Summary: SharedMutex purposely allows the inline reader count to underflow in some
situations while preserving proper locking behavior (the inline reader
count is only trusted if all deferred locks have been applied), but there
was an additional way that this could occur that wasn't documented or
allowed by the asserts.  The effect was a false positive assert in rare
conditions or the possibility of losing track of a deferred lock slot.
This diff fixes both the over-aggressive assert and the potential loss
of the shared slot.  If the assert didn't fire for you then this diff
won't change the correctness of your program.

Reviewed By: @yfeldblum

Differential Revision: D2269018

Summary: Because I didn't want to write it again.

Reviewed By: @yfeldblum

Differential Revision: D2217246

Summary: fixing compiler errors when compiling with Wunused-parameter

Reviewed By: @yfeldblum

Differential Revision: D2267014

Summary: Thanks @​peijinz for finding this.

Reviewed By: @​peijinz

Differential Revision: D2268532

Summary: `get_ptr()` checks if the index is past the end of the array, but it
doesn't check if it is less than 0, while `at()` does.

Reviewed By: @yfeldblum

Differential Revision: D2258548

Summary: A timeout now raises `TimedOut()` on the current Future.

Reviewed By: @fugalh

Differential Revision: D2261559

Summary: This fixes github issue https://github.com/facebook/folly/issues/243

I don't understand why this is broken on osx, but the solution is to just `#include <thread>` in the header instead of trying to forward declare `std::thread`.

Reviewed By: @yfeldblum

Differential Revision: D2255026

Summary: fixing C++ compiler warnings for the -Wunused-parameter warning switch on.
This is fixing only the header files, not the library cpp files.

Reviewed By: @yfeldblum

Differential Revision: D2259957

Summary: This is causing a log of spew in proxygen logs

Reviewed By: @afrind

Differential Revision: D2262006

Summary: Forces consumers to handle the empty sequence case instead of cumbersome exceptions.

Reviewed By: @​jrichey, @yfeldblum

Differential Revision: D2219505

Summary: [Folly] Fix a namespace nit in folly/futures/Future.cpp.

As soon as someone introduces a namespace `folly::futures::detail` this will blow up. Fix it so it won't blow up when that happens.

Reviewed By: @​hannesr

Differential Revision: D2258799

Summary: Allow access to a FiberManager's currently running fiber

Reviewed By: @alikhtarov, @andriigrynenko

Differential Revision: D2257201

Summary: `folly::Optional` returns the stored value by reference when the object
is an rvalue.  This causes three issues:

  * If the user calls `value()` on an rvalue `Optional`, and assigns the result
    to a new variable, the copy constructor gets called, instead of the move
    constructor.  This causes the added test `value_move` to not compile.
  * If the user calls `value()` on an rvalue `Optional`, and assigns the result
    to a const lvalue reference, they might expect the lifetime to be extended
    when it isn't. See the added test `value_life_extention`.
  * Assigning the results of `value()` on an rvalue `Optional` to a mutable
    lvalue reference compiled in the old code, when it shouldn't, because that
    is always a dangling reference as far as I can tell.

I'm not sure how strict `folly` is with compatibility, but I believe the
breakage would be minimal, and any code that gets broken probably deserves it.

I'm not exactly sure who I should add as a reviewer, so hopefully herald has got
my back.

Reviewed By: @yfeldblum

Differential Revision: D2249548

Summary: The creator thread ID is saved to indicate the singleton is already being built (to help detect dependency cycles).  However if the creation function throws an error, that thread ID persists, and then if the same thread tries again to build the singleton it will be falsely detected as a dependency cycle.  This clears that state in the case of failure.

Reviewed By: @chipturner

Differential Revision: D2256441

Summary: This reverts commit 956351018a495af89575526536af7e7c0bb285aa.

Reviewed By: @​labrams

Differential Revision: D2258219

Summary: In nested loop, loop condition is incorrect.  Fixed var (should be `ii` not `i`)

Reviewed By: @pgriess

Differential Revision: D2255702

Summary: I'm upgrading assertions to throws, since these are fatal in all circumstances. If something is explicitly `Optional`, it makes sense to fail loudly if it is misused in this manner.

Reviewed By: @yfeldblum

Differential Revision: D2247612

Summary: to unbreak OSS wangle tests build

Reviewed By: @bugok

Differential Revision: D2240264

Summary: What it says on the tin.

Reviewed By: @fugalh

Differential Revision: D2230390

Summary: guard pages may make debugging more painful. For example, in some cases they increased "perf" initialization time.

Reviewed By: @alikhtarov

Differential Revision: D2247188

Summary: I figured it out. This works. The two extra futures are a small overhead
(just two pointers). The `Core`s are allocated anyway, so this is pretty
much optimal.

A timeout now raises on the current Future, and a fulfilled promise
cancels the timeout Future.

Reviewed By: @yfeldblum

Differential Revision: D2232463

Summary: As the comment says, we can ignore errors in setting the size.
So it stands to reason we can ignore setting the size as well.

Reviewed By: @yfeldblum

Differential Revision: D2242882

Summary: There are more use cases that the Destruction/Guard pattern can be
used than current DelayedDestruction provides. This diff makes the pattern more
general (remove self destruct) and lets DelayedDestruction derive from that.
The functionalities of DelayedDestruction is kept unchanged.

I leave destroy(), Destructor class, and destroyPending_ in DelayedDestruction
since they are not required by our CallbackGuard in proxygen.

I add a shouldDestruct() function to allow customized conditions on when to
call destructor.

I haven't made destroyNow() a std::function since I only need it to be set at
instatiation time. If there is any other use case that needs destroyNow() to be
a std::function, I can do that as well.

Reviewed By: @afrind

Differential Revision: D2202575

Summary: Before we didn't do anything at all with the ::infinite value for our
generators, now all the sources operators and sinks are properly notated. The
one signifcant change regarding what is allowed concerns 'cycle' which now (when
called with no arguments) always produces an infinite generator. This is fine
for all but the weirdest of generators fed into cycle.

Reviewed By: @ddrcoder

Differential Revision: D2240328

Summary: When adding in the 'filter()' default behavior, I considered adding in similar
behavior for 'any' and 'all'. However, we had 'any' with no funciton call
basically check if anything was present, not testing a predicate. This can
create a confusing senario, so I removed this behavior from 'any' and added in
the 'isEmpty' and 'notEmpty' sinks. Now the calls 'any()' and 'all()' (called
with parens, so old uses won't compile) check for truthy values simlar to
'filter()'.

I also added some unit tests and changed 'static const' objects to 'constexpr'.

Reviewed By: @ddrcoder

Differential Revision: D2234637

Summary: Integrating RequestContext into fibers library. RequestContext is saved for every task, when that task is created. If RequestContext is overriden when a task is being run (within fiber, in runInMainContext, within function passed to await call) the new context will continue to be used for the task.

Reviewed By: @alikhtarov

Differential Revision: D2240152

Reviewed By: @philippv

Differential Revision: D2240628

Summary: [Folly] Fix Build: folly/io/async/test/ScopedEventBasedThreadTest.cpp

Failure with latest clang:

    folly/io/async/test/ScopedEventBaseThreadTest.cpp:72:8: error: explicitly moving variable of type 'folly::ScopedEventBaseThread' to itself [-Werror,-Wself-move]
      sebt = std::move(sebt);

Reviewed By: @markisaa

Differential Revision: D2238762

Summary: [Folly] File ctor should take StringPiece.

This way we can use it with `std::string` and `folly::fbstring` a touch more easily.

Reviewed By: @luciang

Differential Revision: D2235870

Reviewed By: @chipturner

Differential Revision: D2235232

Summary: This is only a simple #include file split, no functional change was made. SmallLocks.h provides 2 classes: MicroSpinLock and PicoSpinLock, with the latter not being available on 32bit platforms. There are several classes in folly that included SmallLocks.h but only needed MicroSpinLock, these also refused to compile on 32bit, e.g. folly/futures/Future.h. Now these compile fine.

Reviewed By: @yfeldblum

Differential Revision: D2234263

Summary: [Folly] An has_member_type macro.

Reviewed By: @juchem

Differential Revision: D2229775

Summary: After discussion with Tom about frozen files, we noticed that the use
case of filtering out somthing that looks like false (0, nullptr, folly::none)
is unnecessarily tedious. So folly::gen::filter now filters by the value of
the item by default.

Reviewed By: @ddrcoder

Differential Revision: D2220582

Summary: Add mocks for the new isBufferMovable methods.

Reviewed By: @yfeldblum

Differential Revision: D2222642

Summary: [Folly] ThreadedExecutor.

It's an Executor that runs functions each in its own thread.

Kind of simple. Suitable for a few types of strange cases.

Reviewed By: @​hannesr

Differential Revision: D2226211

Summary: Add a way to tell whether an IOBuf (either indvidually or the whole chain)
refers to memory that's outside of IOBuf's control (via WRAP_BUFFER). That is,
can you assume that clone() will extend the lifetime of the memory? Is it safe
to use clone() instead of copying the data (and avoid a copy)?

Reviewed By: @simpkins

Differential Revision: D2191883

Summary: Early in the startup process there may not be a default signal handler installed, and stack traces are not available; also during the startup process is when init-order fiascos occur.  Dump a stacktrace and fatal when an unregistered singleton is used.

Also fatals -- with glog `LOG(FATAL)`, which triggers an ABRT signal -- on other illegal and unrecoverable usage like double-registration or circular dependency.

Reviewed By: @andriigrynenko

Differential Revision: D2200408

Summary: Ran into a bug in D2158570 where we dtor'ing these data structures before the event bases destructed, so the assert on line 47 (of the old code) failed.

Reviewed By: @andriigrynenko

Differential Revision: D2198318