Summary:
[Folly] Define `to_narrow` in terms of implicit conversion to take advantage of ubsan's truncation checks.

Note that integer truncation is not undefined behavior per se but is commonly unintended, so ubsan checks for it. Uses of `to_narrow` should not be subject to truncation; wherever truncation is anticipated, better to use an explicit conversion with a named destination type.

Requires suppressing `-Wconversion` around the implicit conversion to avoid extraneous warnings and errors when the compiler detects narrowing implicit conversions. Since `to_narrow` models explicit conversion while merely being defined in terms of implicit conversion, it is already anticipated by all users that a narrowing conversion may occur; the warning is there to inform users only about unanticipated cases.

Reviewed By: luciang

Differential Revision: D19201430

fbshipit-source-id: b3739d3d9aa05e95f7b3e4dff54e719691c1f04c

Summary: [Folly] Mark `co_error` as `final`.

Reviewed By: lewissbaker

Differential Revision: D19173904

fbshipit-source-id: 3dedf9a27629dd495d7097d00566a92753b65778

Summary: [Folly] Forbid `co_error` with empty `exception_wrapper`.

Reviewed By: lewissbaker

Differential Revision: D19172250

fbshipit-source-id: 5ffa7502eb97b6a084be3112b17f29bad2d96a0f

Summary:
Found with modernize-loop-convert
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Pull Request resolved: https://github.com/facebook/folly/pull/1260

Reviewed By: markisaa

Differential Revision: D18747876

Pulled By: yfeldblum

fbshipit-source-id: f2b19654bb3fcbb75b1210edeef536c88f3052d1

Summary: [Folly] Let `PriorityUnboundedQueueSet` align its queues, which have extended alignment, even when `std::allocator` does not honor extended alignment.

Reviewed By: magedm

Differential Revision: D19174993

fbshipit-source-id: 0bc0d75c6d239c97b6e1c7380bffff0363008e16

Summary: [Folly] Let AlignedSysAllocator consider the natural or specified alignment of the type for which memory is being allocated, rather than only considering a constant or fixed alignment.

Reviewed By: nbronson

Differential Revision: D19174932

fbshipit-source-id: e8ed0fbaf30d285cadd061d0fe5d69fcbb16f9e2

Summary: The tagged/specific exception variant of thenError and deferError propagate interrupts where currently the untagged variant of thenError does not. As far as I can tell this was an oversight. This makes untagged thenError behave as expected.

Reviewed By: yfeldblum, mpark

Differential Revision: D18643814

fbshipit-source-id: 42688c4363de2f6b027766b19276b2e8ec6a48a8

Summary: [Folly] Remove spelled default ctor in `AlignedSysAllocator`, which was needed only for gcc49.

Reviewed By: aary

Differential Revision: D19171223

fbshipit-source-id: ee42f6ac188dc896519537870353116c0dfd3acd

Summary:
[Folly] Extended constructibility for `co_error` - constructible from everything `exception_wrapper` is constructible from, but not default-constructible. This permits:

```lang=c++
co_yield folly::coro::co_error(std::runtime_error("foo"));
```

Reviewed By: lewissbaker

Differential Revision: D19172210

fbshipit-source-id: df21c4f2a15ad2286e7cb34aae7c1be05e797a94

Summary: [Folly] Avoid a too-large pointer literal in StlVectorTest, keeping the literal value divisible by 8 to avoid ubsan violations.

Reviewed By: igorsugak

Differential Revision: D19170467

fbshipit-source-id: 2c93d2b3d9f7515761668d3364c4b8b5093a6145

Summary: [Folly] Only use `explicit` copy-ctor in `to_narrow` with C++17 and higher, since C++17 introduces mandatory copy elision and the technique here relies on mandatory copy elision.

Differential Revision: D19175384

fbshipit-source-id: 9d3234a71b1b5e4f31d14137e42dbf3a73c79b2e

Summary:
Fixing warning exposed by -Wpointer-bool-conversion

```
 folly/container/test/F14MapTest.cpp:1370:35: error: address of function 'Tracked<0>::counts' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
            << "key_type ops " << Tracked<0>::counts << ", mapped_type ops "
                               ~~ ^~~~~~~~~~~~~~~~~~
folly/container/test/F14MapTest.cpp:1370:35: note: prefix with the address-of operator to silence this warning
            << "key_type ops " << Tracked<0>::counts << ", mapped_type ops "
                                  ^
                                  &
folly/container/test/F14MapTest.cpp:1371:16: error: address of function 'Tracked<1>::counts' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
            << Tracked<1>::counts;
            ~~ ^~~~~~~~~~~~~~~~~~
folly/container/test/F14MapTest.cpp:1371:16: note: prefix with the address-of operator to silence this warning
            << Tracked<1>::counts;
               ^
               &
2 errors generated.

Reviewed By: yfeldblum

Differential Revision: D19131722

fbshipit-source-id: 9db48848ab5d68bc73ab0d6a4ef557d0db05414e

Summary: [Folly] Extract `has_extended_alignemnt`.

Reviewed By: aary

Differential Revision: D19149753

fbshipit-source-id: c6fa5cf2adcab732a21fbb31ab8ab60e978b9bc8

Summary: [Folly] Canonical impl of futures `Core::removeStaleDependents` using std algorithms.

Reviewed By: leikahing, igorsugak

Differential Revision: D19167292

fbshipit-source-id: 702fdf07bdcc295ed990d2c02cd3380ea81694a2

Summary:
In cores we're only interested in the ElfPhdrs (and there generally
aren't any sections), so apart from some asserts, the code already
does everything we need.

Reviewed By: paulbiss

Differential Revision: D19161810

fbshipit-source-id: fe6e2f34413d61067156858fc652ffffd910433c

Summary:
Exposed by UBSAN's misaligned-pointer-use:
```lang=bash
> folly/test/stl_tests/StlVectorTest.cpp:544:12: runtime error: upcast of misaligned address 0x0000feebdaed for type 'DataTracker<false>', which requires 8 byte alignment
> 0x0000feebdaed: note: pointer points here
> <memory cannot be printed>
>     #0 0x6c9b93 in DataTracker<false>::~DataTracker() folly/test/stl_tests/StlVectorTest.cpp:544
>     #1 0x6c94fe in Data<0u, 0ul>::~Data() folly/test/stl_tests/StlVectorTest.cpp:605
>     #2 0xcc5f93 in void test_iteratorInsertionN2<folly::fbvector<Data<0u, 0ul>, std::allocator<Data<0u, 0ul> > > >(std::integral_constant<bool, true>) folly/test/stl_tests/StlVectorTest.cpp:2422
>     #3 0x5c9bac in void test_iteratorInsertionN3<folly::fbvector<Data<0u, 0ul>, std::allocator<Data<0u, 0ul> > > >() folly/test/stl_tests/StlVectorTest.cpp:2422
>     #4 0x5c67bd in FBVector_iteratorInsertionN_Test::TestBody() folly/test/stl_tests/StlVectorTest.cpp:2422
>     #5 0x7f9c4e5316c9 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:2464
>     #6 0x7f9c4e530dcc in testing::Test::Run() xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:2480
>     #7 0x7f9c4e5350a0 in testing::TestInfo::Run() xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:2662
>     #8 0x7f9c4e539408 in testing::TestCase::Run() xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:2780
>     #9 0x7f9c4e55a672 in testing::internal::UnitTestImpl::RunAllTests() xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:4655
>     #10 0x7f9c4e5595de in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:2464
>     #11 0x7f9c4e558b72 in testing::UnitTest::Run() xplat/third-party/gmock/googletest-1.8.0/googletest/src/gtest.cc:4263
>     #12 0x6591f3 in RUN_ALL_TESTS() buck-out/cells/fbsource/gen/xplat/third-party/gmock/gtest_headers#header-mode-symlink-tree-with-header-map,headers/gtest/gtest.h:2247
>     #13 0x659139 in main folly/test/stl_tests/StlVectorTest.cpp:3074
>     #14 0x7f9c4c75b1a5 in __libc_start_main /home/engshare/third-party2/glibc/2.26/src/glibc-2.26/csu/libc-start.c:308:16
>     #15 0x4de029 in _start /home/engshare/third-party2/glibc/2.26/src/glibc-2.26/sysdeps/x86_64/start.S:120
>
> SUMMARY: UndefinedBehaviorSanitizer: misaligned-pointer-use folly/test/stl_tests/StlVectorTest.cpp:544:12
```

Make the crafted pointer address aligned.

Reviewed By: Gownta

Differential Revision: D19166262

fbshipit-source-id: f766656d031079350838598b135275bdbc047642

Summary:
Not sure if there is any predefined cross-platform macro that I can use the
detect the build mode.

Reviewed By: luciang

Differential Revision: D19161841

fbshipit-source-id: 49dd12096ab20bbcaada566f2ad854a9ea340c11

Summary: [Folly] Canonical implementation of `IoUringBackend::NotAvailable` - need to export exceptions since they are the most likely use-case for RTTI and can just bring the base class's ctors into scope.

Differential Revision: D19154080

fbshipit-source-id: efaf9440a5ec3d78201448160efe4b8893314956

Reviewed By: yfeldblum, lewissbaker

Differential Revision: D19156701

fbshipit-source-id: 80bd8b7fc6dfde71756411342e5f4eb912150f06

Summary:
Exposed by UBSAN's unsigned-integer-overflow:
```
> folly/experimental/observer/detail/Core.cpp:179:9: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned long')
>     #0 0x7f605837dfea in folly::observer_detail::Core::removeStaleDependents()::$_4::operator()(std::vector<std::weak_ptr<folly::observer_detail::Core>, std::allocator<std::weak_ptr<folly::observer_detail::Core> > >&) const folly/experimental/observer/detail/Core.cpp:179
>     #1 0x7f6058344b0c in auto folly::SynchronizedBase<folly::Synchronized<std::vector<std::weak_ptr<folly::observer_detail::Core>, std::allocator<std::weak_ptr<folly::observer_detail::Core> > >, folly::SharedMutexImpl<false, void, std::atomic, false, false> >, (folly::detail::MutexLevel)1>::withWLock<folly::observer_detail::Core::removeStaleDependents()::$_4>(folly::observer_detail::Core::removeStaleDependents()::$_4&&) folly/Synchronized.h:210
>     #2 0x7f6058344917 in folly::observer_detail::Core::removeStaleDependents() folly/experimental/observer/detail/Core.cpp:174
>     #3 0x7f60583785cb in folly::observer_detail::Core::~Core()::$_2::operator()(std::unordered_set<std::shared_ptr<folly::observer_detail::Core>, std::hash<std::shared_ptr<folly::observer_detail::Core> >, std::equal_to<std::shared_ptr<folly::observer_detail::Core> >, std::allocator<std::shared_ptr<folly::observer_detail::Core> > > const&) const folly/experimental/observer/detail/Core.cpp:156
>     #4 0x7f6058343cdc in auto folly::SynchronizedBase<folly::Synchronized<std::unordered_set<std::shared_ptr<folly::observer_detail::Core>, std::hash<std::shared_ptr<folly::observer_detail::Core> >, std::equal_to<std::shared_ptr<folly::observer_detail::Core> >, std::allocator<std::shared_ptr<folly::observer_detail::Core> > >, folly::SharedMutexImpl<false, void, std::atomic, false, false> >, (folly::detail::MutexLevel)1>::withWLock<folly::observer_detail::Core::~Core()::$_2>(folly::ob
server_detail::Core::~Core()::$_2&&) folly/Synchronized.h:210
>     #5 0x7f6058343a17 in folly::observer_detail::Core::~Core() folly/experimental/observer/detail/Core.cpp:154
>     #6 0x7f605838b8ca in std::_Sp_counted_ptr<folly::observer_detail::Core*, (__gnu_cxx::_Lock_policy)2>::_M_dispose() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/shared_ptr_base.h:378
>     #7 0x7f605834d411 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/shared_ptr_base.h:156
>     #8 0x7f605834d332 in std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/shared_ptr_base.h:686
>     #9 0x7f605834d23a in std::__shared_ptr<folly::observer_detail::Core, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/shared_ptr_base.h:1125
>     #10 0x7f605833c416 in std::shared_ptr<folly::observer_detail::Core>::~shared_ptr() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/shared_ptr.h:93
>     #11 0x7f6058376413 in folly::observer_detail::ObserverManager::scheduleRefresh(std::shared_ptr<folly::observer_detail::Core>, unsigned long)::'lambda'()::~() folly/experimental/observer/detail/ObserverManager.h:91
>     #12 0x7f6058377014 in unsigned long folly::detail::function::execSmall<folly::observer_detail::ObserverManager::scheduleRefresh(std::shared_ptr<folly::observer_detail::Core>, unsigned long)::'lambda'()>(folly::detail::function::Op, folly::detail::function::Data*, folly::detail::function::Data*) folly/Function.h:592
>     #13 0x7f6058377788 in folly::Function<void ()>::exec(folly::detail::function::Op, folly::detail::function::Data*, folly::detail::function::Data*) const folly/Function.h:649
>     #14 0x7f6058376380 in folly::Function<void ()>::~Function() folly/Function.h:781
>     #15 0x7f6058477b99 in folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()::operator()() const folly/experimental/observer/detail/ObserverManager.cpp:73
>     #16 0x7f6058473de8 in void std::__invoke_impl<void, folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()>(std::__invoke_other, folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()&&) buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/invoke.h:60
>     #17 0x7f6058473c08 in std::__invoke_result<folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()>::type std::__invoke<folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()>(folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()&&) buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/bits/invok
e.h:95
>     #18 0x7f6058473b66 in decltype(std::__invoke(_S_declval<0ul>())) std::thread::_Invoker<std::tuple<folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>) buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/thread:234
>     #19 0x7f6058473a43 in std::thread::_Invoker<std::tuple<folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()> >::operator()() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/thread:243
>     #20 0x7f6058473549 in std::thread::_State_impl<std::thread::_Invoker<std::tuple<folly::observer_detail::ObserverManager::UpdatesManager::CurrentQueue::CurrentQueue()::'lambda'()> > >::_M_run() buck-out/cells/fbsource/gen/third-party/gcc/7.x/stdc++-headers#header-mode-symlink-tree-with-header-map,headers/thread:186
>     #21 0x7f60576bac5f in std::execute_native_thread_routine(void*) third-party/gcc/7.x/libstdc++-v3/src/c++11/thread.cc:83
>     #22 0x7f605639e6b5 in start_thread /home/engshare/third-party2/glibc/2.26/src/glibc-2.26/nptl/pthread_create.c:465:7
>     #23 0x7f6055ecdebe in __GI___clone /home/engshare/third-party2/glibc/2.26/src/glibc-2.26/sysdeps/unix/sysv/linux/x86_64/clone.S:95
>
> SUMMARY: UndefinedBehaviorSanitizer: unsigned-integer-overflow folly/experimental/observer/detail/Core.cpp:179:9
```

Fix the error by rearranging increment and decrement operations.

Reviewed By: leikahing

Differential Revision: D19164999

fbshipit-source-id: d3c9b638492d0bf44c2acaac1e95fafe8b785182

Summary:
- __cxa_get_globals signature closer of the libcxxabi.
- malloc.h exists now on FreeBSD but prevents stdlib.h inclusion if __STDC__.
Pull Request resolved: https://github.com/facebook/folly/pull/1281

Reviewed By: Orvid

Differential Revision: D19140640

Pulled By: yfeldblum

fbshipit-source-id: 525014b5a367b8d8e95cf10e3e779cd7f0647bd5

Summary: An alternative to co_return Try that works for Task<void>

Reviewed By: yfeldblum

Differential Revision: D19136334

fbshipit-source-id: 72a18482b326dbc40b691712a5fd311efad45785

Summary:
The general idea is to change cache to a mapping between an address and array of frames instead of just one frame.

Also changed Dwarf to directly fill frames array with inline function calls, instead of allocating extra LocationInfo array.

Moved shared data structure like LocationInfo and SymbolizedFrame into a separate file so that it can used in both Dwarf.cpp and Symbolizer.cpp.

Reviewed By: luciang

Differential Revision: D18825831

fbshipit-source-id: fe963a1adbbc6f0055c466b91708eee732abc141

Summary: Skip the EventBase tests if the backend is not available

Reviewed By: yfeldblum

Differential Revision: D19002064

fbshipit-source-id: a995df02998c80de2f9076ea16a0281b6288d6b5

Summary: Fix io_uring backend tests

Reviewed By: yfeldblum, danobi

Differential Revision: D19023775

fbshipit-source-id: d696064d26b37f52529c84601f6797ef82b0ddb5

Summary: EventBase test lib rework

Reviewed By: yfeldblum

Differential Revision: D19001877

fbshipit-source-id: d99ad41007012c7bd21ee259a0a0b5ee2b709512

Summary: Add IoUringBackend::NotAvailable exception

Reviewed By: kevin-vigor

Differential Revision: D19143143

fbshipit-source-id: 7b55106d50882d34fc6100a81ff2a4e5748e9b85

Summary: This allows makeObserver to work even during shutdown.

Reviewed By: yfeldblum

Differential Revision: D19136597

fbshipit-source-id: 17e946a66743a56d24904697c02ce7165bcaf397

Summary:
Linux thread identifier is something that we can get with `gettid`.
http://man7.org/linux/man-pages/man2/gettid.2.html

This TID is super usefully for providing thread information while debugging on Linux (this is
the thing that `ps` command uses, or procfs), but is not really mappable from
`std::thread::id` (e.g. the thread handle we get with `pthread_self()`).

Reviewed By: yfeldblum

Differential Revision: D19134596

fbshipit-source-id: 32ad025c5e378e3c7b55da1aad8dd9f3e26d0892

Summary:
While running a system lots of different values will be added to lots of different `MultiLevelTimeSeries`. These values can be timestamps, lengths of time, file sizes, just about anything. There's no way for the underlying library to know before hand how large they will be. So it's always going to be possible to cause undefined behavior.

That means we could fix this one of two ways. We could make this code be ignored for ubsan, or we could make it never roll over.

I have made it so that the code won't roll over here. This seems better because it will continue to give more representative numbers. Rather than going from a very large number to a very small number, we'll remain at a very large number. That should still convey to every one that the numbers being accumulated are very large.

Reviewed By: mzlee

Differential Revision: D16970762

fbshipit-source-id: c56f6db1dbdecefd190e6ac357133886a3642571

Summary: New 20191216 liburing

Reviewed By: danobi

Differential Revision: D19125513

fbshipit-source-id: 38d2800ee75865cb76cb06edc0328feaa44bab3e

Summary: Integrate calls into logging framework to allow tracking of source and use of the global executor.

Reviewed By: andriigrynenko

Differential Revision: D18232728

fbshipit-source-id: e714b870cc041af9c99a95baf8f32c3819852b37

Summary: Adds sampled logging to track executors passed to Future::via.

Reviewed By: andriigrynenko

Differential Revision: D18233242

fbshipit-source-id: b5c004f643261a36fd0b63fb6e033263ece1662f

Reviewed By: Orvid

Differential Revision: D19053964

fbshipit-source-id: dd31937cbeb3c7ef202e4b91c1b153f849376bdf

Summary: [Folly] Prefer `TEST_F` and tests named `...Test` in `folly/experimental/coro/`.

Reviewed By: lewissbaker

Differential Revision: D18746584

fbshipit-source-id: 49156a1dca5ef115bf12add5ceb38cb7905fac3d

Summary: These files fail to build when a different version of glog is used. Notice that both cpp files use gflags but don't include its header.

Reviewed By: pixelb

Differential Revision: D18974446

fbshipit-source-id: 4cfaa6dc62c795f4fe7f6624f078cffe550ecfec

Summary:
D18890515 broke folly builds when zstd isn't present. (My bad!!)

This should fix it.

Reviewed By: lukaspiatkowski

Differential Revision: D19029293

fbshipit-source-id: 2ede5a8402e60af61a294c9db35ca15dffdf4c49

Summary:
`folly::AtomicBitSet<N>` used `N` to denote the number of blocks
(32-bit or 64-bit each) instead of number of bits as used by
`std::bitset`. This confusion of unit led to unintentional allocation
of extra storage in many cases.

A simple fix would be to make `N` denote number of bits. However,
changing meaning of `N`could lead to silent breakage of code during
run time for some users who used `N` to denote number of blocks.

Therefore, to make the new meaning of `N` more explicit,
`AtomicBitSet` is renamed to `ConcurrentBitSet` & `N` now denotes the
number of bits.

Reviewed By: al13n321

Differential Revision: D18866751

fbshipit-source-id: 17741646862776e1a080eaac7877f495bb56b656

Differential Revision: D19001755

fbshipit-source-id: bda1a278017059e83c9a529aac7b429f074e42c1

Summary: We should be able to associate rootId with the TID the request is running on.

Reviewed By: yfeldblum

Differential Revision: D18918492

fbshipit-source-id: 539cd78729b438928a9a4b0c93e8e17295b642d5