Summary:
[Folly] Namespace the `UBSAN_DISABLE` symbol.

Symbols defined by Folly should typically be namespaced to Folly.

Reviewed By: igorsugak

Differential Revision: D4378401

fbshipit-source-id: ff72f5f44e7c9d1bbf08efcec24bd3dc05d10ee7

Summary:
[Folly] Backport `ceil`, `floor`, `round` from C++17 `std::chrono`.

These functions for operating on `std::chrono::duration` and `std::chrono::time_point` values are useful

Note: The implementations are derived from cppreference.com, which has a notice listing all content there as licensed under CC-BY-SA.

Reviewed By: ericniebler

Differential Revision: D4375603

fbshipit-source-id: 36a098bf5f75db071c1670518fc42bbc6df2817d

Summary:
[Folly] Keep the `std::exception*` or `std::type_info*` in `folly::exception_wrapper`.

In the case of construction with a `std::exception_ptr`. Instead of keeping a pair of `std::string`s, strictly losing information (not that we use any more information, but theoretically we could).

Of note:
* Shrinks the size of `folly::exception_wrapper`, in all cases, to 48 bytes. Down from 32 bytes + 2 S bytes on 64-bit architectures, where S is the size in bytes of `std::string`. In particular, `libstdc++`'s implementation is 32 bytes, while `libc++`'s and Folly's implementations are 24 bytes on 64-bit architectures, for total original sizes of 96 bytes or 80 bytes.
* Allows to avoid rethrowing in `with_exception` in the case of an instance constructed with an `std::exception_ptr` plus an `std::exception&`.

Reviewed By: ericniebler

Differential Revision: D4369935

fbshipit-source-id: 35155e0b271959a4878fe077fc911b17767a2358

Summary:
libc++ 4.0 and above define the throw* functions in `stdexcept`, so
Folly doesn't need to define them itself. In case those definitions are
backported to 3.9, add a Folly macro to skip the definitions regardless
of the libc++ version number.

Reviewed By: yfeldblum, Orvid

Differential Revision: D4378102

fbshipit-source-id: 674d98d7c448aa7e75bdd8b6e9fe965cd34a83d7

Summary:
[Folly] `folly::_t` and use it in `folly::exception_wrapper`.

Intended in part for use in Folly code, but can be used outside.

Instead of:

```lang=c++
namespace folly {
using original = //...
using decayed = typename std::decay<original>::type;
}
```

In C++14:

```lang=c++
namespace folly {
using original = //...
using decayed = std::decay_t<original>;
}
```

And in C++11:

```lang=c++
namespace folly {
using original = //...
using decayed = _t<std::decay<original>>:
}
```

Not perfect, but better.

HT ericniebler and https://github.com/eniebler/meta.

Reviewed By: ericniebler

Differential Revision: D4371539

fbshipit-source-id: 9046d9caab73141b95f4bce4fb1af26e0c1ac739

Summary: [Folly] 2017.

Reviewed By: Orvid

Differential Revision: D4378593

fbshipit-source-id: 4a448228bb1ddbe191b6e8562483867a399be846

Summary:
Fix this error:

  In file included from FooUtils.cpp:2:
  folly/experimental/ReadMostlySharedPtr.h:323:21: error: 'ptr_' is a private member of 'folly::detail::ReadMostlySharedPtrCore<Foo, folly::TLRefCount>'
        return impl_->ptr_;
                      ^
  ... in instantiation of member function 'folly::ReadMostlySharedPtr<Foo, folly::TLRefCount>::getStdShared' requested here:
          getSomeReadMostlySharedPtr().getStdShared();
                                       ^
  buck-out/dev/gen/folly/__default_headers__#default,headers/folly/experimental/ReadMostlySharedPtr.h:94:22: note: declared private here
    std::shared_ptr<T> ptr_;
                       ^
  1 error generated.

The added test case repro's the above error (and the changes to the class fixes it).

Alternatives include just making `ReadMostlySharedPtr` a friend class of `ReadMostlySharedPtrCore`, but that seems uglier than this fix, which was to simply use the public `getShared` method which already exists.

As luck would have it, I had tried that, and also found that a `const ReadMostlySharedPtr` would still give some trouble because `getStdShared` was not marked `const`.  Fixed that too.  (I assume if a copy of a const `shared_ptr` member / such a member of a `const` instance is permissible, then the method should be const as well.  Plus it's const in the other `ReadMostlySharedPtr` class.)

Reviewed By: djwatson

Differential Revision: D4377690

fbshipit-source-id: 8e9e778ca991fd04b0eb1e5762795d871ce0ee8d

Summary:
[Folly] Drop the `boost` dependency from `Traits.h` and `FBVector.h`.

Should not need it anymore with the currently supported compilers.

Reviewed By: ericniebler

Differential Revision: D4375572

fbshipit-source-id: df890c07f49b0499d2d2d08aa21c226b2893281e

Summary: It's only accessible within EventBase, and is never used.

Reviewed By: yfeldblum

Differential Revision: D4375541

fbshipit-source-id: a0c6d86a2b1968c37c67303c8411a23ed936d9d5

Summary: Same as D4312617 but this time not excluding source files with `#define`.

Reviewed By: soumith

Differential Revision: D4344811

fbshipit-source-id: 5a314960c319f029c6737c8c8ac8224ec2f20218

Summary:
[Folly] Drop `<boost/operators.hpp>` as a dependency of `FBVector.h`.

We can rough it.

Reviewed By: wqfish

Differential Revision: D4375986

fbshipit-source-id: 6b8c16ca9a55341fee396a253f7ad0c4d0201b0e

Summary:
[Folly] Move the traits factories up, and remove `<boost/mpl/has_xxx.hpp>`.

Also, they now generate aliases to the types aliased by `std::true_type` and `std::false_type`. So now the API is entirely compatible with the requirements of `std::integral_constant` (because it is `std::integral_constant`).

Reviewed By: wqfish

Differential Revision: D4375944

fbshipit-source-id: dfd41283f13d793f7fc1f173590cd93cdee39a10

Summary:
This expresses the intention of long predicate on OpenSSL version and
OPENSSL_NO_TLSEXT more clearly.

This also enables ALPN and SNI support when BoringSSL is in use.

ALPN is an essential function to make HTTP/2 work when building Proxygen
with BoringSSL.
Closes https://github.com/facebook/folly/pull/534

Reviewed By: Orvid

Differential Revision: D4375391

Pulled By: yfeldblum

fbshipit-source-id: 009f311bceb0ee911d904d96a3e678a5f7241575

Summary: Fix assorted missing includes.

Reviewed By: wqfish

Differential Revision: D4375902

fbshipit-source-id: 2b32631857c8f94e505153d32932cdf97d8d0b33

Summary:
Sending OOB messages allows for single byte to be sent truly out of band and placed in an OOB buffer. This byte can then be read (by default) independent from normal data.

The two test-cases validate that

(1) We can receive OOB and normal data on same socket
(2) Sending OOB byte does not affect regular data

NOTE: sending more than one byte usually means the OOB data interleaved with regular data.

Reviewed By: alandau

Differential Revision: D4370652

fbshipit-source-id: a573dae7e5afba5a4a410be5371faf4f065c74e9

Summary:
Moved decodeUtf8 -> folly::utf8ToCodePoint.
Implementation was not changed to make sure no bugs are introduced.

Reviewed By: yfeldblum

Differential Revision: D4372739

fbshipit-source-id: a015a9c47ece825e09e7c243fae454f21f99db80

Summary:
[Folly] Let `Future::then` call callbacks outside of the catch handler.

And `Future::onError`.

This makes the behavior of calls to `Future` callbacks with respect to currently-handled ("active") exceptions consistent - there will not be an active exception by the time the `Future` callback is called. (Unless `Future::then` or `Future::onError`, etc., is itself called with an active exception. Or unless the `Promise` is fulfilled, outside of the `Future` implementation code, with an active exception.)

This will affect any code which tries to call `std::current_exception()` or `throw;` from within a `Future` callback, such as an `onError` handler. That code will crash. (It was incorrect anyway, and relied on misusing Folly Futures.)

Reviewed By: ericniebler

Differential Revision: D4372173

fbshipit-source-id: 600b22e4db63c98358de29a6abcee807fbc53b0f

Summary:
[Folly] Const-correctness for `folly::exception_wrapper::with_exception` with non-`std::exception`.

This also lets us unify the various flavors of `with_exception` and `is_compatible_with`. And fix `is_compatible_with` for non-`exception` types.

Reviewed By: ericniebler

Differential Revision: D4364474

fbshipit-source-id: 417edfd45f7cfba952ce961559da67769b7c41bc

folly::TryException inherits from std::logic_error, like std::bad_optional_access; becomes no-throw copyable

Summary:
folly::TryException was inheriting from std::exception and managing its own message in a std::string data member.
That is suboptimal for the following reasons:

1) The analagous std:: type, std::bad_optional_access, inherits from std::logic_error. According to the Principle of Least
   Astonishment, folly::TryException should follow suit.
2) std::logic_error has a nothrow copy constructor. (This is typically implemented with a ref-counted string.)
   std::string does not. By explicitly managing its own message, folly::TryException picks up a throwing copy
   constructor. Exception classes should try to be nothrow copyable.
3) With most stdlib implementations, std::string is larger by a lot than the std:: exceptions. By changing
   folly::TryException as suggested, its size drops from 40 bytes to 16 on clang and gcc >=5.0.

Reviewed By: yfeldblum

Differential Revision: D4368760

fbshipit-source-id: 327f78f428419ccf9c7af3e0f57cc478d147fb37

folly::FutureException inherits from std::logic_error, like std::future_error; becomes smaller and nothrow-copy

Summary:
folly::FutureException was inheriting from std::exception and managing its own message in a std::string data member.
That is suboptimal for the following reasons:

1) The analagous std:: type, std::future_error, inherits from std::logic_error. According to the Principle of Least
   Astonishment, folly::FutureExpception should follow suit.
2) std::logic_error has a nothrow copy constructor. (This is typically implemented with a ref-counted string.)
   std::string does not. By explicitly managing its own message, folly::FutureException picks up a throwing copy
   constructor. Exception classes should try to be nothrow copyable.
3) With most stdlib implementations, std::string is larger by a lot than the std:: exceptions. By changing
   folly::FutureException as suggested, its size drops from 40 bytes to 16 on clang and gcc >=5.0.

Also, I took the liberty of fixing some copy-pastas that gave some of these exception types explicit default
constructors.

Reviewed By: yfeldblum

Differential Revision: D4367909

fbshipit-source-id: 1639d404237493f929db6116a760c2d0e599877d

Summary:
To support following code:
```
void foo(folly::FunctionRef<void(void)> callback = {}) {
  if (callback) {
    callback();
  }
}
```

Reviewed By: yfeldblum

Differential Revision: D4372296

fbshipit-source-id: 7d21e6a44b6f6b046b424f0139465511dbae7b8b

Summary: If two `SYNCHRONIZED` blocks are nested the internal `SYNCHRONIZED_*` variables can be compatible shadows (`SYNCHRONIZED_state` always is), so GCC will issue a warning with `-Wshadow-compatible-local`. This diff disambiguates the variable names for each `SYNCHRONIZED` block (as long as they appear on different lines).

Reviewed By: yfeldblum, philippv

Differential Revision: D4371263

fbshipit-source-id: b467a1a2651667c679382a1cc1eaa28f7ee4e6b3

Summary:
Enable folly to build with OpenSSL alternatives (e.g., BoringSSL).

Some SSL-related tests are disabled:

 - Async session cache ones (BoringSSL has an async cache impl but with a different API)
 - TFO tests
 - Some changes to error tests which expect specific error strings. This is
   flaky as a test because it will break everytime even within a version, so we
   should fix that first.

This should be a noop for OpenSSL 1.0.2.

BoringSSL commit used is 35c8afd3143289c99aa3820e01950c564d7aced8 (10/26/2016)

Closes: https://github.com/facebook/folly/issues/198

Reviewed By: siyengar

Differential Revision: D3280382

fbshipit-source-id: 4141d992e0d8dd797ac4af479cfe90844a23278f

Summary:
[Folly] `folly::copy`.

Usable when you have a function with two overloads:

    class MyData;
    void something(MyData&&);
    void something(const MyData&);

Where the purpose is to make copies and moves explicit without having to spell out the full type names - in this case, for copies, to invoke copy constructors.

When the caller wants to pass a copy of an lvalue, the caller may:

    void foo() {
      MyData data;
      something(folly::copy(data)); // explicit copy
      something(std::move(data)); // explicit move
      something(data); // const& - neither move nor copy
    }

Reviewed By: markisaa, ericniebler

Differential Revision: D3462023

fbshipit-source-id: 6c777be288f2a7012c1b4b46dc988890b8662595

Summary:
API of `UNSYNCHRONIZED` is confusing as if you have two nested
`SYNCHRONIZED` blocks, `UNSYNCHRONIZED` always unlocks the inner-most,
even if you pass in the variable name used in the outer `SYNCHRONIZED`
block.

The macro was marked as "deprecated" in D3526489, remove it here.

Reviewed By: yfeldblum

Differential Revision: D4371297

fbshipit-source-id: 13ddc1ff77cb3d5045844c5ade0e95dbe2bccf6d

Summary:
[Folly] A smaller implementation of `try_and_catch`.

No longer done as a derived class. This lets us make the protected members of `exception_wrapper` into private members.

Reviewed By: ericniebler

Differential Revision: D4366065

fbshipit-source-id: ae4763b55e431ac08260f74f6a23a257581247c9

Summary: Make UncaughtExceptionCounter public by moving it from folly/detail to folly. I am adding a scope performance counter that works in a similar way to SCOPE_EXIT/SCOPE_ERROR and I need the UncaughtExceptionCounter functionality.

Reviewed By: yfeldblum, ericniebler

Differential Revision: D4342783

fbshipit-source-id: a1848e89cbb6340e2ac48adabf7bf76cece1b86d

Summary: The Doxegen-generated documentation for exception_wrapper is unreadable. The code needs to be denoted with \code...\endcode tags; otherwise, it is formatted like a paragraph and newlines are ignored.

Reviewed By: igorsugak

Differential Revision: D4367636

fbshipit-source-id: 680bedfb152300d8a6287bf441dd9b81b9b94c80

Summary: folly::Random was taking the RNG by value (not reference) so it was not updating the RNG's state on each invocation -- so the RNG would not advance to the next value in the sequence.

Reviewed By: yfeldblum, nbronson

Differential Revision: D4362999

fbshipit-source-id: f93fc11911b92e230ac0cc2406151474d15f85af

Summary:
Histogram-defs.h depends on Histogram.h, so it should include it.

This missing dependency is especially annoying because users who
include both Histogram.h and Histogram-defs.h will find that
clang-format reorders the includes such that Histogram-defs.h will
be included before Histogram.h, which breaks the build.

Same for BucketedTimeSeries-defs.h and TimeseriesHistogram-defs.h.

Reviewed By: pixelb

Differential Revision: D4366282

fbshipit-source-id: 518ef315154c28beb091e5c097db2bec6eea3ba0

Summary: [Folly] Fix a wrong filename in a comment in `ExceptionWrapper.h`.

Reviewed By: pixelb

Differential Revision: D4366224

fbshipit-source-id: cab31dc0a934ae9e9714436e28c8a1a295f7d3de

Summary: Because `std::chrono` makes it clear exactly what unit of time is in use.

Reviewed By: yfeldblum

Differential Revision: D4363560

fbshipit-source-id: 47aeef21f842f39d8e886bec441897ecf1f3761b

Summary:
The hard requirement for libdwarf when building libfollyinit does not appear to be needed.

Without libfollyinit, code with calls to folly::init() won't build. Notably this is breaking build/execution of tests + examples for the Watchman C++ client in Watchman.

Reviewed By: yfeldblum

Differential Revision: D4361498

fbshipit-source-id: f3586d8cdca36eda3634663e95a4a61d879de6cf

Summary:
[Folly] Move `Thrower` into `exception_wrapper`.

It is only used by `exception_wrapper`, so it might as well be a member type.

Also, make it private. That means we need to tweak `try_and_catch`.

Since we are tweaking `try_and_catch`, tweak all similar cases.

Reviewed By: luciang

Differential Revision: D4361815

fbshipit-source-id: c5025894465a2c7760bd79dbbd272079fd34dd79

Summary:
[Folly] Move the guts of `try_and_catch` into a `detail` namespace.

Just a bit cleaner this way. Also, now we always slice before returning the derived object, so the derived type never escapes.

Reviewed By: luciang

Differential Revision: D4361471

fbshipit-source-id: 5c9567d3c5480ee9943a85139b8f27ba3b9da2d6

Summary: Updated the future interrupts example to get rid of the shared pointer circular reference problem

Reviewed By: djwatson

Differential Revision: D4360037

fbshipit-source-id: cb959929a508df4dcf3b81d01012bc55044a0b17

Summary:
As part of open-sourcing the Watchman C++ client I'm adding an (optional) dependency in Watchman to Folly. When I tried to build this client with Folly on OS X I ran into some problems using the libfolly pkg-config file. This diff addresses these issues:

1. When using `build/bootstrap-osx-homebrew.sh`, the compile config for gflags and OpenSSL are overriden. If present, these custom flags will now be propagated to `libfolly.pc`.
2. I changed the the package requirements in `libfolly.pc` from `Requires.private` to just `Requires`.

Both of these changes are needed as much of Folly's implementation is in header files. As such, consumers of libfolly need to use the same library/include paths when building.

Reviewed By: yfeldblum

Differential Revision: D4332720

fbshipit-source-id: 6a051ae318ac10bdeb4dc383a16de81f1c0327bb

Summary:
[Folly] `to_weak_ptr`.

Make a `weak_ptr` and return it from a `shared_ptr` without specifying the template type parameter and letting the compiler deduce it.

So you can write this:

    auto wptr = to_weak_ptr(getSomethingShared<T>());

Instead of this:

    auto wptr = weak_ptr<T>(getSomethingShared<T>());

Useful when `T` is long, such as:

    using T = foobar::FooBarAsyncClient;

Reviewed By: nbronson

Differential Revision: D4361276

fbshipit-source-id: 782a1d2d57b6e5823cb4018e445110098f1ce41f

Summary: `FileUtil.cpp` uses `fchmod`, which Windows doesn't have, so implement it and also include the correct portability headers for the use of `mkstemp` and now `fchmod` as well.

Reviewed By: yfeldblum

Differential Revision: D4360650

fbshipit-source-id: 300163689c54574548e7bf274a56264714d216ed

Summary:
[Folly] Add missing includes in `folly/experimental/observer`.

In particular, the missing includes of `folly/ExceptionString.h`.

Motivation.

Reviewed By: andrewjcg, nbronson

Differential Revision: D4360991

fbshipit-source-id: 4e4407669926b55d6d85df08edea70784a8f348c