Summary:
It's somewhat common to want to ignore `stdout` / `stderr` when spawning a child, and the current mechanism we provide to do this is `folly::Subprocess::CLOSE`.

However, this is somewhat dangerous when used without care, since any new files or sockets the child process opens will take on these low fds. From `man 2 open`,

> The file descriptor returned by a successful call will be the lowest-numbered file descriptor not currently open for the process.

Note that stdin/stdout/stderr are *not* special-cased here.

To provide a safer way to not inherit or pipe the standard fds, provide a `folly::Subprocess::DEV_NULL` option instead, which hooks up the OS-relevant null device to the fd.

`folly::Subprocess::CLOSE` will subsequently be removed.

Reviewed By: yfeldblum, luciang

Differential Revision: D30901400

fbshipit-source-id: 0b59de5da6c6a0f714233c09788fa2d0020f3823

Summary:
This change updates the CMake config to detect whether GCC's `-fcoroutines` flag is supported and enable it for the build. This is required to enable support for Folly coroutines.

Followed the instructions in GCC page about C++ coroutines to get them enabled.
https://gcc.gnu.org/wiki/cxx-coroutines

NOTE: This Wiki page used to indicate that exceptions had to be disabled to enable subroutines, but this only applied to experimental support for coroutines and it's no longer the case.

This was uncovered by the fbthrift build, which needs Folly coroutines to implement streaming. A new fbthrift test using a stream type uncovered this missing feature in our build on Fedora.

Reviewed By: yfeldblum

Differential Revision: D30026779

fbshipit-source-id: 3324c2fc52fe5db793bdaba9c81f41bfe6ef2242

Reviewed By: vitaut

Differential Revision: D30676171

fbshipit-source-id: f820b1c08750c4d844925a82d5fd710bc8a1ca5c

Summary:
Rearrange invoking asynchronous reclamation in executor.

Eliminate the LOG message about skipping asynchronous reclamation.

Reviewed By: yfeldblum

Differential Revision: D30908286

fbshipit-source-id: ee79714bf8e6253a01d04c6d2ffa81895c4133c8

Summary:
`FOLLY_HAS_STD` and `FOLLY_HAVE_STD` are now `FOLLY_HAVE_SDT`.

This typo reveals that the tests aren't run on platforms that don't have this feature enabled :/

Reviewed By: yfeldblum

Differential Revision: D30780817

fbshipit-source-id: 338fdd5e5b08f3b5347609dd783f0a75506f9e30

Reviewed By: yfeldblum

Differential Revision: D30914679

fbshipit-source-id: 79a609ed1eda97a97e6eeeb47038a1e746b75e2d

Summary:
This is useful if we want to bind to a nonlocal address or an address that doesn't exist yet.

       IP_FREEBIND (since Linux 2.4)
              If enabled, this boolean option allows binding to an IP
              address that is nonlocal or does not (yet) exist.  This
              permits listening on a socket, without requiring the
              underlying network interface or the specified dynamic IP
              address to be up at the time that the application is
              trying to bind to it.  This option is the per-socket
              equivalent of the ip_nonlocal_bind /proc interface
              described below.

Reviewed By: yfeldblum, mjoras

Differential Revision: D30903919

fbshipit-source-id: 09058cac1c14a4003525b0a7c5381ea301ca28da

Summary: Adds a new method `co_schedule()` that takes a task, schedules it on the current executor and adds it to the AsyncScope.

Reviewed By: andriigrynenko

Differential Revision: D30005811

fbshipit-source-id: 48c7aa240dc73c0b4dd54e539e620cf69c68c4fd

Summary:
From documentation in https://linux.die.net/man/2/ftruncate
> The file offset is not changed.

Reviewed By: Orvid, Skory

Differential Revision: D30843563

fbshipit-source-id: 9314576d927d9ddc07df6d0ceae394d148d7af94

Summary: getdeps.py pulls repos from master branch by default. For FBOSS force it to pull from 'main'

Reviewed By: shri-khare

Differential Revision: D30857755

fbshipit-source-id: 9891f1ddc08c8f13bdcb00385e1ad4516a84776c

Summary:
std::vector<bool>::iterator::operator* returns a temporary proxy bool accessor
in many implementations.  So range-based for loops over it don't work if we
assume non-const lvalue-ref binding, eg.
```
for (auto& ref : vectorBools) { ... }
```
Won't compile.  Silly std::vector<bool>.

Reviewed By: SmithAndr

Differential Revision: D30833990

fbshipit-source-id: cb8d53a48eb2a40587911ad2f0c50b99a472a59c

Summary: Shard the domain's list of untagged retired objects.

Reviewed By: davidtgoldblatt

Differential Revision: D30806913

fbshipit-source-id: 93061ebcd3f62c49eb0f96193e5961c4eeb6f061

Summary:
Consolidate retired_, the list of non-cohort retired objects, with untagged_, the list of cohort untagged objects, in the domain.

Eliminate redundant functions.

Reviewed By: davidtgoldblatt

Differential Revision: D30806882

fbshipit-source-id: bdcbc4990a3d114f7f6bea294df498c5743bed43

Summary:
Remove hazptr_priv, the thread-local list of retired objects.

Non-cohort retired objects are pushed directly into the domain.

Reviewed By: davidtgoldblatt

Differential Revision: D30806863

fbshipit-source-id: 526c90f5a198b4e42a55062cb7344e5286bf28fd

Summary:
The primary branch in the GitHub wangle repository has been renamed from
`master` to `main`.  Update the getdeps manifest to reflect this, so that
getdeps builds correctly clone the repository.

Reviewed By: xavierd

Differential Revision: D30822418

fbshipit-source-id: 9670fff1e85e77adf84485ff8f2236f8826630ef

fbcode: symbolizer: clang-12 DWARF5 emits Split DWARF inlining as DW_TAG_skeleton_unit instead of DW_TAG_compile_unit

Summary:
```name=clang-9
$ llvm-dwarfdump --show-form buck-out/gen/aab7ed39/folly/experimental/symbolizer/test/symbolizer_test_utils_dwarf5_split_dwarf_inlining#compile-SymbolizerTestUtils.cpp.o1ef1b890\,platform009-clang/SymbolizerTestUtils.cpp.o
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000127, format = DWARF32, version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset = 0x0000, addr_size = 0x08, DWO_id = 0x7d3c88943756aebb (next unit at 0x0000012b)

0x00000014: DW_TAG_compile_unit
              DW_AT_stmt_list   (0x00000000)
              DW_AT_str_offsets_base    (0x00000008)
              DW_AT_comp_dir    (".")
              DW_AT_GNU_pubnames        (true)
              DW_AT_GNU_dwo_name        ("buck-out/dbg/gen/aab7ed39/folly/experimental/symbolizer/test/symbolizer_test_utils_dwarf5_split_dwarf_inlining#compile-SymbolizerTestUtils.cpp.o1ef1b890,platform009-clang/SymbolizerTestUtils.cpp.o")
              DW_AT_low_pc      (0x0000000000000000)
              DW_AT_ranges      (indexed (0x0) rangelist = 0x00000010
                 [0x0000000000000000, 0x000000000000005b)
                 [0x0000000000000000, 0x0000000000000065)
                 [0x0000000000000000, 0x000000000000005a)
                 [0x0000000000000000, 0x0000000000000065)
                 [0x0000000000000000, 0x000000000000000b)
                 [0x0000000000000000, 0x0000000000000076)
                 [0x0000000000000000, 0x0000000000000014)
                 [0x0000000000000000, 0x0000000000000065)
                 [0x0000000000000000, 0x0000000000000076)
                 [0x0000000000000000, 0x0000000000000014)
                 [0x0000000000000000, 0x0000000000000065)
                 [0x0000000000000000, 0x0000000000000085)
                 [0x0000000000000000, 0x000000000000000b))
              DW_AT_addr_base   (0x00000008)
              DW_AT_rnglists_base       (0x0000000c)

```
```name=clang-12
$ llvm-dwarfdump --show-form buck-out/gen/aab7ed39/folly/experimental/symbolizer/test/symbolizer_test_utils_dwarf5_split_dwarf_inlining#compile-SymbolizerTestUtils.cpp.o1ef1b890\,platform009-clang-12/SymbolizerTestUtils.cpp.o
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000127, format = DWARF32, version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset = 0x0000, addr_size = 0x08, DWO_id = 0xb881aa098abf71b5 (next unit at 0x0000012b)

0x00000014: DW_TAG_skeleton_unit
              DW_AT_stmt_list [DW_FORM_sec_offset]	(0x00000000)
              DW_AT_str_offsets_base [DW_FORM_sec_offset]	(0x00000008)
              DW_AT_comp_dir [DW_FORM_strx1]	(".")
              DW_AT_GNU_pubnames [DW_FORM_flag_present]	(true)
              DW_AT_dwo_name [DW_FORM_strx1]	("buck-out/dbg/gen/aab7ed39/folly/experimental/symbolizer/test/symbolizer_test_utils_dwarf5_split_dwarf_inlining#compile-SymbolizerTestUtils.cpp.o1ef1b890,platform009-clang-12/SymbolizerTestUtils.cpp.o")
              DW_AT_low_pc [DW_FORM_addr]	(0x0000000000000000)
              DW_AT_ranges [DW_FORM_rnglistx]	(indexed (0x0) rangelist = 0x00000010
                 [0x0000000000000000, 0x000000000000004c)
                 [0x0000000000000000, 0x000000000000005f)
                 [0x0000000000000000, 0x0000000000000054)
                 [0x0000000000000000, 0x000000000000005f)
                 [0x0000000000000000, 0x000000000000000b)
                 [0x0000000000000000, 0x0000000000000070)
                 [0x0000000000000000, 0x0000000000000014)
                 [0x0000000000000000, 0x000000000000005f)
                 [0x0000000000000000, 0x0000000000000070)
                 [0x0000000000000000, 0x0000000000000014)
                 [0x0000000000000000, 0x000000000000005f)
                 [0x0000000000000000, 0x0000000000000086)
                 [0x0000000000000000, 0x000000000000000b))
              DW_AT_addr_base [DW_FORM_sec_offset]	(0x00000008)
              DW_AT_rnglists_base [DW_FORM_sec_offset]	(0x0000000c)
```

Differential Revision: D30755400

fbshipit-source-id: 6e7fd8bc9d3bef90a5195dc30dff60c489c4df35

Summary: Add build-time flags for setting default spin and yield counts.

Reviewed By: fadimounir

Differential Revision: D30761279

fbshipit-source-id: 3b74bae438b1f87b1ca8b955bb244eb907b22891

Summary: Deprecate folly::svformat in favor of fmt::format

Reviewed By: vitaut

Differential Revision: D30521196

fbshipit-source-id: 944054191bbfd296d1f666eb6ace6c4308f6d1ea

Summary:
Extend cleanup to cover retired cohort objects.

The change includes incrementing num_bulk_reclaims_ before invoking do_reclamation either directly or in an executor. The corresponding decrement is done at the completion of do_reclamation, which may happen on a different thread if reclamation is done in an executor.

Reviewed By: davidtgoldblatt

Differential Revision: D30513628

fbshipit-source-id: 80227e85301274c66cc200ee5228654f1ca07d08

Summary:
The primary branch in the fb303 github repository was renamed from `master` to
`main`.  Update the `fb303-source` manifest to reflect this.

The main `fb303` manifest was already updated in D30700180 (https://github.com/facebook/folly/commit/60d9f5d791d7c6afb5f044538ae45fbe91a043e5).  The
`fb303-source` manifest is a separate manifest that only fetches the fb303
source code without building it.  This is only used by the `eden_scm`
manifest.

Reviewed By: fanzeyi

Differential Revision: D30794650

fbshipit-source-id: 0e7790f8ceb737ce2f26ab213e1f0f94c5b3f045

Summary:
The naive coinflip algorithm generates a random variable each time the function
is called. We can avoid many of these calls to a random number generator by
doing some tricky business with math stuff.

See https://fb.workplace.com/groups/135724786501553/permalink/5767297086677600/
for some discussion on the topic.

The intention behind this code is that we will use it in HHVM. That's why it provides the static methods that allow the caller to supply their own storage space for the counter and their own random number generator.

Reviewed By: bmaurer

Differential Revision: D30440295

fbshipit-source-id: ee0c3e49da3ec82a9fd6c8854b15ef107755ff39

Summary:
Pull Request resolved: https://github.com/facebook/folly/pull/1641

There's a bug in C++ SDK shipped on Apple platforms that marks `std::optional`'s `value()` as unavailable. To resolve that we should use `operator*` instead.

Reviewed By: tcw165

Differential Revision: D30755147

fbshipit-source-id: 4edcf60a7d29abe7eaddceb66501535031553678

folly: symbolizer: tests: switch from qsort to lfind -- ASAN in LLVM12 adds an __interceptor_qsort.part.0 which makes stacks differ between ASAN and non-ASAN

Summary:
LLVM 12's ASAN intercepts qsort and adds a new stack frame for the intercetor `__interceptor_qsort.part.0`.

That can be solved by switching offsets between mode/dev & mode/opt, but it only makes tests harder to read.

So switch to `lfind` which also lives in a separate `.so` (feature used in tests), but is simple enough that ASAN doesn't need to intercept it.

Differential Revision: D30665575

fbshipit-source-id: ba540aede33c37bea8e1f4777bd7325699f9a8d2

Summary:
folly::symbolizer now supports both DWARF4 and DWARF5 debug info
- http://www.dwarfstd.org/doc/DWARF4.pdf
- http://www.dwarfstd.org/doc/DWARF5.pdf

Split DWARF (Debug Fission)
- with `-fsplit-dwarf-inlining`: folly::symbolizer will use the debug info from the skeleton CU.
- without `-fsplit-dwarf-inlining`: folly::symbolizer won't read .dwo sections and can't symbolize it (yet).

Major things that changed between the standards that affect folly::symbolizer:
- new forms DW_FORM_addrx*, DW_FORM_loclistx, DW_FORM_rnglistx, DW_FORM_strx*, whose values are interpreted against new CU attributes DW_AT_addr_base, DW_AT_loclists_base, DW_AT_rnglists_base, DW_AT_str_offsets_base
- The .debug_line line header format is completely re-written and the constraint that the file register must be >= 1 was lifted.
- DWARF5 `.debug_loclists` replaces DWARF4 `.debug_ranges`

Differential Revision: D25521092

fbshipit-source-id: 5b48e8abed495f379d8b119177913f55ae11bd2b

Summary: This diff adds support to customize main branch name when generating GitHub Actions.

Differential Revision: D30679305

fbshipit-source-id: 0fc7eb1c97c27e2b42e60cc1ab69a48ab93b93fa

Summary:
Some changes that had to be done in Debian for the build to work:

* Installation of system deps failed as it was not detecting the OS correctly
* Updated the CMake manifest to uncomment the deb dependency as the CMake versions are newer
* fb303 was not getting cloned as it was looking for a non-existent master branch

Pull Request resolved: https://github.com/facebook/watchman/pull/943

Differential Revision: D30700180

Pulled By: fanzeyi

fbshipit-source-id: 62eb9f8ba57510eb98d6bd56e40384bf38a74d8c

Reviewed By: capickett

Differential Revision: D30712092

fbshipit-source-id: 642e642bab883259f177f4419a0c3d562c929beb

Summary: Part of folly vformat and svformat deprecation

Reviewed By: vitaut

Differential Revision: D30656958

fbshipit-source-id: 0cccb7b2294fada3c61e36cd527af2ef05bb5a0a

Summary:
Fix an algorithm bug that occurs when the Key or Value types are not nothrow copy constructible.
- Nodes (the entities protectable by iterators) may be cloned as a result of rehashing.
- Key-value item objects are unique (because they are not copyable).
- Multiple nodes may point to the same key-value item.
- In the incorrect algorithm, each node has a bool member that indicates if it owns the key-value item or not (i.e., if it is responsible for deleting it).
- When a node is cloned, its bool member is cleared.
- The problem is that if the key is erased and the clone (or  descendant clone) may be reclaimed (because it is unprotected by iterators) then the key value item will be reclaimed, even if a cloned-from node is still protected by iterators.
- The failure happens when an iterator holder to a cloned-from node tries to access the already-reclaimed key-value, expecting it (correctly) to be still protected.

The fix:
- Eliminate the bool owned member in the node structure.
- Add a link counter to the key-value item structure.
- Increment (atomically) the link counter when the (latest) node to the key-value item is cloned.
- Decrement (atomically) the link counter when a node pointing to the item is reclaimed.
- Reclaim the item only when its last link is released.
- Note that atomic increments  and decrements are used only if the node pointing to an item is cloned.

Added a test to detect the incorrect behavior.
This change fixes only the regular (non-SIMD) version.
Currently, the SIMD version fails the added test, therefore (for now) the test is enabled only for the regular version.

Reviewed By: davidtgoldblatt

Differential Revision: D30371519

fbshipit-source-id: 29e143712afb3ef794f9f6f4d99919d5b4688416

Summary: Add cFollyPromise method declarations that are needed to create an empty `folly::Promise`

Reviewed By: Gownta

Differential Revision: D30519790

fbshipit-source-id: 46092d5a400b0fccc11a9e77271a18b4f6fa3f6d

Summary: This ensures the token passed to child tasks continues to be signalled when the token applied to collect* is even after collect returns

Reviewed By: ispeters

Differential Revision: D30542448

fbshipit-source-id: b286175f4a8c5e5b3e2e628c6611f368ac79c1b6

Summary:
When compiled with `-Wcovered-switch-default`, Folly fails to build because it adds `default` to switches which are already exhaustive. For C++ safety, these switches are intentionally including a default, so wrap them in a pragma block to indicate that and locally disable the warning.

Causes -fmodules import issues for upstream library in D30379442.

Still remaining issues with C++ definition: P445339268

Reviewed By: ispeters

Differential Revision: D30397871

fbshipit-source-id: adead9e01d0ba3b21c2e1446150cc6fed0f58602

Summary: The len and bytes functions only operate on the current IOBuf, so add some comments explaining it.

Reviewed By: nanshu

Differential Revision: D30501776

fbshipit-source-id: 997dd77db52a3c11722efff8ae83b05e073e1285

Summary:
Fix SIMD version to return iterator to new item in insertion operations.

Added a test to detect the incorrect behavior.

Changed existing tests that di not test the SIMD version to do so. Three of these tests fail without the fix.

Reviewed By: davidtgoldblatt

Differential Revision: D30435627

fbshipit-source-id: 20ba400be9213fa138fda06e0e7bd84cf9d8cf12

Summary: I noticed two mispellings while reading through the code.  This fixes them.

Reviewed By: Orvid

Differential Revision: D30429734

fbshipit-source-id: b976cc4ae4534a9f065b8a7e6fee5a39d7241a28

Summary: This definition is the same cython uses for make_shared and make_unique

Reviewed By: yfeldblum

Differential Revision: D30232407

fbshipit-source-id: 6a0cf4637721bc9d5e5f7f87f3c0f2b031810a5f

Summary:
Original commit changeset: 7b10cb9dd2c4

`configerator_proxy2` reports a big memory regression. Reverting until we understand what's going on and have a plan to address it.

(Note: this ignores all push blocking failures!)

Differential Revision: D30401909

fbshipit-source-id: 28443ba08b75c634021965319fead2f8a36b7235

Summary:
Implements step 13 of ["Adding a new version of an existing project"](https://www.internalfb.com/intern/wiki/Third_Party2/Usage/#adding-a-new-version-of)

Steps are:
1. Update `fbcode://third-party2/config.py` to use the new CLI11-2.0.0 version
2. `fbcode $> tp2_update_fbcode CLI11` (updated third-party2 symlink)
3. `fbcode $> tp2_config buckify CLI11` (updated symlink to third-party-buck)
4. `fbcode $> buckify_tp2` (added TARGETS & other metadata files to third-party-buck)

Differential Revision: D30286158

fbshipit-source-id: 2a0bd5c92f9022eda2ae3f24b757fd2120bfcd4d

Summary:
The LifecycleObserver already tracks connect() but does not notify on
connectError().  Follow the same pattern.

Note that we intentionally added this to AsyncSocket's LifecycleObserver
rather than AsyncTransport b/c AsyncTransport is not supposed to have
a concept of a 'connection'.  This is counter to the 'connect()' callback
that already exists in AsyncTransport::LifecycleObserver so marked a quick
TODO to remember to move that.

Reviewed By: bschlinker

Differential Revision: D28612132

fbshipit-source-id: cefa650bd007d48e38f9cb67bc9a82d322036d4c

Summary: This diff adds the manifest file for delos_core so we can build using getdeps.

Reviewed By: hanm

Differential Revision: D26011286

fbshipit-source-id: becb1a665a95f0d593072885c3ddfcf5c4403f51