Summary:
Based on diff where this was introduced in {D360195} it seems like

```
  // This value should we multiple of word size.
  static size_t const kHeapifyCapacitySize = sizeof(
    typename std::aligned_storage<
      sizeof(InternalSizeType),
      alignof(value_type)
    >::type);
  // Threshold to control capacity heapifying.
  static size_t const kHeapifyCapacityThreshold =
    100 * kHeapifyCapacitySize;
```

So anything above 100*sizeof(SizeType) should do.

Reviewed By: philippv

Differential Revision: D2871422

fb-gh-sync-id: a69e47286c53887ac05e89dab565b9d609e183a0

Summary: Folly synchronized requires disabling the shadow warning in a macro, but that doesn't work under MSVC, so abstract a mechansim out that allows them to be handled gracefully.

Reviewed By: yfeldblum

Differential Revision: D2870357

Pulled By: Orvid

fb-gh-sync-id: a4b0e425736ddd5293f020b360244554571d397f

Summary: This change adds a flag to AsyncSSLSocket which forces the socket to cache local and remote addresses right after TCP connection is established. Cached address values will be available after the connection is closed. Caching addresses can be halpful in SSL handshake failure investigations.

Reviewed By: yfeldblum

Differential Revision: D2863274

fb-gh-sync-id: d7b415292988c2fb187a80422e8ccbf8ba8ab0e3

Reviewed By: yfeldblum

Differential Revision: D2869494

fb-gh-sync-id: 889957a92dd7f59c4b9564d1946e9f4058293839

Summary: [Folly] Extract endianness checks into Portability.h.

Reviewed By: fugalh

Differential Revision: D2857924

fb-gh-sync-id: 23ecd2a3cad661024acb62769cd85df394786c59

Summary: Without this MSVC can't compile.

Reviewed By: lbrandy

Differential Revision: D2856598

fb-gh-sync-id: 0e146afe844b0ce5d3782528ed9c3de53f7c8b05

Summary:
This scripts uses fpm to build a somewhat reproducible set of debs which can be deployed to Ubuntu 14.04 hosts. The main library package carries the Folly major version number, allowing multiple versions to be installed alongside. The -dev deb is simply called libfolly-dev and will be upgraded as Folly moves forward. In accordance to the Debian packaging policies the shared libraries have their (debug) symbols stripped and saved to external symbol files, contained in the -dev deb.

sgolemon, yfeldblum you guys are my best guess to review this. Feel free to suggest additional folks if needed.

Reviewed By: yfeldblum

Differential Revision: D2806082

fb-gh-sync-id: 42605acccdec781f7a6b59a925121e6ed7c7cdf5

Summary: MSVC correctly gives an error about the constexpr constructor not initializing all members.

Reviewed By: yfeldblum

Differential Revision: D2856806

fb-gh-sync-id: cef97639906dd3c39e3d3dc2ba939021e15edcb9

Summary:
Adds a thread-safe putIfAbsent operation to the RequestContext. The current setContextData() is not sufficent to do it safely.
Just like setContextData, this method is unfair, as a high volume of reads will block the spinlock.

Reviewed By: fugalh

Differential Revision: D2850752

fb-gh-sync-id: 2ff22ea9e9bd8f27f6ae7a57214a6dbc4fdcd4c5

Summary: GCC will now dead-code eliminate the folly-based version of this test without a mechanisms to force the result to be live.

Reviewed By: ttsugriy

Differential Revision: D2854633

fb-gh-sync-id: 0e3841ed22c040fda7653bcfb5a3f19ca3d1f835

Summary: Making `EXPECT_EQ(dyn1, dyn2)` easier to debug

Reviewed By: luciang, ot, yfeldblum

Differential Revision: D2848318

fb-gh-sync-id: 0c7cdd292665a493f2b792798df4e6966c1f28db

Reviewed By: elindsey

Differential Revision: D2850760

fb-gh-sync-id: 60dbc3117e658d2fd083a87884892924bf313019

Summary:
So that these deleter and unique_ptr types don't have to be redeclared every single place they are used.
To be expanded on.

Reviewed By: mzlee

Differential Revision: D2850376

fb-gh-sync-id: e7f8bba320163b8b12a93b5cf3cd9a5921d38edc

Summary: k-th bit selection could be efficiently implemented via new BMI2 instruction set.

Reviewed By: ot, philippv

Differential Revision: D2843311

fb-gh-sync-id: 4c0cf52176a03422aef276ce5f677080f67f5fdf

Summary: StringTest.cpp is a mix of benchmarks and normal unittests. Fixing this.

Reviewed By: yfeldblum

Differential Revision: D2840804

fb-gh-sync-id: d3efc357f5f09385e9f69b70e38b64d59045ff0d

Summary: Starting with this, but I will keep digging through these. The tests will be compiled into one combined test with a single main.

Reviewed By: yfeldblum

Differential Revision: D2841391

fb-gh-sync-id: 78fd153e282f1ca2dbe7ada942dc04fc8ba5d42d

Summary: Needed to use StringPiece with boost::algorithm::trim()

Reviewed By: yfeldblum

Differential Revision: D2833657

fb-gh-sync-id: 3430b1a2540279b2f69f04c871df3bca748f2cb1

Summary: Null by itself was printing as 0, now it prints as null, which is consistent with the 'pseudo json' output.

Reviewed By: yfeldblum

Differential Revision: D2789284

fb-gh-sync-id: f318b8d0f8349f4b36f868c419842fb50bee9517

Summary: D2800746 broke buck with an unsigned/signed compare

Reviewed By: dkgi

Differential Revision: D2835102

fb-gh-sync-id: a0b8311b38a199e089d3ed5a69b12f8f8abe38b1

Summary: Added the ability for SSLContext to load X509 Certificates and private keys from memory

Reviewed By: yfeldblum

Differential Revision: D2800746

fb-gh-sync-id: 14cad74f8d761b9b0f07e2827b155cec9ba27f50

Summary:
folly::fibers have a bunch of dependencies that are shaky on mobiles.
Decoupling it by using folly::Baton instead of folly::fibers::Baton. Should have
zero effect on fbcode cases.

Reviewed By: djwatson, yfeldblum

Differential Revision: D2821603

fb-gh-sync-id: 0ce3472c9eedf97224e8584d25e04515396cd18e

Reviewed By: yfeldblum

Differential Revision: D2828789

fb-gh-sync-id: 71e45ffe31061220e06d7e7762058f8a1501b5cc

Summary:
Adding the standard preprocessor guard around the `#define
__STD_LIMIT_MACROS` in IOBuf.cpp.

public

Reviewed By: knekritz

Differential Revision: D2825816

fb-gh-sync-id: 191824ec8d1f837e2b8380a2f8451972c421ceaa

Summary: Provide a more Android compatible version of sformat.

Reviewed By: sgolemon

Differential Revision: D2825105

fb-gh-sync-id: ce328d17b9f8008d81bc7dd5bf7f0905e560dfe1

Reviewed By: yfeldblum

Differential Revision: D2816450

fb-gh-sync-id: 3d3b0bf20a3f20570f847e3c5ec91a5e3786a370

Reviewed By: siyengar

Differential Revision: D2805183

fb-gh-sync-id: 9ed320dd3762658e993daa658100d0c3c617d210

Summary:
[Folly] `SingeltonVault::ScopedExpunger` - RAII class to clear singletons.

Clears all singletons in the given vault at ctor and dtor times. Useful for unit-tests that need to clear the world.

This need can arise when a unit-test needs to swap out an object used by a singleton for a test-double, but the singleton needing its dependency to be swapped has a type or a tag local to some other translation unit and unavailable in the current translation unit.

Other, better approaches to this need are "plz 2 refactor" ....

Reviewed By: andriigrynenko

Differential Revision: D2802459

fb-gh-sync-id: c24cebd3a464ed5da29ea1d9e7b86c51d61cf631

Reviewed By: alikhtarov

Differential Revision: D2813735

fb-gh-sync-id: ab3c3e18618ed8bf15f478bcfca008786834e65c

Summary:
added functionality in Symbolizer.cpp to handle multi-segment binary and to allow symbol lookup via /proc/self/exe when some or whole text is relocated to ANON pages such as during hugification. An example of multi-segment binary : P56071432

cc markw65 - a part of the change include logic pulled from hphp/runtime/base/stack-logger.cpp:symbolize_huge_text so that hugified consumers of dumpStackTrace need not fork off.

Reviewed By: edwardc

Differential Revision: D2802837

fb-gh-sync-id: 577ab1b4ef8f22059894bfdd9c0526a22ee89ca8

Summary: `insert()` returns `fbstring` in most cases, but `iterator` (that is, `value_type*`) when the first argument is an iterator. Two overloads of `operator+` used `insert` as if it returned `fbstring`, which by chance works anyway unless the resulting string contains a `'\0'` (plus it does an extra string copy). This diff fixes the bug.

Reviewed By: philippv, luciang, Gownta

Differential Revision: D2813713

fb-gh-sync-id: 015188b72813da2dabe23980f50f00832d62aa14

Reviewed By: yfeldblum

Differential Revision: D2803911

fb-gh-sync-id: 65023cae7fd8e06c30fed100826b4b834ee2e9b1

Summary:
This PR is necessary for both Folly and HHVM to compile on PPC64 (https://github.com/PPC64/hhvm) and other platforms that are not compatible with SSE instructions.

It also removes GroupVarint32 tables generator dependency on x86 platform.
Closes https://github.com/facebook/folly/pull/339

Reviewed By: mxw

Differential Revision: D2760156

fb-gh-sync-id: b4e93b54b62d6f68ccf684d34840678f677bf276

Reviewed By: lbrandy

Differential Revision: D2803778

fb-gh-sync-id: 0cb21413bb1c78d256b4408322f8d585f53cb0ac

Summary:
Determine if the cursor can advance N bytes. This is useful if
applications want to check before reading so an exception isn't thrown.
It tries to walk the minimal amount of links needed in the chain.

I had a task that could have used this, though caching totalLength and
macro magic ended up being the implementation chosen. I think this just
adds to the cursor API.

Reviewed By: djwatson

Differential Revision: D2728498

fb-gh-sync-id: 8657653b82a48828cccab143653dc169ef715702

Summary:
SYS_gettid is different on Linux vs. OSX.  `__NR_gettid` is
only sometimes present and `SYS_gettid` is only sometimes present, but
we can pick one name and just follow that one.

Reviewed By: dcolascione

Differential Revision: D2800515

fb-gh-sync-id: 4245de4b9184ac4233ade9da297409c1031869a3

Summary: Clean up and remove unecessary gflags use.

Reviewed By: yfeldblum

Differential Revision: D2795904

fb-gh-sync-id: 99cccb4dc32a051b3d552b72cbc9243e20ba8127

Summary:
When a large number of processes concurrently bind and close `AsyncServerSocket`s with `port=0` (for example in tests) binding the IPv4 socket on the same port bound with the IPv6 socket can currently fail, because sockets are closed in the same order as they are opened, which makes the following scenario possible:

```
P0: close IPv6 port
P1: open IPv6 port (succeed)
P1: open IPv4 port (FAIL)
P0: close IPv4 port
```

This diff reverses the closing order, and also fixes a couple of outdated comments.

Reviewed By: philippv

Differential Revision: D2795920

fb-gh-sync-id: 0b5157a56dfed84aed4a590c103050a2727847b3

Summary: As above

Reviewed By: alandau

Differential Revision: D2791829

fb-gh-sync-id: 8ae5b875464dfa910b88dc12465879a9420d398c

Reviewed By: yfeldblum

Differential Revision: D2784472

fb-gh-sync-id: 84c7426cc82edabb04c662fa699764ffc0864b7e

Summary: adding GCC compatible wrappers for clang attributes to folly.

Reviewed By: yfeldblum

Differential Revision: D2706913

fb-gh-sync-id: 17db34089d48a6a01c20904321a47ff98141c2fe