Summary:
The refcounting logic is correct, however, decreasing the next node's
refcount only happens in ~NodeT, after going through hazptr bulkReclaim.

The current default for bulkReclaim is 1k, which exceeds the value of
refcount uint8_t.  Increase size to uint16_t so that we don't wrap refcount
before bulkReclaim calls the node destructors.

Reviewed By: magedm

Differential Revision: D6900530

fbshipit-source-id: 9b2530dc6cd0609b4795b909fd46aeffbb1ae821

Summary:
Now that we have Travis CI builds enabled and passing, add a link to the build
status to the README.

Reviewed By: yfeldblum

Differential Revision: D6903206

fbshipit-source-id: 643b72a63a4113e00ff1602b1c3638384115b23d

Summary:
Allow retrieving sub-tree from folly::dynamic using JSON pointer syntax (RFC6901). This adds new overload for the `get_ptr` method, retrieving raw pointer to a sub-tree, or returning `nullptr` if element is not found.

The `folly::dynamic` implementation traverses the path specified by JSON pointer string dynamically every time, since the underlying object may change, and JSON pointer traversal depends on the underlying object structure. E.g. "123" could be a key name for `dynamic::object` and index in `dynamic::array`.

Reviewed By: yfeldblum

Differential Revision: D6790515

fbshipit-source-id: bb6ea10acb83673e87721cf1e5a02506b44bb273

Summary: Debian 8.6 comes with a CMake version that is too old for folly. Add commands to update cmake.

Reviewed By: snarkmaster

Differential Revision: D6842797

fbshipit-source-id: 22f4c407f82a92c3fa90a5c2de334cf8b92e584b

Summary:
Unfortunately it looks like D6880256 was not sufficient to make
function_scheduler_test pass reliably on Travis CI builds.  This just disables
function_scheduler_test on open source CMake-based builds for now.

Ideally in the future we should try to convert most of the function scheduler
to use proper synchronization mechanisms (like folly::Baton) for synchronizing
between threads, rather than sleeping and expecting the other thread to have
completed its work before we wake up.

Reviewed By: yfeldblum

Differential Revision: D6891889

fbshipit-source-id: 9ee98f5807e1d90f083bd942ba98df6fad656ba6

Summary:
The XLOG() macros compute the log category based on the source file name, as
defined by `__FILE__`.  Both gcc and clang set the `__FILE__` contents to the
file name passed in on the command line, so if they are invoked with absolute
path names `__FILE__` will contain an absolute path.  This is normally
undesirable for `XLOG()` behavior.  Furthermore, CMake always invokes the
compiler with absolute path names, so it is difficult to avoid this situation
in open source builds.

This adds support for a `FOLLY_XLOG_STRIP_PREFIXES` macro.  This can be defined
to a string containing a colon-separated list of directory prefixes to strip
from `__FILE__` before using it to compute the log category name.  If
`FOLLY_XLOG_STRIP_PREFIXES` is not defined then the code continues to use
`__FILE__` as-is.

Reviewed By: yfeldblum

Differential Revision: D6868773

fbshipit-source-id: a5c3276d8d22d3b27ae621700a75b1362d049292

Summary:
Many of the tests in FunctionSchedulerTest appear to frequently fail on
Travis CI builds.  It looks like this is probably due to timing issues where
events do not fire within the expected time interval.

This diff increases the `timeFactor` value to hopefully make the tests more
reliable, at the expense of making them take longer to run.

It would be nicer if we had a better solution here that did not involve
potentially unreliable timing-dependent checks.  Increasing `timeFactor` seems
like the easiest solution in the short-term though, and avoids just disabling
the tests entirely.

Reviewed By: yfeldblum

Differential Revision: D6880256

fbshipit-source-id: 59da3b20f2bb9c982834752942a984e3f91442fd

Summary:
Most of the tests in FunctionSchedulerTest sleep for lengths of time based on
the timeFactor constant set at the top of the file.  However a couple of places
that need to sleep for non-integral timeFactor durations used manual `usleep()`
calls instead.  This made the tests break if you change the `timeFactor` value.

This changes `delay()` to accept floating point numbers, and updates the tests
that were using hard-coded `usleep()` calls to use `delay()` instead.

Reviewed By: yfeldblum

Differential Revision: D6880258

fbshipit-source-id: 0cfdf84d3ba27aa2acd1f5210becbc7306b857bf

Summary:
Most of the tests in FunctionSchedulerTest update a variable in one thread (the
FunctionScheduler thread) and then check its value in the main thread.  These
previously were not using any synchronization between the threads.  This fixes
them to use `std::atomic` to ensure proper synchronization.

Reviewed By: wez

Differential Revision: D6880254

fbshipit-source-id: facfbdf06312f731c64389fb4382b5cb078b76b9

Summary:
Hi! I noticed this repo could use some documentation to help new contributors.

**why make this change?:**
Regarding the `CONTRIBUTING.md` -> Including instructions for new contributors to open source is a courtesy that will foster a welcoming and safe open source community at Facebook.

Regarding the Code of Conduct ->

Facebook Open Source provides a Code of Conduct statement for all
projects to follow, to promote a welcoming and safe open source community.

Exposing the COC via a separate markdown file is a standard being
promoted by Github via the Community Profile in order to meet their Open
Source Guide's recommended community standards.

As you can see, adding this file will improve [the folly community profile](https://github.com/facebook/folly/community)
checklist and increase the visibility of our COC.

Closes https://github.com/facebook/folly/pull/719

Reviewed By: flarnie

Differential Revision: D6881011

Pulled By: simpkins

fbshipit-source-id: a6f0988ac2b49f81bb13d3219095105b7b27e66f

Summary: Add a constexpr implementation of `strcmp()`

Reviewed By: yfeldblum

Differential Revision: D6881816

fbshipit-source-id: 08a9e5ab9ef4a422ff6d004ec13b8ec8c71b0d6f

Summary:
- Use `FOLLLY_HAS_FEATURE(cxx_constexpr_string_builtins)` to check for the
  availability of `__builtin_strlen()` on clang, as recommended by the clang
  documentation (https://clang.llvm.org/docs/LanguageExtensions.html)
- Only use `std::strlen()` on gcc, rather than having checks to exclude all
  other compilers.  `strlen()` happens to be constexpr on gcc, but this is not
  required by the standard and cannot be assumed to be true in general.

Reviewed By: yfeldblum

Differential Revision: D6881815

fbshipit-source-id: 88c614419ae390464893087513dc764b0bfddfb8

Summary:
This test has been failing in travis because it is missing test/certs/tests-cert.pem
Mark it as a content dir

Reviewed By: yfeldblum

Differential Revision: D6884000

fbshipit-source-id: c7d42a4b23334781de28f1586ecbde04aea74ff2

Summary:
Update the build steps in the README to build using cmake instead of autoconf
on Linux platforms.

I haven't updated the instructions for Mac OS X or the
`bootstrap-osx-homebrew.sh` script primarily because I have not tested the
steps on Mac.  It sounds like the build is close to working on Mac, but
currently fails due to missing compiler flags to disable some warnings on
clang.

Reviewed By: akushner

Differential Revision: D6780814

fbshipit-source-id: 9c9c211c306d5b35235549ae451bb620098f37e3

Summary:
Update the CMake build process to always invoke test programs from the root of
the repository.  This makes the CMake build consistent with how we run tests
internally at Facebook.

Reviewed By: yfeldblum

Differential Revision: D6880257

fbshipit-source-id: 4c27cc643faa21d9c26faf8c77f6700ec5fe6393

Summary: DeferredExecutor suffered from a case where boosting would not work if no work was present. This change modifies is so that on a call to via the next executor will be set in the DeferredExecutor. When add is called the callback will be stored. Whichever happens second actually enqueues the work on the chained executor. get uses via to correctly implement this.

Reviewed By: andriigrynenko

Differential Revision: D6663244

fbshipit-source-id: 74600d511373e0f6f7ca4128f25f3947a4981200

Summary: Android also has limited support for thread_local so we should not enable it at all as a precaution

Reviewed By: magedm

Differential Revision: D6884145

fbshipit-source-id: f39dd8fd5405ca0bc5be9b3538718a6f58058442

Summary: Make EventBaseLoopController not dependent on EventBase's runOnDestruction. This will allow us to make FiberManager work with any Executor.

Reviewed By: yfeldblum

Differential Revision: D6828478

fbshipit-source-id: 4d74776044a02954d022ef6f6f1e6834839973b8

Summary:
FunctionSchedulerTest.cpp was unfortunately copied into folly twice in separate
locations.  D1845525 moved it into `folly/test`, D2051557 moved it into
`folly/experimental/test`

The version in `folly/experimental/test` has had several updates and new tests
added; the version in `folly/test` has had no significant changes since it was
first added.

This diff deletes the older copy in `folly/test`

Differential Revision: D6880255

fbshipit-source-id: 8a4d5f6421ec18b319ffd76f98915e925b407468

Summary:
Sometimes the compiler lies to us and says it supports thread_local when it is not always fully implemented.

Unconditionally disable this when `FOLLY_MOBILE` is set

Reviewed By: yfeldblum

Differential Revision: D6875230

fbshipit-source-id: 051f79eac78da03973bad9090b6577393b88998b

Summary:
Disable running the async_test in open source builds.  A few of the tests
functions in this binary are flaky.

Additionally, this test consistently hangs in Travis CI builds.  It hangs in
`AsyncSocketTest.ServerAcceptOptions`; I suspect it never sees the socket
accept event and therefore never breaks out of the loop.  I suspect that even
if we fixed this test other subsequent tests would also hang.  We should
ideally update all of the tests to always have their own internal event base
loop timeout rather than potentially looping forever, so it could at least run
other test functions after a hang like this.

Reviewed By: yfeldblum

Differential Revision: D6874011

fbshipit-source-id: 46c07a1cf3216eda1900e214447e6e49b6c8e489

Summary:
[Folly] Move `invoke` helpers into a special detail namespace.

So that code in `namespace folly::detail` can use `invoke_result`, etc., unqualified.

Reviewed By: aary

Differential Revision: D6869406

fbshipit-source-id: 1b0ebbfb16621cf7e32c0f89162a19410a70605a

Summary:
Update our continuous integration configuration files to invoke ctest with the
`--output-on-failure` flag so it will print the output of all tests that fail.
Without this flag it is rather difficult to debug test failures in CI.

Reviewed By: yfeldblum

Differential Revision: D6869299

fbshipit-source-id: 02d2e1ac03f786034b20797d02e9c3aa64c1b30b

Summary: #title

Reviewed By: yfeldblum

Differential Revision: D6864158

fbshipit-source-id: 13c98c3e44db6febae844f099baa9fbecc9db673

Summary:
Change some `EXPECT_EQ()` statements to `EXPECT_TRUE()` and `EXPECT_FALSE()`.
This was causing compilation failures on some gcc-4.9 platforms.

Reviewed By: yfeldblum

Differential Revision: D6869102

fbshipit-source-id: c3294eeca90130fec601c60a76cfa4dc1bc81639

Summary: Removed instances of logging reclaim_

Reviewed By: mzlee

Differential Revision: D6864752

fbshipit-source-id: d36205052799d2307e1cd6a0307c094ac3fa8b26

Summary:
Various folly tests failed to compile when using the older gcc-4.9 version.
Since we apparently want to keep supporting gcc-4.9 for a bit longer, update
the code so that it can be compiled with gcc-4.9.

Reviewed By: yfeldblum

Differential Revision: D6817546

fbshipit-source-id: a5224560330b49e94e10d21f81a83538ec7f34e9

Summary: Add fbcode_builder configs for folly to folly/build.

Reviewed By: yfeldblum

Differential Revision: D6700053

fbshipit-source-id: 3b9e974f727e7b7815580d8a12a6adfc3b529866

Summary:
The code in PriorityThreadFactoryTest.ThreadPriority attempted to set the
thread niceness to 1.  This would fail if the process was already running at a
higher niceness value and was not being run as root.

This updates the test to get the current niceness first, and to use that plus 1
as the niceness value to change to.

Reviewed By: yfeldblum

Differential Revision: D6817548

fbshipit-source-id: 80e740f1fbe751865a418a58081bde4086b21679

Summary:
Update the ExceptionWrapperTest to check typeid strings against the result of
calls to `demangle()`, rather than expecting `typeid(int)` to always be
demangled as the string "int".  When building with gcc-7.2 on Ubuntu 17.10
these type strings appear to be demangled simply as "i".

Reviewed By: yfeldblum

Differential Revision: D6817545

fbshipit-source-id: 134952106ad812f6980516247081bb9718b5ab38

Summary:
Update folly's TestMain program to enable glog logging to stderr by default.

Some of the tests in folly/experimental/test/TestUtilTest.cpp require that this
is enabled, and fail if log messages are not logged to stderr.

Reviewed By: yfeldblum

Differential Revision: D6817543

fbshipit-source-id: 87724c52124e72ad19f65524bcbd6536680f02ec

Rename hazptr DEBUG_PRINT macro to HAZPTR_DEBUG_PRINT to avoid name clashes with other uses in code.

Reviewed By: yfeldblum, magedm

Differential Revision: D6863117

fbshipit-source-id: 1626eacafbdddcfdaf181b2a5d0f6e216425b1ff

Summary:
Drop instructions for building on Ubuntu 12.04, 13.10, and 14.04.  The oldest
Ubuntu platform we support these days is 16.04.

Our Travis CI configurations do still test building on Ubuntu 14.04 for now,
but it is not a vanilla 14.04 installation.  We upgrade gcc to 4.9 and CMake to
3.2 in order to build folly on this older Ubuntu version.

Reviewed By: yfeldblum

Differential Revision: D6780815

fbshipit-source-id: 0d27cdbb928d32c1527623c8862d50ce2215dd48

Summary:
Fix a few unused parameters. One was unconditional; the other two are conditional based on some configuration values set during CMake configure time.
Closes https://github.com/facebook/folly/pull/747

Reviewed By: djwatson

Differential Revision: D6858958

Pulled By: yfeldblum

fbshipit-source-id: acb7fa5a79b9abfdf3dc210f649d0dea8ca4a87a

Summary: [Folly] Generate group varint tables at compile time in C++, rather than as a separate custom build step in Python.

Reviewed By: simpkins

Differential Revision: D6832563

fbshipit-source-id: fa218c512cbac383f153e7b6fd4df7f181bcb0de

Summary: [Folly] Generate format tables at compile time in C++, rather than as a separate custom build step in Python.

Reviewed By: ot

Differential Revision: D6830372

fbshipit-source-id: 25770676e59c8070eaef7cbb691a5ba1c4b0a8f8

Summary: [Folly] Generate format tables at compile time in C++, rather than as a separate custom build step in Python.

Reviewed By: ot

Differential Revision: D6829681

fbshipit-source-id: 160b5a7616b015cc37ff389adabfec095cf136ec

Summary: Fleshes out the SemiFuture API with waiting versions of xVia calls that take a TimedDrivableExecutor that can be driven until some time point.

Reviewed By: yfeldblum

Differential Revision: D6658862

fbshipit-source-id: 74906d8101d2a762a27da1a1ec8348f106037f5d

Summary:
[Folly] Use `invoke` in `applyTuple` implementation.

V.s. reimplementing `invoke` as `makeCallable`

Reviewed By: spacedentist

Differential Revision: D6843993

fbshipit-source-id: 82f3e121486972245b75f808654d0a1299b7eafe

Summary:
[Folly] Fix missing "last-minute-reprieve" load-acquire in `Baton` and `SaturatingSemaphore`.

If the CAS fails, it is because `post` with its store-release was invoked just after spinning but just before parking the thread. So the failure load needs a matching load-acquire.

We cannot actually move the load-acquire into the CAS until C++17, since the failure memory order must be not stronger than the success memory order until C++17. Therefore, simulate the effect with an acquire fence in the CAS failure case.

The CAS success case does not need a load-acquire; there is already a load-acquire after the thread is unparked.

Reviewed By: davidtgoldblatt

Differential Revision: D6851304

fbshipit-source-id: a43243ad6a35bd9a53a9d2a5958b50a6c8806419