Summary: [Folly] Simplify impl of `setThreadName`.

Reviewed By: Orvid, ot

Differential Revision: D6075179

fbshipit-source-id: 720f29cc688f97b936813898238b8eb26b8a6141

Summary: Do not set WriteFlags::WRITE_MSG_ZEROCOPY if the buffer isShared()

Reviewed By: yfeldblum

Differential Revision: D6068711

fbshipit-source-id: fff14dcd4fcb20c9dbb60794420845042518922c

Summary: [Folly] Un-templatize `Range::str`.

Reviewed By: ot

Differential Revision: D6075642

fbshipit-source-id: 08fc399c43750d34463de7634be4fe386b5db97c

Summary:
[Folly] Refactor `ShutdownSocketSet` atomic state machine.

* Format.
* Use `while` over `goto`.
* Avoid `memory_order_acq_rel` as the single-argument memory order; some platforms fail to build that.
* Use `memory_order_relaxed` for all atomic operations because stronger memory orders are not actually required: the atomic state never serves as a barrier for synchronizing loads and stores of associated data because there is no associated data.

Reviewed By: davidtgoldblatt

Differential Revision: D6058292

fbshipit-source-id: d45d7fcfa472e6e393a5f980e75ad9ea3358bab3

Summary:
[Folly] An `InlineExecutor` singleton.

Using the Leaky Meyers Singleton pattern, so that it is always available whenever required.

Differential Revision: D6074534

fbshipit-source-id: bd4c9cd6a1e60c80de5d2eef1cb6a1e7f16b4e50

Summary:
This overload of estimateSpaceNeeded was taking a Src by
value, but Src is constrained by IsSomeString which only returns
true for std::string or fbstring, so this was inducing a copy
in any situation where folly::to<> is used with varargs which
contain fb/string arguments.

Reviewed By: yfeldblum

Differential Revision: D6059517

fbshipit-source-id: adc239f9049e161fc4b750bae0e3de5dbdcd1bfc

Summary:
[Folly] Make `Range.h` and `FBString.h` mutually independent.

This means that `Range` cannot directly know about `fbstring`, so any interactions between the two types must be indirected through templates.

Motivation: `FBString.h` is a relatively heaviweight `#include` for things that need `Range.h` but which do not use `fbstring`.

Reviewed By: ericniebler

Differential Revision: D6062434

fbshipit-source-id: e2f21c33f482eadffd0a8679eff4ece59bab53e9

Summary:
[Folly] Shrink integral `hasher` specialization implementations.

Instead of giving them bodies, just use inheritance.

Reviewed By: luciang

Differential Revision: D6067757

fbshipit-source-id: f71bd36132e1b66002493474825894b03754b34f

Reviewed By: simpkins

Differential Revision: D6068742

fbshipit-source-id: a3b3b7fe4a6da8f250e5b9593f66b9f8a9345136

Summary: Closes https://github.com/facebook/folly/pull/692

Differential Revision: D6066294

Pulled By: yfeldblum

fbshipit-source-id: a533527058b8b5bc71fb6f40bad31a50e8c3f585

Summary:
[Folly] 4-way overloads for `SemiFuture::value`.

Overload on the receiver reference category and `const`-qualification, deriving the return type reference category and `const`-qualification. Like `Optional`, `Try`, etc.

Differential Revision: D6062006

fbshipit-source-id: d7396cd4d4bb62e99445d5f61cb360898fa1c3f3

Summary:
`folly/Hash.h:379:12: error: implicit instantiation of undefined template 'folly::hasher<unsigned long, void>'`
So, folly is unable to hash the very type it returns: `size_t`. Namely, folly has overloads for `uint32_t` and `uint64_t` which on my Mac map to `int` and `long long` respectively. `size_t` on the other hand maps to `long` which is neither.
Rather than overloading library types (which are just typedefs), we should overload all the built-in types: `char`, `short`, `int`, `long`, `long long`, `signed` and `unsigned` variants (with special treatment of `char`).

Reviewed By: yfeldblum, luciang

Differential Revision: D6051600

fbshipit-source-id: d59569dab963cbe0329aa589ff321cfb22308193

Summary:
Partially inspired by WillerZ's investigation into faster compiling
StringPiece work, I thought this would be an easy drop in that short
circuits some compilation logic (or possibly is strictly better, since the
StringPiece conversion method isn't constexpr).

Reviewed By: yfeldblum

Differential Revision: D6059537

fbshipit-source-id: 072f56e58aa47db10b54825cac8a05dc035b295c

Summary: folly/futures depends on folly/Random.h, which in turn depends on <random>, which is a fairly large header. Most users of folly::futures do not use retrying, so separate it into a separate header.

Reviewed By: yfeldblum

Differential Revision: D6028468

fbshipit-source-id: d8155fe2ddff1a65c265a18f040ee6f1be3f3f0a

Summary:
[Folly] Style fixes for `folly/experimental/gdb/README.md`.

Should have no effect on Github rendering, but should affect PHabricator rendering.

Reviewed By: Orvid, kennyyu

Differential Revision: D6055017

fbshipit-source-id: 54204a2b77beeb884cdc486207809f78ac80afe2

Summary: Add AsyncSocketException.cpp to the list of files to build in Makefile.am

Reviewed By: knekritz

Differential Revision: D6051989

fbshipit-source-id: 72083a609fc994770eca078bfef5a0ed04322bfc

Summary:
We recently found out that ShutdownSocketSet consumes 150+MB for our service, which uses duplex channels. The problem is that we create ~1000 of ThriftServers, and each of the creates its own ShutdownSocketSet.
In reality, ShutdownSocketSet is only needed to kill all socket's FD in emergency before crash dump is taken, so they don't hand around waiting for crash dump to complete. There is no need to keep a SSS per ThriftServer, singleton should work just fine.
There is a problem here, though. Currently a ThriftServer has 'immediateShutdown' method, which kills all sockets from SSS. So, if SSS becomes a singleton, and we have more than one ThriftServer, calling 'immediateShutdown' on one will kill sockets from the other one. First, it's a quite surprising behavior, and second, it complicates unit tests, which emulate thrift servers running in different processes.

As a result,
1. ShutdownSocketSet is created as a singleton, but each ThriftServer still keeps weak ptr to it (mostly for unit tests support).
2. replaceShutdownSocketSet method is added to ThriftServer.h, so unit tests could set different SSS for different ThriftServers.
3. method immediateShutdown is removed from ThriftServer, because its behavior would be 'surprising'.

There still may be unexpected consequences of this change for the tests because of Singleton, but let's see.

Reviewed By: yfeldblum

Differential Revision: D6015576

fbshipit-source-id: dab70dbf82d01bcc71bbe063f983e862911ceb24

Reviewed By: yfeldblum

Differential Revision: D6042832

fbshipit-source-id: c716ee672c4acfa39cab9f10f3b3f88ca770cd20

Summary: [Folly] Move `folly/Checksum.h` into `folly/hash/`.

Reviewed By: Orvid

Differential Revision: D6045825

fbshipit-source-id: 02d3e6a49e2c0fc115cfee09e1186be7a13525ba

Summary: Newer versions of clang >=3.4 support intrinsic constexpr

Reviewed By: Orvid

Differential Revision: D6008856

fbshipit-source-id: 4e40a7032464216d181d76a854cafb2ab4be1be0

Summary:
According to folly::Singleton::try_get(), https://fburl.com/23wqby9i, the caller is responsible for handling a nullptr return. In this case, we handle it poorly, via a crash both in production and debug code.

This diff opts for handling the nullptr more gracefully, via a future loaded with an exception.

Reviewed By: yfeldblum

Differential Revision: D6006864

fbshipit-source-id: e8fde57ed161b33fa1f157ce663ed85e69640c25

Summary: Add SO_ZEROCOPY support

Reviewed By: djwatson

Differential Revision: D5851637

fbshipit-source-id: 5378b7e44ce9d888ae08527506218998974d4309

Summary:
[Folly] Let `EventBase::runInEventBaseThreadAndWait` consume its argument.

Likewise `EventBase::runImmediatelyOrRunInEventBaseThreadAndWait`.

And enforce that the function is destructed before returning, so that, in the case of a wrapped lambda, all captured objects' destructors run before returning from the function.

Reviewed By: elsteveogrande

Differential Revision: D5994106

fbshipit-source-id: 816c9431a85a3d41e4fda321065614f4c18f0697

Summary:
Document that `future.then()` is identical to `future.unit()`.

Put functions next to each other to make it clear, and use identical
wording.

Reviewed By: yfeldblum

Differential Revision: D5955451

fbshipit-source-id: 1b55d5785dc0995d4d9364f48241e98ad01b31f4

Summary:
[Folly] Remove `Executor::addPtr`.

It was there to support passing non-copyable callable objects wrapped as `std::shared_ptr`. It is no longer useful since we have `Function`, which is a non-copyable version of `std::function` which can support capturing non-copyable objects, and it is generally unused.

Reviewed By: spacedentist

Differential Revision: D5983801

fbshipit-source-id: b49a86f8dd7e5250a097b0e714a1bdf9ac362916

Summary: I recently got a gcc crash when using `ConcurrentHashMap`

Reviewed By: djwatson

Differential Revision: D5994587

fbshipit-source-id: 412d48aa6da12c428bb9ab5ed7a317d89c9580b9

Summary:
Add `SocketAddress::makeFromPath(StringPiece)` static member function to
constructor `SocketAddress` from a path to Unix domain socket.

Reviewed By: yfeldblum

Differential Revision: D5974523

fbshipit-source-id: b5c1537e67d07d1ef401fea75e35753392eeaf6b

Summary:
[Folly] Use fewer keep-alives in `VirtualEventBase::keepAliveRelease`.

{D5982132} mistakenly used `VirtualEventBase::add`, which holds a keep-alive on the master `EventBase`, instead of calling `EventBase::add` directly.

(Note: this ignores all push blocking failures!)

Reviewed By: andriigrynenko

Differential Revision: D5992403

fbshipit-source-id: f427025c06f01e6a93d6eae8a051c3553f58be20

Summary: [Folly] Make `keepAliveRelease` consistent between `EventBase` and `VirtualEventBase`.

Reviewed By: elsteveogrande

Differential Revision: D5982132

fbshipit-source-id: 536d48e5672567e78786691bfb283c34d1f31960

Summary:
[Folly] Move `GlobalThreadPoolList.h` into `folly/concurrency/`.

This seems like a better place than the top-level. It seems reasonable because this has *something* to do with concurrency. This is used by executors, but is not itself an executor, so it was not clear that it should go to `folly/executors/`, although that also seems like quite the reasonable choice.

Reviewed By: Orvid

Differential Revision: D5985142

fbshipit-source-id: 6117d133757af74023d6cffb838741da83d173bd

Summary: Allows calling backlashify on a StringPiece.

Reviewed By: yfeldblum

Differential Revision: D5930015

fbshipit-source-id: ca14c78d9a90c45781da7229eb5d2f437792b2d1

Summary:
Offer a clean separation between future as a vocabulary type for crossing
library interfaces, and future as a type to manage continuations.

The principle is that if we want an API with clean separation of execution it
should both return and receive SemiFutures. The returned SemiFuture would
only be awaitable, but not continuable. If the caller wants to enqueue a
continuation then it is efficiently convertable into a folly::Future by
calling .via.

This means that an API a) Does not have to take an executor to ensure it
returns a valid future. That can be deferred to the caller or the caller's
caller/target for true separation. b) The API can ensure that its own executor
is not exposed to the caller, while still having a clean API.

Obviously if some API wants to allow returning of a continuable future, then it
can also provide an executor-taking API.

Reviewed By: yfeldblum

Differential Revision: D5769284

fbshipit-source-id: 46241d1274bf7b1698a7d28a47cff2a65a983740

Summary: Exception types should have default visibility, otherwise RTTI doesn't work right.

Reviewed By: elsteveogrande

Differential Revision: D5976415

fbshipit-source-id: 45dcfe3476b513aa49a6f78352318f31d381ada7

Summary:
[Folly] Move keepalive-acquire code into `Executor::keepAliveAcquire` overrides.

This makes the API more symmetric and allows for more flexibility. Also serves as preparation for generalizing the keepalive-token interface.

Reviewed By: andriigrynenko

Differential Revision: D5974080

fbshipit-source-id: 26209e49a0f5834ba229d4bbfc9272c2e4ffb3fd

Summary:
I couldn't find anything that consumes `--json` output, so I made this. It prints out benchmark results from two runs, comparing each benchmark to its corresponding baseline. This should help with benchmarking changes across revisions.

Along the way:
- Two small transparent `struct`s replaces the use of `tuple`s everywhere.
- New output JSON format (additive), formatted as array of arrays so order is preserved.
- New comparison binary in `folly/tools/benchmark_compare`

Sample output:

{P58307694}

Reviewed By: yfeldblum

Differential Revision: D5908017

fbshipit-source-id: d7411e22b459db16bd897f656e48ea4e896cb1bf

Summary:
[Folly] Let keep-alive tokens from `VirtualEventBase` be destroyed from any thread.

This case was missed in {D5951397} (facebook/folly@6f3b7616f3402355441c62ca60a36159435aa818).

Reviewed By: andriigrynenko

Differential Revision: D5970670

fbshipit-source-id: 19e2b00134516e68113234acd6111e21c3e23e8d

Summary: The previous change can lead to deadlock. Backing out.

Reviewed By: djwatson

Differential Revision: D5957084

fbshipit-source-id: 72ea1cb6236367912b4b087da7e4d57f8a2daed0

Summary:
Three fixes:
(1) The compiler reports UB in line 432 for the case M > HAZPTR_TC_SIZE even though it is executed only if M <= HAZPTR_TC_SIZE. Added a condition M <= HAZPTR_TC_SIZE to help the compiler determine that line 432 is not executed in that case.
(2) Added missing management of empty state in hazptr_array move operator
(3) Added nullptr argument to empty hazptr_array in Array test

Reviewed By: djwatson

Differential Revision: D5951283

fbshipit-source-id: cb8e61421ab06c7733f67bf2d2274d3311260ac4

Summary: [Folly] Let keep-alive tokens be destroyed from any thread.

Reviewed By: andriigrynenko

Differential Revision: D5951397

fbshipit-source-id: 91e72588de4ef33a730ebef5770e77635d4e93ba

Summary:
```lang=cpp
folly/test/stl_tests/StlVectorTest.cpp:1975:11: error: parentheses were disambiguated as redundant parentheses around declaration of variable named 'm' [-Werror,-Wvexing-parse]
    Vector(m);
          ^~~
folly/test/stl_tests/StlVectorTest.cpp:1975:11: note: add a variable name to declare a 'Vector' initialized with 'm'
    Vector(m);
          ^
           varname
folly/test/stl_tests/StlVectorTest.cpp:1975:5: note: add enclosing parentheses to perform a function-style cast
    Vector(m);
    ^
    (        )
folly/test/stl_tests/StlVectorTest.cpp:1975:11: note: remove parentheses to silence this warning
    Vector(m);
          ^ ~

1 error generated.
```

Reviewed By: Gownta

Differential Revision: D5955613

fbshipit-source-id: 3015570ce111603b3561914d07b55365a221c686