Summary:
Move `FatalHelper.cpp` to the new folly/logging/test/helpers directory created
in D13984692.

Reviewed By: yfeldblum, dmaone

Differential Revision: D13994517

fbshipit-source-id: e2b7e4b4f649fed5b882df47424d24e4fc4f717a

Summary:
Fix a problem where `LoggerDB::get()` could crash when called after `main()`
has returned.

The `LoggerDBSingleton` object may have been destroyed already, so calling
`LoggerDBSingleton::getDB()` was not allowed.  This updates the code to just
store the singleton in a simple raw pointer, and only use the singleton helper
object for flushing log handlers.

Reviewed By: dmaone

Differential Revision: D13984692

fbshipit-source-id: a0c8550af367458ca39fefa9090e3165ad6a82bb

Summary: Judging from the number of things that needed fixing, pushmi has been busted on gcc-5 for some time.

Reviewed By: yfeldblum, kirkshoop

Differential Revision: D13979146

fbshipit-source-id: 95def0ef6289b41e116a55359476ffec91787706

Summary: It's not needed

Reviewed By: yfeldblum

Differential Revision: D13993615

fbshipit-source-id: 7e53224d39502b96e13bff352dab778df4782a1c

Summary:
[Folly] Fix `SingletonRelaxedCounter` in `T::~T()` of `ThreadLocal<T>`.

Given a type `T` which has a dtor which increments some `SingletonRelaxedCounter`, and given some use of a `ThreadLocal<T>` where, within some given thread, the only time `SingletonRelaexCounter` is incremented is in the `T` dtor, there would be a leak of the `LocalLifetime` and this leak would cause subsequent `SingletonRelaxedCounter::count()` to segfault with access to a deallocated local counter.

C++ `thread_local` destructors run before `pthread` thread-specific destructors. If a `pthread` thread-specific destructor triggers initialization of a C++ `thread_local`, then that `thread_local` will be leaked in that its destructor will never be run.

Fix this with `ThreadLocal` by detecting when `ThreadLocal` per-thread destructors have begun running. This is a larger issue with `pthread` thread-specific objects overall, but as long as we stick to using `ThreadLocal`, it can be papered over.

Reviewed By: davidtgoldblatt

Differential Revision: D13970469

fbshipit-source-id: a4c7f36d2c0d63f8f0e363ddb9d35a44b027aea6

Summary: Executor::KeepAlive<> is now implicitly constructible from Executor*.

Reviewed By: capickett

Differential Revision: D13954744

fbshipit-source-id: 523a860a337429a995152dc7171c0f6e8be8cecb

Summary: Deprecate delayedUnsafe to stop people adding it to code.

Reviewed By: yfeldblum

Differential Revision: D13949215

fbshipit-source-id: ffc4eec113964a0b247f16f3c37f3f8c69fbb0df

Summary: Update futures documentation for consistency with tag type changes.

Reviewed By: yfeldblum

Differential Revision: D13975003

fbshipit-source-id: 7015ffb8bd2b306e2dd31f6e2eb9e45b2618fa5f

Summary: Add support for microsecond timers

Reviewed By: spalamarchuk

Differential Revision: D13765262

fbshipit-source-id: ab5e2d876195a726dc654aee28cb40f695cf2277

Summary:
Basic benchmarks to validate performance of similar string
formatting functions.  Notably, `stringPrintf` is always inferior to
either format-based alternative.

```
============================================================================
folly/test/StringBenchmark.cpp                  relative  time/iter  iters/s
============================================================================
libc_tolower                                               714.38ns    1.40M
folly_toLowerAscii                                          66.03ns   15.14M
stringPrintfOutputSize(1)                                  170.06ns    5.88M
stringPrintfOutputSize(4)                                  198.54ns    5.04M
stringPrintfOutputSize(16)                                 202.94ns    4.93M
stringPrintfOutputSize(64)                                 204.82ns    4.88M
stringPrintfOutputSize(256)                                  1.32us  759.95K
stringPrintfOutputSize(1024)                                 4.47us  223.70K
stringPrintfAppendfBenchmark                                25.38ms    39.40
fmtOutputSize(1)                                           104.62ns    9.56M
fmtOutputSize(4)                                           121.50ns    8.23M
fmtOutputSize(16)                                          125.27ns    7.98M
fmtOutputSize(64)                                          125.59ns    7.96M
fmtOutputSize(256)                                         633.15ns    1.58M
fmtOutputSize(1024)                                          1.06us  939.38K
fmtAppendfBenchmark                                          8.22ms   121.71
follyFmtOutputSize(1)                                      122.76ns    8.15M
follyFmtOutputSize(4)                                      149.51ns    6.69M
follyFmtOutputSize(16)                                     148.90ns    6.72M
follyFmtOutputSize(64)                                     147.45ns    6.78M
follyFmtOutputSize(256)                                    150.71ns    6.64M
follyFmtOutputSize(1024)                                   584.94ns    1.71M
follyFmtAppendfBenchmark                                    11.39ms    87.79
BM_cEscape                                                 321.10us    3.11K
BM_cUnescape                                               290.97us    3.44K
BM_uriEscape                                                 2.99us  333.92K
BM_uriUnescape                                               1.56us  639.36K
BM_unhexlify                                               525.33ps    1.90G
splitOnSingleChar                                            1.21us  823.13K
splitOnSingleCharFixed                                     466.79ns    2.14M
splitOnSingleCharFixedAllowExtra                             0.00fs  Infinity
splitStr                                                     1.86us  536.53K
splitStrFixed                                              620.41ns    1.61M
boost_splitOnSingleChar                                      2.34us  427.23K
joinCharStr                                                947.58ns    1.06M
joinStrStr                                                 956.37ns    1.05M
joinInt                                                      2.24us  447.21K
============================================================================
```

Reviewed By: vitaut

Differential Revision: D13940303

fbshipit-source-id: a26d984cde26b1a5eb3eba1935722cdcd221fe44

Summary:
futures.h includes folly/python/executor_api.h, this header needs to be
available to downstream projects (Thrift) which use python/futures.h.
Pull Request resolved: https://github.com/facebook/folly/pull/1010

Reviewed By: Orvid

Differential Revision: D13915880

Pulled By: calebmarchent

fbshipit-source-id: 3c47fc4fe4ba425a4c12dcefd8980703765bdad5

Summary: We do not need this spammy logging.

Reviewed By: siyengar, mingtaoy

Differential Revision: D13950327

fbshipit-source-id: 6fc91d3efa27d2d88ab7571233ce04a6e28b15f7

Summary:
We're always scheduling negative timeouts to fire immediately. However, there's a branch with invalid timeout that may end up getting us into an invalid state (in particular, setting negative `expireTick_`).

To avoid that, this adds input sanitization by making sure we don't have anything negative.

Reviewed By: yfeldblum

Differential Revision: D13934881

fbshipit-source-id: 28d7dc48f57da67d3266a7f33e058ff6994eb756

Summary:
Fixes a missed r-value parameter case for exceptions passed to thenError continuations.

Adds tests to separate l-value for onError from r-value from thenError.

Reviewed By: yfeldblum

Differential Revision: D13928271

fbshipit-source-id: 0a720730d32c158fb82b61dccd0426b1fe55169f

Summary: So that the fd overload can be removed.

Reviewed By: yfeldblum

Differential Revision: D13628683

fbshipit-source-id: 5201d3ef351042ebaf2d30c3987b931f8d13d336

Summary: [Folly] `folly::chrono::abs`, backporting `std::chrono::abs`.

Reviewed By: nbronson

Differential Revision: D13584287

fbshipit-source-id: 92adbfcdac34d89674e6494af4ff3329d2f6974a

Summary:
There is a need for KeepAlive copy constructor from various users. Adding them after chatting with Andrii.
Background: move is preferred to copy as the latter does an atomic counter increment. `copy()` was introduced but there is a need for more user-friendly way of copying.
TODO: maybe get rid of `copy()` and its usages?

Reviewed By: andriigrynenko

Differential Revision: D13864057

fbshipit-source-id: 38b2e45285566a3c2dba01706e82f421285b6bae

Summary: Pull Request resolved: https://github.com/facebook/folly/pull/1006

Reviewed By: Orvid

Differential Revision: D13782299

Pulled By: calebmarchent

fbshipit-source-id: 7662c67a18c10a04d8d68e3f729da81c6df38336

Summary:
Even though this is a test, we are still reallocating a vector (resizing until re-sized/reallocated to 32), which in theory calls for allocation 5 times. But we can save this by just reserving the vector pre-hand (we know the size).
Pull Request resolved: https://github.com/facebook/folly/pull/998

Reviewed By: magedm

Differential Revision: D13834292

Pulled By: yfeldblum

fbshipit-source-id: 6b0d16ef0200184d10ba292a0b1d8d3afdadf56d

Summary: Adds functions for DH length to the compat library.

Reviewed By: yfeldblum

Differential Revision: D13584117

fbshipit-source-id: ef753d58ee400fbaf8d47f59b7d39e17380ed417

Summary:
[Folly] Apply `clang-format` to non-compliant locations (partial).

(Note: this ignores all push blocking failures!)

Reviewed By: igorsugak

Differential Revision: D13858983

fbshipit-source-id: 668c3ee209456befd3c03d85945321143da2b00a

Summary: They aren't needed

Reviewed By: yfeldblum

Differential Revision: D13855963

fbshipit-source-id: c822a4b806350ef178906401b2239a865fd77119

Summary: It was broken due to oddities with how MSVC handles expanding `##__VA_ARGS__` within the parameters to macros. Rather than deal with the pre-processor, just return the check to how it was and use `EXPECT_TRUE(false)` to achieve the same effect.

Reviewed By: yfeldblum

Differential Revision: D13850142

fbshipit-source-id: 887b39fb3c6072219c3f4748599bc7b707efbf25

Summary: [Folly] SemiFuture::deferError and Future::thenError overloads taking exception-type-carrying tag to distinguish the exception type. Solves the case where `.deferError` or `.thenError` is called on an object with a dependent type, where passing the exception type otherwise requires the `template` keyword.

Reviewed By: LeeHowes

Differential Revision: D13855497

fbshipit-source-id: 74200853043e3fdbc08419b33b959f3519d704ef

Summary: [Folly] A generic tag type for all your generic tag-related needs. With naming following the pattern of `std::in_place_t` and `std::in_place`.

Reviewed By: kirkshoop

Differential Revision: D13855499

fbshipit-source-id: 50b7e41fbbb843c6c9b766f8b66484d6aa23c167

Summary:
`value_before` looks like a pre-C++11 artifact, replace with `std::prev`.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D13852269

fbshipit-source-id: c2e4e8178754a694650f53633f099d05da4127d7

Summary:
Upgrade locks allow access concurrently with readers, so mutating the state under an upgrade lock can potentially introduce a race unless proven otherwise.
The main goal of this diff is to make the accessors to `Synchronized` state `const` under upgrade lock, as it happens under a shared lock. To achieve so, the diff changes the mechanism by which `const` is added: instead of unconditionally closing a `const Synchronized` in the `LockedPtr`, it captures the same constness as the `Synchronized`, and then the `const` decision is done at access time.

This enables having an extra method `asNonConstUnsafe()` that gives non-const access when needed without requiring a `const_cast`. This is now provided for shared locks as well.

Reviewed By: yfeldblum, aary, davidtgoldblatt

Differential Revision: D13817413

fbshipit-source-id: 8c315a925db9b1da8821984c59e55e90571b194e

Summary: [Folly] Apply `clang-format` to `folly/FBString.h`. A previous change was not properly formatted.

Reviewed By: ot

Differential Revision: D13831558

fbshipit-source-id: 318404a3a14d6969cc2aa9601e72fae6ad6cfac2

Summary: Remove duplicate code from Future::onError and have it call Future::thenError.

Reviewed By: yfeldblum

Differential Revision: D13823960

fbshipit-source-id: d2e48e4e65e30c80adbbd70ff314e1a418b7c1e2

Summary: As per Yedidya Feldblum comment on my previous diff, we need a duration cast in here.

Reviewed By: yfeldblum

Differential Revision: D13833032

fbshipit-source-id: 8819694875bd3a7e4f54102d8ac77490f8287fbb

Summary:
* Split thenError into future-returning and not-future-returning forms as we cannot rely on onError for this.
 * Move core functionality from onError into thenError to avoid thenError depending on onError.
 * Makes thenError's continuation consistent with other forms such that the parameter is passed by r-value, hence an l-value reference is no longer valid.

Reviewed By: yfeldblum

Differential Revision: D13820171

fbshipit-source-id: cf42a7d1c0759c5cfbb03f8e66a6d6988f7e10c7

Summary: This makes it easier to debug and diagnose build problems

Reviewed By: simpkins

Differential Revision: D13831342

fbshipit-source-id: 3921a05715fb00264b2e1a6e134686d68aea804d

Summary: [Folly] Cut various sites supporting MSVC <= 2015, which is insufficiently compatible.

Reviewed By: Orvid

Differential Revision: D13747631

fbshipit-source-id: 3d63d3a57258b5695b1236a81f3ddfe2f4af9cb4

Summary:
Title. This gets rid of benign TSAN lock order inversion detections.

(Note: this ignores all push blocking failures!)

Reviewed By: spalamarchuk

Differential Revision: D13820662

fbshipit-source-id: f092a988faa2cc897a1d046385e4bc4fd0422c7c

Summary: Add an HHWheelTimer-fwd.h header

Reviewed By: djwatson

Differential Revision: D13780411

fbshipit-source-id: 795352c3eeed38cd52a270ebdf5dd734604415fa

Summary:
This should allow more direct testing of changes without waiting for things to land on github first.

As part of this, to avoid a conflict between the deps that bistro downloads and those used by
the rest of the fbcode builder CI, I've updated the version of gtest used by bistro.

Reviewed By: zertosh

Differential Revision: D13802637

fbshipit-source-id: fd71bfabd2a85f4f63c21b44a1e868f2d293180a

Summary: This is useful to avoid extra allocations when integrating with code that doesn't use folly::futures.

Reviewed By: yfeldblum

Differential Revision: D13812866

fbshipit-source-id: aa76b8cda43d1a781e058f6edbe2ecb8100268de

Summary: The headers are installed, but we weren't compiling the implementation.

Reviewed By: simpkins

Differential Revision: D13778568

fbshipit-source-id: 4d297b732d1e70bbd69100f13eb68f9477d7f014

Summary: This helps avoid executor re-schedule when Future is ready.

Reviewed By: yfeldblum

Differential Revision: D13805939

fbshipit-source-id: f553c7a581882a7b53b004fd6bbb5087ea5787f8

Summary: Currently, `runOnDestruction` aims to be thread-safe; new callbacks are added to the `onDestructionCallbacks_` list while the associated mutex is held. However, the caller may own the `LoopCallback` and wish to destroy/cancel it before the `EventBase` destructor runs, and this callback cancellation is not thread-safe, since unlinking does not happen under the lock protecting `onDestructionCallbacks_`. The primary motivation of this diff is to make on-destruction callback cancellation thread-safe; in particular, it is safe to cancel an on-destruction callback concurrently with `~EventBase()`.

Reviewed By: spalamarchuk

Differential Revision: D13440552

fbshipit-source-id: 65cee1e361d37647920baaad4490dd26b791315d