Summary:
# Note: This is a resubmission after reverting this change.
The failing `DCHECK` has been fixed with an explicit cast to `size_t` to accommodate long lists.

# Summary

This diff introduces the following changes to the EliasFanoReader implementation.

- `EliasFanoReader` no longer requires knowledge of the last value in the list at construction time. This removes the need to access the last byte of the encoded list.
- Operations in `UpperBitsReader` are now responsible for ensuring validity.
- Removes constraint that the last set bit in upperBits must be in the last byte of the encoded list.

In addition, the diff also extends the unit-tests for Elias Fano coding to add arbitrary extensions to the upperBound at construction to ensure that additional 0-blocks at the end of the list do not affect the behavior of the reader.

Reviewed By: ot, luciang

Differential Revision: D22211304

fbshipit-source-id: 0dbe904c9fd8cd9568a480355e5e6a4525922966

Summary: Only accept Async input now

Reviewed By: yfeldblum

Differential Revision: D22268635

fbshipit-source-id: cd974af7a7a3adc25b3c90029efe4c6080c3739a

Summary: When zero copy is enabled on AsyncSSLSocket every IOBuf written via writeChain is accumulated in idZeroCopyBufInfoMap_ and never freed.

Differential Revision: D22272411

fbshipit-source-id: 576d16ddb4e5c7c19209b77f7346949f10fbf32d

Summary:
This provides a set of three functions under folly::fibers::async, to schedule then wait for work on a remote fiber manager.
The functions cover those 3 (legitimate) needs:

- Blocking current thread: `T executeOnRemoteFiberAndWait`
- Blocking current fiber: `Async<T> executeOnRemoteFiber`
- Awaitable (barebone version for now): `Future<T> addFiberRemoteFuture`

See code docblock for more details

Reviewed By: pranavtbhat

Differential Revision: D22252598

fbshipit-source-id: add9c23f5bdacb233e47f30b2639d376027167e3

Summary: More io_uring file read/write tests

Reviewed By: kevin-vigor

Differential Revision: D22236012

fbshipit-source-id: 37abd398d07af2bb41cfe3b3b6dfeb40410554d5

Summary:
Koray reported issue with OpenNSA while using build VM and observed that we
don't hit the issue on devserver thanks to downloading the lfs cached file.

The root cause:

Broadcom added License notice and uploaded new 6.5.19 with same name.
This changed the hash though - causing fbcode builder to complain.
Fix it by adjusting the hash.

See the first line in the recursive diff of before vs. after: P134467317

(the broken symlinks is an unrelated existing issue, which we have reported to
Broadcom).

Reviewed By: bkoray

Differential Revision: D22280971

fbshipit-source-id: 781079df426f83901509225156cf77a3966d3301

Summary:
After pursuing adoption and more discussion, it seems clear that this was probably trying to push "hiding fiber details" one step too far.
See comment in code for more details

Reviewed By: yfeldblum, pranavtbhat

Differential Revision: D22259585

fbshipit-source-id: 798cada6527332faf7e4db9942a964d6b7cca1e4

Summary: This diff converts `await` into a callable object.

Reviewed By: yfeldblum

Differential Revision: D22175597

fbshipit-source-id: 689e11c62161a2e4b82699bf52835e92c96beff7

Summary:
If `func` is mutable, then the lambda applying `init_await` must be mutable too in order to call `func`'s non-const () operator.

This diff marks the `init_await` applying lambdas mutable.

Reviewed By: yfeldblum

Differential Revision: D22238824

fbshipit-source-id: 20f202b121edd0bdfcf7a6f707a4f1d4df0181d8

Summary:
to avoid hit TSAN issue when using coro::Baton

(Note: this ignores all push blocking failures!)

Reviewed By: lewissbaker

Differential Revision: D22192037

fbshipit-source-id: ee35179be79deb1d3b79b7b432c8a65c793f7d8f

Summary:
The C++20 specification for coroutines included a late change that
now requires the `co_await promise.final_suspend();` expression to
not be potentially throwing (ie. it needs to be declared `noexcept`).

This change updates all coroutine types in folly to make sure that
`final_suspend()` methods and the methods on awaitables returned from
these methods are all declared `noexcept` so that folly can be used
with compilers that enforce this requirement.

Reviewed By: yfeldblum

Differential Revision: D22203834

fbshipit-source-id: 4a5bbcbad644349d2ff0b08f6460fa13c3165aec

Summary: This diff adds a README for the async annotation library.

Reviewed By: andriigrynenko, A5he

Differential Revision: D22080510

fbshipit-source-id: 2b1800fd44596e0e4bddff8a321a88fcd9304739

Summary: Use the intrusive list's clear_and_dispose API to simplify things somewhat.

Reviewed By: yfeldblum

Differential Revision: D22199152

fbshipit-source-id: fb6ec4e206660bc7628ddd87edba3698d8a2af6d

Summary:
This diff implements a new API to schedule a function on a new fiber and block the existing fiber till completion.

The API should be used sparingly to deal with fiber-stack-overflow issues

Reviewed By: A5he

Differential Revision: D22074021

fbshipit-source-id: 893e578b1acd6dd5cca34187fc8431202cdb73da

Summary:
This diff implements a wrapper around `fibers::collectAll` to accept annotated functors.

It also implements version of `collect` that accepts variadic arguments, and returns a tuple.

Reviewed By: A5he

Differential Revision: D22142416

fbshipit-source-id: dab320f7e1718c3872c54e168c24ea4bc39051d5

Summary:
This diff implements addFiber, a wrapper around fiberManager.addTask.

It should mainly be used to 'fire-and-forget' a fiber.

Reviewed By: A5he

Differential Revision: D22073924

fbshipit-source-id: 52516e86b7b03a7bc59166fae4db79f60cddffb7

Summary:
This diff has two goals:
- To provide an API that allows users to schedule async annotated functors to run on fibers (thereby removing the need to use `init_await` at the top of the stack)
- To provide a boilerplate-free entry point into fiber code that should work for a majority of testing/benchmarking interactions with fiber manager.

The diff implements two APIs:
-addFiberFuture: wrapper around `fiberManager.addTaskFuture`. The differing name is to mainly avoid namespace collisions and avoid confusion with `coro::Task`
- blockingWait: Fiber entry point helper

Reviewed By: A5he

Differential Revision: D22071005

fbshipit-source-id: 24ceea005d32f6e2c84b4599042703207504bd0f

Summary: 6.5.19 is now available, switch OSS to pick that instead of old 6.5.17.

Reviewed By: rsunkad

Differential Revision: D22199286

fbshipit-source-id: 231346df8d2f918d2226cfe17b01bde12c18a5a7

Summary:
Due to Thrift design of "include" statements in fbcode the thrift structures has to be contained in folders that are identical to the folder layout inside fbcode.

This diff changes the folder layout on Cargp.toml files and in fbcode_builder, there will be a next diff that changes this for ShipIt as well.

Reviewed By: ikostia

Differential Revision: D22208707

fbshipit-source-id: 65f9cafed2f0fcc8398a3887dfa622de9e139f68

Reviewed By: LeeHowes

Differential Revision: D22181192

fbshipit-source-id: 279c56398cd7e4c9274bc43c3564062588c9c81a

Differential Revision:
D18662578 (https://github.com/facebook/folly/commit/42d5bf14cd6feafa91beeb214d2441bf27ab03c7)

Original commit changeset: e04a99208848

fbshipit-source-id: 57a66a9c90955d67f942db4a3cad15910ee74178

Summary: Avoid allocation during startup by creating the exception objects the first time getXXXX is called.

Reviewed By: yfeldblum

Differential Revision: D22128606

fbshipit-source-id: b5ba662dcfac9f859dc9c972d1906fe1c29c42cc

Summary: name change

Reviewed By: LeeHowes

Differential Revision: D22162997

fbshipit-source-id: 8431a25fe46df2b5e4bfb162fc982b1c55bce7ce

Summary:
This diff introduces the following changes to the EliasFanoReader implementation.

- `EliasFanoReader` no longer requires knowledge of the last value in the list at construction time. This removes the need to access the last byte of the encoded list.
- Operations in `UpperBitsReader` are now responsible for ensuring validity.
- Removes constraint that the last set bit in upperBits must be in the last byte of the encoded list.

In addition, the diff also extends the unit-tests for Elias Fano coding to add arbitrary extensions to the upperBound at construction to ensure that additional 0-blocks at the end of the list do not affect the behavior of the reader.

Reviewed By: ot

Differential Revision: D18662578

fbshipit-source-id: e04a9920884844abd5ffe6796b0062bb59a334ae

Summary:
This diff adds a new StrandExecutor executor-type that is similar
to SerialExecutor in that it serialises execution of work enqueued
to it, but is more general in that it allows different tasks to be
executed on different executors.

To do this, it separates the queue out into a StrandContext object
which can be passed to multiple StrandExecutor objects, allowing them
each to share a queue, while allowing each StrandExecutor to dispatch
work queued to it to a different parent Executor.

Reviewed By: andriigrynenko

Differential Revision: D21848165

fbshipit-source-id: 4dda6bd13a9cd5b275a11f13101242cd73b327e7

Summary:
We had to fork OpenNSA and clone from it, see D19437386 for details.
Broadcom has now started hosting OpenNSA as a tarball.
Thus, we no longer need to maintain a fork (yay!)

This patch points opennsa manifest to fetch opennsa from this new location.

Reviewed By: bkoray

Differential Revision: D22175932

fbshipit-source-id: 51cd777ab836e4f191d78fbb2312925e446ca38f

Summary: This bug can be triggered when your computer name contains emoji. getdeps.py will fail to create this file due to Python attempts to write the file as cp1252 (Windows's default encoding)

Reviewed By: wez

Differential Revision: D22171935

fbshipit-source-id: fc3be2d1050c17ddbe05a0fc91d6613865f092ce

Summary: F14 class member fields are often in headers, and often the default constructor is implicit. The current implementation unconditionally instantiates `reserve()`, which has non-negligible cost. By specializing the default constructor we can avoid that in the common case.

Reviewed By: philippv, luciang

Differential Revision: D22166465

fbshipit-source-id: d31ebc7f6ab71392d49a6722545f8df9027d034b

Summary:
As per https://github.com/actions/virtual-environments/issues/709 there started to be some issies with Ubuntu envs running out of space. This should fix it.

Also our Cargo builds use a lot of space, changing them to be non-incremental and removing debug symbols keeps the build fast, but greatly reduces the disk space usage leaving us enough space on GitHub Actions virtual machines.
Pull Request resolved: https://github.com/facebookexperimental/eden/pull/23

Reviewed By: farnz

Differential Revision: D22160020

Pulled By: lukaspiatkowski

fbshipit-source-id: c23393e310c15ebf5a18b80f0bb5f1f894d24849

Summary: Try to fix the OSS build

Reviewed By: yfeldblum

Differential Revision: D22145695

fbshipit-source-id: a1290441b982f8df78ffa8dcd772f0c02c4535aa

Summary: [Folly] Missing public base class for `unicode_error`. which should publicly inherit `std::runtime_error`.

Reviewed By: Mizuchi

Differential Revision: D22153547

fbshipit-source-id: 4c60e8e072f0fc9240d199b6d81c7e85c99eaf34

Summary:
These optimizations were introduced in D1793554, mostly to mitigate the high cost of `select64`. We've had an efficient implementation of `select64` for Haswell for a while, and Haswell is more than 5 years old, so we can drop the optimization, which actually harms performance on modern microarchitectures.

While on a real workload this shows significant benefits, the microbenchmarks for very small skips are degraded:
```
============================================================================  ====================
folly/experimental/test/EliasFanoCodingTest.cpp relative  time/iter  iters/s    time/iter  iters/s
============================================================================  ====================
Next                                                         2.58ns  388.22M       2.55ns  391.93M
Skip_ForwardQ128(1)                                          4.81ns  207.72M       4.31ns  231.79M
Skip_ForwardQ128(2)                                          5.96ns  167.75M       4.67ns  214.07M
Skip_ForwardQ128(4_pm_1)                                     7.40ns  135.16M       4.87ns  205.29M
Skip_ForwardQ128(16_pm_4)                                    8.20ns  121.97M       5.38ns  185.93M
Skip_ForwardQ128(64_pm_16)                                  12.04ns   83.06M       8.97ns  111.51M
Skip_ForwardQ128(256_pm_64)                                 16.84ns   59.39M      13.19ns   75.79M
Skip_ForwardQ128(1024_pm_256)                               17.67ns   56.61M      14.19ns   70.45M
Jump_ForwardQ128                                            25.37ns   39.41M      25.47ns   39.26M
----------------------------------------------------------------------------  --------------------
SkipTo_SkipQ128(1)                                           7.27ns  137.59M      10.77ns   92.87M
SkipTo_SkipQ128(2)                                          10.99ns   91.01M      14.39ns   69.51M
SkipTo_SkipQ128(4_pm_1)                                     13.53ns   73.93M      16.15ns   61.90M
SkipTo_SkipQ128(16_pm_4)                                    20.58ns   48.59M      17.72ns   56.45M
SkipTo_SkipQ128(64_pm_16)                                   32.08ns   31.18M      31.16ns   32.09M
SkipTo_SkipQ128(256_pm_64)                                  38.66ns   25.87M      38.22ns   26.16M
SkipTo_SkipQ128(1024_pm_256)                                42.32ns   23.63M      42.07ns   23.77M
JumpTo_SkipQ128                                             47.95ns   20.86M      47.85ns   20.90M
----------------------------------------------------------------------------  --------------------
Encode_10                                                  103.99ns    9.62M     104.89ns    9.53M
Encode                                                       7.60ms   131.53       7.55ms   132.46
----------------------------------------------------------------------------  --------------------
defaultNumLowerBits                                          3.59ns  278.69M       3.61ns  276.97M
slowDefaultNumLowerBits                                     10.88ns   91.90M      10.98ns   91.06M
============================================================================  ====================
```

It is important to note however that these micro-benchmarks have very little variability in terms of effective skip distance for small skips, producing almost perfect branch prediction in the linear scan loop. In a real workload, the overhead of branch misprediction ends up being significant.

Reviewed By: philippv

Differential Revision: D22139846

fbshipit-source-id: 8df17a74aa57c92413709d9e11c60a77d5462422

Summary: Without FDO Clang generates very suboptimal code, adding this hints brings it almost to parity with FDO-compiled code.

Reviewed By: philippv, luciang

Differential Revision: D22139847

fbshipit-source-id: 2cdaf383ca1afd21db1b7ad2aafb3d3c7ce335b0

Summary: `folly::get_default()` returns a copy of shared_ptr that gets immediately discarded. The change avoids that.

Reviewed By: yfeldblum

Differential Revision: D22119215

fbshipit-source-id: 36aab580d7042d19b6b076cad20586697fbfa5e3

Summary:
Provide an Async wrapper for fibers::await, which blocks current task until promise is fulfilled.
This isn't a build block that is used in very common scenario, so prefered to put it in its own file.

Differential Revision: D22135318

fbshipit-source-id: 753dbefc4ac9a907f5b1f656f70291c88187b5e8

Summary:
Currently RequestContext::getRootidsFromAllThreads() can access StaticContext root ids concurrently with RequestContext::setRequestContext() without synchronization guards, which is not safe cross other platforms than x64 and also causing TSAN warnings when used in server contexts.
Therefore we can make it std::atomic and access it with relaxed order. This won't affect performance in major platform like x64 since the loads/stores instructions will be the same.
Also as a side effect this prevents RequestContext::StaticContext from generating copy/move constructor, so we remove an extra copy of root id in StaticContext in setRequestContext path.

Reviewed By: yfeldblum

Differential Revision: D22083558

fbshipit-source-id: ed70e394f1172b07ba00c15f05a370f84265785c

Summary: Pull Request resolved: https://github.com/facebook/folly/pull/1386

Reviewed By: yfeldblum

Differential Revision: D21992975

Pulled By: Orvid

fbshipit-source-id: 7d52e3e9f8db899079263ef15e9f1bbfbedadc44

Summary: This macro has been deprecated and given that there are not that many uses, it seems relatively simple to remove it entirely.

Reviewed By: yfeldblum, aary

Differential Revision: D16904736

fbshipit-source-id: 56daffd480c586be2a5636b3ce20c6fe1d5ea018

Reviewed By: yfeldblum

Differential Revision: D22071829

fbshipit-source-id: c7f0e1bc5a4257731bafee09144c33c9fb474e10

Summary: The ValueType alias in the multiplex function is not used and caused a build failure when I tried to use it, possibly because we have some extra warnings enabled in our code.

Reviewed By: lewissbaker

Differential Revision: D21685780

fbshipit-source-id: 3235c6444a623d5f484f0849679b1497f9456fa9