Summary: [Folly] Parameterize `AlignedSysAllocator` by a policy.

Reviewed By: ot

Differential Revision: D7246946

fbshipit-source-id: 5b6a89707c242e49bdbafba9dec6df4c65ef385c

Summary:
For some reason, compilation of certain Observable code fails in opt mode with the error that Observer::core_ is private.

It seems that ObserverCreator is not recognized as a friend of Observer. This forward declaration of ObserverCreator seems to fix this issue.

Reviewed By: yfeldblum

Differential Revision: D7268318

fbshipit-source-id: 1ea76efb0f50cb8a6b28147305ec7547f55338b8

Summary: [Folly] Enable `-Wunused-value`.

Reviewed By: Orvid

Differential Revision: D7266246

fbshipit-source-id: dc9b85a5f8ce67802cc2fa94746a26529012ec22

Summary:
F14 was missing the MSVC portability shims, and also needs to
use an MSVC-specific intrinsic to get the high word of a 64-bit multiply.

Reviewed By: yfeldblum

Differential Revision: D7263349

fbshipit-source-id: f47ceb2b2370d9bef1409e4790b236752c9f6ac4

Summary:
Currently, an error is thrown if a user tries to hash an instance of `folly::dynamic` which is of type `object` or `array`. Primitive underlying types are fine.

There doesn't seem to be a strict reason for this, as objects and arrays are just as hashable as primitive types. Additionally, the inability to hash here causes some unnecessary drawbacks (e.g. interacting with `unordered_map`s).

This diff uses the existing dependency on `folly/hash/Hash.h` to start allowing `folly::dynamic` objects/arrays to be hashed as well.

Reviewed By: ot

Differential Revision: D7219760

fbshipit-source-id: 1dff3f99bdacb66f719c614040cbd668ce51a33e

Summary: EventBase meets the definition of IOExecutor (it is an executor that "manages" at least one EventBase) and is already claimed to be one in the docstring.

Reviewed By: yfeldblum

Differential Revision: D7064481

fbshipit-source-id: 026e0e4c24d6fb15a32bc4772b35689f830ed944

Summary: deferError adds an error handling callback to SemiFuture, enqueued on the internal deferred executor, and thus will run on the chained executor or inline with .get() as for defer.

Reviewed By: yfeldblum

Differential Revision: D7243193

fbshipit-source-id: 9fe7dab9fbc8b236d717b058c81a303d87fa9253

Summary:
F14 is a 14-way probing hash table that resolves collisions by double
hashing.  Up to 14 keys are stored in a chunk at a single hash table
position.  SSE2 vector instructions are used to filter within a chunk;
intra-chunk search takes only a handful of instructions.  "F14" refers
to the fact that the algorithm "F"ilters up to "14" keys at a time.
This strategy allows the hash table to be operated at a high maximum
load factor (12/14) while still keeping probe chains very short.

F14 provides compelling replacements for most of the hash tables we use in
production at Facebook.  Switching to it can improve memory efficiency
and performance at the same time.  The hash table implementations
widely deployed in C++ at Facebook exist along a spectrum of space/time
tradeoffs.  The fastest is the least memory efficient, and the most
memory efficient is much slower than the rest.  F14 moves the curve,
simultaneously improving memory efficiency and performance when compared
to the existing algorithms, especially for complex keys and large maps.

Reviewed By: yfeldblum

Differential Revision: D7154343

fbshipit-source-id: 42ebd11b353285855c0fed5dd4b3af4620d39e98

Summary: This avoids ambiguity with an auto-parameterised lambda and leads on to a consistent use of deferError in a followup diff.

Reviewed By: yfeldblum

Differential Revision: D7224490

fbshipit-source-id: df410cd97ca0991db8fcb46267dd6a4236f3f6a3

Summary:
When compiling using autoconf, automake, make and make install, SequencedExecutor.h is not installed automatically.
Closes https://github.com/facebook/folly/pull/799

Reviewed By: meyering

Differential Revision: D7241820

Pulled By: yfeldblum

fbshipit-source-id: 03c608c8ece2e7870a7bacce399ecc9455691948

Reviewed By: djwatson

Differential Revision: D7251343

fbshipit-source-id: e5ce0c897f0d96c8717d544ac98a1faf12f08c02

Summary:
[Folly] Suppress `-Wshadow-compatible-local` in `folly/test/stl_tests/StlVectorTest.cpp`.

That test source file is heavily macro-driven, and using `SCOPED_TRACE` repeatedly in macros can lead to violations of `-Wshadow-compatible-local`.

Reviewed By: meyering

Differential Revision: D7231029

fbshipit-source-id: 122e1d86032cf884a83ef1716fa48b8f4864a363

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