Summary: For compatiblity with `openssl errstr`.

Reviewed By: yfeldblum

Differential Revision: D7246053

fbshipit-source-id: dcf77b67ae3b3dd7b6b85e9b73f2d382e59aa7b9

Summary:
Add try_wait_for and try_wait_until.

Algorithm -

We could use a doubly-linked list, but this would double the number of contended
CAS for push/post.  Instead, assume timeouts are infrequent, and just walk the list
from the head to remove nodes.

A lock bit is added to the head, which is taken only on timeout.  We assume
timeouts are infrequent.

If a concurrent post() removes the node before the timeout can remove it,
we must wait for the corresponding post() (but it is likely to arrive soon),
instead of timing out.

Reviewed By: magedm

Differential Revision: D7167894

fbshipit-source-id: ea5242098d9ccd286a72fade6292223e95c44a81

Summary: Use unbounded queue in NotificationQueue

Reviewed By: djwatson

Differential Revision: D7164130

fbshipit-source-id: d1b445d6730cbb2a68ad78506abe0165e28f5811

Summary: Add folly::Optional<T> UnboundedQueue::try_dequeue() method

Reviewed By: magedm

Differential Revision: D7164049

fbshipit-source-id: 659de2d26067bb1a5bdea50f4cd7711e6955ba61

Summary: NotificationQueue benchmark

Reviewed By: yfeldblum, djwatson

Differential Revision: D7163944

fbshipit-source-id: f7fe2124b8c61ff3ab39be94d9c50c82a6f8816b

Summary: [Folly] Fix `propagate_const` under gcc49.

Reviewed By: andrewjcg

Differential Revision: D7230851

fbshipit-source-id: 0cd4df15d5a0f7ae06e26a82ca725b30d479f458

Summary:
[Folly] Rewrite allocators for the era of `std::allocator_traits`.

Provide minimal interfaces which comply with all required elements of C++ concept `Allocator`. Change all (*) uses to use `std::allocator_traits` consistently, as is required of all allocator-aware library types.

* Rename `SysAlloc`.
* Replace `StlAllocator` with `CxxAllocatorAdaptor` with stricter semantics.
* `Arena` is no longer a C++ Allocator because it is not freely copyable. Change code which used it as a C++ Allocator to use `CxxAllocatorAdaptor` instead.
* `ThreadCachedArena` likewise.

(*) Hopefully.

Reviewed By: nbronson

Differential Revision: D7208794

fbshipit-source-id: 270588c9c3d817f4abd9fb49eed5eb9f03f96da2

Summary: [Folly] Cut dead iterator-traits `ifdef`s in `fbstring`.

Reviewed By: elsteveogrande

Differential Revision: D7195605

fbshipit-source-id: 7a398cffab153b1571064a7d9e610e844f33bc20

Temporarily remove onError returning a future that completes on the original executor due to production issues.

Summary: https://fb.facebook.com/groups/fbcode.investigations/permalink/407299856363159/ showed issues coming from this diff. The change to return an executor-tied future from onError was intentional, and correct behaviour, but it was a change that seems to have caused issues. Temporarily removing it to rethink how we should approach it.

Reviewed By: andriigrynenko

Differential Revision: D7219231

fbshipit-source-id: 95b91f3a5ea7d854d5df052e6cd5851c7e6fbdab

Reviewed By: phoad

Differential Revision: D7220254

fbshipit-source-id: 3a2a49fd17d0aca4acc590c1c16db75ace472216

Summary: It currently only sets the lower 32 bits.

Reviewed By: nbronson, philippv

Differential Revision: D7216798

fbshipit-source-id: 090f6dba990eeb7f1a9cc56e8615161c11eea026

Summary:
This diff adds folly::IsAvalanchingHasher<H, K>, which identifies
hash functors that exceed the standard's quality requirement by also
being avalanching.  This is useful for code that wants to map hash values
onto a restricted range or compute a secondary hash value without doing
extra work.

Reviewed By: yfeldblum

Differential Revision: D7180217

fbshipit-source-id: 8c402937d0a654c0ec32c62666e9dc4e0943f769

Summary:
This diff clang-formats a couple of files in preparation for
additional changes.

Reviewed By: yfeldblum, shixiao

Differential Revision: D7197983

fbshipit-source-id: 8995bdaca29bcc44cd5379fc64c76cee89635ac1

Summary:
Update folly::initLogging() to call getBaseLoggingConfig() to get a base
configuration string that is applied before the argument that it was called
with.  getBaseLoggingConfig() is defined as a weak symbol, and is intended to
be overridden on a per-executable basis if desired.

This allows individual programs to control their default logging settings, but
still let them be overridden via a command line flag.  The command line flag is
used to update this base configuration.  The command line flag can fully
override all of the base configuration settings if desired, but settings from
the base config that are not overridden will still be used.

For example, if the base configuration defines settings for the categories
"foo" and "bar", and the command line flag defines settings for the categories
"bar" and "wub", the base configuration settings for "foo" will still be used.

Reviewed By: yfeldblum

Differential Revision: D7164832

fbshipit-source-id: e172f746d7bd004948872adbbb87c597765e283c

Reviewed By: yfeldblum

Differential Revision: D7203193

fbshipit-source-id: 440daa2f79a919aa95ae3fdb4006f8d501c0ad93

Summary: This just extends D4988025 to one more location, which wasn't covered in the initial fix.

Reviewed By: yfeldblum

Differential Revision: D7181160

fbshipit-source-id: 8dd0866d916674870f04252a80725ecce0cd69e1

Summary: folly::hasher<T> for integral and floating point types T uses a different algorithm depending on the key type.  At the moment this is taken from the actual argument type, rather than the explicitly provided one.  This is likely to be confusing.

Reviewed By: yfeldblum

Differential Revision: D7194941

fbshipit-source-id: efa3e4bbad62e53842ec6fb80d316706324e98aa

Summary:
There is currently an unnecessary data dependency loading the
current backing buckets + size, reading the size, then again indexing
in to the array.

Rework the Buckets struct to make a single allocation, and store the bucket_count_ in the Segment directly.  The bucket pointer and segment are protected by a seqlock.

Reviewed By: ot

Differential Revision: D7167919

fbshipit-source-id: 10ddceffad19f54c790b3ab7a87260445571f81d

Summary: Allow passing in a custom comparator to compare keys

Reviewed By: yfeldblum, aary

Differential Revision: D7175777

fbshipit-source-id: e1e8d836a908b595a74b172b04ca847a5c5eb435

Summary:
Add ConfigHelpers.cpp to the folly_test_support library.
This was accidentally broken in D7164831, but wasn't caught due to
infrastructure errors kicking off the continuous OSS builds.

Reviewed By: yfeldblum

Differential Revision: D7186076

fbshipit-source-id: f13bdd920bb289ae19fdb46e265123fe088b42c3

Summary:
This method can be used to get configuration about all currently defined log
categories, including ones that are using the default config settings.

The existing LoggerDB::getConfig() method only returns information about
categories that have non-default config settings.

Reviewed By: yfeldblum

Differential Revision: D7164833

fbshipit-source-id: e1c043553dc4f69be58c33f2bc5b1a63763f0984

Summary:
[Folly][coro] Suppress deprecation warning in `Promise.h`.

`Try(std::exception_ptr ep)` is deprecated. The underlying behavior doesn't improve much with this diff. But there would be a whole lot of warnings once `Promise.h` gets included by more files.

Reviewed By: andriigrynenko

Differential Revision: D7178381

fbshipit-source-id: 9f45706283a5aaa436cbab3e7b02e085bdc8c792

Summary:
[Folly][coro] Let all `Promise<T>` be friend of `Task`.

The code would not compile:

```lang=c++
coro::Task<void> taskVoid() {
  co_await task42();
  co_return;
}
```

```
folly/experimental/coro/Promise.h:84:28: error: 'viaInline' is a private member of 'folly::coro::Task<int>'
    return std::move(task).viaInline(executor_);
                           ^
folly/experimental/coro/tests/CoroTest.cpp:40:3: note: in instantiation of function template specialization 'folly::coro::Promise<void>::await_transform<int>' requested here
  co_await task42();
  ^
folly/experimental/coro/Task.h:60:13: note: declared private here
  Future<T> viaInline(folly::Executor* executor) && {
            ^
```

Reviewed By: andriigrynenko

Differential Revision: D7178238

fbshipit-source-id: 7dca6834ac56f4c9bdb4d702996b51e932f2aae6

Summary:
Move some utility functions from ConfigParserTest and ConfigUpdateTest into a
new ConfigHelpers module.  This eliminates some duplicated logic and will make
it easier to re-use these functions in other tests in the future.

Reviewed By: yfeldblum

Differential Revision: D7164831

fbshipit-source-id: 115a227e4cb2db486f57079483b8ae9aadaa0187

Summary:
Define a FOLLY_ATTR_WEAK helper macro in CPortability.h, and update existing
code in folly that declares functions as weak to use this new macro.  This will
make it easier to declare weak functions in other files in the future.

Reviewed By: yfeldblum

Differential Revision: D7164834

fbshipit-source-id: 87e03401400f2912fcd5e719af0d667251cd642b

Summary:
Define interface include directories for the folly target.

This lets downstream dependencies of folly list Folly::folly in
target_link_libraries() and have the correct include directories be
added automatically.

Reviewed By: yfeldblum

Differential Revision: D7162335

fbshipit-source-id: 2a6aad57142e038450fd35a94446f5b865029155

Summary: Free up the session if its not null before assigning a new one

Reviewed By: shamdor-fb

Differential Revision: D7169809

fbshipit-source-id: fd026e8688525a764b9937c7f4b7bfb0cdece9eb

Summary: toUnsafeFuture is intended to return a future that is the same as .via(&folly::InlineExecutor::instance()) without propagating InlineExecutor throughout future-using code during a transition to SemiFuture. This will highlight call sites better and encourage either fixing, or making clear that this non-deterministic behaviour is the intent.

Reviewed By: yfeldblum

Differential Revision: D7162989

fbshipit-source-id: c7092a53560e05d463d9170be254a50d23cc6ef7

Summary:
The range check to identify its "own" memory could inadvertently pick
up an allocation from outside the range, resulting in an alignment
assertion later on, and causing us to permanently leak the memory
(when assertions are disabled).

Reviewed By: alikhtarov, andriigrynenko

Differential Revision: D7146394

fbshipit-source-id: d9d8b63eea1ffa045e1bd07c0258d1f2b089e9bf

Summary: Modify folly::window to replace Promise::getFuture calls with Promise::getSemiFuture. The requirement for an executor on the semifuture here meant that I had to modify all of the SemiFutures with an executor in the vector. This may come with a small performance hit in some cases, but appears to be behaviourally better.

Reviewed By: yfeldblum

Differential Revision: D7104920

fbshipit-source-id: 7d105df553c28bb362b37ff64270ee16bf59fbd6

Summary: There was previously a bug in that defer used within a continuation would not correctly chain the deferred executor on the executor in the returned (and hence in the original) folly::Future like it would when .via was called on a SemiFuture. This fixes that situation by returning a semifuture from a continuation by correctly chaining it onto the outer future's executor.

Reviewed By: yfeldblum

Differential Revision: D7156241

fbshipit-source-id: ed6db3ad0de7a921b72459fcd2b1228114832853

Add getSemiFuture and storage of executor to FutureSplitter so that returned future completes on the expected executor.

Summary:
Remove calls to Promise::getFuture in FutureSplitter test.

Add getSemiFuture to FutureSplitter for consistency with Promise.

Keep getFuture method but ensure that it completes on the same executor as the input future (or Inline if the executor on the input future was null, due to legacy code).

Reviewed By: yfeldblum

Differential Revision: D7105806

fbshipit-source-id: 63a919ba9dcf0f189782a3e2a362fad4d86ac91f

Summary:
[Folly] Fix waiting in `Baton`, `SaturatingSemaphore`.

If condition passes or overall deadline expires, just return. If only a component timeout expires, continue on to the next component.

Reviewed By: magedm

Differential Revision: D7151564

fbshipit-source-id: 48c33ccc6970604b23221bc94af247945bdc34e5

Summary: Replaces calls to Promise::getFuture in onError calls. Modifies the returned future to complete on the same executor as the caller. No assumption that the future already has an executor (though it should in principle, the codebase is not ready for that yet).

Reviewed By: yfeldblum

Differential Revision: D7104850

fbshipit-source-id: ea152102f8ecd612e322b98a54d9440495b14bf8

Summary:
UndefinedBehaviorSanitizer: invalid-null-argument folly/io/IOBufQueue.cpp:53:38
```

Add a check that the length is greater than zero.

Reviewed By: meyering

Differential Revision: D7139027

fbshipit-source-id: 37585092429af52d14c98c193ecc495752bbda1c

Summary: This implements Executor-aware coroutine library.

Reviewed By: wqfish

Differential Revision: D7133189

fbshipit-source-id: 43022e0b4a44378dae670720d8144f2e042f1a54

Summary: Strings terminating in a backslash shouldn't throw if strict is set to false. However, the default implementation results in an undefined behavior, since the iterator goes beyond the end position of the string.

Reviewed By: simpkins

Differential Revision: D7123155

fbshipit-source-id: 4311037ccdbfd95f402109dcc1b5862e52fb97a1

Summary:
[Folly] Fix waiting in `UnboundedQueue::dequeue` suite.

`SaturatingSemaphore::try_wait_until` does not return early with the result `false`, so the loop could result in incorrect long waits.

Reviewed By: magedm

Differential Revision: D7151562

fbshipit-source-id: cd90583f0b4520464ed1877df8396df43ebbef00

Summary: [Folly] Simplify `MemoryIdler` pre-idle check.

Reviewed By: magedm

Differential Revision: D7151565

fbshipit-source-id: 34ae69f16439640669cd9aaf02a09282a1a1cc3f

Summary: [Folly] An extra deadline check in `DynamicBoundedQueue` enqueue path just for completeness.

Reviewed By: magedm

Differential Revision: D7151563

fbshipit-source-id: 2d6abd906091db20a650d0f3120bf4b1d8bcf00c