Summary:
Update AsyncFileWriter to use pthread_atfork() to stop the I/O thread around a
fork() operation.  Both the parent and child restart the I/O thread after the
fork.  Messages that were queued up at the time of the fork are logged in the
parent process after the fork occurs.

Previously after a fork() the child process would not have an I/O thread
running at all, so any messages sent to this handler would not actually be
written.  This also triggered some ASAN warnings which I did not fully track
down.  In the child process ASAN claimed that the exit handlers were run twice:
from both the main thread and the I/O thread, which is surprising since the I/O
thread should not run in the child process at all.

Reviewed By: mnv104

Differential Revision: D7946725

fbshipit-source-id: e4ad398f7bb334882c5c0b2afacc30c27bf3f6e4

Summary:
fix #839
Closes https://github.com/facebook/folly/pull/846

Reviewed By: yfeldblum

Differential Revision: D7987128

Pulled By: Orvid

fbshipit-source-id: 626ed1724f3df5fecc83413574cfd72f1f0b1fa1

Summary:
* Relax some loads in BufferedStat
* Cache which cpu local buffer to use, similar to SharedMutex

Reviewed By: djwatson

Differential Revision: D7986764

fbshipit-source-id: 581266abc60e3f23f24181264da163baee9fce3f

Summary: [Folly] Use `throw_exception` in `Expected`, replacing the one-off throwing functions and outlining `throw` statements.

Reviewed By: Orvid

Differential Revision: D7985812

fbshipit-source-id: 396b92d1ec40c909c9c37dd7f7d9ed94b2bcf709

Summary: [Folly] Use `throw_exception` in `Try`, replacing the one-off throwing functions.

Reviewed By: Orvid

Differential Revision: D7984674

fbshipit-source-id: 3996e09fd8a7446fbb53760f1ce30a66cb7c13e9

Summary:
[Folly] Let `Pomise` handle setting `BrokenPromise` in its dtor, since it is logically always the thing that invokes `setResult`, rather than having `Core` do it.

This splits up the various responsibilities a little better.

Reviewed By: marshallcline

Differential Revision: D7964264

fbshipit-source-id: a4871fd1a83a0a54d4a6c91fcb74c6df5aa592ba

Summary: Drop this expensive include and just implement the operators.

Reviewed By: yfeldblum

Differential Revision: D7803316

fbshipit-source-id: 969fef54204cf3caa09d67e05be61c3c9a14b67e

Summary: MSVC 2017 Update 7 has issues with expanding empty parameter packs in certain situations.

Reviewed By: yfeldblum

Differential Revision: D7983735

fbshipit-source-id: d90c01a36885b94269b3dbc260142abd6556102d

Summary:
MSVC 15.7 (VS 2017 Update 7) was released a couple days ago, and includes a bug that's breaking Folly. Temporarily work around it.
A point release should be out soon(ish) to resolve the issue: https://developercommunity.visualstudio.com/content/problem/246602/157-fails-with-folly.html
There is still another issue in 15.7 that needs to be worked around, which will happen in a separate diff.

Reviewed By: yfeldblum

Differential Revision: D7937972

fbshipit-source-id: 4a2bc4ae0ea7165c45d100ad0a29409b60a0287a

Summary:
This diff fixes the move constructor form that takes an explicit
allocator for F14VectorMap and F14VectorSet (which may also include
F14FastMap and F14FastSet depending on the value_type).  It also includes
test coverage for exception safety, which did not reveal any problems.

Reviewed By: yfeldblum

Differential Revision: D7981324

fbshipit-source-id: f4ca39aa2654d75289b554a9081621b2a3a6c136

Summary: InitThreadFactory allows running initialization function on newly created threads. This is useful to do preconditioning work on the threads before putting them to use.

Differential Revision: D7947389

fbshipit-source-id: 6a161c887def3862b47473155516c03ba3f10e8b

Summary:
Internal memory fragmentation is responsible for a non-trivial
amount of the memory footprint of a dynamically-allocated hash table.
This diff adds an API visitAllocationClasses that allows the caller to
count exactly how many dynamic allocations were performed and of what
size, so that they can accurately account for overheads not included in
getAllocatedMemorySize's simple sum of the underlying malloc requests.

This diff also exposes F14Table's reset() via F14 maps and sets, which
was an unintentional omission.

Reviewed By: WillerZ

Differential Revision: D7894385

fbshipit-source-id: 2d7cadd3806e3f38a9e38cb94c90492a9965ff47

Summary:
The first allows disabling CMake's google test integration, as it doesn't play nice with the Visual Studio IDE itself.
The second allows setting the version of C++ to use when compiling with MSVC.

Reviewed By: yfeldblum

Differential Revision: D7976567

fbshipit-source-id: e6fe3cc28a23334d69e8cd18f633afab2efecd59

Summary:
Previously the alignment of small_vector did not take into account the alignment of the value_type. Since the value_type is stored directly internally, this is problematic.

This change does increase the sizeof small_vector in a couple cases, but I don't think the previous size was legitimate as sizeof(small_vector<value_type>) was not an even multiple of alignof(value_type).

Reviewed By: yfeldblum

Differential Revision: D7969483

fbshipit-source-id: 968c78bf03d7c0ddfe1338754f12f97be8d0f771

Summary: Start with the easy one.

Reviewed By: yfeldblum

Differential Revision: D7957655

fbshipit-source-id: 0c2227402673306e1e6ba3f463b1a93db2582b07

Summary: socketConnect() is not invoked if we have TFO enabled. Need to explicitly disable it once new socket is created, and noTransparentTls flag is set.

Reviewed By: djwatson

Differential Revision: D7945457

fbshipit-source-id: 739b7ae5bc146b50255254e644fba2618147c4f4

Summary:
Enforce two aspects of folly::futures::Core<T>:

- that it is heap-constructed (prevent clients from constructing it other than via `new`)
- that it cannot be deleted early (prevent clients from explicitly deleting it)

Reviewed By: yfeldblum

Differential Revision: D7900761

fbshipit-source-id: c1c5a149e3d96c4cea04c17909c2ffd42383973e

Summary: It was spamming the MSVC build log with warnings.

Reviewed By: magedm

Differential Revision: D7954677

fbshipit-source-id: 1f2d1163483518382543aacb7e8fbc17e291e650

Summary:
clang whines about these to varying degrees. They seem like
braindead fixes.

Reviewed By: yfeldblum

Differential Revision: D7918701

fbshipit-source-id: a5aae179c2df89ef52148a500e95cd1cd25a1f0b

Summary:
There is a subtle race between thread destruction and task addition (ensureActiveThreads).

For an executor with a single thread, the race would be:
threadid
1 cpu thread returns from try_take_for by timing out.
2 someone from a different thread calls add()
2 add() finds lifosem empty, calls ensureActiveThreads
2 ensureActiveThreads grabs the lock, finds active=1, total=1, returns doing nothing, assuming thread is still running.
1 cpu thread decrements activeThreads_ to 0 in taskShouldStop.

There are now *no* threads running until the next call to add(), and one task waiting.

Fix: Grab lock in taskShouldStop (like the documentation says we should be doing).  Also double check that there are no currently pending tasks.

This probably only affects pools with size of 1, otherwise we would have added a second thread and there may temporarily be one fewer threads running.

Reviewed By: davidtgoldblatt

Differential Revision: D7943241

fbshipit-source-id: 502e5809ccf4ecca85205c14c4d97b508897de9b

Summary:
SerialExecutor used to have public constructors and could be
constructed on the heap or on the stack. In order to be able
to reference the shared stater later from the parent executor,
the task queue was implemented in a separate class, of which
the SerialExecutor would create one, managed by a `shared_ptr`.

With the recent move towards `folly::Executor::KeepAlive`, the
SerialExecutor itself always has to be constructed on the heap
(hence no public constructor anymore but factory functions).
However, that means that we can embed the task queue implementation
in SerialExecutor, using `KeepAlive` objects to access it from
the parent executor.

This change simplifies the implementation of SerialExecutor and
reduces the number of heap objects and thus memory allocations.

Reviewed By: andriigrynenko

Differential Revision: D7927260

fbshipit-source-id: d3b6a2376bfdf512a946f2f45c730ed68176a441

Summary: This turned out to only be useful in tests. Clean up the tests and get rid of it

Reviewed By: yfeldblum

Differential Revision: D7907221

fbshipit-source-id: f5e0263c1426e1af97c190e6b2bd47d7db37d403

Summary: When cleaning up the interface with r-value qualification for SemiFuture it seems we missed deferError.

Reviewed By: yfeldblum

Differential Revision: D7942259

fbshipit-source-id: c0cf05eb2b6357e6f6eb3fab6aef87ec6416caf7

Reviewed By: saifhhasan

Differential Revision: D7943135

fbshipit-source-id: 6b66b7b2ea6343b99ec113febca991eb840b1860

Summary: gcc-5.x does not allow brace elision in these std::array initializer lists.

Reviewed By: yfeldblum, mnv104

Differential Revision: D7923970

fbshipit-source-id: 807f2e0d376c9ac4f4f6988fb811590531b6334d

Summary:
Running the xlog test binary stand-alone revealed a bug that
was otherwise masked when running with buck test. The bug was that
2 tests ended up depending on the log-level associated with a default
category and would thus fail since the tests did not clean up
the log-level setting associated with those categories.
Attached diff fixes the issue by restoring the category's log-level in
a scope exit block.

Reviewed By: simpkins

Differential Revision: D7922086

fbshipit-source-id: 9d8ed917633ae214dc81075fbd38275160e64376

Summary: [Folly] Simpler SFINAE in variadic `F14BasicSet::emplaceItem`, without using `std::tuple_element_t` unsafely when `sizeof...(Args) == 0`.

Reviewed By: shixiao

Differential Revision: D7920929

fbshipit-source-id: d74d5b36ac683f72e21d83294aa890f49194280d

Summary:
Check if the compiler supports -Winconsistent-missing-override before trying to
disable this warning.

It looks like gcc wouldn't actually fail the build if
`-Wno-inconsistent-missing-override` was specified but was not supported.
However, if the build failed due to other compile errors the error messages
about this flag would make it confusing to identify the actual build failure
reason.

Closes issue #836.

Reviewed By: yfeldblum

Differential Revision: D7920577

fbshipit-source-id: 322444a9df3f4f36bb5420f0720c1e433c2856b7

Summary:
[Folly] Fix `ThreadPoolExecutor::getPendingTaskCount` decl return type to match defn.

Fixes #843.

Reviewed By: djwatson

Differential Revision: D7914071

fbshipit-source-id: a22658b1dd48a5e73fae3a0312f72007230e36c8

Summary:
One (artificial) test case creates ~1000 threads, resulting in lots of spinning contending for this lock.

Changing to folly::SharedMutex fixes the issue, allowing the actual working thread to finish.

Reviewed By: magedm

Differential Revision: D7847705

fbshipit-source-id: b2a8c3acdb4c62f347ef4ec761acbe7681ced9f3

Summary: Allows for conditional logging of messages.

Reviewed By: simpkins

Differential Revision: D7888834

fbshipit-source-id: d1fe47d82fe8889f6b597062f5542e7eb61ed9e6

Summary: Take now as input to improve performance when updating many buffered stats at once

Reviewed By: yfeldblum

Differential Revision: D7906107

fbshipit-source-id: cf09bc2c2673b0a336628b3e6b31ee2d55dbb10c

Summary: [Folly] Fix race condition in collectN where the future may be completed with too few values or by reading the values while they are in-process of being written.

Reviewed By: djwatson

Differential Revision: D7900639

fbshipit-source-id: 3eafa821abda4f93232db3b8114de54c6faf798a

Summary:
This reverts commit 5102e9c3de026c021bf322b5109aafcc115207a2

bypass-lint

An infra SEV is better than not reverting this diff.
If you copy this password, see you in SEV Review!
cause_a_sev_many_files

Differential Revision:
D7840699

Original commit changeset: 5102e9c3de02

fbshipit-source-id: 13e97d5497ac383c0eff18a4b947d5b3d82a19b7

Summary: [Folly] Fix outdated mention of `TSSLSocketFactory`.

Reviewed By: stevegury, knekritz

Differential Revision: D7892382

fbshipit-source-id: 7b267e5de857f9c5976b26d53d36b1545a46af2a

Summary:
[Folly] Use `size_t` for `ThreadPoolExecutor::getPendingTaskCountImpl`, as it is the canonical size type for counting the number of entries in in-memory data structures.

Prevents confusion when using values returned from this function with other sizes, especially in contexts where the two types are required to match as might occur in calls to `std::min` without explicitly specifying the type.

Fixes #843.

Reviewed By: djwatson

Differential Revision: D7898443

fbshipit-source-id: eec789f661351d09545bc7118f2e4b3587fd7302

Summary: Add thread local destroy benchmark

Reviewed By: yfeldblum

Differential Revision: D7892479

fbshipit-source-id: f16462820354a6cf27d9348a76b28be027cef20c

Summary:
SemiFuture::get() & Future::get() both render the `this` object in a consumed / moved-out state. However Future::get()'s postcondition was untestable by callers - it consumed the value within the core but left `this->valid()` true.

Goal: make Future::get():
- function like SemiFuture::get()
- testable by callers (see `valid()`)

Reviewed By: yfeldblum

Differential Revision: D7840699

fbshipit-source-id: 5102e9c3de026c021bf322b5109aafcc115207a2

Summary:
Lets callers determine whether a Future/SemiFuture/Promise has a shared-state.
`x.valid()` (where `x` is a Future, SemiFuture, or Promise) is is true if/only if the object has a shared state.

The `valid()` method will also be key in a near-term diff that will use it to clarify the contracts/rules.

Note: the concept of validity already shows up in the doc-blocks; this gives callers a conceptual oppty to check it.

Reviewed By: yfeldblum

Differential Revision: D7839038

fbshipit-source-id: f8390b3d1a8c3d5d89356ae48937e03c424d1174

Summary:
PIC is implied by BUILD_SHARED_LIBS in CMake, so the test is confusing.
Note that if one wants to build static and use it to create a shared library with it, he will need to compile either shared
or static with CMake option -DCMAKE_POSITION_INDEPENDENT_CODE
Closes https://github.com/facebook/folly/pull/833

Reviewed By: Orvid

Differential Revision: D7890111

Pulled By: yfeldblum

fbshipit-source-id: e3996cb83d30ae368dc5fdd4f55b721f7f89d0a0