Summary:
Remove calls to Future::then(executor, callback).

This form of Future::then is ambiguous, and does not yet implement the stronger
typing of thenValue and thenTry. It is also tempting to use instead of via,
where it is not obvious that it has the behaviour of wrapping a via call in a
push and pop of the current executor:
.pushCurrentExecutor().via(executor).then(callback).popCurrentExecutor().

With the addition of inline continuations, we can instead make the nesting
explicit at low cost by making it an inline continuation that launches an
asynchronous task on the passed executor.

Reviewed By: yfeldblum

Differential Revision: D15100419

fbshipit-source-id: e929e2eaf2fc30313cb099150be3a9535ae729a6

Summary:
TimeKeeper::after and TimeKeeper::at return Futures that for the majority of implementations complete on a TimeKeeper owned executor. This can lead to problems.

Consistent with other API cleanups, this diff switches TimeKeeper APIs to return SemiFuture, requiring that the caller attach an explicit executor when work is to be scheduled downstream of the TimeKeeper.

Reviewed By: yfeldblum

Differential Revision: D17005944

fbshipit-source-id: 98d7e8aaf1ad40ce2180503f632f2f0003bb12be

Summary: Under some circumstances the DeferredExecutor might already have nested executors and this code adds more. Both incoming futures should instead nest within a fresh DeferredExecutor returned that is part of the SemiFuture from the operation.

Reviewed By: mpark

Differential Revision: D17121117

fbshipit-source-id: b4507bf5d7b0c98e5e5de6f73ff4bd3e2790374c

Summary:
[Folly] RTM re-nits for `xabort`.

* Remove param pack.
* Always noreturn.

Reviewed By: nbronson

Differential Revision: D17117350

fbshipit-source-id: b16056b1f02956d334da4494c689a4b988a961d4

Summary:
The `materialize()` algorithm meterializes values from a stream into a stream of events that represent each value and also the end-of-stream and stream-error events.

`dematerialize()` reverses a materialized stream by replaying the events recorded in the input stream to an output stream.

Reviewed By: lewissbaker

Differential Revision: D16772236

fbshipit-source-id: 27de543ea2d02691a376fd0f11d0113c5c39287d

Summary:
boost.fiber is not available on macos and is required by fbzmq,
so disable the build on darwin.

In D17128935 I tried to make libzmq build with cmake to build
on windows, but there's a problem with its cmake and it fails
to configure.

So let's just nop out the build for !linux for now.

Reviewed By: jstrizich

Differential Revision: D17129362

fbshipit-source-id: db89010d18707a4105b8d395b1758f738336495d

Summary:
In order to foster healthy open source communities, we're adopting the
[Contributor Covenant](https://www.contributor-covenant.org/). It has been
built by open source community members and represents a shared understanding of
what is expected from a healthy community.

Reviewed By: josephsavona, danobi, rdzhabarov

Differential Revision: D17104640

fbshipit-source-id: d210000de686c5f0d97d602b50472d5869bc6a49

Summary:
This module provides a `add_fbthrift_library()` convenience function that can
be used to generate thrift libraries for multiple languages with a single
call.

Reviewed By: wez

Differential Revision: D16742275

fbshipit-source-id: c13120cf9e051629951282141eb22f3e085782f9

Summary:
This module helps generate Python libraries from thrift files.
It is the Python equivalent of `FBThriftCppLibrary.cmake`

Reviewed By: wez

Differential Revision: D16742274

fbshipit-source-id: ef0dc7f24eb1c7375d2587ee6b71fd25bd6f35a7

Summary:
Fix a minor bug in the argument parsing for `add_fbthrift_cpp_library()`:
only a single value should be supplied for the `THRIFT_INCLUDE_DIR` argument.
This parameter should not accept a list of arguments.

Reviewed By: strager

Differential Revision: D17125810

fbshipit-source-id: 31f354e4d6299d3626a94f3b4b5ff8c58bb0cf7b

Summary:
An AsyncGenerator coroutine now has an implicit associate CancellationToken that is inherited from the calling context of each `co_await gen.next()` call.

This means that generators that correspond to long-running subscriptions now have an in-built channel that allows them to cancel the subscription.

This is also useful for algorithms that introduce concurrency in processing of stream data. eg. The `buffer()` or `merge()` algorithms.

Reviewed By: kirkshoop

Differential Revision: D16833864

fbshipit-source-id: be8faf1ec438c4248091e02d6a264d3760e2d73d

Summary:
Pull Request resolved: https://github.com/facebook/folly/pull/1212

MSVC has a bug and can't match definitions of some of the constructors to the corresponding declarations in a class body. This diff workarounds the bug by inlining constructors.

Reviewed By: LeeHowes

Differential Revision: D17119718

fbshipit-source-id: eb7a9d4916b962c718d047eb0ee7fa4a9761776e

Summary:
The `collectAll()`, `collectAllRange()` and `collectAllWindowed()` functions now cancel their subtasks when either the parent task is cancelled or when any of the subtasks fail with an exception.

The `collectAllTry()`, `collectAllTryRange()` and `collectAllTryWindowed()` functions now cancel their subtasks if the parent task is cancelled, but not if the child tasks fail with an exception.

The logic between the distinction here is that if you are calling one of the 'try' functions then you are intending to handle partial failure and so probably want each of the operations to run to completion independently of the others.

Reviewed By: kirkshoop

Differential Revision: D16820619

fbshipit-source-id: 5c203b41592a0145ff7be1c609dfccd39c41a3df

Summary: `clang-cl` on Windows also defines `__PRETTY_FUNCTION__` which has a format different from `__FUNCSIG__`. Therefore folly breaks users of this macro. Alias should be defined only when "real" MSVC compiler is used.

Reviewed By: akrieger, Orvid, blackm00n

Differential Revision: D17094657

fbshipit-source-id: 4b191a61201704382e6b6e178bcc1c673511c537

Summary:
Rename the `ThriftCppLibrary.cmake` file to `FBThriftCppLibrary.cmake`, and
also rename `add_thrift_cpp2_library()` to `add_fbthrift_cpp_library()`.

Explicitly calling this `fbthrift` helps clearly distinguish that this is
intended for use with fbthrift (https://github.com/facebook/fbthrift/), as
opposed to Apache thrift.

Reviewed By: wez

Differential Revision: D16738440

fbshipit-source-id: 9b255e06b71c98ad74a34989f564a211958dcdd5

Summary:
CacheLocality's parsing code for /proc/cpuinfo doesn't properly
handle systems in which there are offline CPUs. This diff makes it so
we fall back onto the sequential cache locality implementation in the
problematic scenarios.

This should address https://github.com/facebook/folly/issues/1208

Reviewed By: shixiao

Differential Revision: D17093176

fbshipit-source-id: 4da3a9dc53622f829af37ed70a2531c66fd92ddb

Summary:
Use folly::cacheline_align_v to prevent failures when running folly on platforms
where extended alignment is not supported.  The thread pools only used extended
alignment as an optimization; so it is safe to disable it when not needed

Reviewed By: yfeldblum

Differential Revision: D17077439

fbshipit-source-id: 63ba59aaf7ce45231bb25427af84292c3a3464a9

Summary:
The non-atomic field `inUse_` is protected by a lock in `getStackCache`, but not in `giveBack`. This
is a data race and it is caught by TSAN.

Reviewed By: yfeldblum

Differential Revision: D17109710

fbshipit-source-id: 7c0d5d948740516422efca0895a702566c804bb4

Summary:
Windows and macOS compilers are sensitive to this,
and this was overlooked in D16636130

Reviewed By: selat

Differential Revision: D17113825

fbshipit-source-id: 16fe9210b07a096a58f3370df64874514e28ea46

Summary:
Compiler passes rvalue reference for named local variable to return_value:
https://reviews.llvm.org/D51741

Reviewed By: lewissbaker

Differential Revision: D16963353

fbshipit-source-id: 98d846153adb2235b61bb8fb54d10f032d4c0055

Summary:
- Prior to commit 8cb615a2
  (Differential Revision: D3394612), `Range:size()` had an assert checking
  that the beginning iterator of the range is less than or equal to the end
  iterator. Unfortunately, due to GCC bug 71448, the `assert` was not allowed
  if we wanted `size()` to remain a `constexpr` function.
- This bug is no longer an issue with our current supported versions of GCC.
  As such, add the assert back in.
Pull Request resolved: https://github.com/facebook/folly/pull/1155

Reviewed By: ericniebler

Differential Revision: D15641627

Pulled By: yfeldblum

fbshipit-source-id: 0677053c18fa55aaa4727947c241f0675362861b

Summary:
Update install_fb_python_library() to work with CMake versions older than 3.7.

Previously the code used a generator expression in the directory argument
supplied to `install(DIRECTORY)`.  Support for generators in this parameter
was only added in CMake 3.5, but it was buggy and did not correctly handle
absolute paths until 3.7.

This updates the code to avoid using a generator expression.  This does
require that the corresponding `add_fb_python_library()` statement appear
before the `install_fb_python_library()` statement, but this seems like a
pretty reasonable restriction.

Reviewed By: chadaustin

Differential Revision: D17103597

fbshipit-source-id: 54d6af93a3f530373cfe3137db99436d8484f308

Summary:
[Folly] RTM nits.

* No nested namespace.
* All status values supported.
* Tests included in cmake builds.
* API functions avoid `SIGILL` at runtime.

Reviewed By: nbronson

Differential Revision: D16636130

fbshipit-source-id: 9f9dc99b0826abbda295b069eb4823b3416af5d1

Summary:
This is a useful testing utility that people can use if they use timeout APIs
like `folly::futures::sleep()`

Reviewed By: LeeHowes

Differential Revision: D17065352

fbshipit-source-id: f9ea8366af7fc9429bfb1065328ed746c824f810

Summary: The sorted vector types have constructors which "steal" capacity from a pre-filled container.  Add tests to cover the cases where this is a folly:small_vector, and a std::pmr::vector.

Reviewed By: nbronson

Differential Revision: D17074150

fbshipit-source-id: e94b7e136553653081abe86559c4c013b9aac031

Summary:
Adds static factory `CancellationSource::invalid()`.

This can be used to construct a `CancellationSource` that can't be cancelled but that doesn't perform any heap-allocations.

Reviewed By: kirkshoop

Differential Revision: D16816764

fbshipit-source-id: bb87273903a6a8d245d207f4e6bda94e5c3d3dad

Summary: Tweak futures::within to be completely deferred, including the timeout path, allowing it to support a SemiFuture-returning TimeKeeper.

Reviewed By: yfeldblum

Differential Revision: D17006080

fbshipit-source-id: cbed58579d33f6d6ecf60dce5f9c8b886fc4d4c4

Summary:
wait() is guaranteed to succeed and not throw for either Baton type, so
using a reference here is safe. When the future is completed on another thread,
the shared_ptr causes cache contention.

```
Thread 1            Thread 2
make_shared/inc
inc
...
                    dec ref
dec ref/free
```

Reviewed By: yfeldblum

Differential Revision: D17077672

fbshipit-source-id: a6010ed159353decefbd5c51f4347370b16f7f60

Summary:
Update the generated `run_cmake.py` script to use `os.execve()` rather than
`subprocess.call()`, so that it now propagates CMake's return code back to its
caller.

Reviewed By: chadaustin

Differential Revision: D17089206

fbshipit-source-id: e01f05f492ccb842d4967e59fd0bc9a3e59b8a42

Summary:
Fix printing the manifest context in the error message if we cannot find a
project fetcher.  Previously the context in the message would be printed as
something like `<getdeps.manifest.ManifestContext object at 0x7fcce987e610>`,
now it shows instead as something like
`{distro=ubuntu, distro_vers=18.04, fb=off, os=linux, test=off}`

Reviewed By: chadaustin

Differential Revision: D17089208

fbshipit-source-id: c16549b61030d813b7b5ff9f65966436dc1e1898

Summary:
This just strips off a trailing '/' from the `INSTALL_DIR` property that we
set on python targets, to avoid having double-slashes in the paths that we use
during installation.  This shouldn't really have any material difference other
than cleaning up the paths that get printed during the installation phase.

Reviewed By: chadaustin

Differential Revision: D17089207

fbshipit-source-id: ab36bb76c19fa60fe037f7a5290ccfd6bdbf13b0

Summary:
Update fboss to use `ThriftCppLibrary.cmake` directly from fbcode_builder
rather than maintaining its own copy of this file.

Reviewed By: chadaustin

Differential Revision: D17005421

fbshipit-source-id: a64df426118df6088b47f09410dad7b8b7e79a43

Summary:
Update `add_thrift_cpp2_library()` to pass in the correct `-I` flags when
invoking the thrift compiler so that it can find all of the other thrift files
that this library depends on.

D16062657 was a previous attempt to do this, but suffered from a few problems:
- It required all dependencies to be defined before
  `add_thrift_cpp2_library()` was called.  This requires users to carefully
  order their CMake files and subdirectory include ordering.
- It only handled one level of dependencies, and did not propagate include
  paths for deeper dependencies.
- It set the include path for dependencies to the source directory path where
  the dependency was originally built, rather than the directory where the
  thrift file for that dependency would be installed.

This change does require CMake 3.8+.  Previous versions of CMake do not
support using generator expressions to generate multiple arguments for a
custom command.

Reviewed By: strager

Differential Revision: D17005381

fbshipit-source-id: 31190beba94b4d1010445375a5e2791450230f7d

Summary: Allow futures::when to pass through a SemiFuture-returning function.

Reviewed By: yfeldblum

Differential Revision: D17001974

fbshipit-source-id: dbe8b347f0a4c3fd19774c68c4e58e3b523b971f

Reviewed By: yfeldblum

Differential Revision: D17086382

fbshipit-source-id: 318834a1d82025bc0c34bcf7a95fedfffdb02ddb

Summary: times is hard to use with SemiFutures, leading to potential use of inline executors just to make it work. This adds native support.

Reviewed By: yfeldblum

Differential Revision: D16992774

fbshipit-source-id: 483110d923ca51e037439ccc80173ffa9299cd64

Summary: Use FOLLY_CL_USE_FOLLY_TLS for CacheLocality to avoid an iOS build issue

Reviewed By: mzlee

Differential Revision: D17085507

fbshipit-source-id: acd407c9e0045eb4d8a59348a20874dbe75fd651

Summary: Earlier change to duration waiting broke propagation of the interrupt handler. This change correctly propagates it into the new future that is returned.

Reviewed By: yfeldblum

Differential Revision: D17061618

fbshipit-source-id: b228221acbfab3ae94118c1197a485e01aa2e41e

Summary: whileDo is hard to use with SemiFutures, leading to potential use of inline executors just to make it work. This adds native support.

Reviewed By: yfeldblum

Differential Revision: D16988569

fbshipit-source-id: abaf36180d6ff8a5277eebb277f7f0a254315d36

Summary:
All of the requisite headers are now open sourced and eden
has been converted to use them. This removes any logic that references
this directory and kills the now unused cmake file.

Reviewed By: chadaustin

Differential Revision: D16994732

fbshipit-source-id: 573b8b50540ee64590682be2a54aa94659f12368