Summary:
When compiling folly with clang, the compiler warns about our
use of GCC-specific pragmas to silence incorrect compiler warnings:

folly/Optional.h:79:33: warning: unknown warning group '-Wpragmas', ignored [-Wunknown-pragmas]
folly/Optional.h:80:33: warning: unknown warning group '-Wmaybe-uninitialized', ignored [-Wunknown-pragmas]

Thankfully, those incorrect compiler warnings are not emitted by
clang, so we can just disable the pragmas in clang.

Test Plan:
Built folly in gcc and ran it through clang. Warning above
is gone.

Reviewed By: andrei.alexandrescu@fb.com

FB internal diff: D733323

Test Plan: async_io_test

Reviewed By: philipp@fb.com

FB internal diff: D730100

Summary:
In hopes of keeping 'busywork' helpers out of folly, I've moved this
closer to the code that needed to do this.

Test Plan: Unit tests

Reviewed By: andrei.alexandrescu@fb.com

FB internal diff: D729194

Blame Revision: D726916

Summary:
Now that we have truthy files, it would be nice to be able to simply
//try// opening files and return a possibly-initialized File.

Test Plan: Unit tests

Reviewed By: chaoyc@fb.com

FB internal diff: D726916

Summary:
File has a default constructor so it can be initialized late, but it
doesn't have a good canonical way to see if it's been initialized. This adds an
//explicit// operator bool so you can test files like `if (file) ...`.

Test Plan: Unit tests

Reviewed By: chaoyc@fb.com

FB internal diff: D726914

Summary: Added Adaptor(size_t, const value_type&)

Test Plan: test added

Reviewed By: soren@fb.com

FB internal diff: D726358

Summary:
'open() failed' isn't too helpful. Seeing a filename there is. So I
added it.

Test Plan: Unit test

Reviewed By: mohittalwar@fb.com

FB internal diff: D725204

Summary:
Add a --bm_min_iters flag to control the minimum number of iterations
that the benchmark code starts with on each epoch.

This can be used on benchmarks that test very cheap operations, but take
a long time to set up.  Otherwise the benchmark code may have to retry
many times before it hits a large enough number of iterations to get a
meaningful result, and each time it still pays the fixed setup cost.

This also helps with benchmarks when some of the setup cost cannot be
hidden with BenchmarkSuspender for some reason.  --bm_min_iters can be
set to a large enough value so that the extra startup cost will not
affect the measurements too much.

Test Plan:
Used this with the thread local stats benchmark.  During setup/cleanup,
this benchmark starts and synchronizes with many threads.  The entire
setup time cannot be reliably hidden with BenchmarkSuspender; the
synchronization between the threads takes a relatively long time
compared to the cost of the operation being benchmarked.  --bm_min_iters
allows a relatively high number of iterations to be used, masking this
cost.

Reviewed By: rajat@fb.com

FB internal diff: D723304

Summary:
Helper method for creating a folly::Optional<T> by just passing
in a T reference.  Analogous to boost::make_optional.

Test Plan: Added test case

Reviewed By: tjackson@fb.com

FB internal diff: D721762

Summary: MemoryMapping::data() returns StringPiece ::range() returns ByteRange

Test Plan: tests

Reviewed By: philipp@fb.com

FB internal diff: D720985

Summary:
There are platforms other than clang that don't support ifuncs. (The one
I'm concerned about is ARM.) I changed the ifdef __clang__ around the
ifunc attributes to be more abstract, so we can can pass in this flag on
the command line, or use autoconf to detect it.

Test Plan:
fbmake runtests. Manually define HAVE_IFUNC 0 and make sure the
popcount() and popcountll() functions get compiled as calls to
popcount_builtin.

Run autoreconf, ./configure, make sure the feature gets detected
properly by looking at config.h.

Reviewed By: andrewjcg@fb.com

FB internal diff: D712192

Summary:
This flag conflicts with the flag with the same purpose in
`common/files/MemoryMappedFile.cpp`. Just renaming it for now.

Test Plan: Build

Reviewed By: lucian@fb.com

FB internal diff: D717067

Summary: MemoryMapping is a C++ wrapper object around mmap. It works with `folly::File`s, and provides bitwise-range access for reading and writing files.

Test Plan: Unit test

Reviewed By: lucian@fb.com

FB internal diff: D452384

Summary: Change State to enum class, and add debugging helper to AsyncIOOp and AsyncIO.

Test Plan: n/a

Reviewed By: philipp@fb.com

FB internal diff: D715676

Summary: Moving File into `/folly`.

Test Plan: Same unit tests, rebuild affected code outside folly.

Reviewed By: philipp@fb.com

FB internal diff: D714462

Summary:
Our SSE version of find_first_of was reading past the end of
the StringPiece in some cases, which (very rarely) caused a seg-fault
when we were reading outside of our allotted virtual address space.

Modify the code to never read past the end of the underlying buffers
except when we think it's "safe" because we're still within the same
page. (ASSUMPTION: if a process is allowed to read a byte within a
page, then it is allowed to read _all_ bytes within that page.)

Test Plan:
Added tests that verify we won't go across page boundaries.

Sadly, this code hurts our benchmarks -- sometimes by up to 50% for
smaller strings.

Reviewed By: philipp@fb.com

FB internal diff: D707923

Blame Revision: D638500

Summary:
AsyncIOOp no longer requires derivation to be able to use callbacks; the
callback is passed in.  This makes composition easier (see AsyncIOQueue, added
in this diff).

Test Plan: async_io_test, test added

Reviewed By: lucian@fb.com

FB internal diff: D709648

Test Plan: No

Reviewed By: philipp@fb.com

FB internal diff: D709795

Summary: Compilation is failing in 'opt' build

Test Plan: compile

Reviewed By: andrewjcg@fb.com

FB internal diff: D707869

Test Plan: No

Reviewed By: philipp@fb.com

FB internal diff: D707792

Summary: Minor clang compiler fixes

Test Plan: - fbmake runtest

Reviewed By: andrewjcg@fb.com

FB internal diff: D707663

Summary: It is set once, and is never changed afterwards.

Test Plan: compiled, unit tests

Reviewed By: tudorb@fb.com

FB internal diff: D706125

Summary: codemod with 'Yes to all'.

Test Plan: None really.

Reviewed By: abirchall@fb.com

FB internal diff: D693769

Test Plan: folly/io/test, both dbg and opt, standalone and in valgrind

Reviewed By: philipp@fb.com

FB internal diff: D702755

Summary: TSIA

Test Plan: Unit tests

Reviewed By: tulloch@fb.com

FB internal diff: D701890

Test Plan: async_io_test

Reviewed By: lucian@fb.com

FB internal diff: D699175

Summary:
- Add CursorBase::operator-() implementations for Cursor and BufType;
useful for figuring out the distance between two objects

Test Plan: - Used in some other code

Reviewed By: simpkins@fb.com

FB internal diff: D690046

Test Plan: ran tests in dbg

Reviewed By: tudorb@fb.com

FB internal diff: D696964

Test Plan: async_io_test

Reviewed By: delong.j@fb.com

FB internal diff: D698919

Summary:
Interface extended and cleaned up.  Also, now
actually allows you to retrieve IO errors.  Also moved some useful functions
out of Subprocess.cpp into a separate header file.

Test Plan: async_io_test, subprocess_test

Reviewed By: philipp@fb.com

FB internal diff: D698412

Summary:
1. Incorporates @tjackson's offline comments.
2. See docstrings and examples for basic usage.
3. The usecase this covers (for me and others) was where I have some map or
vector of elements, and I want to form a string representation of this (for
logging, fb303 exported values, etc.). Various uses have existed in fbcode (e.g.
UP2X shard representations), and this seemed like a useful utility.

Test Plan: unit tests.

Reviewed By: tjackson@fb.com

FB internal diff: D696794

Summary: asVector() doesn't exist.

Test Plan: Nope.

Reviewed By: tjackson@fb.com

FB internal diff: D697240

Summary: TSIA

Test Plan: Unit tests

Reviewed By: tulloch@fb.com

FB internal diff: D680177

Summary:
clang complains that the explicit specializations in dynamic.cpp
come after references in dynamic-inl.h.

Test Plan:
- built dyamic.o with clang
- built folly normally and ran unittests

Reviewed By: delong.j@fb.com

FB internal diff: D691081

Summary: adding some missing remove_reference in make_stl_allocator and is_simple_allocator

Test Plan: unit tests

Reviewed By: jon.coens@fb.com

FB internal diff: D689524

Summary:
Seems like we can drop this, as the case that motivated
adding it wouldn't have been caught by it.

Test Plan: Compiled folly/test.

Reviewed By: tudorb@fb.com

FB internal diff: D684200

Summary:
gcc seems to treat this as declaration:

RWSpinLock::UpgradedHolder ug(
RWSpinLock::WriteHolder(
RWSpinLock::ReadHolder(&lock)));

Test Plan: add LOG(INFO) to make sure the holder converstions did get executed.

Reviewed By: marcelo.juchem@fb.com

FB internal diff: D688748

Summary: fixes for clang support

Test Plan:
rm -rf ~/fbcode/_build/* && fbconfig --clang folly/test && fbmake
rm -rf ~/fbcode/_build/* && fbconfig folly/test && fbmake
_bin/folly/test/format_test
_bin/folly/test/optional_test
_bin/folly/test/has_member_fn_traits_test

Reviewed By: tudorb@fb.com

FB internal diff: D688295

Summary: ##static## handling adds ~2 more ns overhead per call (and the first call is kinda slow), but now the logic is correct now. Also inlined ##qfind_first_byte_of##.

Test Plan: unittests

Reviewed By: tudorb@fb.com

FB internal diff: D687947

Summary:
- moving simple allocator *_ptr and convenience functions to folly
- getting rid of arena_new - it encourages manually constructing smart pointers when folly::allocate_* should be used instead
- using std::allocate_shared to construct shared_ptrs, thus properly using the allocator for the ref-counter too
- fixing forwarding of parameters in the convenience functions
- uniform allocation of smart pointers using both stl and non stl-like allocators

Test Plan:
- build + tests of existing client code
- basic unit tests for arena smart pointers

Reviewed By: delong.j@fb.com

FB internal diff: D672818