Summary:
To remove OpenSSL dependencies from some of our public interfaces, we need to
make `AsyncTransportCertificate` more implementation-agnostic. To start, we can
create an `OpenSSLTransportCertificate` that will have the `getX509()` method
instead of the `AsyncTransportCertificate`.

I start here by making `OpenSSLTransportCertificate` a dummy class, then I'll
update all our callsites to ensure that `getX509()` is only called on instances
of this class. After that, I can move `getX509()` exclusively to
`OpenSSLTransportCertificate`.

This means that in the future interfaces can use `AsyncTransportCertificate`
without depending on OpenSSL.

Reviewed By: yfeldblum, mingtaoy

Differential Revision: D26583479

fbshipit-source-id: 664e697a32fce61d22ee9842f998c4de1182924c

Summary: The actual shim type may sometimes not be linkable. So fake it - as long as the vtable is the same, it should not make a difference.

Reviewed By: luciang

Differential Revision: D28216291

fbshipit-source-id: 8c493a207cfb5414684147ddb850835bc0965bc5

Summary:
This applies the formatting changes from black v21.4b2 to all covered
projects in fbsource. Most changes are to single line docstrings, as black
will now remove leading and trailing whitespace to match PEP8. Any other
formatting changes are likely due to files that landed without formatting,
or files that previously triggered errors in black.

Any changes to code should be AST identical. Any test failures are likely
due to bad tests, or testing against the output of pyfmt.

Reviewed By: thatch

Differential Revision: D28204910

fbshipit-source-id: 804725bcd14f763e90c5ddff1d0418117c15809a

Summary:
Rather than specializing standard library numeric traits for `signed __int128` and `unsigned __int128`, bring these traits into folly and choose them where needed.

Note that it is undefined behavior to specialize the standard traits types.

Reviewed By: ericniebler

Differential Revision: D26506904

fbshipit-source-id: 0f7b0fa445c2713961b345b453fef8ff58032ee5

Summary: GCC seems to be generating incorrect code for some mix of co_invoke and start/startInline. This workaround makes coro tests pass.

Reviewed By: yfeldblum

Differential Revision: D28174118

fbshipit-source-id: b8178d7711ed5619a37c169f8f18dd125bf08f0b

Summary:
Replace DCHECK(tagged_empty()) with a warning.

The rationale is that the DCHECK was intended to help higher level users detect memory leaks, but since the DCHECK fails at domain destruction, the stack trace is not really helpful to users. By changing it to a warning, at least the user gets a hint that there may be a leak of object(s) that use hazptr_obj_cohort (e.g., ConcurrentHashMap, RequestContext).

Reviewed By: yfeldblum

Differential Revision: D28145864

fbshipit-source-id: 8a79e25efd21f0b1d713202f2fe8954c17a7d4de

Summary: Fix for the proxygen fuzz [build error]( https://oss-fuzz-build-logs.storage.googleapis.com/log-e58a42bb-98c0-4643-b842-b06f708eba12.txt) introduced by D27384053 (https://github.com/facebook/folly/commit/cdf0badc831c3aed7a740185d23728f779be8ba7)

Reviewed By: yfeldblum, lnicco

Differential Revision: D28154352

fbshipit-source-id: 6d98d9a3c9064de8f70506425dd790aa0cc3d9a6

Summary:
Suppose we have this:

```
void myBenchmark() {
    do_setup();
    do_processing();
}
```

Maybe we want to benchmark both including and excluding the setup.  Today, we have some options:

One possibility:
```
void myBenchmarkIncludeSetup() {
    do_setup();
    do_processing();
}

void myBenchmarkExcludeSetup() {
    BENCHMARK_SUSPEND {
       do_setup();
    }
    do_processing();
}
```

Another possibility -- but this is pretty verbose:

```
void myBenchmark(bool exclude_setup) {
    BenchmarkSuspender bs;
    bs.dismiss()

    if(exclude_setup) bs.rehire();
    do_setup();
    if(exclude_setup) bs.dismiss();

    do_processing();
}
```

We can simplify if we no longer require that BenchmarkSuspenders begin life as "hired".

After this diff, we can instead do this.  I think it reads better:
```
void myBenchmark(bool exclude_setup) {
    BenchmarkSuspender bs{BenchmarkSuspender::Dismissed};

    if(exclude_setup) bs.rehire();
    do_setup();
    if(exclude_setup) bs.dismiss();

    do_processing();
}
```

Reviewed By: yfeldblum, ot, luciang

Differential Revision: D28151318

fbshipit-source-id: bca5a41158430844748a812bbe30173adbad5307

Summary: Ideal for dependent return types to be calculated in the template param list rather since the putting them in the leading or trailing return type slot makes the function name opaque to demangling.

Reviewed By: Orvid

Differential Revision: D28140885

fbshipit-source-id: 0f9bc182f12a6383205863ce9a79b01961d644a6

Summary:
Currently to_ascii_port_clzll() in ToAscii.h always returns 0 in x86. This switches to __builtin_clzll() backed by a polyfill.

Closes https://github.com/facebook/folly/issues/1566.

Pull Request resolved: https://github.com/facebook/folly/pull/1567

Reviewed By: luciang

Differential Revision: D28162903

Pulled By: yfeldblum

fbshipit-source-id: 1872cda7aa155b84086bd15ad6cd40475eeb0ac4

Summary: Best to use C++ syntax `thread_local` instead since it is language-native and cross-platform.

Reviewed By: Orvid

Differential Revision: D27671626

fbshipit-source-id: 8ef0c487bfa20ab323067c05862998df25d2a53b

Summary: The port is not accessed in such a state, but nevertheless zero it.

Differential Revision: D28155314

fbshipit-source-id: 0ee6a617be5de66d1e068c242d52423adb31f486

Differential Revision: D28163554

fbshipit-source-id: 2167a39e88f7aa6053dea5119a30947d2f3304f3

Summary: Add support for AsyncUDPSocket SO_BINDTODEVICE

Reviewed By: danobi

Differential Revision: D28100917

fbshipit-source-id: bcc66d943342cbd40b634ef095eccf3e599fcb65

Summary: Revise all overloads of `folly::exceptionStr` in terms of `type_info_of`, `exception_ptr_get_type`, and `exception_ptr_get_object`. No longer rely on `catch_exception` and no longer have inline preprocessor conditionals.

Reviewed By: Orvid, luciang

Differential Revision: D26333081

fbshipit-source-id: 318ce83b9f15a12d5a33f528134e6fb38bb78a62

Summary: The table is large while the array is small.

Reviewed By: luciang

Differential Revision: D27986020

fbshipit-source-id: b6896514408758c592e2b74d801e38f217163f61

Summary:
Introduce functions `exception_ptr_get_type`, `exception_ptr_get_object` for inspecting and upcasting the content of `std::exception_ptr`. Since these facilities are not exposed in any standard way, reach into the platform abi/runtime to implement them.

Includes implementations for these platforms:
* libstdc++
* libc++
* win32

Reviewed By: mzlee, luciang

Differential Revision: D26306199

fbshipit-source-id: 3b655476b69f4456f4e4f88135fbba70a8c4a2a6

Reviewed By: Orvid

Differential Revision: D27671636

fbshipit-source-id: 82cab152ecb606235ee66c026ecafecfe52a88a5

Summary:
This correctly walks the async stack traces. Previously, we were not following the async stack root
from the last async stack frame.

High level stack walking strategy is as follows:
1) Start walking the normal stack up to the first normal stack frame holding the first async stack root
2) Walk the async stack frame chain from the provided async stack root
3) When we reach the end of the current async stack frame chain, check if the last async stack frame references an async stack root R1.
   If there is one, use R1 to find the start of the next normal stack frame when walking the normal stack frame.
4) If that async stack root R1 has a next async stack root R2, the normal stack frame walk should end at the normal stack frame
   holding the next async stack root R2. Otherwise the normal stack frame walk should continue all the way until it hits nullptr.
5) The next async stack walk should begin at the top async frame referenced by the next async stack root R2.
6) Repeat until we've reached the end of both the normal and async stack frame chains.

Reviewed By: andriigrynenko

Differential Revision: D28102128

fbshipit-source-id: c412a2a253720867c257d5cbaa9a6b22e96154f2

Reviewed By: Orvid

Differential Revision: D27671208

fbshipit-source-id: 44710468544eebbb8f4ed0ecd5621bce0b56d248

Summary:
It is monomorphized but called rarely. Best to optimize for size.

The `UniqueInstance` ctor is currently called in the constructor of each translation unit for each distinct instance of `SingletonThreadLocal`.

`UniqueInstance` may be extended to more use-cases so it is worthwhile optimizing for size.

Reviewed By: luciang

Differential Revision: D27602938

fbshipit-source-id: e4077830544516219485814ccc48805b7bb38e34

Summary: Need this to migrate CO_TEST using FAIL() fully on coroutines.

Reviewed By: ispeters

Differential Revision: D28099628

fbshipit-source-id: c79658809210184d8895c3d1551e04b1baf88cae

Summary: To reduce build size, avoid creating unnecessary functions. If the provided callable is already a function-pointer, the callee will already not be inlined.

Differential Revision: D27984345

fbshipit-source-id: a5a31330541338eb04e802bd9dafd99188af3ab9

Summary: Some older versions of gcc cannot deduce the relevant types correctly, and they are still in use in corners of the codebase.

Differential Revision: D28111907

fbshipit-source-id: 0367cb102f450f0f601350308a5831c7fd68f775

Differential Revision: D27582896

fbshipit-source-id: e4228117ba02fe18bd6e8964640f293c963a8732

Summary:
Fixes warnings about implicit type truncation. By making the conversions explicit, react-native-windows will be able to remove suppressions for several warnings required per SDL.

Pull Request resolved: https://github.com/facebook/folly/pull/1565

Reviewed By: igorsugak

Differential Revision: D27964258

Pulled By: yfeldblum

fbshipit-source-id: b13f8728ecda0b38c2fd661199d6551c5ff87993

Summary: Complex expressions involving certain tokens parse at preprocessor time as multiple preprocessor arguments. Quite awkward. The trick is to change the preprocessor macro to deal in variadic arguments.

Reviewed By: ot, Orvid, luciang

Differential Revision: D27986071

fbshipit-source-id: a126fca260396418b14b7367e3e41ddeea78b7af

Summary: QueueMessage is now a variant of NewConnMessage and ErrorMessage

Reviewed By: praihan

Differential Revision: D27384053

fbshipit-source-id: a92f514b56f31e879dc329984bf0a615ed339836

Differential Revision: D27582476

fbshipit-source-id: 376fecda16de8a4836f9ba5196701a9045799ce7

Summary: So that it is possible to have both `Foo<K0, K1, X, Y>` and `Bar<K0, K1, A, B>` where both `Foo` and `Bar` use `UniqueInstance`.

Differential Revision: D27600228

fbshipit-source-id: a5d58726ea0009d7a45c0234f9cff723662a4604

Summary: Parameterises CPUThreadPoolExecutor to allow us to construct one that prohibits blocking operations on its threads. The flag is stored as a thread local and applied using a scoped guard.

Reviewed By: yfeldblum

Differential Revision: D27893465

fbshipit-source-id: 71af1c0b7c23752f499712f498b6abb58a345979

Summary:
Similarly to `IoUringOp::getSqe()`, expose underlying submission data
structure.  The end goal is to perform certain introspection in client code to
report aggregated stats (number of IO, total size of IO, ...).

Reviewed By: ot

Differential Revision: D28022188

fbshipit-source-id: edc51420ed901f0a0d9b5b1338308ad680371298

Summary:
I have a use case where I would like to check if the
AsyncPipe is still active without pumping something in to
write(). Could set up an onClosed callback, but this would introduce
more complexity.

This adds a function to determine if the queue inside the AsyncPipe
still exists.

Reviewed By: iahs

Differential Revision: D28015007

fbshipit-source-id: 1ba37466218abd2f42eab1d8ea5677c3945e31f5

Summary: For TCP sockets, it may not be possible to query the peer address from the fd if the endpoint is no longer connected (closed with reset).  In most server cases, the peer address is known when the connection is accepted, so it can be prepopulated.

Reviewed By: mjoras

Differential Revision: D27985942

fbshipit-source-id: 630098ac00930b978fe8a9cad1894834c44d4d93

Summary:
```
folly/executors/InlineExecutor.h:29:11: error: '~InlineLikeExecutor' overrides a destructor but is not marked 'override' [-Werror,-Wsuggest-destructor-override]
  virtual ~InlineLikeExecutor() {}
          ^
folly/Executor.h:57:11: note: overridden virtual function is here
  virtual ~Executor() {}
          ^
In file included from tupperware/agent/system/Mounts.cpp:18:
In file included from folly/futures/Future.h:36:
In file included from folly/fibers/Baton.h:297:
In file included from folly/fibers/Baton-inl.h:19:
folly/fibers/FiberManagerInternal.h:588:10: error: 'timeoutExpired' overrides a member function but is not marked 'override' [-Werror,-Wsuggest-override]
    void timeoutExpired() noexcept { run(); }
         ^
folly/io/async/HHWheelTimer.h:95:18: note: overridden virtual function is here
    virtual void timeoutExpired() noexcept = 0;
                 ^
In file included from tupperware/agent/system/Mounts.cpp:18:
In file included from folly/futures/Future.h:36:
In file included from folly/fibers/Baton.h:297:
In file included from folly/fibers/Baton-inl.h:19:
folly/fibers/FiberManagerInternal.h:589:10: error: 'callbackCanceled' overrides a member function but is not marked 'override' [-Werror,-Wsuggest-override]
    void callbackCanceled() noexcept {}
         ^
folly/io/async/HHWheelTimer.h:100:18: note: overridden virtual function is here
    virtual void callbackCanceled() noexcept { timeoutExpired(); }
                 ^
3 errors generated.
```

Reviewed By: simpkins

Differential Revision: D27988235

fbshipit-source-id: 799484c52f89fa20f647ff0801b8d136b657b395

Summary:
Add a termination tag that carries through the blocking context chain. This flag notifies logging operations that they may go as far as to terminate the process if blocking operations are detected.

The flags carry through the blocking scopes so the termination flag will stay present while we enable and disable blocking - it would be sticky for a given thread once set.

Reviewed By: yfeldblum

Differential Revision: D27869075

fbshipit-source-id: 27014a3e6c9b28c0f433949a576bb6116e7c06c0

Summary: Internals are not portable between versions or across platforms.

Reviewed By: Orvid

Differential Revision: D27990286

fbshipit-source-id: b70d8d3f67a1e5262efa842f70817e3ae3972339

Reviewed By: Orvid

Differential Revision: D27582035

fbshipit-source-id: 0f0c35adca1c44dcd0ef88f2443f769d7991e6aa

Summary: Add a source file for the function bodies of `getThreadID` and `getOSThreadID`.

Differential Revision: D27698463

fbshipit-source-id: 255961954b1be07e59b19ef3006dcd6149795861

Summary: `folly/stats/StreamingStats.h` uses `std::min` and `std::max` so must `#include <algorithm>`.

Reviewed By: Orvid

Differential Revision: D27986054

fbshipit-source-id: 1c1160101e1ebb4e0b1a16d3d97fd2931db9eeb0