Summary: [Folly] Lower quadratic iteration count in an elias-fano test to make it take less wall time to run.

Reviewed By: philippv

Differential Revision: D14821341

fbshipit-source-id: 726fe5bd17442661196593ea6279314509622832

Summary:
- Mark `swap(Replaceable&)` noexcept iff `Replaceable` is
  noexcept-swappable. As the comment aludes to, this is a C++17 feature,
  but we have it backported in `folly/Traits.h`
Pull Request resolved: https://github.com/facebook/folly/pull/1070

Reviewed By: LeeHowes

Differential Revision: D14518839

Pulled By: yfeldblum

fbshipit-source-id: 966cca1733cf2a397c2406577baf941992f362d6

Summary: Prefer `FOLLY_HAS_COROUTINES` from `<folly/Portability.h>` over directly testing `__cpp_coroutines` because of MSVC.

Reviewed By: yfeldblum

Differential Revision: D14816497

fbshipit-source-id: 1f569824d5a79beca5255dfd43da8baf1556f8fe

Summary: Original commit changeset: e533bfa6b9d2

Reviewed By: heslami

Differential Revision: D14818275

fbshipit-source-id: 06ecb8058538ca150b941df56a050cf572f7eeea

Summary:
[Folly] Use wide multiplication for ints in UnboundedQueueTest

Fixes #1101.

Reviewed By: magedm

Differential Revision: D14794551

fbshipit-source-id: 223f9bb957eebb2fa065fe4945ce5a4339710823

Summary: All calls have been converted to the NetworkSocket overload

Reviewed By: yfeldblum

Differential Revision: D13566829

fbshipit-source-id: c6a3b155ffe35534c0297eba7819413e4ce77282

Summary: [Thrift] Cut `fbcode_builder` dep for `thrift` on `krb5`. In the past, Thrift depended on Kerberos and the `krb5` implementation for its transport-layer security. However, Thrift has since migrated fully to Transport Layer Security for its transport-layer security and no longer has any build-time dependency on `krb5`. Clean this up.

Reviewed By: stevegury, vitaut

Differential Revision: D14814205

fbshipit-source-id: dca469d22098e34573674194facaaac6c4c6aa32

Summary:
Add functions for concurrently awaiting a collection of SemiAwaitable objects.

* `folly::coro::collectAllRange()` takes an InputRange of SemiAwaitable objects and concurrently awaits them, producing a `std::vector` of the results. This will throw an exception if any of the input operations failed with an exception.
* `folly::coro::collectAllTryRange()` takes an InputRange of SemiAwaitable objects and concurrently awaits them, producing a `std::vector<folly::Try<T>>` containing the results. Failure of individual operations can be determined by inspecting the corresponding `Try` value.

This diff also refactors the existing implementations of `folly::coro::collectAll()` to make use of a new `Barrier` and `BarrierTask` implementation detail rather than using `DetachedInlineTask`, `Baton` and an atomic counter. This allows delaying the start of the child corouines until after all coroutines have been created which was necessary for cases where we didn't know the number of elements in the input range to allow storage for the results to be allocated in a vector before the tasks start producing results.

Reviewed By: andriigrynenko

Differential Revision: D14430147

fbshipit-source-id: 5ba4b7cdc3c9b65d1736f14a2d39f7beb6cb82b0

Summary: It's dead.

Reviewed By: yfeldblum

Differential Revision: D14191959

fbshipit-source-id: 8cfb68fa8f10b1f847bf6601aec8d869cb9c008d

Summary: To reflect the fact that the concept `SingleSender` is a refinement of `Sender` (there is no "`ManySender`"), rename `(any_)?(flow_)?many_sender` to `(any_)?(flow_)?sender`.

Reviewed By: kirkshoop

Differential Revision: D14803648

fbshipit-source-id: 5987ebe5ba877d0a3ab38e84b036f97302bcc70b

Summary:
The pushmi library has grown to the point where a little more structure would aid comprehensibility.

Also, finer-grained headers and build targets would make it easier for downstream projects to include only what they absolutely need.

Reviewed By: kirkshoop

Differential Revision: D14802895

fbshipit-source-id: 8d253f97c5d0529530cc3b7110505000f513ce83

Summary:
This is a performance optimization to avoid an executor re-queue for the collect[All] continuations which just move the result.

The biggest problem with this now is that these futures are often on a thread pool backed with a blocking MPMCQueue which means the add can potentially deadlock. This diff is not meant as a true fix to the problem though; just an improvement.

Reviewed By: yfeldblum

Differential Revision: D14754908

fbshipit-source-id: e533bfa6b9d2d820d50422b612c1489b560ec9d5

Summary: [Folly] `PriorityUnboundedBlockingQueue`, paralleling `UnboundedBlockingQueue` and `PriorityLifoSemMPMCQueue`.

Reviewed By: andriigrynenko

Differential Revision: D14536886

fbshipit-source-id: b3ea04c3f67d3e1e9d80626d963be70de1ae79ba

Summary: [Folly] Cut traits for old-ABI `std::basic_string` under libstdc++.

Reviewed By: pixelb

Differential Revision: D14764155

fbshipit-source-id: fa4991f4b70fb407672212886c84f1be4c33581f

Summary: For consistency adds thenExValue and deferExValue.

Reviewed By: yfeldblum

Differential Revision: D14793864

fbshipit-source-id: 700f02cfb27b93e1739c511f01142c30c1896990

Summary:
D14531266 defaulted static linking on macOS because of a link error in
folly/stats. A better fix for the issue is instantiating the
subclasses of BufferedStat, so add those.

Reviewed By: andrewjcg

Differential Revision: D14767345

fbshipit-source-id: eaa597dec468264595547f338348d7d74b49dd69

Summary: Renames defer taking an executor-taking continuation to deferExTry and modifying to take a KeepAlive for consistency with thenExTry.

Reviewed By: yfeldblum

Differential Revision: D14761230

fbshipit-source-id: af95afabb662197edcf2eeb432bc64c57011c776

Summary:
Add coroutine support to pushmi by making all sender types that satisfy the `SingleTypedSender` concept awaitable; that is, you can get their result by `co_await`-ing them in a coroutine.

In addition, all Awaitable types automatically satisfy the `SingleTypedSender` concept; that is, you can pass them to `pushmi::submit` along with a `Receiver` that is invoked with the result of `co_await`-ing the awaitable.

Reviewed By: kirkshoop

Differential Revision: D14688373

fbshipit-source-id: 8598b303aebcaa070033868abd440245c165bd73

Summary: Types opt in to receiver-ness with pushmi::receiver_traits, analogous to sender_traits (and std::iterator_traits). Alternatively, they can simply define a nested ::receiver_concept typedef that is an alias for one of "sink" or "flow".

Reviewed By: kirkshoop

Differential Revision: D14668335

fbshipit-source-id: 230abfcffef0cd231196b5f6a7ed05e1ac86ef0c

Summary:
* The sender concepts are now defined in terms of a `sender_traits` class template, in which the user can specify additional sender metadata like what values and errors it sends to the Receiver. This will make it possible to automatically make Senders awaitable from within coroutines.

* Remove the now-unused is_sender<>, is_single<>, and is_many<> properties.

* Define a `SingleSender` concept and a `TypedSender` concept.

* Define a `pushmi::sender` class template from which a Sender can inherit to declare the sender category (single/many/flow), and the types of the values and errors.

Reviewed By: kirkshoop

Differential Revision: D14631770

fbshipit-source-id: afcfd10bcd4e0e7ba224ea2c713d7fa92249ab7f

Reviewed By: lbrandy

Differential Revision: D14766712

fbshipit-source-id: 78c84117aa1c35825c72eb4bcd04e0bebb20c67f

Summary: Adds the option of providing a continuation that takes an executor and a Try. This way an executor is always available to child tasks. Uses a separate thenExTry API to avoid potential overload set ambiguity.

Reviewed By: yfeldblum, andriigrynenko

Differential Revision: D14726443

fbshipit-source-id: ab635c502c8a010b9b68af38add86ff7c200ff38

Summary: it doesn't change any state

Reviewed By: siyengar

Differential Revision: D14296359

fbshipit-source-id: 0bb8acd1a55f2b6ed431adcd54b97e76b8f377f6

Reviewed By: yfeldblum

Differential Revision: D14719902

fbshipit-source-id: d3bc7b61d666c796c3c19f7fa198252acb472970

Summary:
InlineFuctionRef fails to compile on 32-bit machines and fails the
static assert. This diff makes the assert generic to add support for 32-bit as
well.

Reviewed By: yfeldblum

Differential Revision: D14752182

fbshipit-source-id: eb00487248c93c6c32226cb227e8d119bcc7af7a

Summary:
There's no need in the atomic refcount decrement from 1->0, because we're the last live reference and using it to bump 1->2 is already undefined behavior.

Added benchmark:

Before:
```
stepan@devvm329:~/fbsource/fbcode$ buck-out/opt/gen/folly/io/test/iobuf_benchmark --bm_min_usec=1000000
============================================================================
folly/io/test/IOBufBenchmark.cpp                relative  time/iter  iters/s
============================================================================
createAndDestroy                                            36.35ns   27.51M
cloneOneBenchmark                                           40.40ns   24.75M
cloneOneIntoBenchmark                                       27.03ns   37.00M
cloneBenchmark                                              42.23ns   23.68M
cloneIntoBenchmark                                          28.35ns   35.27M
moveBenchmark                                               15.20ns   65.79M
copyBenchmark                                               35.00ns   28.57M
cloneCoalescedBaseline                                     334.59ns    2.99M
cloneCoalescedBenchmark                          660.01%    50.69ns   19.73M
takeOwnershipBenchmark                                      50.57ns   19.78M
============================================================================
```

After:
```
stepan@devvm329:~/fbsource/fbcode$ buck-out/opt/gen/folly/io/test/iobuf_benchmark --bm_min_usec=1000000
============================================================================
folly/io/test/IOBufBenchmark.cpp                relative  time/iter  iters/s
============================================================================
createAndDestroy                                            30.04ns   33.29M
cloneOneBenchmark                                           41.27ns   24.23M
cloneOneIntoBenchmark                                       26.37ns   37.92M
cloneBenchmark                                              43.91ns   22.77M
cloneIntoBenchmark                                          28.49ns   35.10M
moveBenchmark                                               15.50ns   64.52M
copyBenchmark                                               35.85ns   27.89M
cloneCoalescedBaseline                                     318.49ns    3.14M
cloneCoalescedBenchmark                          643.69%    49.48ns   20.21M
takeOwnershipBenchmark                                      45.15ns   22.15M
============================================================================
```

Reviewed By: yfeldblum, davidtgoldblatt

Differential Revision: D14715579

fbshipit-source-id: 3c0373b8423dda680920860979cfa240bf3d8d7a

Summary:
`IOBufQueue` has packing logic, that would copy data instead of chaining `IOBufs`. However, that API unnecessary requires exclusive ownership of the chain.

This diff adds an API that takes reference to IOBuf, copies as much as necessary and then clones/chains the rest.

Reviewed By: yfeldblum

Differential Revision: D14715581

fbshipit-source-id: e047d1c69ca19eec95a7adbca6df740440d23db3

Summary:
`AlignedSysAllocator` doesn't implement the optional `rebind`
or `size_type` portions of the C++ allocator concept.  This is ok
in GCC if the C++11 ABI is in use but causes compilation to fail
with errors like these:

```
folly/Range.h: In instantiation of ‘void folly::Range<Iter>::res
et(folly::Range<Iter>::string<Alloc>&) [with Alloc = folly::AlignedSysAllocator<char>; Iter = const char*; folly::Range<Iter>::string<Alloc> = std::
basic_string<char, std::char_traits<char>, folly::AlignedSysAllocator<char> >]’:
folly/test/RangeTest.cpp:235:18:   required from here
folly/Range.h:420:27: error: ‘folly::Range<const char*>::string<
folly::AlignedSysAllocator<char> >’ {aka ‘const class std::basic_string<char, std::char_traits<char>, folly::AlignedSysAllocator<char> >’} has no me
mber named ‘size’
     reset(str.data(), str.size());
                       ~~~~^~~~
```

This diff works around this issue by only compiling in the problematic
test if the C++11 ABI is enabled.

Reviewed By: yfeldblum

Differential Revision: D14702585

fbshipit-source-id: ea0c5fcfb0d69994d2958c2c236fe002959c824d

Summary:
- Replace a wordy type alias in `Future-inl.h` to use `remove_cvref_t`.
Pull Request resolved: https://github.com/facebook/folly/pull/1099

Differential Revision: D14721023

Pulled By: yfeldblum

fbshipit-source-id: e9de76a851162163046dfa088a8cc7e5a075562c

Summary: The eventual plan will ban the use of `to/fromFd` on `NetworkSocket` when compiling on Windows.

Reviewed By: yfeldblum

Differential Revision: D14592244

fbshipit-source-id: cbf965f6822cbd5b6b1098c7dab9ab65aafd8192

Summary:
1) There's no need to exit the loop if we encounter and IOBuf of length 0.
2) We should do `n <= tailroom()` instead of `n < tailroom()`.

Reviewed By: yfeldblum

Differential Revision: D14715582

fbshipit-source-id: 9a30454bd536929414f7c9013dbcf6e59e6e7f2c

Summary:
was trying to see if I could repro the issue described here:

Refs: https://github.com/facebook/folly/issues/1092

Reviewed By: yfeldblum

Differential Revision: D14702579

fbshipit-source-id: d90cbf5742883a26d9ac5dbfd56eed1965cbc64e

Summary:
Running down various warning/error issues is proving
to be a tiresome game of wackamole.   Here's the latest issue:

```
folly/container/test/F14TestUtil.h:400:16: error: ?void* mem
      std::memcpy(p, &n, sizeof(std::size_t));
      ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /opt/rh/devtoolset-8/root/usr/include/c++/8/bits/stl_algobase.h:64,
                  from /opt/rh/devtoolset-8/root/usr/include/c++/8/bits/char_traits.h:39,
                  from /opt/rh/devtoolset-8/root/usr/include/c++/8/string:40,
                  from /opt/rh/devtoolset-8/root/usr/include/c++/8/stdexcept:39,
                  from /data/users/wez/scratch/dataZusersZwezZfbsource/fbcode_builder_getdeps/shipit/folly/folly/container/F14Map.h:30,
                  from /data/users/wez/scratch/dataZusersZwezZfbsource/fbcode_builder_getdeps/shipit/folly/folly/container/test/F14MapTest.cpp:17
/opt/rh/devtoolset-8/root/usr/include/c++/8/bits/stl_pair.h:198:12: note: ?struct std::pair<const std::basic_string<char>, int>? declared here
      struct pair
            ^~~~
```

The targeted solution is to use `-Wno-class-memaccess` as we do with our
internal builds, but that is a gcc-specific option that fails when used with
the apple clang compiler.

The simplest option is just to disable warning->error promotion in
the cmake build, as it feels like a losing battle to keep chasing
the different combinations/permutations.

Reviewed By: yfeldblum

Differential Revision: D14702575

fbshipit-source-id: d8daa6c9588e7c84c991a0ef86baf700bd32fe8c

Summary:
move the FindGMock to the common cmake library and adjust
folly and wangle to consume it from there.

Reviewed By: strager

Differential Revision: D14710329

fbshipit-source-id: 35ac9d6d2ec03468f389f5b9f1c126b007c7c798

Summary:
In D14702587 I made a change to workaround an ICE in gcc 8.
It turns out to be a gift that keeps giving; with the code as-is
on windows we now encounter:

```
folly\io\async\test\AsyncTimeoutTest.cpp(29): error C3493: 'expected' cannot be implicitly captured because no default capture mode has been specified
```

Adding `expected` to the capture list yields this error with gcc, either with or without the reference:

```
stderr: folly/io/async/test/AsyncTimeoutTest.cpp:29:45: error: lambda capture 'expected' is not required to be captured for this use [-Werror,-Wunused-lambda-capture]
      AsyncTimeout::make(manager, [&value, &expected]() noexcept { value = expected; });
                                         ~~~^~~~~~~~
1 error generated.
```

the solution is to make `expected` not be `const`.

Reviewed By: yfeldblum

Differential Revision: D14721418

fbshipit-source-id: b65c17414c161b9dee7f269b2e2a22a980766a6c

Summary: It was observed in D14238146 that `ThreadPoolExecutor::numThreads()` is not marked `const`, and it seems that it really should be. This patch marks that function `const` as well as others in this class that seems they should be `const`.

Reviewed By: yfeldblum

Differential Revision: D14681960

fbshipit-source-id: f274b9788ae7e27d6bec22aec2818abeb6441531

Summary: [Folly] `PriorityUnboundedQueueSet`, wrapping `UnboundedQueue`.

Reviewed By: andriigrynenko

Differential Revision: D14719777

fbshipit-source-id: 529ddd8de5879908e36f6fc26e7a091230cb03da

Summary:
```
folly/io/async/test/AsyncTimeoutTest.cpp: In lambda function:
folly/io/async/test/AsyncTimeoutTest.cpp:31:70: internal compiler error: Segmentation fault
       AsyncTimeout::make(manager, [&]() noexcept { value = expected; });
                                                                      ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
```

I'm using:

```
 $ /opt/rh/devtoolset-8/root/usr/bin/c++ --version
c++ (GCC) 8.2.1 20180801 (Red Hat 8.2.1-2)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
```

This has been fixed in gcc 8.3, but the workaround is to explicitly
name the captures as is done in this diff.

Reviewed By: yfeldblum

Differential Revision: D14702587

fbshipit-source-id: 1998ef5de8eb4df520edcc41fdc9cd9547dec824

Summary:
I finally got to the bottom of the weird `-levent` or `event.lib`
linker errors that crop up in the cmake builds.

The issue is that if you have installed a recent libevent it deploys
a cmake CONFIG package that exports just a bare `event` target as the
dep on libevent.  This is unfortunate because it is interpreted as
meaning `-levent` with no library path, which for an installation
of libevent that is not in the default path will result in linker
errors in libraries downstream of folly.

To resolve this, I've given the common `FindLibEvent.cmake` file
(that was derived from the folly library of the same name) a similar
treatment to the recent changes to find glog and taught it how to
locate libevent from a config package and to fall back on a basic
include/library check.

If we find an `event` target then we extract the actual library
path from it and export that.

I've removed folly's and wangle's own FindLibEvent.cmake so that it will pick
up the common library which gets shipit sync'd out to
https://github.com/facebook/folly/blob/master/CMake/FindLibEvent.cmake
and https://github.com/facebook/wangle/blob/master/build/fbcode_builder/CMake/FindLibEvent.cmake

Reviewed By: yfeldblum

Differential Revision: D14702577

fbshipit-source-id: d35d9f741e009dcd77976c0637ba3024a8a4aef3

Summary:
```
folly/experimental/test/FutureDAGTest.cpp:46:7: error: ‘source_node’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
       if (it->first != source_node) {
       ^~
cc1plus: all warnings being treated as errors
```

Reviewed By: yfeldblum

Differential Revision: D14702569

fbshipit-source-id: 949ecde007a8d84498c5d87f4a4c2db463ba83a9