Summary:
Allows you to construct a `Future<A>` from a `Future<B>` if A can be constructed from `B&&`.

The constructor is `implicit` if and only if `B&&` is convertible to `A`.

This is the same philosophy as Optional, and has the same use-cases.

Reviewed By: yfeldblum

Differential Revision: D5264185

fbshipit-source-id: e2fae373ab549c186a69dc5f4e32481ef7b11bba

Summary: There is no difference, as the statements are already implicitly volatile.

Reviewed By: yfeldblum

Differential Revision: D5363491

fbshipit-source-id: ab5bb878f5ca72aa0de96f82e345213729c071e2

Summary:
[Folly] In-place construction for `Try`.

Using `in_place` as the first argumenbt. Avoid move operations.

Reviewed By: Orvid

Differential Revision: D5362568

fbshipit-source-id: 5c2aaf5dba1253c59e384940add411f0f2b570b2

Summary:
[Folly] In-place construction for `Optional`.

Using `in_place` as the first argument. Avoid move operations.

Reviewed By: Orvid, ot

Differential Revision: D5362563

fbshipit-source-id: 771db2556842d5dec35d1bf2ad6c23358a417d54

Summary:
[Folly] Move `in_place` and friends to `Utility.h`.

Document that they are backports from C++17.

Reviewed By: Orvid

Differential Revision: D5362364

fbshipit-source-id: 495cb7f339fc558f20d89100c141fc7a243239d5

Summary:
[Folly] Remove `construct_in_place`.

It is an alias for `in_place`, and unnecessary.

Reviewed By: Orvid

Differential Revision: D5362354

fbshipit-source-id: 39ce07bad87185e506fe7d780789b78060008182

Summary:
[Folly] Disambiguate the various `in_place` overloads, following C++17.

Forwarding `folly::in_place` is ambiguous because there are multiple overloads and we depend on deduction to choose the correct overload. For example:

```lang=c++
enum struct Err {};
Expected<Expected<int, Err>, Err> val(in_place, in_place, 3); // fails to compile
```

So we must disambiguate the three overloads: the default, the typed, and the indexed.

C++17 defines `std::in_place`, `std::in_place_type<typename>`, and `std::in_place_index<std::size_t>`. Let us mimic that exactly, so that it becomes trivial to swap out our implementations for the standard implementations once we jump to C++17.

Reviewed By: Orvid

Differential Revision: D5362339

fbshipit-source-id: d4012b01796390e74d8c14cdf68af70102608039

Summary:
There is no way to lock a socket on Windows, so these calls will always fail. Just don't do the lock on Windows.
To do it properly with sockets, this should probably be forwarding to `sendmsg`/`recvmsg`, but this is good enough for now.

Reviewed By: simpkins

Differential Revision: D5307901

fbshipit-source-id: 9855274e932a3e2ec3cacae10363200187e0c01b

Summary: This also silences a few warnings in the stl vector tests.

Reviewed By: yfeldblum

Differential Revision: D5350383

fbshipit-source-id: 84df2a7dbfbb23ebb3f15a09f0cb58080b3e06d6

Summary: Xcode 9 is throwing errors because `-Wshadow-local` and `-Wshadow-compatible-local` are undefined in Clang.

Reviewed By: Orvid

Differential Revision: D5356476

fbshipit-source-id: 4cc9f48f796f66decb4beaa66d3e66f486449c19

Summary: Folly no longer supports GCC 4.8, so this is no longer needed.

Reviewed By: yfeldblum

Differential Revision: D5354542

fbshipit-source-id: bd9a2732f22f2176f64f92f0af6f7d59dd59a8d9

Summary: This is so we can do some magic internally.

Reviewed By: yfeldblum

Differential Revision: D5354341

fbshipit-source-id: 96abf92f4765f5ae21aa3c0dc4bcadcc22560ab5

Summary: This was breaking Windows builds.

Reviewed By: Orvid

Differential Revision: D5351468

fbshipit-source-id: 3385931b82b11d71d98861fb45efc71a632d470b

Summary: Because `#warn` isn't actually a thing.

Reviewed By: ot

Differential Revision: D5356878

fbshipit-source-id: 57751ca57e7f6aaf9f4d8be70958b9cacc4f7335

Summary: The empty file was left to stop the bleeding without breaking things. Time to remove it.

Reviewed By: mzlee

Differential Revision: D5354310

fbshipit-source-id: cd3039811cf9d7371578e4078cd7d32e3bc6d8a1

Summary: reserved

Reviewed By: djwatson

Differential Revision: D5352232

fbshipit-source-id: e3c27e22320e12bd635acb8a1b394a9de02cecfc

Summary:
- Fixed leak in hazptr_priv destruction
- Updated tests to detect leak

Reviewed By: djwatson

Differential Revision: D5351280

fbshipit-source-id: 724810cbbe0565f0cbd41f9d2121abefd98487bd

Summary: It doesn't need to exist anymore

Reviewed By: yfeldblum

Differential Revision: D5318746

fbshipit-source-id: c70b184f4b3fc12ede4632d6b3d43de16ed758c7

Summary:
Versions of gcc prior to 5.x only support C++11 constexpr functions, and
require that they consist of only a single return statement.

This updates isLogLevelFatal() to meet those requirements so that it can still
be compiled with gcc 4.9.

Reviewed By: ikobzar

Differential Revision: D5350304

fbshipit-source-id: 2a9c256236c484f8c3d5f83690fde8b7333aa4fc

Summary:
Using RSA free and removing unnecessary Bignum allocations to prevent
test failures due to memory leaks

Reviewed By: anirudhvr

Differential Revision: D5348232

fbshipit-source-id: 7c76f3dced26a3080fc82b4bacc06bc0768d6fda

Summary:
- Add support for private lists of retired objects
- Add an option for one domain
- More scalable thread cache managemnt
- hazptr_rec alignment
- FOLLY_ALWAYS_INLINE
- Refactor management of retired objects in hazptr_domain
- Refactor benchmarks

Reviewed By: davidtgoldblatt

Differential Revision: D5322646

fbshipit-source-id: 9d31582b9a8216861e7e78e2e1cd08dc11cf7f88

Summary: So we can use writeFile in projects which compile with -fno-rtti

Reviewed By: mzlee

Differential Revision: D5341469

fbshipit-source-id: bb77baf9576604ff862d54d59bf382862bd0dd58

Summary:
writeFileAtomic variants all have a mode, lets just hoist the mode parameter
up and use what was hardcoded as the default.

Reviewed By: Orvid

Differential Revision: D5341481

fbshipit-source-id: 6976915dd73d2382b42bd991782730601b918978

Summary: There's no reason these utilities should only be used by folly.

Reviewed By: mzlee

Differential Revision: D5317894

fbshipit-source-id: 5a9bdf4c5efaa5bcbe78e6723a03a468f2fe5e32

Summary:
Added getter and setter methods for the RSA struct in OpenSSL. This is
needed for compatibility between OpenSSl 1.1.0 and other versions.

Reviewed By: yfeldblum

Differential Revision: D5331948

fbshipit-source-id: ab52ffd38bb5e0bd59e058bcbc6ec6122839844e

Summary:
GCC 7 has issues with `this->` in trailing return type declarations. This takes the approach of eliminating the trailing return types entirely.

Closes https://github.com/facebook/folly/pull/621

Reviewed By: yfeldblum

Differential Revision: D5324763

fbshipit-source-id: e38ae76c13ff60bc227146c1ec25afbac8b6982f

Summary:
[Folly] Fixes for `Try::withException`.

* Fix the overload with the exception type specified so that the specified exception type is checked. A mismatch between the specified exception type and the parameter type of the passed invokable will result in the expected compiler error.
* Add an overload where the exception type is deduced intentionally, as opposed to accidentally.

Of course, these simply forward to their corresponding `exception_wrapper::withException` overloads.

Reviewed By: ericniebler

Differential Revision: D5216691

fbshipit-source-id: 7e85c906c3aa17dfede6e0980c6ac8bf75034073

Summary: As title.

Reviewed By: WillerZ, yfeldblum, ivmaykov

Differential Revision: D5312308

fbshipit-source-id: 91ad4bb39df0619f2885e13c1fda1e018292a40e

Summary:
Add attachEventBase() and detachEventBase() methods to AsyncSignalHandler,
similar to the methods of AsyncSocket.

The main benefit of this is that it allows creating an AsyncSignalHandler with
an initially null EventBase, and then attaching it to an EventBase at some
later point in time.

Reviewed By: yfeldblum

Differential Revision: D5315325

fbshipit-source-id: 8a4ca483a62ca86837ea0bb54fa9a70d59f2f04e

Summary:
Clang's UndefinedBehaviorSanitizer flagged an issue that pushAtMost() could
call `memcpy(dest, nullptr, 0)` if the input was an empty `ByteRange`.  A
default constructed `ByteRange` (or `StringPiece`) will be empty and both its
begin and end pointers will be null.  Unfortunately it is undefined behavior to
call `memcpy()` with a null source pointer even if the length is 0.

This updates the `Cursor` and `Appender` code to avoid calling `memcpy()` at
all when the input length is 0.

Reviewed By: yfeldblum

Differential Revision: D5322917

fbshipit-source-id: 67fce9579f97e7e93a5767b11cc5e43ff7be5876

Summary:
`FormatValue` holds non-integral objects by reference, which
can cause subtle problems if a formatter is constructed with temporary
arguments and used beyond the expression that constructs it.

With this diff the arguments are perfectly forwarded into a tuple, so
the formatter will take ownership of the temporaries while holding
references to lvalues as before.

The only downside is that now `FormatValue` objects are constructed
every time the formatter is used, rather than only at formatter
construction. This should not be noticeable as those objects'
constructors should just take a reference to the argument.

Note that the format string is still held by reference, but this is
fine because it should almost always be a string literal.

Reviewed By: ericniebler

Differential Revision: D5317382

fbshipit-source-id: ef8355194b634d3751ef1ccca32dd1db29e27c48

Summary: Previously, only marking it as non-blocking was supported.

Reviewed By: simpkins

Differential Revision: D5307769

fbshipit-source-id: 03ed7c35632dbc9551552b21c401ea709bd6eaaa

Summary: Edited the example function for withWLock

Reviewed By: simpkins

Differential Revision: D5322000

fbshipit-source-id: 6d95b173087dec33cfdc0d0cee9c605cdf4e2593

Summary:
[Folly] Let `make_exception_wrapper` construct on-heap objects in-place.

Currently, it constructs on-heap objects on the stack and then move-constructs them into on-heap storage.

Reviewed By: ericniebler

Differential Revision: D5315104

fbshipit-source-id: cc0493e7d98aacadd342eb56601028ced4a19bb3

Fix SharedPromise::isFulfilled doesn't get back correct value when it's running in a different thread of SharedPromise::setValue

Summary: The implementation of `SharedPromise::isFulfilled` return `hasValue_` directly without taking a lock. `isFulfilled` can be accessed concurrently, but `hasValue_` is not synchronized. Adding a lock fix the issue.

Reviewed By: yfeldblum

Differential Revision: D5319030

fbshipit-source-id: a94b12ed277aa64254680ae84cb18946226cceea

Summary: There was a circular dependency between the `detail/ThreadLocalDetail.(cpp|h)` files and `ThreadLocal.(cpp|h)`, this resolves that circular dependency by moving a couple of declarations into the detail file.

Reviewed By: yfeldblum

Differential Revision: D5318875

fbshipit-source-id: 61de7c4b3ffa30f9eb11bd97e0493e9de12c5804

Summary: This reverts commit f16634ce92ee6c299613d3db22f0537bd31ac14d

Differential Revision: D5312574

fbshipit-source-id: 1557ac17f79fb8e3530a09d69fa978ddd38e5093

Summary:
`toDelim` with a single parameter of the same type as the target type was
previously copy-constructing its result. It will now construct it with perfect
forwarding which is more efficient if the input is a temporary.

This brings `toDelim` into line with the similar implementations of `to` and
`tryTo`

Reviewed By: yfeldblum

Differential Revision: D5301427

fbshipit-source-id: 843a2d93384de88cce42f26da6562a1a6ed0dc9c

Summary: In the parameter declarations for the `gettimeofday` portability header implementation. More details on exactly why can be found in the newly added comment on the function.

Reviewed By: yfeldblum

Differential Revision: D5281301

fbshipit-source-id: 1b246adc7743b5470201e452c008418429f7f142

Summary: It's an example, not part of the main Folly library.

Reviewed By: yfeldblum

Differential Revision: D5304985

fbshipit-source-id: 7cfb95da5795af61e9307882f71836ef7fa5a463