Summary:
Adds bzip2 support to `folly/io/Compression.h`.
Adds bzip2 to the default set of supported codecs for the `AutomaticCodec`.

Reviewed By: yfeldblum

Differential Revision: D4873771

fbshipit-source-id: d4f4861aef7e4b9efb67095e8892c265b5ae5557

Summary:
Well, MSVC 2017 anyways.
MSVC 2017 wasn't able to handle the decltype in the type specialization, which was also entirely unnecesary.

Reviewed By: yfeldblum

Differential Revision: D4880272

fbshipit-source-id: b6deed72a12d4b58d6eca200e7287e536f94ca30

Summary:
This is a bit too magical -- it's not clear that the thing produces an Options object. If you do know that you can chain further option setters off this thing, it's nice, but otherwise, the first impression is "what just happened?".

So, let's have one good way for doing things.

Reviewed By: yfeldblum

Differential Revision: D4863947

fbshipit-source-id: 3dfe83cfc077d47f604f47dcb21149fbaa2d2243

Summary:
This operator is WRONG. It has not worked correctly for years, e.g. it lacks support for chdir, and several other options.

The operator is not really useful after C++11. Usually, you should just chain setters, e.g. `Subprocess::Options().pipeStdout().pipeStderr()`. If you must repeatedly mutate options in a fixed way, in the C++11 world you can use a lambda instead.

Reviewed By: yfeldblum

Differential Revision: D4862698

fbshipit-source-id: a2d8ace53424b9232e178cf202cf51beb7b59b12

Summary:
Since IOBuf rounds to a good malloc size, zlib and lzma waste space.
For a 4 MiB `length`, about 1 MiB of the IOBuf is wasted.

Reviewed By: yfeldblum

Differential Revision: D4872830

fbshipit-source-id: 42fc83277b2dae22b75403e0e71c43e8f2b19f21

Reviewed By: anirudhvr

Differential Revision: D4830205

fbshipit-source-id: 55f34c3bddead8a73174c403f76572248c541a10

Summary:
Template pack expansion plays much nicer when being expanded into the template parameters of a base class than it does as the template parameters to a templated `using` when under MSVC.
This fixes the other half of `folly::exception_wrapper`.

Reviewed By: yfeldblum

Differential Revision: D4874047

fbshipit-source-id: 6593d10f8737b940bd550353e54f43bc96402a48

Summary: opensource changes for t16702532

Reviewed By: yfeldblum

Differential Revision: D4846899

fbshipit-source-id: 67a610ff399e95c7cf1c9c8a5950f79bfc3aabb9

Summary: This is a follow up commit for the thread https://github.com/facebook/folly/pull/378

Reviewed By: nbronson

Differential Revision: D4860356

fbshipit-source-id: f10a0d12a593c18b1abf94da5b477c524c04f4be

Summary:
This diffs adds supports on folly::Subprocess to be able to take clone flags and
use them to call clone(2) instead of the default vfork()

I checked that all tests pass when I replace vfork with fork on trunk. So there
isn't anything built assuming the parent is paused for an execve. Correct me if
I am wrong here.

(Note: this ignores all push blocking failures!)

Reviewed By: snarkmaster

Differential Revision: D4853169

fbshipit-source-id: 7e5851df3a49996a4a5dc1945457686dd042e1f4

Summary: As per the title, this adds methods to convert IPv(46) to their inverse representation, this is useful for applications that needs to calculate the inverse arpa representation, typically used when making PTR DNS requests.

Reviewed By: Orvid

Differential Revision: D4867502

fbshipit-source-id: 190e5c309b17a633e1c97b077f212ab38725860f

Summary:
The purpose of this reimplementation of `exception_wrapper` is threefold:

- Make `exception_wrapper` smaller. It goes from 48 bytes to 24.
- Give it `noexcept` ~~copy and~~ move
- Store small exception objects in an internal buffer; i.e., with zero allocations.

The ultimate goal is to change `folly::Try<T>` to a thin wrapper over `folly::Expected<T, exception_wrapper>`. (Currently, it stores the `exception_wrapper` on the heap.)

As part of this redesign, I:

- Remove `exception_wrapper::getCopied`. The user shouldn't care how the `exception_wrapper` stores the exception.
- Remove `exception_wrapper::operator==`. It was only used in 2 places in test code. The existing semantics (return true IFF two `exception_wrapper`s point to the //same// exception object) prevented the small-object optimization.
- Add new `handle()` API that behaves like cascading `catch` clauses. For instance:
```lang=c++
exception_wrapper ew = ...;
ew.handle(
    [&](const SomeException& e) { /*...*/ },
    [&](const AnotherException& e) { /*...*/ },
    [&](...) { /* catch all*/ }, // yes, lambda with ellipses works!
```
- Add a `type()` member for accessing the `typeid` of the wrapped exception, if it's known or can be determined with a `catch(std::exception&)`.

This table shows the percent improvement for the exception_wrapper_benchmark test:

| Test  | Percent improvement (gcc-5)  | Percent improvement (gcc-4)
| -----  | -----  | -----
| exception_wrapper_create_and_test  | 14.33%    | -6.50%
| exception_wrapper_create_and_test_concurrent | 11.91% | 20.15%
| exception_wrapper_create_and_throw | -0.82% | -0.25%
| exception_wrapper_create_and_cast | 15.02% | 14.31%
| exception_wrapper_create_and_throw_concurrent | 18.37% | 8.03%
| exception_wrapper_create_and_cast_concurrent | 28.18% | -10.77%

The percent win for gcc-5 is 15% on average. The non-throwing tests show a greater win since the cost of actually throwing an exception drowns out the other improvements. (One of the reasons to use `exception_wrapper` is to not need to throw in the first place.) On gcc-4, there is roughly no change since the gcc-4 standard exceptions (`std::runtime_error`, std::logic_error`) are non-conforming since they have throwing copy operations.

Reviewed By: yfeldblum

Differential Revision: D4385822

fbshipit-source-id: 63a8316c2923b29a79f8fa446126a8c37aa32989

Summary: On Windows, the OpenSSL headers have to be included in a specific order relative to WinSock. Fixing the issues ad-hock is not a viable way to continue, so treat it as completely non-portable and require all includes of it in Folly to go through the portability header.

Reviewed By: yfeldblum

Differential Revision: D4856858

fbshipit-source-id: 56aca1fb0fe095f41a8af12488c6c2080344603d

Summary:
It doesn't exist on OSX or Windows, so implement it.

Closes https://github.com/facebook/folly/issues/567

Reviewed By: yfeldblum

Differential Revision: D4783463

fbshipit-source-id: 0a2586aced7123b797a8e55a3e86124b449634e4

Summary: TSAN has a limitation for the number of locks held concurrently - https://github.com/llvm-mirror/compiler-rt/blob/master/lib/sanitizer_common/sanitizer_deadlock_detector.h#L126, so we have to work around that.

Reviewed By: yfeldblum

Differential Revision: D4866477

fbshipit-source-id: 958251e97d91c1c46ef4e907de2cf189fb04f88e

Summary: facepaw

Reviewed By: yfeldblum

Differential Revision: D4856227

fbshipit-source-id: 17a73d4d630c6efe1763bbd8aff8b7a2c7721c27

Summary: This reverts commit a80aabb5a223264746ab45e3138d065bce5fe99c

Differential Revision: D4832473

fbshipit-source-id: 1a78d61f3f09f1064876a786c15601a091f4402b

Summary: Cleanup: remove superfluous std::move for return values.

Reviewed By: yfeldblum

Differential Revision: D4856421

fbshipit-source-id: bf2cb66f3b43eb8f3b183e22b0acd31e0a0c0958

Summary:
`std::max(uint64_t, size_t)` was called.
Fixes https://github.com/facebook/folly/issues/576.

Reviewed By: Orvid

Differential Revision: D4861336

fbshipit-source-id: 1b6f67b291451048ba79d638d2c1184f9245dc0c

Summary: I landed a change to Folly that used a feature I had just re-written in Folly without updating the change. This has broken everything. Whoops.

Reviewed By: yfeldblum

Differential Revision: D4861562

fbshipit-source-id: 05beadbe233d1fdf90fb4435e65b718cdec7f63e

Summary:
It was defining the same functions as OpenSSL, but it was putting them in the `folly::ssl` namespace and requiring a manual `use namespace` everywhere to actually be able to use it. Proper portability headers require no interaction to function correctly other than including them in the build.
This adjusts it so including it is all that is required to get an OpenSSL 1.1.0 compatible API.
This also re-organizes the code to significantly lower the amount of nesting in the `#if`'s, and puts it in order from oldest APIs to newest, rather than haphazard.

Reviewed By: yfeldblum

Differential Revision: D4856784

fbshipit-source-id: 7c00fdf4a3e51e37287d2b1ef294046f38a96a43

Summary:
Use RequestChannel to construct Thrift Clients.

use folly/python/futures.h to marry up thrift client rpc futures to
asyncio futures. No gil exchanges

py3 clients are async context managers now.

Reviewed By: ambv, yfeldblum

Differential Revision: D4639677

fbshipit-source-id: 6b400747507446882d3cfcb1cf7e85c3daa07a2e

Reviewed By: yfeldblum

Differential Revision: D4856138

fbshipit-source-id: 19eee4f8c4108ef168d82d5e9b1f2d65ff9b03bd

Summary: Currently clang-format cannot be run on any file using the macro because it breaks it. By putting the warning name in a string clang-format no longer breaks it.

Reviewed By: yfeldblum

Differential Revision: D4856945

fbshipit-source-id: ebd2d223dd97f66224e9e2912610057e36287dae

Summary:
[Folly] All template params for `PriorityMPMCQueue`.

Mimic the suite of template params of `MPMCQueue`.

Reviewed By: magedm

Differential Revision: D4857179

fbshipit-source-id: 3d441099c46ea1223155bd3f4cc819595814c47b

Summary: When including OpenSSL on Windows, the portability header must be included before including any OpenSSL headers.

Reviewed By: yfeldblum

Differential Revision: D4856376

fbshipit-source-id: a8e6533b2ba3c003314ae2426605031fa67be05f

Summary: MSVC doesn't allow non-static locals to be accessed within a non-capturing lambda, and some were introduced into the json code.

Reviewed By: yfeldblum

Differential Revision: D4856242

fbshipit-source-id: b2db36ca37a79a41237d39cc7e7b839a5416922f

Summary: `EliasFanoCompressedList` requires explicit freeing.

Reviewed By: lbrandy, philippv, yfeldblum, luciang

Differential Revision: D4855200

fbshipit-source-id: ccee44b6371ae743ef15a72af9b691d5b56e37c2

Summary: Because these `atomic<int>` are referenced in the destructor of the `ReadMostlyMainPtr`, they must be declared before it, otherwise they are destroyed before it i.

Reviewed By: yfeldblum

Differential Revision: D4854964

fbshipit-source-id: 625a8f890bba166b682ca13558f8bcde86edcc75

Summary: This test actually stores references to `sum` in objects it puts into the `EvictingCacheMap`. Those references get accessed in the destructor of the objects, which is the destructor of the `EvictingCacheMap`. That means the `sum` variable must outlive (and be declared -before-) the `EvictingCacheMap` it's testing.

Reviewed By: yfeldblum, meyering

Differential Revision: D4854619

fbshipit-source-id: b0a3109278f48d10b4cd0c52a12cb2064f4a00c5

Summary:
D4406876 replaced EVP_MD_CTX and HMAC_CTX on the stack with heap-allocated
versions. We omitted the _cleanup functions thinking those didn't actually free
anything, but turns out HMAC_CTX_cleanup internally calls EVP_MD_CTX_cleanup
which OPENSSL_frees a bunch of stuff.

Reviewed By: yfeldblum

Differential Revision: D4850388

fbshipit-source-id: 4ef1413a4105f3638140e4d12aeae64afe43f099

Summary: Make sure that the last use of `s6` is sequenced before it is moved-from.

Reviewed By: nbronson

Differential Revision: D4850480

fbshipit-source-id: 5272c14475ae2c62bc613cfd54f5df482b19d3dc

Summary: The problem with catching the exception here is stack information is lost.  Just let it std::terminate if it throws

Reviewed By: ikobzar

Differential Revision: D4831909

fbshipit-source-id: 42139bd7caee0fedff13328d52fa3be1c517e730

Summary: Improve error message and change DFATAL to FATAL.

Reviewed By: yfeldblum, meyering

Differential Revision: D4837840

fbshipit-source-id: 54ae53c9356fc2e85266b037996aa7b2bae3d4e4

Summary:
Benchmark each type with its native key type and with its non-native key type.
This allows you to make a more-informed decision about which to use based on
the types you have available at insertion/lookup time.

Reviewed By: yfeldblum

Differential Revision: D4826527

fbshipit-source-id: ee4ef5255d2bdd955e9deb30dc4c28be183cee07

IndexedMemPool: Fix race condition on size_ that can cause the destructor to access nonexistent slots

Summary:
Contention on allocation when there is exactly one slot remaining can cause size_ to exceed actualCapacity_.
Without taking the min of size_ and actualCapacity_ the destructor may try to destroy out-of-bound slots.

Added a test to test/IndexedMemPoolTest.cpp that failed before the fix and passes after the fix.

Reviewed By: nbronson

Differential Revision: D4837251

fbshipit-source-id: a887487727f17eaf2ba66345f40fc91d2fe3bc00

Summary: There's a comment in that code that states that it *it* noexcept, and that is common for most folly async io callbacks.

Reviewed By: yfeldblum

Differential Revision: D4831800

fbshipit-source-id: 78894ad72504b9dfe540c14b8d7bbb29247aaf87

Summary:
Add trimAtMost start and trimAtMost end.
These are useful functions to have if you
don't care about trimming an exact amount.

Reviewed By: yfeldblum

Differential Revision: D4658087

fbshipit-source-id: f7dd62c0f4837503e59cdec75fdad433be20306c

Summary:
Implementing `clearenv()` correctly on multiple OS's without relying on underlying implementation details is significantly more complicated, and this is preventing being able to build on OSX.
This function isn't actually used anywhere currently.

Reviewed By: yfeldblum

Differential Revision: D4832473

fbshipit-source-id: a80aabb5a223264746ab45e3138d065bce5fe99c

Summary: fixing D4825412

Reviewed By: lbrandy

Differential Revision: D4826815

fbshipit-source-id: 94691ff293dad53b16e7a2f139c1df490a61e565