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

Summary: SYS_gettid is not available on all platforms, but __NR_gettid should be.

Reviewed By: dcolascione

Differential Revision: D2787003

fb-gh-sync-id: ee024437ac95281a3573e2440653847f6f7d1738

Summary:
`dynamic` is one of the few unfortunate recursive types that have a constructor of the form `T(initializer_list<T>)`. After the Defect Report 95 (http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1467) a statement `T t = {v};` where `v` is of type `T` invokes the copy constructor instead of the initializer list constructor. Clang 3.7 implements the new behavior, and GCC probably will soon.
This diff only fixes a test where the ambiguous syntax is used, but a better solution would be preferable.

Reviewed By: philippv

Differential Revision: D2786455

fb-gh-sync-id: 7fa5235e4041cbc8dd3ce685b5a0c23c343f78d2

Summary:
D2078239 added a template method to HistogramBuckets but didn't add an instantiation for it, similar to getPercentileBucketIdx() and getPercentileEstimate() (see comment in Instantiations.cpp). This diff adds it, making `computeTotalCount()` usable without including `Histogram-defs.h`.

Also removes the weird `const` in return type.

Reviewed By: simpkins

Differential Revision: D2783534

fb-gh-sync-id: 9226489820116e0cbcb1f6a631b389439558061e

Summary: This is not used within the file.  Cleaning up.

Reviewed By: yfeldblum

Differential Revision: D2784500

fb-gh-sync-id: 60270cb20c40b79f988c5536fa00e0a0f1d08e46

Summary: Move ThreadLocal.h out of Random.h so we don't over include.

Reviewed By: yfeldblum

Differential Revision: D2770085

fb-gh-sync-id: e6934d606236c2b5cdde728639f372641ee716dc

Summary:
Fixing by deleting unnecessary macro checks - folly already requires at least g++4.8
Closes https://github.com/facebook/folly/pull/338

Reviewed By: yfeldblum

Differential Revision: D2742024

Pulled By: fredemmott

fb-gh-sync-id: c0ecc7edceeebd1f972b0be4f4740214211f1c24

Summary:
Existing scheduleThreadSafe implementation had 2 potential races on destruction:
1. (very unlikely) insertHead is complete, but fiber loop is already running on another thread, so it finishes processing all of the fibers, destroys FiberManager or EventBase or both. By the time we get to scheduleThreadSafe EventBaseLoopController is already destoyed
2. (more likely) scheduleThreadSafe is complete, but FiberManager loop which is already running, picks complete fiber, finishes the processing. After that FiberManager may be destoyed. So when EventBase actually executes the callback FiberManager is already dead.

This solution fixes both races. Holding the alive shared_ptr when completing sheduleThreadSafe assures EventBase can't be destoyed until its completed (or it won't try to schedule anything after EventBase was destroyed). Locking alive weak_ptr in the EventBase loop callback ensures FiberManager and thus EventBaseLoopController were not destroyed yet (they can be destoyed only by the same thread which is running EventBase loop).

Reviewed By: spalamarchuk

Differential Revision: D2763206

fb-gh-sync-id: 1972d6c0c11aa931747ebdaed4029a209130f69c

Summary: Add configuration for disabling unaligned reads in SpookyHashV2

Reviewed By: yfeldblum

Differential Revision: D2750885

fb-gh-sync-id: 9f48dcdfd5af05478a38e354f6fa0332b1332c14

Summary: There is an optimized assembler version of memcpy that is showing 1.5% gain on TAO, add it to folly

Reviewed By: yfeldblum

Differential Revision: D2218473

fb-gh-sync-id: d5ac7f5ab30ff6febe7e94b017766c68dbd8934d

Summary: gzip files can be easier to work with operationally than raw zlib thanks to gzip+gunzip.  zlib supports adding/stripping the gzip header; expose that through a new CodecType.

Reviewed By: chipturner

Differential Revision: D2759554

fb-gh-sync-id: 67e0f5f88e087d363db1c349cabb909fb3f00417

Summary:
Change next pick logic to use `std::discrete_distribution`.  Use folly::Random::DefaultGenerator as the generator.
Update the TARGETS to have sslcontext depend on random (which was the build break in D2741855)

Reviewed By: siyengar

Differential Revision: D2749166

fb-gh-sync-id: 7a6b400173b1e8c69a961f9e75e97d4777d5467a

Summary: this is way simpler than D2623385 + D2709121. There will be a followup diff to clean the existing per-write call BufferCallback. The new one is on per-socket basis, much straightforward. I will only setup this in HTTPUpstreamSession.

Reviewed By: afrind

Differential Revision: D2723493

fb-gh-sync-id: 6b1c21a719281b9693330b6a4074f7149d7c342a

Summary: Remove per-write buffer callback from AsyncSocket

Reviewed By: afrind

Differential Revision: D2733142

fb-gh-sync-id: 91214a8c833bbd479bf049c2bb72d660e0c30f50

Summary:
If we're going to have a constructor for it, we should have operator=.

Otherwise, gcc-4.9 goes via the copy constructor effectively "ignoring" the attempted nesting for e.g..

```
d = { other_dynamic };  // Should be ARRAY containing dynamic
```

NOTE: this only fixes gcc-4.9, there's still issues in clang.

Reviewed By: yfeldblum

Differential Revision: D2745180

fb-gh-sync-id: 667787c788fc7c131d8a34c608c355f5b875be50

Reviewed By: alikhtarov

Differential Revision: D2741459

fb-gh-sync-id: c4bd068cf735ae25364edba40960096fb35e8c43

Summary:
By default signal handlers are run on the signaled thread's stack.
In case of stack overflow running the `SIGSEGV` signal handler on
the same stack leads to another `SIGSEGV` and crashes the program
Use `SA_ONSTACK`, so alternate stack is used (only if configured via
`sigaltstack`).

Reviewed By: luciang

Differential Revision: D2747021

fb-gh-sync-id: 48388acd6147e2919412ec32acfca1ca76f22a16

Summary:
[Folly] Use `SharedMutex` as the default mutex type in `Synchronized`.

`folly::SharedMutex` is, overall, a faster mutex than `boost::shared_mutex`. Let's upgrade.

Reviewed By: nbronson

Differential Revision: D2743132

fb-gh-sync-id: e36881495e8e1002cd481607e05e555c5da19b9a

Summary: Revert D2741855

Reviewed By: mzlee

Differential Revision: D2744015

fb-gh-sync-id: b1e9b0a5ab95cb988d2b5c08c86139452b092465

Summary: Unit test showing array assignment problem on gcc 4.9

Reviewed By: lbrandy

Differential Revision: D2739900

fb-gh-sync-id: 6b0fde956672b8248fbd4e620fd112195c45c646

Reviewed By: pavlo-fb

Differential Revision: D2743230

fb-gh-sync-id: 4a52d1758a43fd103318bbe0913776340eaa6af7

Summary: There is slight drift in external deps between the TARGETS and automake files, keeping tests from linking in the 'make check' step when building folly outside of fbcode.

Reviewed By: yfeldblum

Differential Revision: D2740482

fb-gh-sync-id: ae6243f9bb112a7d2680017b3d577a1f23ef4f60

Summary: Update the protocol pick logic to use discrete_distribution

Reviewed By: siyengar

Differential Revision: D2741855

fb-gh-sync-id: 244bd087124a7a9584a1108fe8f8150093275878

Summary:
This also introduces a new try_get_fast() API which returns ReadMostlySharedPtr.
We should eventually migrate all users onto this API.

Reviewed By: elsteveogrande

Differential Revision: D2706745

fb-gh-sync-id: d558d705f431fc6147334c188fd0c6156644ba5c

Summary: With openssl-1.0.2 and later add support for ALPN.  Clients can request NPN only, but the default is to support either (client will send ALPN list, server will send NPN advertisement if ALPN is not negotiated).

Reviewed By: siyengar

Differential Revision: D2710441

fb-gh-sync-id: a8efe69e1869bbecb4ed9e0a513448fcfdb21ca6

Summary: EINTR should be retried

Reviewed By: afrind

Differential Revision: D2735879

fb-gh-sync-id: 6f25cd26e29ab8e7e13a3d63f24bf2d104c14809

Summary:
This is an experimental diff that may improve the performance of `HHWheelTimer::cancelAll`. If there are no timers to cancel, then it can bail early.

Since perflab is unlikely to be conclusive, and since this diff looks like a strict improvement, I'll proceed with landing it.

Reviewed By: djwatson

Differential Revision: D2735297

fb-gh-sync-id: 9f5a811ee6d9fa9434576e9abd3ef3443a7579b7

Reviewed By: pavlo-fb

Differential Revision: D2708425

fb-gh-sync-id: 665d077210503df4f4e8aa8f88ce5b9b277582f3

Summary: New version.

Reviewed By: cyan

Differential Revision: D2730844

fb-gh-sync-id: 4305bdfba2e8d25eba295bbf3f13a140c0d04a1c

Summary:
Mark some methods as virtual.  This makes writing some
better unit tests on the associated task possible.

Reviewed By: siyengar

Differential Revision: D2730126

fb-gh-sync-id: f79f7632e873cb218bb49883d9b53beea7bb96e7