Summary:
Disable the -Wunevaluated-expression warning for this test:

EXPECT_EQ(typeid(ie), typeid(IntException));

Otherwise, clang warns about the unevaluated expression because
the expansion of EXPECT_EQ applies sizeof to an expression
with side effects:

folly/test/ExceptionWrapperTest.cpp:179:122: error: expression with side effects has no effect in an unevaluated context [-Werror,-Wunevaluated-expression]
switch (0) case 0: default: if (const ::testing::AssertionResult gtest_ar = (::testing::internal:: EqHelper<(sizeof(::testing::internal::IsNullLiteralHelper(typeid(ie))) == 1)>::Compare("typeid(ie)", "typeid(IntException)", typeid(ie), typeid(IntException)))) ; else ::testing::internal::AssertHelper(::testing::TestPartResult::kNonFatalFailure, "folly/test/ExceptionWrapperTest.cpp", 179, gtest_ar.failure_message()) = ::testing::Message();

Test Plan:
Ensure this compiles with clang-3.4, 3.5 and clang:dev.
I.e., ensure that this prints PASS at the end.

for i in '' 3.5 dev; do
test -n "$i" && i=--with-project-version=clang:$i
fbconfig -r --clang $i folly/test:exception_wrapper_test && fbmake dbgo
done && echo PASS

Reviewed By: mpawlowski@fb.com

Subscribers: mathieubaudet, folly-diffs@, yfeldblum

FB internal diff: D1850778

Tasks: 6244745

Signature: t1:1850778:1424111029:136478e9a3cc3a219047547d501de4c579a1a181

Summary:
* folly/wangle/channel/test/MockChannelHandler.h:
Avoiding a new warning that rendered this file uncompilable
by clang-3.5 and older.  Add cpp conditionals to protect
against that.

Test Plan:
Ensure it works with clang-3.4, 3.5 and clang:dev.
I.e., ensure that this prints PASS at the end.

for i in '' 3.5 dev; do
test -n "$i" && i=--with-project-version=clang:$i
fbconfig -r --clang $i folly/wangle/channel/test && fbmake runtests_dbgo
done && echo PASS

Reviewed By: meyering@fb.com

Subscribers: mpawlowski, fugalh, mathieubaudet, folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1849474

Tasks: 6244745

Blame Revision: D1848330
@build-break

Summary:
Clang's new -Wself-move warning dings this code:

b = std::move(b);

But in this case, that is a deliberate test of
this capability, so we suppress that particular
warning for the duration of this small test function.

Test Plan:
Run this and note that it now compiles: (it passes the tests, too)
fbconfig --clang --with-project-version=clang:dev -r folly/test:optional_test && fbmake dbgo

Reviewed By: watashi@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1849689

Tasks: 6244745

Signature: t1:1849689:1423877932:4f479d682bd8ba97dcabed7fc29ce0a22c013969

@build-break (using this to work around bogus push failure: https://phabricator.fb.com/P19730606)

Summary:
* folly/ExceptionWrapper.h (class_name): Clang is not yet smart enough to
see that there is no harm in dereferencing an "item_" that we've just
verified is non-NULL.  Accommodate it, to avoid this:
./folly/ExceptionWrapper.h:199:30: error: expression with side effects will be evaluated despite being used as an operand to 'typeid' [-Werror,-Wpotentially-evaluated-expression]
return demangle(typeid(*item_));
^

Test Plan:
Run these commands and note there are fewer errors than before:
fbconfig --clang --with-project-version=clang:dev -r folly && fbmake dbgo

Reviewed By: mhorowitz@fb.com

Subscribers: trunkagent, yfeldblum, folly-diffs@

FB internal diff: D1848327

Tasks: 6244745

Signature: t1:1848327:1423869597:a58c9e9e3671befb78ae07fbd274a13d08ffb2a7

Blame Revision:

Summary: [Folly] clang:dev rejects vector<atomic<T>> in EventBaseTest.cpp.

Test Plan: Build and run `folly/io/async/test/EventBaseTest.cpp` using the current `clang`; try building with `clang:dev` and verifying that at least the related failures are gone.

Reviewed By: meyering@fb.com

Subscribers: mathieubaudet, folly-diffs@, yfeldblum, dougw, brettp

FB internal diff: D1848749

Tasks: 6244720

Signature: t1:1848749:1423866420:7b7354d4568b6a6d6a824236ae8d271f6855d90b

Summary:
This avoids warnings about e.g., sizeof(k++) that result
from macro expansion.
* folly/futures/test/ExecutorTest.cpp: Move increment out
of macro argument list.
* folly/test/FBVectorTestBenchmarks.cpp.h: Likewise.
* folly/test/LazyTest.cpp: Likewise.
Otherwise, we'd get errors like this:

folly/test/LazyTest.cpp:49:118: error: expression with side effects has no effect in an unevaluated context [-Werror,-Wunevaluated-expression]
switch (0) case 0: default: if (const ::testing::AssertionResult gtest_ar = (::testing::internal:: EqHelper<(sizeof(::testing::internal::IsNullLiteralHelper(++globalCount())) == 1)>::Compare("++globalCount()", "1", ++globalCount(), 1))) ; else ::testing::internal::AssertHelper(::testing::TestPartResult::kNonFatalFailure, "folly/test/LazyTest.cpp", 49, gtest_ar.failure_message()) = ::testing::Message();
^

Test Plan:
Run these commands and note there are fewer errors than before:
fbconfig --clang --with-project-version=clang:dev -r folly && fbmake dbgo

Reviewed By: njormrod@fb.com

Subscribers: folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1848324

Tasks: 6244745

Signature: t1:1848324:1423860890:bce44c5e0895804a21957893ae6b78e76dfbc4d3

Summary:
Upgrading to clang:dev (clang >3.6) brought in some new warnings.
This change address all of the issues exposed by the new
-Winconsistent-missing-override, usually by simply adding the
missing "override" keyword.  However, in
folly/wangle/channel/test/MockChannelHandler.h, I chose
to ignore those warnings for the mocked functions.
* folly/futures/test/ViaTest.cpp: Add missing "override"(s).
* folly/io/async/AsyncSSLSocket.h: Likewise.
* folly/io/async/AsyncSocket.h: Likewise.
* folly/io/async/EventBase.h: Likewise.
* folly/test/ExceptionWrapperTest.cpp: Likewise.
* folly/wangle/channel/AsyncSocketHandler.h: Likewise.
* folly/wangle/channel/test/MockChannelHandler.h: Ignore
the new warning for these functions.

Test Plan:
Run these commands and note there are fewer errors than before:
fbconfig --clang --with-project-version=clang:dev -r folly && fbmake dbgo

Reviewed By: hans@fb.com

Subscribers: trunkagent, fugalh, folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1848330

Tasks: 6244745

Signature: t1:1848330:1423858909:b167ca220d6c9fe036d3adca08cf3053a7a9de16

Summary:
This seems cleaner. I also moved a Core member around and changed state to be a smaller size to save us 16 bytes. Might be neat to try to get this down to 128?

Fixed compilation with GCC 4.9, too.

Test Plan: Ran all the tests. Will also benchmark.

Reviewed By: hans@fb.com

Subscribers: trunkagent, folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1843129

Signature: t1:1843129:1423789502:60e56d1af553994991195fcc350d37d644a556ca

Summary:
Pass TransportInfo object through connection setup.  This allows us to
pass along additional info from the setup if necessary.

Test Plan:
Run proxygen on my devserver listening on ipv4 and ipv6 for ports 80 and 443.
Configure it to run a lua request rule with the following lines:

io.stderr:write("jonlog: proxy " .. conn:getClientAddrOriginal() .. "\n")
io.stderr:write("jonlog: client " .. request:getClientIPStr() .. "\n")

Run haproxy also on my devserver, listening on ports 8555-8558, with each
forwarding to one of the four pairs (ipv4-localhost/ipv6-localhost, 80/443)

From my laptop, run curls against each of these four endpoints and make
sure that we print out "127.0.0.1" as the proxy IP, and my laptop's IP
as the client IP.

Reviewed By: cgheorghe@fb.com

Subscribers: jsedgwick, yfeldblum, trunkagent, ruibalp, bmatheny, folly-diffs@, dsp, nbm

FB internal diff: D1746590

Tasks: 5688127

Signature: t1:1746590:1423695880:f647964d95636a69a00304e144aef71ee0213d28

Summary:
`EliasFanoReader::position()` used to return `size() - 1` both when
the reader is positioned on the last element, and after `next()` is
called after that (and it return `false`). Now in the latter case
`position()` returns `size()` (consistently with the usual behaviour
of past-the-end iterators).

Also fix the return type of `jumpTo`.

Test Plan:
fbconfig folly/experimental/test:eliasfano_test && fbmake runtests_opt

Reviewed By: philipp@fb.com

Subscribers: trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1846275

Signature: t1:1846275:1423790264:151f5d2e1e09d4e24dfb758473dfb9cd52c070bd

Summary:
A colleague at another company started making fun of
MicroSpinLock for its x86 assembly and ad hoc compiler memory
barriers. Use C++11 (which wasn't really a thing at the time I wrote
this).

Test Plan: folly's runtests. What else would we like?

Reviewed By: andrei.alexandrescu@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1841563

Signature: t1:1841563:1423780458:a447c081fbd72e3420b23e95dcf26575c9a06798

Summary:
Short skips have been optimized by adding special cases that use simple iteration when it is convenient. Large skips have been optimized by using the broadword selection algorithm by Vigna (improved with ideas by Gog&Petri) instead of iterating on the zeros/ones of the upper bits.

The benchmarks had to be made more granular to measure the differences, in particular they used to test skipping with a fixed skip length for each test, while now we average over a range of skips to better simulate a random distribution.

The improvements are very significant for `skipTo()` on short skips, about 2-3x for skips at distance 1 or 2, which can occur when intersecting dense lists. On large skips the gain is about 17%.

`skip()` exhibits slightly smaller improvements.

before               after
============================================================================  ==================
folly/experimental/test/EliasFanoCodingTest.cpp relative  time/iter  iters/s  time/iter  iters/s
============================================================================  ==================
Next                                                         2.52ns  396.26M     2.52ns  397.28M
Skip_ForwardQ128(1)                                          8.66ns  115.52M     3.92ns  255.28M
Skip_ForwardQ128(2)                                          8.37ns  119.42M     5.08ns  197.04M
Skip_ForwardQ128(4_pm_1)                                     9.67ns  103.41M     7.04ns  142.02M
Skip_ForwardQ128(16_pm_4)                                   21.44ns   46.65M    19.68ns   50.82M
Skip_ForwardQ128(64_pm_16)                                  30.86ns   32.40M    27.58ns   36.26M
Skip_ForwardQ128(256_pm_64)                                 37.80ns   26.45M    32.49ns   30.78M
Skip_ForwardQ128(1024_pm_256)                               38.99ns   25.65M    33.39ns   29.95M
Jump_ForwardQ128                                            37.91ns   26.37M    34.05ns   29.37M
----------------------------------------------------------------------------  ------------------
SkipTo_SkipQ128(1)                                          13.87ns   72.10M     4.42ns  226.49M
SkipTo_SkipQ128(2)                                          18.80ns   53.20M     8.58ns  116.55M
SkipTo_SkipQ128(4_pm_1)                                     23.59ns   42.38M    11.43ns   87.50M
SkipTo_SkipQ128(16_pm_4)                                    36.04ns   27.74M    31.19ns   32.06M
SkipTo_SkipQ128(64_pm_16)                                   53.34ns   18.75M    43.88ns   22.79M
SkipTo_SkipQ128(256_pm_64)                                  62.27ns   16.06M    49.08ns   20.37M
SkipTo_SkipQ128(1024_pm_256)                                65.63ns   15.24M    52.24ns   19.14M
JumpTo_SkipQ128                                             65.89ns   15.18M    54.61ns   18.31M
----------------------------------------------------------------------------  ------------------
Encode_10                                                  111.94ns    8.93M   117.24ns    8.53M
Encode                                                       5.35ms   187.02     5.64ms   177.15
----------------------------------------------------------------------------  ------------------
Select64                                                     8.07ns  123.96M     8.04ns  124.35M
============================================================================  ==================

Test Plan:
fbconfig folly/experimental/test:eliasfano_test && fbmake runtests_opt

Reviewed By: philipp@fb.com

Subscribers: yfeldblum, fbcode-common-diffs@, chaoyc, search-fbcode-diffs@, unicorn-diffs@, trunkagent, folly-diffs@

FB internal diff: D1793554

Signature: t1:1793554:1423619344:1b078c0789639f317342ebcc77b11fe91859cd7b

Summary: Saw this while debugging some stuff. Just an oversight, right?

Test Plan: Ran all the tests.

Reviewed By: hans@fb.com

Subscribers: folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1843016

Signature: t1:1843016:1423704557:d9fdb4b879ab4fcfda54a5fcb16a639df15872b5

Summary: That is, for all inputs except r-values. Now with support for GCC.

Test Plan: Run tests

Reviewed By: ajaymenon@fb.com

Subscribers: moharrami, trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1822339

Signature: t1:1822339:1423683482:027871549d69017a7a23a675025851a0b876ad77

Summary:
This was recently added by @andrii to provide stack traces,
but it no longer needed since he now produces them from a hook in
folly/experimental/SingletonStackTrace.cpp

Test Plan: Continues to build without the include.

Reviewed By: andrii@fb.com

Subscribers: folly-diffs@, yfeldblum, andrii

FB internal diff: D1842654

Signature: t1:1842654:1423696133:cfa91851f28696082f790eb13c3b0b015c813590

Summary:
This reverts commit 4ebb2303bbcf343d7c2bcc95d55557c0a3b444f3.
The caching mechanism was based on a misunderstanding of the
implementation of CLOCK_MONOTONIC_COARSE, and is not correct.
On the plus side, the upstream kernel patch

e76b027e6408 x86,vdso: Use LSL unconditionally for vgetcpu

gets the vdso getcpu from 16 nanos down to 10 (half of which is the
inherent indirect call).

Test Plan: unit tests

Reviewed By: delong.j@fb.com

Subscribers: trunkagent, bmaurer, tudorb, folly-diffs@, yfeldblum, jdelong

FB internal diff: D1840690

Signature: t1:1840690:1423693026:33801341ec0b83bf47e050be6528c5dd05021ed5

Summary: Open-source build was broken because Symbolizer is not part of it.

Test Plan: singleton unit test w/ and w/o SingletonStackTrace.cpp linked in.

Reviewed By: alikhtarov@fb.com

Subscribers: trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1840346

Signature: t1:1840346:1423690004:926c2aa21e0b7916260749120997ad56fab6f742

Summary: This is usually available on linux

Test Plan: Existing tests and manual test on arclinux

Reviewed By: mpawlowski@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1840081

Signature: t1:1840081:1423619986:911c95f9f04f286e9f113543ab4b705cf1b17396

Summary: removing // as it could break some comment parser

Test Plan: unitz

Reviewed By: dancol@fb.com

Subscribers: trunkagent, doug, seanc, folly-diffs@, yfeldblum

FB internal diff: D1830591

Signature: t1:1830591:1423203436:9e8b28b714eb2dc080462ab3e8ce04c176df8586

Summary:
I have half a mind to just rip this out and let people use std::bind if they need this. But I won't be so cruel.

Why isn't this just implemented as `then(std::bind(method, object))` anyway? Is the template soup we have now faster?

Test Plan:
Fixed the unit tests to use the new format.
Will look to contbuild to catch all the things this might break (if anyone is using it at all?), and will fix them.

Reviewed By: hannesr@fb.com

Subscribers: trunkagent, exa, folly-diffs@, yfeldblum, jsedgwick, davejwatson

FB internal diff: D1831118

Signature: t1:1831118:1423243771:65db9a89daf14d8bd88331c503ba1ea7ab03b679

Summary:
`futures::chain<A,Z>(a, b, c, d, e, f, ..., z)` where `a` is a callback suitable for `Future<A>::then` and `z` is a callback suitable for `Future<Y>::then<Z>`.

This will be important, at least in the background, for the new `via`. It will probably also be useful to some user sometime.

I imagine this will be tweaked over time if people find magic ways to get it to deduce the types better. But this works and it's not *too* much trouble to specify A and Z.

Test Plan: unit

Reviewed By: davejwatson@fb.com

Subscribers: trunkagent, exa, folly-diffs@, yfeldblum, jsedgwick

FB internal diff: D1831073

Tasks: 6048744

Signature: t1:1831073:1423259292:711be0e047a2acb706fd74e529d5d5fb6abda566

Summary: This adds different types of messages depending on whether Singleton was depending on other Singleton or just leaked. It also adds destruction stack trace for such Singletons (if they were ever destroyed) to help debug such leaks/broken dependencies.

Test Plan: unit test

Reviewed By: chip@fb.com

Subscribers: trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1830526

Signature: t1:1830526:1423266462:ba328b0da0bf4030b1c4f686d8f7b609fd20683c

Summary:
Most of the singleton construction logic is moved to SingletonEntry, and each SingletonEntry is now also a singleton.
SingletonVault becomes only responsible for keeping singleton construction order (and potentially dependencies) and destoying them in correct order.
This also significantly improves perf of get() / get_weak() (not-fast)

This diff is based on D1823663.

Test Plan:
unit test

============================================================================
folly/experimental/test/SingletonTest.cpp       relative  time/iter  iters/s
============================================================================
NormalSingleton                                            333.35ps    3.00G
MeyersSingleton                                   99.99%   333.39ps    3.00G
FollySingletonSlow                                49.99%   666.84ps    1.50G
FollySingletonFast                                95.90%   347.61ps    2.88G
FollySingletonFastWeak                             2.22%    15.00ns   66.66M
============================================================================

Reviewed By: chip@fb.com

Subscribers: trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1827390

Signature: t1:1827390:1423268514:da322d1dcaba54905d478b253f26dd76f890fb4e

Summary: `decodeVarint` now accepts all of `StringPiece`, `MutableStringPiece`, `ByteRange`, and `MutableByteRange`.

Test Plan: fbconfig -r folly unicorn/utils && fbmake runtests_opt -j32

Reviewed By: ott@fb.com, lucian@fb.com

Subscribers: trunkagent, chaoyc, search-fbcode-diffs@, unicorn-diffs@, folly-diffs@, yzhan, yfeldblum

FB internal diff: D1836805

Signature: t1:1836805:1423534085:cca5c3e83ad699e5d56e1d1e3394644ec3f94dab

Summary: Correct typo on docs.

Test Plan: N/A

Reviewed By: alikhtarov@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1836264

Signature: t1:1836264:1423527402:4e5f263f446346f7145c33c671f0b9e694db15fd

Summary:
include was missing, causing build to fail on
Arch Linux with gcc 4.9.2 -- found this while resolving
other issues.

Test Plan: build folly on my personal linux and on dev server

Reviewed By: viswanath@fb.com

Subscribers: fugalh, folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1835143

Signature: t1:1835143:1423513128:5dcff69a82878f47b40512711ed254f239399c2c

Summary:
This reverts commit 4893c09795ad4b1187518b184ac4812079039988.

Fix unit test in D1823663.

Test Plan: fbconfig -r folly fbmake dbg

Reviewed By: alikhtarov@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1832645

Signature: t1:1832645:1423267466:6012f1d7700d540c7290c29b01b33148cf91183c

Summary:
Under Linux the process gtod doesn't contain the current cpu, so
__vdso_getcpu uses RDTSCP, which makes it cost about 20 nanos.  The gtod
_does_, however, contain a nanosecond time (for CLOCK_REALTIME_COARSE)
updated during context switches.  This diff adds a TLS cache that uses
__vdso_clock_gettime_ns(CLOCK_REALTIME_COARSE) to detect context switches.
The end result is that AccessSpreader goes from ~20 nanos to ~6.

Test Plan: unit tests

Reviewed By: davejwatson@fb.com

Subscribers: yfeldblum, trunkagent, folly-diffs@

FB internal diff: D1798922

Signature: t1:1798922:1423264298:32312a5e9bddb3b8aa630c146ef708164a6a4651

Summary: This reverts commit 315cfed207895455ecd359d0c1b9d98f28ed0519.

Test Plan:
fbconfig -r folly && fbmake dbg

Reviewed By: robbert@fb.com

Subscribers: sdwilsh, folly-diffs@, yfeldblum

FB internal diff: D1831932

Signature: t1:1831932:1423258329:0962b939a93bbf1722a9e1c90090dcc024b63765

Blame Revision: D1823663

Summary: [Folly] Dedupe the implementations of EventBase::runInEventBaseThreadAndWait.

Test Plan:
Unit tests:
* `folly/io/async/test/EventBaseTest.cpp`

Reviewed By: subodh@fb.com

Subscribers: trunkagent, folly-diffs@, yfeldblum, dougw, brettp

FB internal diff: D1826291

Signature: t1:1826291:1423225534:42264d8dcc8adec6b90ac8a3d6ce1f4b98f29297

Blame Revision: D1810764, D1823407

Summary: This makes test SingletonVaults more similar to global SingletonVault. It also ensures that every SingletonVault is a singleton, which allows potential optimization of making each SingletonEntry a Singleton too, which itself will make get/get_weak as efficient as get_fast/get_weak_fast.

Test Plan: unit test

Reviewed By: chip@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1823663

Signature: t1:1823663:1423188884:4ab2b47cfba270a66613f6f2458b6affc0ed96ad

Summary:
we still make the new Future, but assign it to ourselves. this avoids the following buggy pattern that people might expect to work

```
auto f = ...
f.wait();

// Careful. f.value() was moved out into the new Future, so you may have lost something
someOperationOn(f.value());

// Nope. We already set a callback internally in wait()
f.then(...);
```

Test Plan: unit

Reviewed By: davejwatson@fb.com

Subscribers: exa, yfeldblum, trunkagent, fbcode-common-diffs@, sammerat, cold-storage-diffs@, folly-diffs@, jsedgwick, aflock

FB internal diff: D1809040

Tasks: 6048284

Signature: t1:1809040:1422900812:1b416408eb5eaa71e88778c9c22ed8bfba087efe

Summary: We're using StringKeyed* from common/datastruct to avoid unnecessary string creation whenever we're looking up string keys. C++14 does offer a solution, see e.g. http://stackoverflow.com/questions/10536788/avoiding-key-construction-for-stdmapfind. That is not supported by current compilers.

Test Plan: unittests

Reviewed By: pavlo@fb.com

Subscribers: trunkagent, net-systems@, folly-diffs@, yfeldblum

FB internal diff: D1825700

Signature: t1:1825700:1423086724:530550c3c80e33c80900f31c0ade05c66b22cbe8

Summary:
Before this diff the code below compiled and did absolutely nothing of interest:

StringPiece fun();
...
fun() = "hello";

i.e. assignment to an rvalue range was allowed. Such code is almost always, if not always, in error. This diff fixes that.

Test Plan: ran unittests

Reviewed By: ldbrandy@fb.com

Subscribers: mpawlowski, net-systems@, folly-diffs@, yfeldblum

FB internal diff: D1825360

Signature: t1:1825360:1423097817:fdaaf893cd1abbe71dc857a315df7c45cb6a0bd0

Summary: Eliminated a potential race condition by removing unnecessary code.

Test Plan: Unit tests pass.

Reviewed By: lesha@fb.com

Subscribers: tudorb, trunkagent, folly-diffs@, yfeldblum

FB internal diff: D1824924

Signature: t1:1824924:1423102017:6bce388dccf9126d6ac3a1741d8300a51c5276ed

Blame Revision: D1492526

Summary: [Folly] Avoid EventBase depending on Baton (mutex/condvar variant).

Test Plan:
Unit tests:
* folly/io/async/test/EventBaseTest.cpp

Reviewed By: subodh@fb.com

Subscribers: trunkagent, fma, folly-diffs@, yfeldblum, dougw, brettp

FB internal diff: D1823407

Signature: t1:1823407:1423088450:71ae1673ed8067103e2aaa1ac9b239eae9ebe9de

Blame Revision: D1810764

Summary: It is true. Also, add a useful message about which thread this Future will complete in.

Test Plan: it should still compile

Reviewed By: davejwatson@fb.com

Subscribers: trunkagent, exa, folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1819849

Tasks: 5705286, 6008465

Signature: t1:1819849:1423074012:79bf11c877eb2f061cb5d07f7ab45fa4cc4a894b

Summary:
(or func returns Future<T>)

Invoke and respond to a timeout with a callback, rather than using `within` and adding `onError` or `then` or something.

Test Plan: new tests

Reviewed By: davejwatson@fb.com

Subscribers: jsedgwick, yfeldblum, trunkagent, fugalh, exa, folly-diffs@

FB internal diff: D1763174

Tasks: 4548494

Signature: t1:1763174:1423074062:05cec1dfb1110b31b599033949ebe0ee70dd0552