Summary:
This code implicitly casts a `long` to `double` but a `double`
can not accurately represent an integer above `2^53` as
the mantissa only stores that many digits. At `2^53 + 1`
`double`s increment by `2`. Thus this cast is lossy. Though,
casting a single value `LONG_MAX` to a `double` is and
being off by one doesn't cause any harm here.

Reviewed By: ispeters

Differential Revision: D25654006

fbshipit-source-id: 3d84092f1786d7879dd48d73af8edbbc80bb3585

folly::symbolizer: drop templated FrameArray from test functions and move test functions to separate compilation unit with minimal dependencies

Summary:
Eliminate `#include` dependencies of `SymbolizerTestUtils.cpp` so that the `.o` file with interesting debug info is tiny and easily inspectable.
- Instead of calling test functions that need to be inlined from the `SymbolizerTest.o` use `call_` trampolines so that the inlined debug info is generated in the minimal/tiny `SymbolizerTestUtils.o`.

 ---

Remove the frames template argument so that:
- removed dependencies from the SymbolizerTestUtils to minimize generated debug info (no longer need to include headers about FrameArray).
- all functions used in tests can be made regular functions
- all functions who's debug info is interesting to debug can be easily emitted in a single object file `SymbolizerTestUtils.o`

Reduce some of the copy-pasta that made test noisy by grouping together function name, file and lineno.

 ---

Test for either fullName/shortName (`DW_AT_linkage_name`/`DW_AT_name`)
- fullName: demangled function name with namespace, qualifiers, argument types, etc. and
- shortName: simple function name to support both cases when either both `DW_AT_linkage_name` and `DW_AT_name` or a single one of them is emitted.
- When `DW_AT_linkage_name` (full mangled name) and `DW_AT_name` (just the function name) match, DWARF emitters omit `DW_AT_linkage_name` (to save space). With `-fsplit-dwarf-inlining` only `DW_AT_name` is emitted in `.debug_info` and the `DW_AT_linkage_name` is emitted in the `.debug_info.dwo` sections.

Differential Revision: D25712808

fbshipit-source-id: 88d2ac22564e3d607fb3864d37e49892a5eaf002

Reviewed By: yfeldblum

Differential Revision: D25527140

fbshipit-source-id: 2a2721ca4418e1a4c57f621f41716e5c8f27869c

Summary:
Small change - adding  logs to connect error/success and eliminating the unnecessary ones.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D25481273

fbshipit-source-id: 437942803bc895bba2eaa36e5eaf104503012d12

Summary:
Adding priorities to `ThreadManagerExecutorAdapter`. The API allows to pass single executor that would be used for all priorities (preserved behavior) but also allows to add custom executors per-priority. In this case, if no executor has been provided for priority, we will spin up default thread manager implementation (which supports upstream queues).

We soon will add upstream queues on top of user-provided executors as well.

Reviewed By: prshreshtha

Differential Revision: D25137444

fbshipit-source-id: db0740a705dd3cca69916f3d1b8c4e32c011aa43

Summary:
Allow callbacks to be attached to a SettingCore (via SettingWrapper),
with lifetime managed by a guard object which automatically unregisters
the callback at destruction. This provides an API for clients to react
to changes in settings without polling.

Reviewed By: yfeldblum

Differential Revision: D25592427

fbshipit-source-id: a11a98ed651ef56a0fc86f5f5e4ed235f2289746

Summary:
the n argument in XLOG_EVERY_N is not captured by it's lambda, so
expressions using local variables can not be passed as n. EdenFS has
a use case where we would like to use local variables here. We want to use a
dynamic config value for n, so that we can easily adjust how often we log
see: D25505654.

It seems like it should be ok to capture the n here, but I am by no means a
macro expert, so please let me know if there is a tricky cpp thing here lurking
that makes capturing n bad.

Reviewed By: simpkins

Differential Revision: D25551033

fbshipit-source-id: e82fa465823d3d2ee2ac26924cc4a93b7b7242dd

Summary: Fix OSS build - move struct/enums into their own namespace

Reviewed By: danobi, lnicco

Differential Revision: D25769992

fbshipit-source-id: 1e337820edbd986bdd47099cf8af942698e6fc75

Summary:
Pull Request resolved: https://github.com/facebook/folly/pull/1512

Hazptr library creates its own CPU executor which name interfere with default executor name. We want to avoid this.
Also insure that the thread is permanent, otherwise folly runtime may destroy and recreate it periodically.

Reviewed By: magedm

Differential Revision: D25708252

fbshipit-source-id: 2b41ad4fa28d2ba9c9bd69bc5d4a02b933d79e66

Summary: Increase the timeout value to avoid false positives

Reviewed By: kevin-vigor

Differential Revision: D25757480

fbshipit-source-id: b3c2498a2573af323a2291f0d0aa875f897bea38

Summary: Initialize the context first to skip the tests if the backend is not available

Reviewed By: kevin-vigor

Differential Revision: D25742461

fbshipit-source-id: 4cbe9545d358dd2bb3ca9297d8b46e80c54f53f7

Summary: Skip the tests if the backend is not avaialable

Reviewed By: kevin-vigor

Differential Revision: D25724617

fbshipit-source-id: 0981f69aca02d7d2b1576df4d82e4ed1167d2935

Summary: Try to allocate all the EventBase instances first before running the test

Reviewed By: kevin-vigor

Differential Revision: D25720889

fbshipit-source-id: 93c837e68771f1ef44e80865bec260813158c6b3

Summary: Let `AsyncPipe::create` return the correct pipe type, namely, the type on which it is a member rather than a different instantiation of the template.

Reviewed By: iahs

Differential Revision: D25717180

fbshipit-source-id: 94a5a657e83b5d4cac866277ec5925c0b5b0af28

Summary: Using std::optional requires including it first.

Reviewed By: yfeldblum

Differential Revision: D25704383

fbshipit-source-id: 755dfd4a6dec9695cb0ed156166d13b550fd8b40

Summary:
Adds a new awaitable that extracs the current async stack-trace as a vector
of program counters from within the current coroutine.

Usage:
```
std::vector<std::uintptr_t> programCounters =
  co_await folly::coro::co_current_async_stack_trace;
```

Reviewed By: andriigrynenko

Differential Revision: D21130683

fbshipit-source-id: bf67a9969f73bdb8b91b4cc2858883b8e87762e2

Summary: Defined new callback - ReadAncillaryDataCallback, which enables getting ancillary data when receive a message using recvmsg API.

Reviewed By: cgrushko

Differential Revision: D24246707

fbshipit-source-id: 3363b5fafe8d370cf5560afe00476fc8ea723e7a

Summary: Also re-order the test slightly to catch this.

Reviewed By: yfeldblum

Differential Revision: D25704580

fbshipit-source-id: 1421daed11a0d41e1b99d573b38fc8fc70381486

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507505

fbshipit-source-id: 4a1ae7578876975e20fd8eba194b9f8ed43d3530

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507540

fbshipit-source-id: 71279e19ddad29622c14729d73f5d0d45f0ba410

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507581

fbshipit-source-id: 5c936f1f81c5c754d3b64fb17b7dab253a178a39

Summary:
Fix gso typo

(Note: this ignores all push blocking failures!)

Reviewed By: kevin-vigor

Differential Revision: D25699054

fbshipit-source-id: bac1a7a5c13efa5a58ecec11edf72c500b0783b5

Summary: [folly] Add `co_cancelled`, effectively a shorthand for `co_error(OperationCancelled{})`.

Reviewed By: Mizuchi, lewissbaker

Differential Revision: D25627993

fbshipit-source-id: 91f80772a8b179a4de0fe3b29dfe7eecaafb8e1b

Summary: Fix nullptr dereference

Reviewed By: kevin-vigor

Differential Revision: D25687105

fbshipit-source-id: 59b0f3e4adc810f6e1a89447667cd167c52f7fb5

Differential Revision: D25683616

fbshipit-source-id: 7f199b0e43e0a5a76c4cf16412b22abdc28833ac

Summary: Fix `Arena` bytes-used accounting across calls to member `merge`.

Reviewed By: luciang

Differential Revision: D25656949

fbshipit-source-id: b230b0cdbf51b146fd566cbf688f49817bdf874d

Summary: [folly] Rename coro `Error.h` to `Result.h` since it has multiple result types.

Reviewed By: Mizuchi

Differential Revision: D25625178

fbshipit-source-id: 45f8194922b764429969329563a4695b1c13da6f

Summary: Fix `Arena` bytes-used accounting across calls to member `clear` after a sequence of all-large allocations.

Reviewed By: luciang

Differential Revision: D25656875

fbshipit-source-id: e79aca5f58b61bf1bd4790f8badd0dad6063a6ed

Summary: folly::Singleton is used for singletons that manage resources (thread, fds etc.) and it's generally not safe to use previously created folly::Singletons in child process after fork.

Reviewed By: yfeldblum

Differential Revision: D25292667

fbshipit-source-id: 5343d26c72bb9203429a918a3bb5d458c44e9f3b

Summary:
Recently I found that its impossible to access elevated Watchman daemon from non-elevated process on Windows.

```
events.js:174
      throw er; // Unhandled 'error' event
      ^
Error: connect EPERM \\.\pipe\watchman
    at PipeConnectWrap.afterConnect [as oncomplete] (net.js:1106:14)
Emitted 'error' event at:
    at Socket.<anonymous> (C:\open\ovrsource\unity\socialvr\_js\node_modules\fb-watchman\index.js:118:12)
    at Socket.emit (events.js:198:13)
    at emitErrorNT (internal/streams/destroy.js:91:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)
```

To fix this, it was suggested by wez to use [his library](https://github.com/wez/EleDo) to force Watchman daemon always start in normal mode on Windows. In this stack of commits I did integrated his library into project and used it to force daemon restart in normal mode when spawned from elevated terminal.

To make it happen, I checked-in library sources and created proxy project which depends on the initial library and contains header bindings and cmake configuration. I did copy pasted Rust cmake macroses from another facebook project - eden, and also created analogue of autogen.sh but for Windows - autogen.cmd.

Pull Request resolved: https://github.com/facebook/watchman/pull/878

Test Plan:
Launch elevated terminal
Start watchman.exe produced from sources
Observe daemon starting and answering
In process monitor, observe watchman.exe process running under user group

Reviewed By: fanzeyi

Differential Revision: D25595879

Pulled By: arhelmus

fbshipit-source-id: 15eb29adcf5bd4a5708b6533a1b2bacbf13f431c

Summary: [Folly] Cut `FOLLY_HAVE_MEMRCHR` since it is now unused.

Reviewed By: Orvid

Differential Revision: D22130149

fbshipit-source-id: b10c5a52354f5c549d96b54e0c165f08b96612b1

Summary: Since this API is discouraged from use, users should call `folly::observer_detail::ObserverManager::waitForAllUpdates` (and face whatever consequences may come with it).

Reviewed By: yfeldblum

Differential Revision: D25629064

fbshipit-source-id: 141b27bbc4f7cf9b628f15f837c38dd4d8a04f31

Reviewed By: zertosh

Differential Revision: D25662961

fbshipit-source-id: f5811a5797fd6dc8733fdf86f35c93d12a08d53a

Summary: Fix `Arena` total-size accounting across calls to `clear`, as reported by member `totalSize`.

Reviewed By: luciang

Differential Revision: D25656867

fbshipit-source-id: b5c7bb0e95199a9fa2c94c04de65b8f494eef146

Summary: Don't use gtest/gtest.h directly.

Reviewed By: yfeldblum

Differential Revision: D25659806

fbshipit-source-id: a8dd0da814465a787ab7904bdd0256f22b6e3ed8

Summary: As per title

Reviewed By: yfeldblum

Differential Revision: D25636982

fbshipit-source-id: a59c2325558175e122941000ab645c8735a3a425

Summary: Use `throw_exception` consistently in `Arena` for consistency.

Differential Revision: D25637401

fbshipit-source-id: 92cda5acc09b871fed78044fa3f3fa2c41b01609

Summary: [folly] `asan_region_is_poisoned` to wrap Address Sanitizer's `__asan_region_is_poisoned`.

Reviewed By: ot, luciang, markisaa

Differential Revision: D25651040

fbshipit-source-id: 0c8f1d0203ada43746b5e2e71c1bd8b883248f68

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507555

fbshipit-source-id: c0be9a04b8a5f502f4753ce6e163a78c428bfad6

Summary:
Fix QUIC OSS build

(Note: this ignores all push blocking failures!)

Reviewed By: danobi

Differential Revision: D25645282

fbshipit-source-id: fcb71d4e930d7ac3802f31d71599338fb346eb80