Summary: `last` was already passed in as a variable, so switch this so there isn't a local variable at all.

Reviewed By: mlogan, yfeldblum

Differential Revision: D4615206

fbshipit-source-id: dd8e3157e54dc2abe3dfd97837ce327371f4f7b2

Summary: [Folly] Drop support for gcc 4.7 with byteswap shim

Reviewed By: igorsugak, Orvid

Differential Revision: D4610746

fbshipit-source-id: 092cd432c7bda9ca5507d0230b6fcaa43b96c500

Summary:
`previousValue` makes the incorrect assumption that `outer_`
is a multiple of the word size. This is incorrect because `skipToNext`
can reposition at an arbitrary point.

The bug is very rare because it can only happen if there is a gap
larger than the skip quantum after the first element in the upper
bits.

Reviewed By: philippv

Differential Revision: D4607270

fbshipit-source-id: ff016f09f3f1f87314b68370e3dc137b82694f45

Summary:
antonl noticed that bulk_insert doesn't remove duplicates.
We now run a std::unique() pass after merging.

Reviewed By: yfeldblum

Differential Revision: D4595304

fbshipit-source-id: 538364150aeea64b95488da158c09e07a6597e7c

Summary: `getCommonName` and `getSubjectAltName` are useful shared utility functions.

Reviewed By: anirudhvr

Differential Revision: D4546866

fbshipit-source-id: bcefc1ff3a02df93fbf0cd2d4f24569928bd1753

Summary:
dbg and dbgo builds of hhvm with gcc-5 crash when generating
backtraces using folly::Symbolizer, because the .debug_aranges for
libc-2.23.so are SHF_COMPRESSED, and folly::Symbolizer doesn't
recognize that.

Just pretend that the section doesn't exist if it has SHF_COMPRESSED
set.

We might eventually want to support decompressing such sections under
an option - but folly::Symbolizer's goal is to just mmap and walk the
debug info without allocating memory (so that it can run while
handling signals etc).

Reviewed By: pixelb

Differential Revision: D4586762

fbshipit-source-id: bef61ed670d1a80caa4f7aac1f80fd2a92cc4ba9

Summary:
Added two variants of Baton by adding two Boolean template parameters with defaults that correspond to the original single poster blocking waiter version:
- SinglePoster (single poster vs multiple posters). Default true.
- Blocking (vs spinning). Default true.

The multi-poster baton (SinglePoster = false) can be handed over by multiple concurrent posters, where redundant post()-s are idempotent but if a post() arrives after the baton is reset() then it unblocks the waiter.

The nonblocking Baton (Blocking = false) has faster common case post(), by avoiding CAS in the critical path. It does so by disallowing waiter blocking and timed_wait().

Reviewed By: nbronson

Differential Revision: D4506728

fbshipit-source-id: e5b65ad93e443fbba22164319c985ebc8424554a

Summary:
[Folly] Fix `exception_wrapper::throwException` when called before `main`.

When the `exception_wrapper` is empty, then `throwException` emits a message to `std::cerr` and terminates. If called before `main` begins or after `main` ends, then `std::cerr` might not have been constructed yet or might have already been destructed. Bad. Segfault, etc. So we need to ensure that `std::cerr` is alive by holding an instance of `std::ios_base::Init`.

Reviewed By: Orvid

Differential Revision: D4576190

fbshipit-source-id: dd84b5e82eb6bd817d405baf530714e0f4c314c5

Summary: [Folly] Drop support for Clang < 3.9.

Reviewed By: igorsugak

Differential Revision: D4567233

fbshipit-source-id: cd94c711f0390d249b6736ab292721a477022b02

Summary: MSVC 2015 has issues with templated `using` declarations using `decltype`, so adjust the definition to use constexpr evaluation to fill a template parameter of a base type instead.

Reviewed By: yfeldblum

Differential Revision: D4510155

fbshipit-source-id: cc2e33625b515085dff4e682971299810905fef0

Summary: This includes both unused parameters (W4100) and conditional expression is constant (W4127).

Reviewed By: yfeldblum

Differential Revision: D4525057

fbshipit-source-id: 7c057dbe239d02fa2e3ce96373d53814591994ec

Summary: They do the same thing, and the first is portable.

Reviewed By: yfeldblum

Differential Revision: D4569649

fbshipit-source-id: db0434766f674a7789d6e59335e122b4d2131e06

Summary: Fixed a data race between an atomic store by the waker and a nonatomic memcpy by the waiter.

Reviewed By: nbronson

Differential Revision: D4572410

fbshipit-source-id: 3982ca433e0f628636916516e35aeb7738ae030f

Summary: In D4558451 I want to pull elements off an atomic list onto a thread-local (single-consumer) vector and pop to get elements in insertion order.  A sweep that provides elements in LIFO order will avoid a redundant pair of list reversals.

Reviewed By: nbronson

Differential Revision: D4564816

fbshipit-source-id: 38cf50418e6afe0be3eec96ce85d571c65f06d7e

Summary:
`defaultNumLowerBits` is heavily used during PL encoding with
optimally-partitioned EF. This diff improves its performance by 3.5x by
avoiding expensive 64-bit division.

Reviewed By: ot, luciang

Differential Revision: D4564615

fbshipit-source-id: 4521d3c05f19573cd2c84f702fcfeaace5f98e77

Summary:
The previous mechanism in SharedPromise doesn't work if the lifetime of the
SharedPromise object ends before the Future which it was splitting is
completed.

This variation on the same theme doesn't have that problem.

Reviewed By: spacedentist

Differential Revision: D4339670

fbshipit-source-id: f619762bff1390481715575b3e638ec26b5c4edd

Summary: memcpy's src cannot be nullptr even if the size is 0.

Reviewed By: djwatson

Differential Revision: D4560100

fbshipit-source-id: 37cd3ed73f902a136f711a5c1a918258f94d1063

Summary: Intended to be used for case-insensitive prefix/suffix matching.

Reviewed By: yfeldblum

Differential Revision: D4552336

fbshipit-source-id: 0030b883426dd67bea27c3f878279359d51e1d33

Summary: Adding an interface to folly::AsyncSocket allowing to receive timestamp notifications collected using recvmsg(fd, MSG_ERRQUEUE, ...).

Reviewed By: djwatson

Differential Revision: D4329066

fbshipit-source-id: 154f5c0d04e5c0e410081d48c937af4069479fc2

Summary:
Add explicit constructors to create Range objects referring to the contents of
a std::array.

D4165608 previously added a folly::range() factory function to create Ranges
around const arrays.  However, it did not support non-const arrays.  However,
providing this as a constructor seems better.  This new constructor does not
appear ambiguous with any existing constructors, and a constructor allows for
more natural support of non-const arrays: the caller can explicitly indicate
if they want to construct a Range to const or non-const data in this case.

Reviewed By: yfeldblum

Differential Revision: D4523515

fbshipit-source-id: c1a262f9e8f76907d87d80b03f252576506e70ab

Reviewed By: lbrandy

Differential Revision: D4544705

fbshipit-source-id: d60f2026d31c94e020df51f8c887b995986ddcd7

Summary: folly/docs/Synchronized.md now reflects the fact that SharedMutex is default mutex for Synchronized

Reviewed By: yfeldblum

Differential Revision: D4529851

fbshipit-source-id: b3b8eafe908ba92e3629392fbc4b856b5a99b658

Summary:
D4499520 added typedefs to `dynamic` which made it start matching
tests for ranges/containers. However, the typedefs are unconditional on the
actual contents of the `dynamic`. This made toDynamic(dynamic) select the
range-based conversion operator, always, which immediately asserts when
trying to do range-based iteration over an Object or a primitive. Add tests
to the converters that enable/disable depending on whether the object is
already a `dynamic` and early-out in that case.

Reviewed By: mzlee

Differential Revision: D4538617

fbshipit-source-id: f3a5aafab07946a221dcead782fc27de51afa0a6

Summary:
hasher<bool> is a trivial thing, but it is useful, if we implement a hash function for a class by writing something like:
  return folly::Hash()(boolField1_, boolField2_, intField3_, boolField4_, someField5_)

Reviewed By: ot

Differential Revision: D4535563

fbshipit-source-id: 5e6672c2eeaebbbac80a8a066a6a0ec4838810f4

Summary:
EventBase and VirtualEventBase already had a loopKeepAlive() mechanism, which enabled libraries to prevent EventBase/VirtualEventBase from being destroyed until all keep-alive tokens were released.

This change adds generic keepAlive() support into folly::Executor. folly::Executors which don't support keep-alive mechanism yet, will just return a no-op KeepAlive token.

Reviewed By: yfeldblum

Differential Revision: D4516649

fbshipit-source-id: 869779621c746cb14d985aa73bc4536859914c03

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