Summary:
Using the formatter is always much slower than using the copy constructor (News at 11).

Comparing the two idioms for formatting out a single string input:
* the unsafe method (`format(theString)`) is (annoyingly) fastest for small strings; probably because cache-hits dominate the need to inspect every character to see if it is `{` or `}`
* the safe method (`format("{}",theString)`) is fastest on large strings (crossover at roughly 256 bytes)
* there isn't a lot in it between 64 and 512 bytes.

Reviewed By: yfeldblum

Differential Revision: D4423088

fbshipit-source-id: 7f8590653ab33fe62887a506ea79a43989fbfb29

Summary:
Add non-const iterators corresponding to existing iterator types
where it makes sense.

Reviewed By: yfeldblum

Differential Revision: D4499520

fbshipit-source-id: dc4ec583d3da1c6701805b30b25389fbf9311a7c

Summary: This allows using folly::Optional<T> in std::unordered_map and std::unordered_set.

Reviewed By: luciang

Differential Revision: D4469938

fbshipit-source-id: b86b1a4510379b337e9de83471a4aafce6d5a6cb

Summary:
Throw custom exception type when ABD fails a result because some other token did not call dispatch:
- This is useful because the caller can catch this exception and discard it if they find some other exception
- The custom exception does not give an indication of the problem. The other exception/s thrown will do that.

Reviewed By: yfeldblum

Differential Revision: D4395742

fbshipit-source-id: be80f66b1297e9faf625a2fb087590a7d0a9335d

Summary: MSVC has warning 4800 which is triggered on implicit coercions to `bool` when not in use as the condition to a control-flow statement.

Reviewed By: yfeldblum

Differential Revision: D4518465

fbshipit-source-id: 858ab9e68215a2a667cb3ea55daf51b74368174d

Summary:
This decouples the format-string-parser from the storage of the arguments to be
formatted: a static analyser can now define a class which derives from
`BaseFormatter` with no storage and use `BaseFormatter::operator()` to verify
the syntax of the format string and determine which arguments will be
referenced.

This method of allowing overrides is resolved at compile time; the benchmarks
confirm that there is no run-time difference.

Reviewed By: yfeldblum

Differential Revision: D4507689

fbshipit-source-id: f109d81ae54dc074ac363720ef6e565520435d26

Summary:
Changes are planned, this will make it easier for the new code to look good
without making the older code look weird.

Reviewed By: yfeldblum

Differential Revision: D4514839

fbshipit-source-id: 43f8cd7d85901e1915cc434a0f4b5fd6bce1ec7a

Summary:
The rest of Folly isn't dependent on C++17 mode in MSVC, so modify this to support not having it enabled.
This will make adoption easier as C++17 mode acts on the things the standard says are removed.

Reviewed By: yfeldblum

Differential Revision: D4509919

fbshipit-source-id: f4644f5f5ba78de8ab5192b89ac6320767b51084

Summary:
Callable objects may implement a separate `operator()` for when
they are called as rvalue references. For example, `folly::partial`
will move captured objects to the function call when invoked as
rvalue reference. That allows e.g. to capture pass a `unique_ptr`
to `folly::partial` for a function that takes a `unique_ptr` by
value or rvalue-reference.

Callbacks for `folly::Future`s are only ever executed once. They
may consume captured data. If the callback is an object that
implements a `operator()() &&`, then that one should be invoked.

This diff makes sure, callbacks passed to `folly::Future` are
invoked as rvalue references.

Reviewed By: ericniebler, fugalh

Differential Revision: D4404186

fbshipit-source-id: 9f33e442a634acb8797183d3d869840d85bd5d15

Summary:
`TestConnectionEventCallback` and `TestAcceptCallback` are very handy and can
be used in other tests outside folly. Specifically I'm going to use them in
`ConnectHookTest`. It'll also allow to avoid copy/paste in `TransparentTlsTest`.

Reviewed By: plapukhov

Differential Revision: D4507461

fbshipit-source-id: dfaa97e26036ebb11da17a53d4a73431a295f4d4

Summary:
environ is documented to not work very well from .dylib-s (dynamic libraries) on macOS. Use the _NSGetEnviron function instead to get a pointer to environ.

<crt_externs.h> is missing from some iOS SDKs, so forward-declare _NSGetEnviron in such cases.

Reviewed By: Orvid, mzlee

Differential Revision: D4491044

fbshipit-source-id: 886d19bdd63dea14225992446b7ba132faf35054

Summary: Currently BucketedTimeSeries does not expose enough functions to allow assessing its data, therefore there is no way to do serialization/deserialization. Adding functions/constructors to support this.

Reviewed By: simpkins

Differential Revision: D4500075

fbshipit-source-id: 656ac8a208547d8d3fadf9ea150606b6e74775c9

Summary:
Add ContainerT&& ctors to sorted_vector_map and sorted_vector_set,
to support more efficient bulk-construction of these containers. With the
prior constructors, the only way to do bulk-construction efficiently was
by using the iterator constructors with a pre-sorted range. If you didn't
have a presorted range, you would need to make a temporary container in
order to get a sorted range. Repeatedly calling insert() without a sorted
range is quadratic, hence not an option.

Reviewed By: yfeldblum

Differential Revision: D4491299

fbshipit-source-id: 041c546578f44ee6928c5506e8d8191092143b12

Summary:
The iterator constructors and the range insert() method previously
had quadratic runtime if given an unsorted range. This is now fixed. We
append the entire range to the container, sort that subrange, and merge it
into the already-sorted container. Sorting and merging is skipped when possible.

Reviewed By: yfeldblum

Differential Revision: D4493534

fbshipit-source-id: e6d73b5c19e374001f9e340ff527c5257bef2ca3

Summary:
GCC 5 doesn't recognize LOG(FATAL) as [[noreturn]],
so remove [[noreturn]] to avoid that warning and build failure.

Reviewed By: yfeldblum

Differential Revision: D4484625

fbshipit-source-id: ca129ca3a52239becd7d80f99107e64745bf8838

Summary: They were based on the signatures of the original functions as defined by MSVC. They should be based on the signatures as defined by Posix instead.

Reviewed By: yfeldblum

Differential Revision: D4471711

fbshipit-source-id: 8a6fd60ba2b326ca57058c119fc77c46f1d21d10

Summary: [Folly] Assorted cleanups for `folly/portability/BitsFunctexcept.h`.

Reviewed By: Orvid, smeenai

Differential Revision: D4492264

fbshipit-source-id: 5e85ac2ad96ef84627cc5473ec0b16c4c9b5da26

Summary: In many cases where MPMCQueue would be used, it's useful to be able to prioritize requests. This implements a thin wrapper on MPMCQueue to accomplish this (albeit in a bit of a memory inefficient way)

Reviewed By: haijunz

Differential Revision: D4465498

fbshipit-source-id: 6630b80ccf3138b5c135e7f7f281133b37d82b4d

Summary: This results in a more uniform API within Folly, allowing for a more uniform API to use outside of Folly.

Reviewed By: yfeldblum

Differential Revision: D4471471

fbshipit-source-id: f798a6498bd1a05ed12adea362ff4aedd25789ee

Summary: `clock_gettime(CLOCK_REALTIME)` is based on `std::system_clock` on Windows, but that only has a resolution that's the same as `FILETIME` (100s of nanoseconds), so modernize things and use `std::chrono::high_resolution_clock` which is intended for this purpose.

Reviewed By: yfeldblum

Differential Revision: D4476671

fbshipit-source-id: 3db1debc8f408f689b5c9fe1966a72b8dad4da93

Summary:
When start() throws because of reasons (in my case it was std::system_error("Resource temporarily unavailalble") coming from std::thread constructo)
and during the exception propagation we will have to destroy FunctionScheduler then
thread_.join() in shutdown will throw again.
This diff sets running_ after the thread is created.

Reviewed By: yfeldblum

Differential Revision: D4469816

fbshipit-source-id: cde54dfbf39f04d3ea9dfa02a65295f5440e5ea4

Summary:
Because it's impossible to require that a parameter to a function is a compile-time constant string this replaces `shellify()` with the user-defined-literal suffix `_shellify()`.

It's trivial to convert previously-correct code: `shellify("whatever {}", A)` => `"whatever {}"_shellify(A)`

The previous `folly::shellify()` API is still present as a transition measure. Compilers will issue a deprecation warning if it is used.

Reviewed By: yfeldblum

Differential Revision: D4435512

fbshipit-source-id: 6639cd91280dc72108e47a8a7775c5160a4e644f

Summary: Different deployments of don't always have access to crt_externs.h.

Reviewed By: yfeldblum, Orvid

Differential Revision: D4480621

fbshipit-source-id: f0b18d15fa253d6ba28dee68859cf9a34bf41255

Summary: Missed a `\`

Reviewed By: Orvid

Differential Revision: D4483602

fbshipit-source-id: 91451c3476756125abdbd0dd98ab9fb38bcf2c32

Summary: TestUtil is primarily a temporary file and temporary directory.  Split out the env variable manipulation into a different file.

Reviewed By: Orvid

Differential Revision: D4482071

fbshipit-source-id: 9d1a4a08010a8fad270aa56a7e1432829eb6484c

Summary: The forward declaration of `extern char ** environ` is inconsistent on some platforms.

Reviewed By: strager, Orvid

Differential Revision: D4474856

fbshipit-source-id: c73a7c7d5a247e962fab06aeb65df7815f0e3bcb

Summary: For debugging purposes, it's often extremely useful to have the duration of the expired timeout in the exception message (in case the timeout was excessively low, or to understand exactly how long the operation ran before failing due to timeout). Here we make a best effort to include the timeout when possible.

Reviewed By: yfeldblum

Differential Revision: D4476038

fbshipit-source-id: f2d0aa5e1f6367a3cfe20579c27577ab91fd8d9c

Summary: Adjusting the iteration count significantly reduces the runtime of the `TLRefCount.Stress` test to ~5 seconds. Working with that same timeframe, we can get away with increasing the iteration count of the (now tested) `RCURefCount.Stress` test to 100k, up from it's previous 10k.

Reviewed By: markisaa

Differential Revision: D4477750

fbshipit-source-id: 6a89dbb65f460655db0cb33926cc331dc1904f1c

Summary:
`folly::literals` is to `folly` what `std::literals` is to `std`.

More importantly we should be consitent;  snake_case is how other folly sub-namespaces are named, such as:

`array_detail`
`apply_tuple`
`format_value`
`threadlocal_detail`
`recordio_helpers`
`exception_tracer`

Reviewed By: ericniebler

Differential Revision: D4468281

fbshipit-source-id: de10bec74c9a38f387d62bd55da947291c23970b

Summary: It is possible to extract a MAC address from a link-local IPv6 address. This diff provides the logic for it.

Reviewed By: simpkins

Differential Revision: D4461970

fbshipit-source-id: cb4a5d774c3b4a20716d1742c961e02952ddf80d

Summary: This completely kills the environment portability header, which was among the earliest, and was created before the general convention of splitting based on the header they are in, in the standard library, existed. The functions that were defined in it are expected to be in stdlib, so move them there.

Reviewed By: mzlee

Differential Revision: D4462502

fbshipit-source-id: c4549b9d1ea623644223db4365b81507f443ad5e

Summary:
This makes a large number of implicit truncations and sign conversions into explicit casts, in preparation for eventually enabling `-Wconversion` on Folly.
This set of changes should have zero semantic change.

This focuses on the core of Folly and leaves the tests alone for the most part. A future diff will cleanup the warnings in the tests as well.

Reviewed By: yfeldblum

Differential Revision: D4454096

fbshipit-source-id: af1e1831675a804ec5679266c30c1fae62e8c35c

Summary:
HHVM uses this heavily in it's ARM JIT, so provide an implementation. With GCC & Clang this function is a no-op on x86_64 where the requirement doesn't exist, so do the same in the portability header.
This doesn't include the Windows portability header on x64 specifically because it is a very heavy header and this is currently very lightweight.

Reviewed By: yfeldblum

Differential Revision: D4451032

fbshipit-source-id: 0af57448577635f9cd690ea9b09ce46a244191e1

Summary:
This is needed if you want to test other scenarios where the
server has other OpenSSL settings.

Differential Revision: D4463587

fbshipit-source-id: ffd4019e921649dee703363b2ff028b4d8063210

Summary: `setenv`/`unsetenv` is not always declared the same way on all of the places folly is compiled.

Reviewed By: matbd

Differential Revision: D4462056

fbshipit-source-id: 6dd68f6fc5a6a435f145cbaa43bee02b5fa7170c

Summary:
The TestSSLServer is useful to have on its own for reuse. This
diff separates it out to make reuse possible.

Reviewed By: yfeldblum

Differential Revision: D4457976

fbshipit-source-id: 1fe6b71e930859ef04487e29047dcf603a79834b

Summary: HHVM compiles without `folly-config.h`, so this was preventing us from updating to the newest version of Folly.

Reviewed By: yfeldblum

Differential Revision: D4456890

fbshipit-source-id: ed118ff0cf7f254a5f99be68f171d1b34ebf5c5c

Summary: Similar to AsyncSocket, allow setting reserved sockopt after bind(). This will be recognized by intercepted accept4() call and forked sockets will properly have the TLS flag disabled.

Reviewed By: djwatson

Differential Revision: D4458831

fbshipit-source-id: fa753b9d849bd661563364d36229113f7abb0ee0

Summary:
It wasn't actually SFINAE the way it was setup previously, which meant it was just a hard error under MSVC.
Whoops.

Reviewed By: yfeldblum

Differential Revision: D4453702

fbshipit-source-id: 5be600fb5ecdc8255795fefbd37c1fe26e7266dd

Summary:
Found with our include analysis tool.

I had to tweak `portability/Environment.h` to avoid a false positive breaking win32.

Reviewed By: yfeldblum, Orvid

Differential Revision: D4452463

fbshipit-source-id: e2e862e204892037ddde8815218e4deab1bfbb06