Summary:
D7479058 changed the exception_tracer code to export their targets in the main
folly-targets.cmake file, but I forgot to remove the `install()` command
installing the old `folly-exception-tracer-targets.cmake` file.

This would cause `cmake configure` to exit with an error if it detected it
could built the exception_tracer code, but it would still generate all of the
necessary Makefiles correctly, so subsequent `make` commands would still work.

Reviewed By: yfeldblum

Differential Revision: D7626710

fbshipit-source-id: f015032c3c42cf2911fcaf9b355fc97616ff20e1

Summary:
The cmake globbing then excluding strategy implies that if the directory
in which we are compiling has a folder named `build` on its path like `/home/alice/project/build/folly/...`, everything breaks.
Note that it is the same for `tools` and `test`, I also fixed the tools one, but the test once has many files.... Using a file list would be the real solution.
Closes https://github.com/facebook/folly/pull/815

Reviewed By: simpkins

Differential Revision: D7624035

Pulled By: yfeldblum

fbshipit-source-id: a3f1d2f82e55e070d13acc5c394d8cfdfabeb7ed

Summary:
The existing histogram approach for estimating quantiles is inadequate for common use cases. This diff introduces TDigests for estimating quantiles of streaming values.

The current histogram approach suffers from two issues:
  - The user needs to know something about the universe of values, U, and the underlying distribution in order to get reasonably accurate values
  - Because the histogram is not biased, estimating tail quantiles such as p99.9 requires a large amount of memory.

t-digests (https://github.com/tdunning/t-digest/blob/master/docs/t-digest-paper/histo.pdf) are biased digests that allow for accurate estimates of tail quantiles, while using a small amount of memory and without requiring the user to know anything about U.

The scaling function in the paper is slow, because it uses arcsin. This approach uses a sqrt function instead. Details of why this works in the comments of the TDigest file.

Reviewed By: simpkins

Differential Revision: D7512432

fbshipit-source-id: 01460433ec7380fed88e5e942ef15f032dd794bb

Summary: [Folly] Fix `constexpr` predicate names, which have embarrassing typos.

Reviewed By: igorsugak

Differential Revision: D7605352

fbshipit-source-id: e04a87fd375f09472b020380bf446c7236a39e51

Summary:
Fix broken Android build

(Note: this ignores all push blocking failures!)

Reviewed By: michalgr

Differential Revision: D7606076

fbshipit-source-id: 0cf0426a34cf62b045acb932d42a8e4a3cd5da71

Summary:
When trying to compile `folly/experimental/exception_tracer` with gcc-7.2, I get the following error:

```
ExceptionCounterLib.cpp: In instantiation of '{anonymous}::throwHandler(void*, std::type_info*, void (*)(void*))::<lambda(auto:9&)> [with auto:9 = std::unordered_map<long unsigned int, folly::exception_tracer::ExceptionStats>]':
../../../folly/Synchronized.h:162:20:   required from 'auto folly::SynchronizedBase<Subclass, (folly::detail::MutexLevel)1>::withWLock(Function&&) [with Function = {anonymous}::throwHandler(void*, std::type_info*, void (*)(void*))::<lambda(auto:9&)>; Subclass = folly::Synchronized<std::unordered_map<long unsigned int, folly::exception_tracer::ExceptionStats>, folly::RWSpinLock>]'
ExceptionCounterLib.cpp:132:4:   required from here
ExceptionCounterLib.cpp:127:21: error: uninitialized variable 'info' in 'constexpr' function
       ExceptionInfo info;
                     ^~~~
In file included from ../../../folly/experimental/exception_tracer/ExceptionCounterLib.h:22:0,
                 from ExceptionCounterLib.cpp:16:
../../../folly/experimental/exception_tracer/ExceptionTracer.h:30:8: note: 'struct folly::exception_tracer::ExceptionInfo' has no user-provided default constructor
 struct ExceptionInfo {
        ^~~~~~~~~~~~~
../../../folly/experimental/exception_tracer/ExceptionTracer.h:31:25: note: and the implicitly-defined constructor does not initialize 'const std::type_info* folly::exception_tracer::ExceptionInfo::type'
   const std::type_info* type;
                         ^~~~
```

Fixed by initializing `ExceptionInfo::type`.

Compiling with gcc 7.2 now works.
Closes https://github.com/facebook/folly/pull/812

Reviewed By: Orvid

Differential Revision: D7598341

Pulled By: yfeldblum

fbshipit-source-id: 0a8859b6d5f174484c8f2148de59a2a592dc2b25

Summary: [Folly] Rename `IOBufEqual` to `IOBufEqualTo` to correspond with the standard naming of `std::equal_to`.

Reviewed By: Orvid

Differential Revision: D7596716

fbshipit-source-id: 2e87aa4b62a002520bdd53b5b7eaba7d9bd822da

Summary:
in Linux environment, `find_package(gflass)` searches `Findgflags.cmake`.
And it cannot find  https://github.com/facebook/folly/blob/master/CMake/FindGFlags.cmake , because linux is case-sensitive environment in filenames and cause error.

```
CMake Error at CMake/folly-deps.cmake:34 (message):
  Unable to determine the target name for the GFlags package.
Call Stack (most recent call first):
  CMakeLists.txt:65 (include)
```

For linux programmers, this line should find `FindGFlags.cmake` file which exists in the same directory.
Closes https://github.com/facebook/folly/pull/805

Reviewed By: yfeldblum

Differential Revision: D7505908

Pulled By: Orvid

fbshipit-source-id: c30097a25569d293df9a1bfecbee84cece260306

Summary:
[Folly] Function objects for performing `constexpr` comparisons for C++11 or gcc49.

After upgrading to C++14 and dropping support for C++11, these may be removed because the corresponding function objects in the C++14 standard library are `constexpr`-invocable.

Reviewed By: Orvid

Differential Revision: D7590351

fbshipit-source-id: a8702115a66836aff25761f374b8a2d7dbe12074

Summary: Delay threadEntry destruction until all instances have completed StaticMetaBase::onThreadExit

Reviewed By: djwatson

Differential Revision: D7471153

fbshipit-source-id: 709a54ed2d616c5dc906b923e9fdd862ac87de9c

Summary: The domain tests seem broken.  Digging in, it seems to be uninitialized ThreadCachedInts variables.  Initialize them.

Reviewed By: yfeldblum

Differential Revision: D7505520

fbshipit-source-id: aca8a6f5b38271bf06ea8a6377bfb692328f1e33

Reviewed By: djwatson

Differential Revision: D7571438

fbshipit-source-id: 1484e5e323c7d57a96ad66d46fd999ce51e69951

Summary: Similar to D7429494, this can be a CAS and save some latency for some readers.

Reviewed By: magedm

Differential Revision: D7505578

fbshipit-source-id: eeeb06c2969a74084edd3df26cf2d135b8b0e132

Summary:
If FOLLY_SETTING_DEFINE(...) is put into .cpp file right now you will get linker error about undefined references.

According to http://en.cppreference.com/w/cpp/language/inline
  2) The definition of an inline function or variable (since C++17) must be present in the translation unit where it is accessed (not necessarily before the point of access).

Hence the linker error. This diff fixes that.

Reviewed By: alikhtarov, mnv104

Differential Revision: D7567469

fbshipit-source-id: 02049e4881e50c414aeb506745e02eed1256daad

Summary:
Update `cmake_configure()`, `cmake_install()`, and `fb_github_cmake_install()`
to support specifying the directory where CMakeLists.txt is found, relative to
the directory where the build is being performed.  Previously these functions
where hardcoded to assume that CMakeLists.txt was always found at '..'

Reviewed By: snarkmaster

Differential Revision: D7540689

fbshipit-source-id: efd3d044345fadc0346e436c01d0a247e1b6fd70

Summary:
Add a macro to help users define the `getBaseLoggingConfig()` function.

While I would prefer to avoid macros if possible, this seems worthwhile.  This
saves 4 or 5 lines of boilerplate code in each program that sets a custom base
logger setting.  It also reduces the likelihood of a developer accidentally
having a typo in the function name, which would still build successfully but
not have the desired results.

Reviewed By: chadaustin

Differential Revision: D7457652

fbshipit-source-id: 1c316c7ea6949c16bd7b61c0440cc1ee69ecb83e

Summary:
Add folly::initLoggingOrDie(), which behaves like `initLogging()` but handles
errors by printing a message to stderr and then calling `exit(1)`.

Most programs are expected to initialize logging early on during program
start-up, and will likely use a command line argument or other configuration
value as the logging settings.  If an error occurs they usually want to print
the message to stderr and exit unsuccesfully. `initLoggingOrDie()` makes it
easy to perform these steps without requiring programs to write their own
exception handlers to handle errors from `initLogging()`.

Reviewed By: chadaustin

Differential Revision: D7164830

fbshipit-source-id: d688046f1b6240c948e4aaabfc9fb24ba3d9ff89

Summary:
- Let's enforce a single definition. Also makes the implementation much simpler.
- Collect all static info about a setting in a Metadata struct

Differential Revision: D7544210

fbshipit-source-id: d3f2ef617bd817d355a37e11fa9425b6a4259384

Summary:
Currently, the memory used by a map instance is available only via computeStats(),
which is quite expensive. A lightweight method is needed for getting the map memory
footprint on a hot code path.

Reviewed By: nbronson

Differential Revision: D7544180

fbshipit-source-id: 3cbc98bb9f1c5e7f75fd9eb7f89016580fbb6523

Summary: Which only supports C++11 style constepxr.

Reviewed By: simpkins

Differential Revision: D7546457

fbshipit-source-id: 52db98379096dd3b25f656e7e62238ce10537bf7

Summary:
According to http://en.cppreference.com/w/cpp/language/operators
  The overload of operator -> must either return a raw pointer or return an object (by reference or by value), for which operator -> is in turn overloaded.

Hence this change.

Reviewed By: mnv104

Differential Revision: D7548832

fbshipit-source-id: d98ff1f96bc00dc6e2e5cb084b96091a61421627

Summary:
Tudor who wrote this left the company... so RB.. you are the reviewers :)

1. make default commands as constants
2. remove fake message about ",h"
3. align quota usage from mix to '
4. add support for version command
5. add function to identify built-in command (is needed for an external application to make a decision if something is mandatory or not)

Reviewed By: marcinpe

Differential Revision: D7048169

fbshipit-source-id: b48cf7df28cfa387e028a1cc869332407314c906

Summary: Adds a few more OpenSSL compatibility functions for working with X509_STORE and its objects.

Reviewed By: knekritz

Differential Revision: D7540930

fbshipit-source-id: 0275a200d673386988bc25140b1d827859b04364

Summary: hazptr_obj is copyable and moveable, but doing so would cause a bug, because the next ptr would point to the object that was copied/moved from, which can oftentimes be garbage or another object that has not yet retired. This diff changes the copy/move constructors and assignment operators to simply check that the rhs has not been retired.

Reviewed By: magedm

Differential Revision: D7539444

fbshipit-source-id: f9325c7b886fcf4b553344ee37f2355ca41268b6

Summary:
Install the CMake package configuration file under lib/cmake/folly rather than
share/folly.  CMake will automatically search both of these locations, but
lib/cmake/folly appears to be a more commonly-used location across other open
source projects.

Reviewed By: Orvid

Differential Revision: D7479056

fbshipit-source-id: becd3d4c05e774d2aede20f6a7a50f57d6c05875

Summary:
- Use CMakePackageConfigHelpers to help generate the file
- Print a message about where folly was found if not using QUIET
- Make the include, lib, and cmake installation directories configurable

Reviewed By: wez

Differential Revision: D7479058

fbshipit-source-id: 2548acc9d6de90d11da02ac576a58ce5ca939766

Summary: Include the new `UTF8String.h` header where needed.

Reviewed By: Orvid

Differential Revision: D7473655

fbshipit-source-id: 9d1b820123a786d8eb3d6405a4ff35331de41694

Summary: Neither Folly nor Thrift actually version anymore and haven't in multiple years, so just remove the code to do this.

Reviewed By: yfeldblum

Differential Revision: D7512580

fbshipit-source-id: 89c61cf4ef3d78ea7c09ba6855e0717cfbe022d6

Summary: Fix compile error: error: variable 'b' set but not used [-Werror=unused-but-set-variable]

Reviewed By: yfeldblum

Differential Revision: D7471259

fbshipit-source-id: 784e874200bb44ec9bddf4a3c12f7a90be12d17b

Summary:
Added missing installation of UTF8String.h
Closes https://github.com/facebook/folly/pull/813

Reviewed By: yfeldblum

Differential Revision: D7506038

Pulled By: Orvid

fbshipit-source-id: 9821a0040c44715cfd68852743b64a32df0dcf57

Summary: MSVC 2015 Update 3 can't parse these with curly-brace init'd, so swap the assignment. The result is the exact same.

Reviewed By: simpkins

Differential Revision: D7508756

fbshipit-source-id: 5e60607f978a87ae8bfed22086d1dccef15759ac

Summary:
Optimized builds of //folly/experimental/coro test Coro.Sleep
would almost always fail because the compiler would generate
code that would only sleep for 0.98 seconds. Perform some
simple rounding in order to ignore slight optimizations like
these.

Reviewed By: wqfish

Differential Revision: D7496416

fbshipit-source-id: f81ff30922fbf3e5d2086fde50f4a469bdf72e51

Summary:
F14HashToken encapsulates the work of hash_function(), which
is the same across F14 containers that have the same key_type and equal
hash_function() (same type and operator==).  This diff adds documentation
that callers may rely on this fact, which means they can use this feature
to reduce work if a single key is access in multiple maps/sets.

(Note: this ignores all push blocking failures!)

Reviewed By: shixiao

Differential Revision: D7506737

fbshipit-source-id: 321032d619434501b1e0544962e54732bfc4c970

Summary:
Allow the user to give their own pair implementation. This allows
using a packed pair.

Reviewed By: yfeldblum

Differential Revision: D7504521

fbshipit-source-id: 11888594b8b3ef3f530ebd95b8006ef6f5afbc65

Summary: Terabytes aren't Web Scale.

Reviewed By: ot, philippv, luciang

Differential Revision: D7479752

fbshipit-source-id: fd353933e642b1ee024c28107c8fcb6a55fe755e

Summary: Until I do a PR on `double_conversion`, we need to work around this by catching the trailing 'e' case.

Reviewed By: luciang

Differential Revision: D7481130

fbshipit-source-id: 2734dbe834e6cd69c6dfe41d6b4e9a7a548a7da8

Summary:
When `startFail()` is called, it sets the state to StateEnum::ERROR.
There is a chance that immediate read callback is scheduled to run in
next event loop. The callback calls handleRead() then triggers
`assert(state_ == StateEnum::ESTABLISHED)` in `AsyncSokcet::handleRead`.

Cancel any immediate read callback when startFail is called.

Reviewed By: yfeldblum

Differential Revision: D7051956

fbshipit-source-id: 0d6693d851b272355a4f36ab8d001969fa47750e

Summary:
At `-O0` each coroutine call results in a heap allocation. This
combined with the increased memory pressure when using ASAN
results in an invalid memory access beyond the maximum address.
Avoid the problem by limiting the recursion to 5,000 frames deep,
instead of 10,000. This still fulfills the intent of the test,
but without pushing the limits of ASAN.

Reviewed By: wqfish

Differential Revision: D7503976

fbshipit-source-id: 7850a9d9db23328d42c25b74a1290caa7773e6a7

Summary: sendRequestSync should only be implemented by channels, which own threads looping EventBases.

Reviewed By: phoad

Differential Revision: D7464392

fbshipit-source-id: bde6edc85438bb406592291330869972f88c787a

Summary:
Using an array of prehash tokens is quite inconvenient without
the ability to default construct them.

Reviewed By: shixiao

Differential Revision: D7490113

fbshipit-source-id: f802a7dc6dc2c603c4682e5f384d9f135220cd54