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

Summary: [Folly] Avoid uses of gflags integer aliases, preferring std integer aliases.

Reviewed By: WillerZ, vitaut

Differential Revision: D20204609

fbshipit-source-id: e00b183ab2574af7ea064b9602f1ab8efced50b0

Summary: g++ aggressively inlines F14VectorMap::operator[] calls from some testing loops with the loop index as a key. On platforms that have SSE2 but not SSE4.2 we use a multiplication and xor based bit mixer, which undergoes a strength reduction in optimized builds. Somehow the resulting code miscalculates the result (no minimal repro yet), which causes the tests to persistently fail. This diff blocks the compiler optimization, allowing the tests to pass.

Reviewed By: yfeldblum

Differential Revision: D19910180

fbshipit-source-id: 6cccba67645481061f923bd7b3e681df573c4039

Summary: [Folly] Let `Init` work without `gflags` support.

Reviewed By: simpkins

Differential Revision: D20150102

fbshipit-source-id: ceaae7ec3373f46457ba0d2a524b1223dec9961c

Reviewed By: vitaut

Differential Revision: D20098574

fbshipit-source-id: 409c3c1e7716a38f253fa3d0d8afe615139426cc

Summary:
This diff adds fb303 dependency to Open/R. fb303 is FB's open-sourced project
which provides basic infrastructure for thrift service e.g. base functions,
counters supports etc.

Using this in Open/R will allow both internal & external users leverage counters
via thrift APIs

Reviewed By: xiangxu1121

Differential Revision: D20134243

fbshipit-source-id: 23782ec99dc749dd27dc19f2b2b023f1c229608b

Summary: Adds a few simple benchmarks to get an idea for the overhead of `folly::coro::Task` coroutines.

Reviewed By: yfeldblum

Differential Revision: D19729527

fbshipit-source-id: cdfbd5c408c24dd258c56bc159af0c03cb1cd55e

Summary: As a step to eventually supporting TLS 1.3 by default for OpenSSL, we want to add the ability to selectively enable TLS 1.3 in folly::SSLContext.

Reviewed By: mingtaoy

Differential Revision: D20102778

fbshipit-source-id: 0865821ad2730482e797b888d16561b6989dca62

Summary: We should probably just free this.

Reviewed By: yfeldblum

Differential Revision: D20119718

fbshipit-source-id: 2a6c79730243b7af5ba90dac631ce0c8e1e0e6a4

Summary: Add API to Set Socket Option for AsyncUDPServerSocket.h, which is the same as AsyncUDPSocket.

Reviewed By: yfeldblum, lnicco

Differential Revision: D20064430

fbshipit-source-id: d448fbc217d0098e0ab94e2f113d4eba97958b02

Differential Revision: D19882830

fbshipit-source-id: 031217f9890351022bc8d171f0ccd7e045dd6972

Summary: Workaround for a TSAN fork deadlock

Reviewed By: kevin-vigor

Differential Revision: D20107616

fbshipit-source-id: df4d6222f63131e49fc1e831ec81d6441269b1f4

Summary: Sanitizers always intercept the allocator, so there's no reason to do the elaborate `usingJEMalloc()` logic -- it will always fail.

Reviewed By: yfeldblum

Differential Revision: D20056781

fbshipit-source-id: c0d4a3b103e26bacc0a6589f8d54b4a2ec85f771

Summary: This makes the function name more accurate. The function does not start the thread pool executor. It only enables the construction and use of a thread pool executor by the default hazptr domain when needed.

Reviewed By: davidtgoldblatt

Differential Revision: D19852860

fbshipit-source-id: 5ae71d0fd2d2d20c9ca66f45d57e90085703b3fb

Summary:
clang fails to optimize the current version even in the opt mode

code:
```
void clear(folly::small_vector<int, 5>& vec) {
    vec.clear();
}
```

before:

cat_huh

```
0000000000000000 <clear(folly::small_vector<int, 5ul, void, void, void>&)>:
   0:	55                   	push   %rbp
   1:	48 89 e5             	mov    %rsp,%rbp
   4:	41 57                	push   %r15
   6:	41 56                	push   %r14
   8:	53                   	push   %rbx
   9:	50                   	push   %rax
   a:	49 89 fe             	mov    %rdi,%r14
   d:	48 8b 07             	mov    (%rdi),%rax
  10:	48 8d 4f 08          	lea    0x8(%rdi),%rcx
  14:	48 85 c0             	test   %rax,%rax
  17:	78 5a                	js     73 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x73>
  19:	48 89 cf             	mov    %rcx,%rdi
  1c:	49 bf ff ff ff ff ff 	movabs $0x7fffffffffffffff,%r15
  23:	ff ff 7f
  26:	48 89 c3             	mov    %rax,%rbx
  29:	4c 21 fb             	and    %r15,%rbx
  2c:	74 3a                	je     68 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x68>
  2e:	48 8d 34 9f          	lea    (%rdi,%rbx,4),%rsi
  32:	48 85 c0             	test   %rax,%rax
  35:	78 53                	js     8a <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x8a>
  37:	48 8d 14 99          	lea    (%rcx,%rbx,4),%rdx
  3b:	48 89 d9             	mov    %rbx,%rcx
  3e:	48 29 f2             	sub    %rsi,%rdx
  41:	74 0e                	je     51 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x51>
  43:	e8 00 00 00 00       	callq  48 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x48>
  48:	49 8b 06             	mov    (%r14),%rax
  4b:	48 89 c1             	mov    %rax,%rcx
  4e:	4c 21 f9             	and    %r15,%rcx
  51:	48 c1 e3 02          	shl    $0x2,%rbx
  55:	48 c1 fb 02          	sar    $0x2,%rbx
  59:	48 29 d9             	sub    %rbx,%rcx
  5c:	49 ff c7             	inc    %r15
  5f:	49 21 c7             	and    %rax,%r15
  62:	49 09 cf             	or     %rcx,%r15
  65:	4d 89 3e             	mov    %r15,(%r14)
  68:	48 83 c4 08          	add    $0x8,%rsp
  6c:	5b                   	pop    %rbx
  6d:	41 5e                	pop    %r14
  6f:	41 5f                	pop    %r15
  71:	5d                   	pop    %rbp
  72:	c3                   	retq
  73:	48 8b 39             	mov    (%rcx),%rdi
  76:	49 bf ff ff ff ff ff 	movabs $0x7fffffffffffffff,%r15
  7d:	ff ff 7f
  80:	48 89 c3             	mov    %rax,%rbx
  83:	4c 21 fb             	and    %r15,%rbx
  86:	75 a6                	jne    2e <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x2e>
  88:	eb de                	jmp    68 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x68>
  8a:	48 8b 09             	mov    (%rcx),%rcx
  8d:	48 8d 14 99          	lea    (%rcx,%rbx,4),%rdx
  91:	48 89 d9             	mov    %rbx,%rcx
  94:	48 29 f2             	sub    %rsi,%rdx
  97:	75 aa                	jne    43 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x43>
  99:	eb b6                	jmp    51 <clear(folly::small_vector<int, 5ul, void, void, void>&)+0x51>
```

after (much better but still 3 instructions too many):
```
0000000000000000 <clear(folly::small_vector<int, 5ul, void, void, void>&)>:
   0:	55                   	push   %rbp
   1:	48 89 e5             	mov    %rsp,%rbp
   4:	48 b8 00 00 00 00 00 	movabs $0x8000000000000000,%rax
   b:	00 00 80
   e:	48 21 07             	and    %rax,(%rdi)
  11:	5d                   	pop    %rbp
  12:	c3                   	retq
```

Reviewed By: ot, philippv, luciang

Differential Revision: D19890921

fbshipit-source-id: 62f1b5325b4deda95976894b476849b5098fad4f

Summary: This class is intended to be useful when part of your project is using folly logging and part is using glog - simply install this bridge up-front and everything is routed to folly logging.

Reviewed By: simpkins

Differential Revision: D19952822

fbshipit-source-id: 898846fc7b647ddd93222f46c56450c1454dc738

Summary:
Fix set SO_REUSEPORT error message, save errno, use throwSystemErrorExplicit

(Note: this ignores all push blocking failures!)

Reviewed By: vitaut

Differential Revision: D20052057

fbshipit-source-id: 2f1b3135ff84242aa7ad38d3063ef9e260c3127c

Summary: Use folly::sizedFree for the ext buffer

Reviewed By: yfeldblum

Differential Revision: D19934204

fbshipit-source-id: 63662ab547f15addc7cdb249704964dfc70ca1f3

Summary:
Instead of using a Linux-specific API for random numbers, use
std::minstd_rand. It's not precisely identical, but probably
sufficient for these tests.

Reviewed By: yfeldblum

Differential Revision: D20039048

fbshipit-source-id: 5ace1a0552f995a48b37e4fa2209394f1b28ca84

Summary: Fix signed/unsigned mismatch in json.cpp

Reviewed By: yfeldblum, jdonald

Differential Revision: D19671088

fbshipit-source-id: 4bc1f4111e0536aa22c7fd03a2a6a6d786b7cfc8

Summary:
The SAI diag shell implementation requires Python3.7.6.
Previous diff in the stack added Python3.7.6 manifest.
Make use of it to build diag shell and link with Python lib.

Differential Revision: D20064315

fbshipit-source-id: c855f8a9f554066e8150ce1d867828a84161961b

Summary:
As titled.

FBOSS depends on Python3.7.6, subsequent diff in the stack adds Python3.7.6
depedency for FBOSS.

Differential Revision: D20064316

fbshipit-source-id: 27b328dc25e326f3927ea6cb003fb7bb45732d61

Summary:
Add function `get_process_phase` that returns indicators of process phases:
- `ProcessPhase::Init`: Not all global variables may have been initialized.
- `ProcessPhase::Regular`: All globals have been initialized and have not been destroyed.
- `ProcessPhase::Exit`: Some globals may have been destroyed.

Add function `set_process_phases` and calls to it from `folly::init` and `common/init/Init.cpp` wherever `SingletonVault::singleton()->registrationComplete` is called.

Will add calls to `set_process_phases` in separate diffs to other places that call `registrationComplete ` directly.

See Section 6.9.3 Start and termination [basic.start] of the C++ Standard Working Draft [N4849](https://github.com/cplusplus/draft/releases/download/n4849/n4849.pdf).

In general this addition is useful for simplifying cases of dependence on the existence of certain globals during main, where it is safe to ignore such globals at shutdown.
For example, the destructor of `hazptr_obj_cohort` normally needs to access the default `hazptr_domain`, but it is safe to skip that access at shutdown.

Reviewed By: yfeldblum

Differential Revision: D19567170

fbshipit-source-id: a44cbd3301aa9dc77a1e992922403635a3ff6552

Summary: (Note: this ignores all push blocking failures!)

Reviewed By: farnz

Differential Revision: D19948740

fbshipit-source-id: 9d0cfc4ccbcb3c08bb969f23229ed3096470fa86

Summary:
Having the fallbacks in the public header files makes searching for classes/methods cumbersome, and some people have mistakenly assumed that F14 classes inherit from `unordered_*` because they landed on the wrong line.

In addition, when the fallback implementation is used, any compilation errors will come from the `*Fallback.h` files, making it clear that the main implementation is not being selected.

Reviewed By: yfeldblum

Differential Revision: D19926873

fbshipit-source-id: 492b0c252f33c0cbbf3c22dae38fa0bd63825f72

Summary: Capacity is known in almost all the modes (except when it's inferred from `malloc_usable_size`, which is probably something we should not do in the first place), so we can easily plug in sized deallocation.

Reviewed By: yfeldblum

Differential Revision: D19976657

fbshipit-source-id: cb03f7107195af614514645c88d12ac4999dea53

Summary:
rootid is the thing we use to correlate running Thrift requests with a folly::RequestContext. The problem is that today rootid is unique only for active requests but not unique throughout the lifetime of the process - as a consequence we see some subtle bugs like mistakenly attributing threads to already finished requests. The root cause of rootid collisions is that default implementation of rootid is just an address of folly::RequestContext - so once request finishes the address is reused.

The solution suggested here is to assign rootids explicitly when folly::RequestContext is set for the request. To construct such rootid we pack two counters:
* 12 MSB are dedicated to an ID of Cpp2Worker (should be more than enough)
* 51 LSB are dedicated to a running counter within Cpp2Worker.

(Note: this ignores all push blocking failures!)

Reviewed By: andriigrynenko

Differential Revision: D20036950

fbshipit-source-id: 76687db12a32f33c82ce86accb4cdaab3e981458

Summary:
generic API for setting socket options on a UDP socket

(Note: this ignores all push blocking failures!)

Reviewed By: yangchi

Differential Revision: D19763927

fbshipit-source-id: d1a7720b04c24592e98c6e30c93c26e650ccd0b0

Summary: delete the folly::AsyncSocket::OptionMap/OptionKey/emptyOptionMap aliases

Reviewed By: yangchi

Differential Revision: D19963346

fbshipit-source-id: 6beae0961a82d12efd4d784ec390031d9445cd2b

Summary: base diff to move AsyncSocket::OptionMap into SocketOptionMap. folly only changes and an alias for previous usages of AsyncSocket::OptionMap

Reviewed By: yangchi

Differential Revision: D19961899

fbshipit-source-id: fab060cc73409c77ea07ced663fbd0ee15a35be7

Summary:
We need to add a separate manifest for SAI 1.4 and build that too, but that is
for later diffs, for now, we need 1.5, so change it.

Differential Revision: D20019016

fbshipit-source-id: 8630340ac7c8b7d94e6b768a2efa96266b2cc3e0

Summary: Pull Request resolved: https://github.com/facebook/folly/pull/1319

Reviewed By: yfeldblum, lnicco

Differential Revision: D19951699

Pulled By: afrind

fbshipit-source-id: b71d96020ca486139472512726183ae4d3555b28

Summary: Use sdallocx for IOBuf::releaseStorage

Reviewed By: marksantaniello

Differential Revision: D19925485

fbshipit-source-id: 142276fb64e570e10bfd0b6e22d8c83b204d1c2b

Summary:
Add FOLLY_CLANG_DISABLE_WARNING for Unistd.h

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D19652177

fbshipit-source-id: 1fcc3bb65c3b0d73870e599f9fc0463c6836cf9b

Summary:
The Buck build of RocksDB supports LZ4, so if an Eden instance's
object cache ends up compressed with LZ4 compression, the opensource
getdeps build cannot open it. Enable LZ4 in the open source getdeps
build of rocksdb.

Reviewed By: pkaush

Differential Revision: D19961878

fbshipit-source-id: 9a4f37e12bd2b40a0c5dcf2dd1684876886fae26