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Summary: [Folly] Fix outdated mention of `TSSLSocketFactory`.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

Summary:
Add the ability to use folly::window without providing a vector ahead of time.
This allows window to scale to a large number of iterations.

Reviewed By: yfeldblum

Differential Revision: D7863481

fbshipit-source-id: 86c6b7926e9c3b7510233fac20a50c1fb38f5b57

Summary:
Pointer value may change when casting.

(Note: this ignores all push blocking failures!)

Reviewed By: lbrandy

Differential Revision: D7884048

fbshipit-source-id: aa55e1b3530bc28f7d2ffd356761d962d6029832

Summary:
I'm continue to try keeping the implementation simple, instead of copy-pasting EventBase/EventBaseLoopController code.
My understanding is that AsyncioExecutor/AsyncioLoopController will always be single threaded because they are tied to a unique asyncio event_loop, so I don't need an atomic counter.
Then it should be cheap to just always aquire/release the counter in runLoop.

Reviewed By: andriigrynenko

Differential Revision: D7875202

fbshipit-source-id: 900a03e6870c5e4828521a99785cfa976baac54a

Summary:
Copied the `const folly::fibers::FiberManager::Options& opts = {}` signature from main `getFiberManager`.
Discussed with Andrii if I should key the FiberManager cache by options' address, but he voted to keep the behavior consistent with FiberManagerMap.

Reviewed By: andriigrynenko

Differential Revision: D7873868

fbshipit-source-id: 0c7f6e6ef0ebe50d9658c2eee7ab1e098dd86ddd

Summary: [Folly] Fix Build: `folly/io/RecordIO.cpp` under MSVC 2015u3, which inexplicably gives `error C2872: 'detail': ambiguous symbol`.

Reviewed By: Orvid

Differential Revision: D7875032

fbshipit-source-id: 2ff5a60c941e20ef9a05cedb2e7d8224a9e83ed2

Summary: Use a single pointer to store Executor pointer and dummy flag.

Reviewed By: yfeldblum

Differential Revision: D7857087

fbshipit-source-id: 529fbfdc6ad14954f5bdd9bef3eb1e335b233ec9

Summary: It's timing out in open source test runs because each individual test was taking 10 seconds. They each now take 2.

Reviewed By: yfeldblum

Differential Revision: D7841938

fbshipit-source-id: eb81c67cc26e98fb0b4b0c736bea747e985f2fcf

Summary:
`{Future,SemiFuture}::poll()`:
- minor chg to impl from assignment to stateless ?:

Reviewed By: yfeldblum

Differential Revision: D7840466

fbshipit-source-id: 201dd7121b713324bb054b72c8ecdf6f4f163b97

Summary: SerialExecutor is always wrapping another Executor, so we shouldn't force users to coordinate their lifetimes.

Reviewed By: yfeldblum

Differential Revision: D7856146

fbshipit-source-id: ac7caaa0f181406dfb6b59d36ae4efe6d1343590

Summary:
This allows using KeepAlive token as a pointer to an specific Executor sub-type (e.g. SequencedExecutor).
getKeepAliveToken() has to be a free function to achieve this goal.

Reviewed By: yfeldblum

Differential Revision: D7847884

fbshipit-source-id: 95dc62433d30212ceb9b9b2fc7d6b38cb5425311

Summary:
This diff adds dynamic thread creation/destruction to ThreadPoolExecutor (mostly CPU).

1) Threads are lazily created when the first task is add()ed (or getEventBase is called), applies to both IO and CPU

and

2) after a timeout in LifoSem, threads are joined in CPUThreadPoolExecutor.

Most of the logic is in ThreadPoolExecutor.  A separate dynamic IOThreadPoolExecutor will be a follow on diff.

To keep the previous behavior, users can set minthread == maxthreads, or gflags --dynamic_cputhreadpoolexecutor=false

Reviewed By: magedm

Differential Revision: D7477390

fbshipit-source-id: 855a35380861111de33656e8fb1b681ae8cd2807

Summary: Fixes two tiny formatting issues with the folly::Function documentation.

Reviewed By: yfeldblum

Differential Revision: D7856507

fbshipit-source-id: dc82256a35f6c2b1eb66a868f419f2c800f1ddc5

Summary: [Folly] Avoid duplicating throw_exception instances taking string literal, which differ only in the length of the string literal.

Reviewed By: marshallcline

Differential Revision: D7853216

fbshipit-source-id: a4648952cc10661322e5e23c6317ba4b75c268fb

Summary:
This diff optimizes the operation of F14 set emplace when
the argument list happens to be a single reference to a key_type.
An intermediate key_type value is removed in that case, which avoids a
move in all cases and avoids a copy when the emplace finds that the key
is already present in the set.

Reviewed By: yfeldblum

Differential Revision: D7845720

fbshipit-source-id: 16a639f53993d9843ffe265edd58c0d74de0c1f7

Summary:
When used in a QuantileEstimator, some sliding window buckets can be sparse or all together empty. In this case, reserving memory in the constructor and in merge is wasteful. Don't reserve in the constructor (this is a complete waste) and call shrink_to_fit in merge.

It's worth noting that the benchmarks *are* shrinking the digest, because the digests are only 85 or so items big, so it is exercising this path.

Reviewed By: yfeldblum

Differential Revision: D7855242

fbshipit-source-id: 61bcbaaf17dd46f8b98d171af43516ceb8d84510

Summary: Included but not used.  Dropped this (expensive) include

Reviewed By: Orvid

Differential Revision: D7781674

fbshipit-source-id: 11180d34cda63ef91f70c64c84bf89346e5d1729

Summary:
- Promise move ctor: use folly::exchange()
- Promise move assign: make 33% faster, more eager to release memory, use folly::exchange()

Reviewed By: yfeldblum

Differential Revision: D7838311

fbshipit-source-id: 6d0ee8d3121ab703b3c54c72532f34d66bd4259c

Summary:
Fix CoreAndCallbackReference move-ctor so it doesn't call this->detach() (my bad; see D7723078).

Also (for clarity/pedantry/obviousness), explicitly delete the class' move-assignment op.

Reviewed By: yfeldblum

Differential Revision: D7848370

fbshipit-source-id: bc051120b3df0557ce9b01cbad8c00a57b8780d8

Summary: Only wake a single waiter.

Reviewed By: davidtgoldblatt

Differential Revision: D6595881

fbshipit-source-id: 9393618bb619cb22b75ca91b27291b784fc5097c

Summary: Re-run small locks bench.  Add server type to comment.

Reviewed By: yfeldblum

Differential Revision: D7830168

fbshipit-source-id: 4b60ec6845bb3518a98f4645e521e95599072433

Summary: [Folly] No need to optimize `MicroSpinLock::lock` in `folly/futures/` after {D7828158} (facebook/folly@6f9d8a145e1c37b2b47ff91491c647fe321de787).

Reviewed By: nbronson

Differential Revision: D7843192

fbshipit-source-id: b40bcc0abcfed561a141864e135d72fe33f4067d

Summary:
This implements a new AsyncioLoopController for FiberManager, wrapping AsyncioExecutor.
Thanks to recent simplication of LoopController, if I haven't missed anything, code is fairly simple, though not optimizer for thread-local.

fiber_manager.pxd|pyx allow to link the life-time of AsyncioLoopController/FiberManager to the asyncio event loop.
Code is similar to (and rely on) executor.pxd|pyd, which does the same for AsyncioExecutor.

fibers.h|pxd provide a helper function for C++/python callers.
Code is similar to futures.h|pyd, which does the same for folly Future.
This is the main reason to keep a separate function/callback parameters. Not necessary for fibers, but a generic callback implementation can work for both fibers/future, which is convenient.

There are a few lines that feel duplicated between future/fibers implementation, but it felt overkill to abstract further.

Reviewed By: andriigrynenko

Differential Revision: D7811432

fbshipit-source-id: af0a07d7554acbab1fac44b7a9a6a98340501ef4

Summary: [Folly] Remove deactivation, a rarely-used facility, from `Future`.

Reviewed By: marshallcline

Differential Revision: D7788059

fbshipit-source-id: 38db16fc3c2694b3cd772844fdafe71f6033a97c

Summary: Nothing breaks so....

Reviewed By: yfeldblum, siyengar

Differential Revision: D4377965

fbshipit-source-id: 53c42e7f6f3a71aedd4b9a089ffca9d3c8472029

Reviewed By: yfeldblum

Differential Revision: D7832437

fbshipit-source-id: 036a89693e247e0d6356980c3bf9db84d322f408

Summary: This abstraction is currently only used in functions executed on Python threads, so it should be unecessary.

Reviewed By: andriigrynenko

Differential Revision: D7828136

fbshipit-source-id: a9ea8b23ffc26505c576106c49e850e1894648d5

Summary: This should allow better differentation between compilers in situations where warnings need to be disabled for a specific compiler. I've reclaimed the GCC_DISABLE version to have it now refer to only GCC, rather than GCC+CLANG, and also added a version for clang only.

Reviewed By: yfeldblum

Differential Revision: D7834730

fbshipit-source-id: 7e0b076f5d9bc55870cfb7e67281190b4add82e6