Summary: Exit synchronization is the worst!  The worst!

Reviewed By: @​bmaurer

Differential Revision: D2253073

Summary: This diff introduces a few breaking API changes to both EliasFanoReader and BitVectorReader in order to fix some inconsistencies:

- As initalized, `EliasFanoReader` and `BitVectorReader` held a value of `0`, thus if `0` is present in the list `skipTo(0)` would not update the position to `0`, as it happens with any other `skipTo(<first element>)`. This fixes `jumpTo` accordingly.
- `jump(i + 1)` would go at position `i`. Now `reader.jump(i)`'s postcondition is `reader.position() == i`.
- It is now illegal to retrieve `value()` from a reader in an out-of-bounds position (before-the-begin or past-the-end). Validity of a reader can be checked with `valid()`.

Reviewed By: @philippv

Differential Revision: D2420023

Summary: Promise<T> has isFulFilled. This patch adds the corresponding functionality to shared promise.

Reviewed By: @jsedgwick

Differential Revision: D2417631

Summary: This works:
  std::vector<T*> v;
  std::vector<std::unique_ptr<T>> uv(v.begin(), v.end())

Make it work for small_vector as well.

Reviewed By: @ot, @Gownta

Differential Revision: D2426919

Summary: 1) Added uniform interval distribution functionality.
2) Added a generic API for custom interval distribution algorithms.
3) Fixed an issue with removing a canceled function.
4) Did some code cleanup along the way.

Reviewed By: @​kaanb

Differential Revision: D2339911

Summary: It's easy to accidentally pass a negative value to ##take()##, which leads to underflow on conversion to ##size_t##.

Reviewed By: @​rosephilip, @philippv

Differential Revision: D2421459

Summary: [Folly] Drop support for GCC < 4.8 in folly/Conv.h.

Can't stay indefinitely backcompat with older compilers.

Reviewed By: @Gownta, @JoelMarcey

Differential Revision: D2422369

Summary: [Folly] Drop support for GCC < 4.8 in folly/test/FBStringTest.cpp.

Can't stay indefinitely backcompat with older compilers.

Reviewed By: @tudor

Differential Revision: D2422425

Summary: In some cases hinting the compiler about conditions that are guaranteed
to be true can help it generate better code. For instance, remove
unnecessary bound checks. Clang has `__builtin_assume` and on GCC we
can simulate it with `__builtin_unreachable`, so better just abstract
both into a function.

Reviewed By: @philippv

Differential Revision: D2419937

Summary: Because MSVC would try to calculate the mmapLength as a long value, which isn't correct, and MSVC issues multiple warnings if you try to do it.
Closes #289

Reviewed By: @yfeldblum

Differential Revision: D2419061

Pulled By: @JoelMarcey

Summary: Needed for boost 1.59.0 which added this as a pure virtual function
in the value_semantic base class. Fixes #314.
Closes #315

Reviewed By: @yfeldblum

Differential Revision: D2419035

Pulled By: @JoelMarcey

Summary: Declaring `extern char** environ` in `experimental/TestUtil.cpp` fixes a compilation issue on OS X 10.10.
Closes #311

Reviewed By: @yfeldblum

Differential Revision: D2419037

Pulled By: @JoelMarcey

Summary: [Folly] Dead Code: GCC-v4.6 Back Compat: folly/Chrono.h

Reviewed By: @philippv

Differential Revision: D2419086

Summary: was using the renamed/nonexistent makeTryFunction

Reviewed By: @elliottneilclark

Differential Revision: D2416178

Summary: Fix MemoryIdler::flushLocalMallocCaches() to use the correct type when querying
jemalloc's "opt.narenas" mallctl.

Reviewed By: @jobenber

Differential Revision: D2414309

Summary: Allow users to access the stack pointer and stack size

Reviewed By: @alikhtarov

Differential Revision: D2407252

Summary: makeFutureWith executes a function and returns a future containing
set to the function's return value. This diff adds a specialisation
for the case when the function returns some type Future<T>. Instead
of returning Future<Future<T>>, makeFutureWith now just passes
on the future that the function returned, which may or may not have
a value set at this time. In case the function throws,
makeFutureWith returns a Future<T> containing the exception.

With this diff, the following two lines produce equivalent results:
  auto f1 = makeFutureWith(func);
  auto f2 = makeFuture().then(func);
except for the fact that f2 requires an additional temporary
Future<Unit> to be created and destroyed.

Reviewed By: @fugalh

Differential Revision: D2388335

Summary: Erasing Cpp2Worker happens in acceptor thread but when evb is
destroyed and drains its callback queue, the callbacks may access the
worker. This moves erasing Cpp2Worer to its own evb thread, after all
callbacks are run.

Reviewed By: @yfeldblum

Differential Revision: D2398089

Summary: Universally update to jemalloc 4.0.0.

Update MALLOC_CONF/malloc_conf configuration, and use the
"arena.<i>.purge" mallctl (replaces "arenas.purge").

Reviewed By: @​bmaurer

Differential Revision: D2355602

Summary: Provide a folly interface for logging the client supported TLS signature algorithms.

Reviewed By: @siyengar

Differential Revision: D2374528

This reverts commit 37f45ee5 which should not have been pushed.

Reviewed By: @​sarals, @siyengar, @​dpittman, @​alephbax

Summary: Contains only the central implementation of the TokenBucket, without moving other files to use the new implementation.

Reviewed By: @yfeldblum

Differential Revision: D2329892

Summary: Projects depending on benchmark library fail to build with clang with the following error
```
./folly/Benchark.h:263:16: error: inline asm not supported yet: don't know how to handle tied indirect register inputs
```

I am not an expert here, just tried to take an approach similar to the MSVC compiler clause

Reviewed By: @andralex, @yfeldblum

Differential Revision: D2368670

Summary: [Folly] Fix the example for folly::static_function_deleter.

The problem is that

    int BIO_free(BIO*)

is not directly compatible.

So have two examples. One using `RSA_free` which is compatible, and one making a compatible wrapper around `BIO_free`.

Reviewed By: @Gownta

Differential Revision: D2381125

Summary: Recently default timeout logic was added to HHWheelTimer interface. This diff adds a unit test exercising this new logic.

Reviewed By: @djwatson

Differential Revision: D2376834

Summary: Don't automatically generate the main function for this test.

Reviewed By: @Gownta

Differential Revision: D2375814

Summary: - Mark all methods in AsyncUDPSocket as virtual
- Create new gmock AsyncUDPSocket: MockAsyncUDPSocket

Reviewed By: @yfeldblum

Differential Revision: D2370668

Summary: [Folly] Rename fixup from TDelayedDestruction to DelayedDestruction.

Just affects comments.

Reviewed By: @haijunz

Differential Revision: D2373364

Summary: [Folly] Rename fixup from TNotificationQueue to NotificationQueue.

    hg locate 'folly/**/*.{h,cpp}' | xargs perl -pi -e 's/TNotificationQueue/NotificationQueue/g'

Reviewed By: @haijunz

Differential Revision: D2373334

Summary: [Folly] static_function_deleter.

So you can write this:

    using BIO_deleter = folly::static_function_deleter<BIO, &BIO_free>;
    auto buf = std::unique_ptr<BIO, BIO_deleter>(BIO_new(BIO_s_mem()));
    buf = nullptr;

In place of this:

    struct BIO_deleter {
      void operator()(BIO* bio) {
        BIO_free(bio);
      }
    };
    auto buf = std::unique_ptr<BIO, BIO_deleter>(BIO_new(BIO_s_mem()));
    buf = nullptr;

Reviewed By: @alandau

Differential Revision: D2364544

Summary: Running ./configure on Fedora 21 failed until I installed some
more prerequisite packages.  Add them to the list in README.md.

Reviewed By: @markisaa

Differential Revision: D2369708

Summary: Currently HHWheelTimer requires providing an explicit timeout value every time a new timeout is scgeduled. This change adds an optional "default timeout" parameter. With this parameter set, HHWheelTimer can be used the same way as AsyncTimeoutSet. Variable timeout functionality is still available even if the default parameter is set.

Reviewed By: @djwatson

Differential Revision: D2366783

Summary: Per Boris's report.

Preparing to re-push this after fixing downstream errors.

Reviewed By: @ot

Differential Revision: D2361333

Summary: clang-3.7 upstream warns that these calls prevent a copy elision
(-Wpessimizing-move).

Reviewed By: @​mzlee

Differential Revision: D2366951

Summary: BREAKING CHANGE! Deprecate Singleton::get() and replace it with Singleton::try_get() that return smart pointer that allows to manage lifetime of a reference and prevents it from being deleted if the reference is still in use

Reviewed By: @chipturner

Differential Revision: D2268791

Summary: This reverts commit aee49bc8a945db9ad6c0ef6a9598ca5c44a4dc8c.

Temporarily reverting the previous diff to investigate possible downstream regression.

Reviewed By: @yfeldblum

Differential Revision: D2359864