

Reviewed By: LeeHowes

Differential Revision: D20355082

fbshipit-source-id: 9ead4905cafeef27a9e2956fc50ebd59098cb80e

Summary:
Use decltype(event::ev_fd) instead of #ifdef

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum, kevin-vigor

Differential Revision: D18525100

fbshipit-source-id: 7cef32def7b40c71b2298f9dc354fbe63607fb8e

Summary:
As written in the documentation, {fmt} should be built alongside folly. This is not possible in my case. My usecase is to provide some kind of small distribution of shared libraries that can be installed on any systems. Hence I really need to have libfmt treated as a normal shared lib.

Moreover, libfmt can be consumed on our side as a normal library outside on cmake. We do not provide the cmake config file which are strongly dependent on the system on which libfmt is installed.

My proposal is to first look for the fmt-config.cmake as it is now but in case of cmake support is not provided by system, we fall back to a normal library lookup.
Pull Request resolved: https://github.com/facebook/folly/pull/1328

Reviewed By: simpkins

Differential Revision: D20312046

Pulled By: yfeldblum

fbshipit-source-id: 2d6b4917b37a8ed1d553600599702259db22c212

Reviewed By: Orvid

Differential Revision: D20353603

fbshipit-source-id: 1910261be637237923b1f1d6a56fc954554176d2

Summary:
The result of `errnoStr` is often converted to `std::string` so returning `fbstring` adds an extra copy. Make it return `std::string` instead. This will also allow removing dependency between `String.h` and `FBString.h`.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D20195395

fbshipit-source-id: 0dc65f1566911156be3fcb715dd105c58f2a8822

Summary:
Ideally we'd be using mkscratch, but this still isn't shipped
to our Windows systems.

Pick a path that is more friendly to our corp windows environment by default.

Reviewed By: pkaush

Differential Revision: D20342277

fbshipit-source-id: c85bccee6701adc03b26c92ba217b18bd684257a

Summary: [Folly] Cut `CachelinePadded` after migrating all uses to `cacheline_aligned`.

Reviewed By: aary

Differential Revision: D19657696

fbshipit-source-id: d2e5b4695bdc3734340723d5d3681e724734691e

Summary:
When Gtest cannot be discovered by CMake config file, the tests fails to compile:
```
In file included from /home/docker/opensource/folly/folly/test/common/TestMain.cpp:23:
/home/docker/opensource/folly/folly/portability/GTest.h:32:10: fatal error: gtest/gtest.h: No such file or directory
   32 | #include <gtest/gtest.h>
      |          ^~~~~~~~~~~~~~~
```
This PR fixes this problem with a classic `find_package`.
Pull Request resolved: https://github.com/facebook/folly/pull/1331

Differential Revision: D20323404

Pulled By: yfeldblum

fbshipit-source-id: 2e41f99172c504063c00c45a9fa5c08a26bcc0c8

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

An earlier change added collectXSemiFuture. This diff adds collectXUnsafe as a migration path.

Reviewed By: yfeldblum

Differential Revision: D20255061

fbshipit-source-id: 379b5ed95aa7782aa121dba8e84cb48f802a57cd

Summary: SingletonThreadLocal is not needed by Future.cpp.

Reviewed By: Orvid

Differential Revision: D20142400

fbshipit-source-id: d0f3b7c1bbef03226c8d6264abeb96822587a465

Summary: As title. Expose the useful portable mlock2() wrapper.

Reviewed By: alikhtarov

Differential Revision: D20239849

fbshipit-source-id: 0fa776faf29ad69e551dfbe6eb69369560800a0e

Summary: Cast from unsigned to signed *before* negating. The resulting assembly code is the same, but there's no warning.

Reviewed By: yfeldblum, jdonald

Differential Revision: D19588115

fbshipit-source-id: d0d61ab0543211e2399f42a86a7a7a2366679d37

Summary:
The absence of GFlags is already partially optional -
portability/GFlags.h defines a number of stub macros / clases if
FOLLY_HAVE_LIBGFLAGS is false.

However the top-level CMake rules don't correctly handle when GFlags
isn't present - they unconditionally add GFlags-related variables to
CMAKE_REQUIRED_xxx variables.

Additionally there are a couple of source files which should not be
compiled if GFlags isn't available.
Pull Request resolved: https://github.com/facebook/folly/pull/1325

Differential Revision: D20252030

Pulled By: yfeldblum

fbshipit-source-id: 7c3441e8b2850d68df125fb9c14b8417f4d08b55

Summary: Support the brand-new TCMalloc version that was just released.

Reviewed By: luciang

Differential Revision: D19943852

fbshipit-source-id: 10ae07051d2bc56a502ee0d5e5767035cf53794f

Summary:
Replace the methods to get CPU and memory usage statistics:
- For the memory: use `VmRSS` of `/proc/[pid]/status`: http://man7.org/linux/man-pages/man5/proc.5.html
- For the CPU%: calculate the process is occupied how much percentage of the CPU time, use `getrusage()`: http://man7.org/linux/man-pages/man2/getrusage.2.html
   - Implemented like the sigar: https://our.intern.facebook.com/intern/diffusion/FBS/browse/master/third-party/sigar/src/sigar.c?commit=4f945812675131ea64cb3d143350b1414f34a351&lines=111-169
  - Formula:
    - CPU% = `process used time` during the period / `time period` * 100
    -  `time period` = current query timestamp - last query timestamp
    - `process used time` = current `process total time` - last query `process total time`
    - `process total time` = CPU time used in user mode + CPU time used in system mode // get from the API `ru_utime` and `ru_stime`

Remove the `fbzmq::ResourceMonitor` and `sigar`:
- Change and rename the UT
  - `ResourceMonitorTest.cpp` -> `SystemMetricsTest.cpp`
  - `ResourceMonitor` -> `SystemMetricsTest` in `openr/tests/OpenrSystemTest.cpp`
- Remove `ResourceMonitor` code and dependency for `Watchdog` and `ZmqMonitor`
- Remove `sigar` dependency used in building

Reviewed By: saifhhasan

Differential Revision: D20049944

fbshipit-source-id: 00b90c8558dc5f0fb18cc31a09b9666a47b096fe

Summary: This seems to not happen reliably and causes rss to grow. The `__dealloc__` cannot fix it completely, although I verified it is called. So calling it explicitly seems to guarantee it to happen.

Reviewed By: yfeldblum

Differential Revision: D20206887

fbshipit-source-id: 6285a8e8943a53d20714e54efd3220a545010102

Summary: as title, just to add a mock function

Reviewed By: yfeldblum, lnicco

Differential Revision: D20130909

fbshipit-source-id: 469d904cce93dc8e88c5dc4728b1f1fbd0baf798

Summary:
We have noticed some inappropriate uses of `assume_unreachable()`, and we believe that the documentation does not convey strongly enough that it is not an assertion.

This diff moves the implementation to a separate header (as the assertions in there might be misleading) and fleshes out more the intended use cases.

Reviewed By: yfeldblum, mkatsevVR, luciang

Differential Revision: D20182339

fbshipit-source-id: 8a3be1ada06dead7ea936971c42c4f30389fc23a

Summary:
[Folly] Fix `small_vector::insert` with non-random-access iterator arguments.

Closes https://github.com/facebook/folly/issues/1322.

Reviewed By: ot, terrelln

Differential Revision: D20150453

fbshipit-source-id: 184e748dcbb7cb60318b5f0a3104d9aeb8352d7b

Summary:
Codel is statically initialized with some default target delay and interval period. It would be useful to have the ability to update these parameters at runtime to fine tune load shedding to a given use case.

Adding methods here to update the target delay and interval parameters.

Reviewed By: yfeldblum

Differential Revision: D19987838

fbshipit-source-id: 4d67277f38037840883f6d9d5fd2d5f9be760f44

Summary: `type_traits` needed for `std::enable_if_t`

Reviewed By: yfeldblum, Orvid

Differential Revision: D20196749

fbshipit-source-id: 4d4e44c523959dda1f04b452d65880ca3401e036

Summary: Might as well store the count of newlines in the Log Message - as the field is already padded to <pointersize> bytes by the alignment requirements of the field either side it will not use any more space than the existing `bool`

Reviewed By: simpkins

Differential Revision: D20200298

fbshipit-source-id: 84cc52898069eae1af5bd0f103d4ab3177c45206

Summary: Add support for futures folly::HighResDuration

Reviewed By: kevin-vigor

Differential Revision: D19981652

fbshipit-source-id: 4a321fda487d5acdee04d138b0e4f0f10a4119f1