Summary:
getdeps.py's find_existing_win32_subst_for_path function tries to reuse an existing build directory alias. (On Windows, the build directory is aliased to a drive letter to shorten paths.) If this function does not find and existing build directory alias, getdeps.py invalidates many of its caches.

On my Windows machine, find_existing_win32_subst_for_path always fails, so all of my builds are super slow. This happens because find_existing_win32_subst_for_path is given a path with a lower-case drive letter ("c:\users\..."), but the subst command returns paths with an upper-case drive letter ("C:\users\...").

When comparing paths, use ntpath.normpath. This makes the comparison case-insensitive for drive letters. (It also makes the comparison case-insensitive for other path components.)

On Linux and macOS, this diff should not change behavior.

Reviewed By: wez

Differential Revision: D15466096

fbshipit-source-id: 1669aa0a6eaeb6012154f3a9e24eba3f835262c6

Summary:
[Folly] Fix returning reference to temporary in futures test.

```
folly/futures/test/FutureTest.cpp: In instantiation of 'typename std::enable_if<(! isTry), R>::type folly::Try<NoThrowTestResult>::get() [with bool isTry = false; R = NoThrowTestResult&&; typename std::enable_if<(! isTry), R>::type = NoThrowTestResult&&]':
folly/futures/Future-inl.h:95:30:   required from 'auto folly::futures::detail::wrapInvoke(folly::Try<T>&&, F&&) [with T = NoThrowTestResult; F = Future_NoThrow_Test::TestBody()::<lambda(NoThrowTestResult&&)>]'
folly/futures/Future-inl.h:1209:39:   required from 'folly::Future<typename folly::futures::detail::valueCallableResult<T, F>::value_type> folly::Future<T>::thenValue(F&&) && [with F = Future_NoThrow_Test::TestBody()::<lambda(NoThrowTestResult&&)>; T = NoThrowTestResult; typename folly::futures::detail::valueCallableResult<T, F>::value_type = NoThrowTestResult]'
folly/futures/test/FutureTest.cpp:1408:14:   required from here
folly/futures/test/FutureTest.cpp:1392:33: warning: returning reference to temporary [-Wreturn-local-addr]
 1392 |     return std::forward<R>(value());
```

Fixes #1130.

Reviewed By: LeeHowes

Differential Revision: D15457369

fbshipit-source-id: 045ae3321f957546a6218ee5e3118753e4c8ceb2

Summary:
This should be ok to do. Main thing I'm not sure about is if it's ok
to change these DCHECKs to CHECKs. We could probably also pass state into
InlineFunctionRunner::run() to keep these as DCHECKS here and CHECK in our
implementation.

Reviewed By: andriigrynenko

Differential Revision: D15463243

fbshipit-source-id: c1de7198e8bf48d8af0e03361bed493642e6c173

Summary: Add the ability to add multiple IOBuf free callbacks

Reviewed By: yfeldblum

Differential Revision: D15423850

fbshipit-source-id: ad0352b345835b0472ec090b5ff07e30e14532d8

Reviewed By: yfeldblum

Differential Revision: D15452123

fbshipit-source-id: 4ceec36f007e10284e8ac0482018099c7cea94d9

Summary:
In the folly/io/async tests, allow an extra 20ms of tolerance when performing
timeout checks on non-Linux platforms.

On Linux we can fairly reliably determine the amount of time that the test
spent waiting to be scheduled on the CPU.  This allows the timeout tests to be
relatively accurate even on overloaded systems.

On non-Linux platforms we cannot determine the time spent waiting to be
scheduled, and the `getSchedTimeWaiting()` implementation always returns 0.
This causes the tests to fail pretty frequently on Mac OS.  Adding an extra
20ms of tolerance should hopefully help reduce the test failure rate on Mac.

Reviewed By: yfeldblum

Differential Revision: D15464672

fbshipit-source-id: 2c3096df6a15dcdc68bf14c947736e4731929c0f

Summary:
Since D3640289 the EventBase destructor has invoked currently scheduled
LoopCallbacks.

Some of the tests in `EventBaseTest` installed loop callbacks and checked that
they were never run during the normal loop invocations.  Prior to D3640289
these callbacks never ran.  However, post D3640289 these functions do run, and
they attempt to update local stack variables that have already gone out of
scope.

This rearranges these functions to ensure the variables in question outlive
the EventBase object.

Reviewed By: yfeldblum

Differential Revision: D15462319

fbshipit-source-id: 8f490ddbb978fe45711eb7cbda4502dd6a0fb36b

Summary:
A few of the EventBase timeout tests fail sometimes on the Travis CI
infrastructure, reporting that timeouts fired sooner than expected.
e.g.: https://api.travis-ci.org/v3/job/535980430/log.txt

I believe these failures are due to the fact that the tests schedule the
events/timeouts before capturing the start time point that they compare
against.  This updates the tests to instead capture the start time point
before scheduling events.

Reviewed By: yfeldblum, chadaustin

Differential Revision: D15462320

fbshipit-source-id: dfc321d899768bc70ddaeaa0ef88b42ddd0b70ca

Summary:
This test was accidentally updating `timestamp1` twice rather than updating
`timestamp0`.

The existing check for `timestamp0` only succeeded because `timestamp0` was
never actually updated.  With the current EventBase behavior, even though we
asked the function to be scheduled immediately, it actually ends up waiting
for a full HHWheelTimer tick interval (10ms by default) before it runs.
Update the check to take this into account.

Reviewed By: yfeldblum

Differential Revision: D15462318

fbshipit-source-id: e1851c9c4f2e082ad73debf85343d99bbf244b23

Summary:
Update the `XCHECK_EQ()` macros to use `folly::logging::objectToString()` to
format the message on failure.

This ensures that `XCHECK_EQ()` will successfully compile and work with any
arguments.  Previously it would fail to compile if called with arguments that
did not work with `folly::to<std::string>()`

Reviewed By: chadaustin

Differential Revision: D14545301

fbshipit-source-id: 442657a1770f30cbf01462ad62d32301e60490e5

Summary:
If `toAppend(std::string*, const Object&)` is defined for a particular object
type, make `objectToString()` simply return the exact output of `toAppend()`.

Previously the code returned `(type_name: toAppendResult)`

The new logic is based on the assumption that if `toAppend()` is implemented
for an object, it should emit all relevant information about the object that
may be needed by a developer.

The old behavior of always including type information was potentially helpful
in cases where `objectToString()` was called only in exceptional cases.
(e.g., after an exception thrown by `folly::format()`).  However it made
`objectToString()` too verbose in other non-exceptional situations where we
want to format objects (e.g., in `XCHECK_EQ()`).  There doesn't really seem to
be a strong need to keep the type information in the `folly::format()`
exception case, so this just drops it rather than adding two separate versions
of this function.

Reviewed By: chadaustin

Differential Revision: D14545303

fbshipit-source-id: 29e2f12d65fd22112486ed11f989b63875980088

Summary:
Update the `logging::objectToString()` and `appendToString)` functions when
converting objects that do not have a `toAppend(std::string*, Object)`
implementation.

Previously the code simply emitted `<no_string_conversion>` after the object
type name.  Now the code emits a hexdump of the object.  The emitted hexdump
size is based compile-type visible type of the object.  For subclass instances
the correct dynamic type name will be emitted (if RTTI is supported), but the
hexdump will only include the portion of object known from the compile-time
type.

Reviewed By: yfeldblum, chadaustin

Differential Revision: D14545305

fbshipit-source-id: d1e3df001b7f7c40c7bcb0888e76bf775512e5d3

Summary:
In LogStreamProcessor.h we previously had some `fallbackFormat()` functions
that attempted to convert arbitrary objects to strings in case an exception
was thrown when formatting them with `folly::format()`.

These functions basically attempt to perform best-effort conversion that
ideally should never fail (barring failure to append to the output string).
These functions attempt to use `toAppend()` for the object, similar to how
`folly::to<std::string>()` works.  However, if no `toAppend()` function is
available, or if it throws an exception, they fall back to returning a generic
string.

This diff moves these functions to a separate header file to make it easier to
re-use them in other parts of the code.  In particular I plan to update the
`XCHECK_EQ()` and related macros to use these functions to format its
arguments.

Reviewed By: chadaustin

Differential Revision: D14545304

fbshipit-source-id: 053a504340ba4513abc9bec186a31ffaa03a943a

Reviewed By: lewissbaker

Differential Revision: D15363390

fbshipit-source-id: 98c30928773992c5bb7f040e6f5afb8ee6fef713

Summary: [Folly] Cut unnecessary template param default of `futexWaitUntil`; the param is deduced from the arguments.

Reviewed By: aary

Differential Revision: D15448750

fbshipit-source-id: ec81fc10efbf68ad328a1fb1b7d2fdb2e93551cd

Summary: Helper function to wrap a nested dispatch. Returns a function object that launches the passed function onto the executor and returns a future representing the return value of the function.

Reviewed By: andriigrynenko

Differential Revision: D15300575

fbshipit-source-id: eca4b4139c6405f216a9f1cbc87a8ec2ff437780

Summary:
[Folly] Remove explicit `throw`, `try`, and `catch` uses from `IOBuf`, preferring scope guards and `throw_exception`.

(Note: this ignores all push blocking failures!)

Differential Revision: D15442544

fbshipit-source-id: 2f182256ff12f5aad6166a7b40ed018c1b32e923

Summary:
[Folly] Mark some more `IOBuf` members as `noexcept` and remove an explicit `abort` which is there to simulate `noexcept`.

(Note: this ignores all push blocking failures!)

Differential Revision: D15442545

fbshipit-source-id: adaef4d1f6c2e551e9c19b151e3f08c6ba11f717

Summary:
- GCC 9.1 warns when moving a local object in a return statement
  prevents copy elision.
- Remove the explicit `std::move` in those return statements.
Pull Request resolved: https://github.com/facebook/folly/pull/1131

Reviewed By: LeeHowes

Differential Revision: D15391413

Pulled By: yfeldblum

fbshipit-source-id: af29ea0f6f65957645fa2debce2f5303906a2507

Summary:
[Folly] Cut `folly/LockTraitsBoost.h`. Also, discourage specializing `LockTraits`.

For ODR sanity, the better mechanism is to wrap mutex types with non-standard interfaces in mutex wrapper types with standard interfaces.

Reviewed By: Orvid

Differential Revision: D15426235

fbshipit-source-id: f54aee8c47951f6214f5b23fce7f8f6c29c8b5c2

Summary: Add lizmq and sigar in prepare for fbzmq oss build migration.

Reviewed By: wez

Differential Revision: D15387435

fbshipit-source-id: 1ec2057972bf801a1598af0a1ae87f958394d812

Summary:
with the reshuffling around getdeps.py, and changes in folly/thrift/wangle,
our internal package stopped building.  This diff brings it back to life.  It is
a little bit interwined:

* Introduce a `--facebook-internal` switch to getdeps that causes `fb` in the
  build context to be set to `on` rather than `off`.  This allows specifying
  options in the manifest that are FB specific.
* Introduce cmake options to control the WATCHMAN_STATE_DIR and whether cmake
  should attempt to create WATCHMAN_STATE_DIR when it is installed.
* For FB specific builds on macOS, set the state dir to match our existing location
  and disable creation of WATCHMAN_STATE_DIR because that will ultimately be
  handling during package installation and we don't have privs for that on
  the machine generating the package.
* Adjust Facebook CI scripts to use getdeps for building and testing watchman

Reviewed By: simpkins

Differential Revision: D15337970

fbshipit-source-id: 8ab3c1f810decf5f0b16337dc1cbe6dc73d26426

Summary: Add a comment that the Dynamic version of MPMCQueue is deprecated and that UnboundedQueue should be used instead.

Reviewed By: yfeldblum

Differential Revision: D15392160

fbshipit-source-id: 5958b7602d3062878dd3e78907cb7091532ad4b8

Summary: Guard pages are cheap (VM only + mapping state). More than one is occasionally useful (e.g. imagine a 10k object on stack that's not used, subsequent function calls will create a frame that jumps over a single 4K guard page and we get hard to debug memory corruption instead of a clean segfault).

Reviewed By: andriigrynenko

Differential Revision: D15367640

fbshipit-source-id: 8f1d42a71926653929dd847eeba172c680f98589

Summary:
The schedule type is used to differentiate between a build run during
code review (and thus runs code that isn't yet in the master branch),
from continuous or other types of run that operate on landed code.

This doesn't change any behavior yet; this diff just adds
the plumbing to pass down an optional arbitrary schedule type string
from the CI system.

In the future, we'll use the schedule type to influence the behavior
of running tests.

Reviewed By: strager

Differential Revision: D15300120

fbshipit-source-id: 3b46afef2ff171b3fa095763dd5006a54ea328b8

Summary:
F14TestUtil's SwapTrackingAlloc's metadata accesses were
triggering a -Wclass-memaccess warning in gcc 9.1 despite being safe. This
diff changes the accesses to use explicit casting to avoid the warning.

Reviewed By: yfeldblum

Differential Revision: D15393963

fbshipit-source-id: 088811354f00d623a58678c3f41a0e8effdb5ce3

Reviewed By: udippant

Differential Revision: D15368849

fbshipit-source-id: 5e101fc38417b807a531fa456b38234d6dd08b7a

Summary: [Folly] Namespace the helper macro in `folly/ssl/OpenSSLPtrTypes.h`.

Reviewed By: Orvid

Differential Revision: D15370971

fbshipit-source-id: aa907f60fee5ef58c5484838a3bde0d68e65b249

Reviewed By: lewissbaker

Differential Revision: D15363378

fbshipit-source-id: 0343d6cc42624a6c3e9b01a338afb1646625928a

Summary: This is not a good default. We can build a dedicated SpinningBaton if needed

Reviewed By: andriigrynenko

Differential Revision: D15387138

fbshipit-source-id: 433ce2b1af7c661edd2c0e264dc618cc9c680aa3

Summary: This diff replaces all 2 occurrences of "NDEBUG" with "folly::kIsDebug" in folly/SharedMutex.h. Compared to NDEBUG, folly::kIsDebug has the equivalent functionally  but helps consolidate the conditional-compilation logic to a single place, namely folly/portability.

Reviewed By: shixiao

Differential Revision: D15379370

fbshipit-source-id: 58c563624e58a4fd18b0cfbe4c0b9ba879f8eea9

Summary:
When the udp socket is connected we shouldn't supply the peer's address. This changes it so that
we can use write() methods in AsyncUDPSocket when the socket is connected.

Differential Revision: D15384587

fbshipit-source-id: ad26e2d04a7303c7ff9e25f32422d7c56e4283e5

Reviewed By: andriigrynenko

Differential Revision: D15366589

fbshipit-source-id: e8d1c17e158437a3ca882f51f12071bf666c1a6e

Summary:
if we find ccache in the path, then we instruct cmake to use
it as the compiler launcher.

Reviewed By: pkaush

Differential Revision: D15375441

fbshipit-source-id: 602fe54742a5ec07b0533bd2cf63cb905b051e85

Summary:
Adds a benchmark to show the benefit of running work inline.

Dev:
| fourThensOnThread | 2.15% | 245.01us | 4.08K |
| fourThensOnThreadInline | 2.36% | 223.51us | 4.47K |
| hundredThensOnThread | 0.67% | 783.54us | 1.28K |
| hundredThensOnThreadInline | 0.88% |  595.24us | 1.68K |

Opt:
| fourThensOnThread                                |   0.18% |    70.37us  |  14.21K |
| fourThensOnThreadInline                          |   0.26%  |   50.11us   | 19.96K |
| hundredThensOnThread            | 0.18% | 72.54us | 13.79K |
| hundredThensOnThreadInline | 0.21%  | 64.79us | 15.43K |

Reviewed By: yfeldblum

Differential Revision: D15319231

fbshipit-source-id: 978c26538d89de15e76eb69bf20c1129b210a442

Summary:
We were computing `SCRATCH/install` and hashing based on that value,
but the build stuff was later computing `SCRATCH/installed` and passing that
to the builders.

Fixup the mismatch.

Reviewed By: simpkins

Differential Revision: D15337969

fbshipit-source-id: 70288f2d9286aaacf4c1f6e0dac4680a55edac6d

Summary:
Adds inline-supporting forms of thenValue and thenTry. Carries this information in the Core through a variant of the HasCallback state. Dispatches the continuation inline rather than on the executor if that state is set.

Propagate completing executor through intermediate promise and make inline execution conditional on matching executors.

Only continue inline if the executor of the completing task matches that of the task-to-be-enqueued, to ensure that calls to via always trigger reposting and that there are no surprises where work runs on the wrong executor.

Reviewed By: yfeldblum

Differential Revision: D15292236

fbshipit-source-id: 51ddd5cfd1196ea9e9f408e2b1337ff9d4fa5b9f

Summary: [Folly] Extract the unique-instance enforcer from `SingletonThreadLocal` into a standalone `UniqueInstance`.

Reviewed By: andriigrynenko

Differential Revision: D14927839

fbshipit-source-id: cfe98ef7a88746a557a64263f3165cd01caeec37

Summary: [Folly] Cut `presorted` and `unsorted` tags; the `presorted` tag has  ambiguous meaning and is replaced by either `sorted_unique` or `sorted_equivalent`.

Reviewed By: vitaut

Differential Revision: D15196179

fbshipit-source-id: a2cdaa06c7c5a55147db67a877b29c5944039e6d

Summary:
See the test for a concrete example.
We have a scenario where both a library, and a service using that library, are using fiber. Managing a separate similar-sized thread and event-base pool costs us complexity and performance. So this seems like a legit need.

The overall solution is to hash the Options struct.
But because that has some cost, I made it optional, by introducing a new FrozenOptions struct.

Reviewed By: andriigrynenko

Differential Revision: D15305274

fbshipit-source-id: 5c53d8c4ed321ae88089c64de41af8229f877d36