Summary:Instead of std::function<bool(int, int)>, use folly::Function to
pass callbacks to Subprocess::communicate. This makes it possible
to pass non-copyable callables, which is especially interesting
because Subprocess::readLinesCallback returns a non-copyable
object.

This diff also fixes the forwarding of the callback passed to
readLinesCallback in case you pass an lvalue reference.

Reviewed By: snarkmaster

Differential Revision: D3169956

fb-gh-sync-id: 7a906f9a3ab50502fc04e0d83a23ca5e0201bb3e
fbshipit-source-id: 7a906f9a3ab50502fc04e0d83a23ca5e0201bb3e

Summary:[Folly] `get_default` and `get_ref_default` variants taking functions.

Useful if the default value is computationally expensive to construct or requires IO.

Reviewed By: andriigrynenko, spacedentist

Differential Revision: D3189247

fb-gh-sync-id: 51c64293f8712d7590348d53cbfd892a5efd9e82
fbshipit-source-id: 51c64293f8712d7590348d53cbfd892a5efd9e82

Summary: The signals were represented using bytes in a pipe or using a count on an event fd (when available). This count was ever growing and caused the pipe to overflow, and in both cases you would get signals on empty queues. This diff only writes to the fd if it there are no bytes to read. Due to races there can still be multiple bytes in the pipe, but overflowing should not be possible. Instead of blindly signaling when there could be messages in the queue, the signals are now synchronized with the state of the queue so that the signals are drained when the queue is empty. This also made it possible to skip the semaphore behavior of the event fd which should improve perf.

Reviewed By: dcolascione

Differential Revision: D3198252

fb-gh-sync-id: 39e620b10c254ffcacabc4c5ac36950a215d4803
fbshipit-source-id: 39e620b10c254ffcacabc4c5ac36950a215d4803

Summary: as titled. When I tried re-adding all functions after cancelAllFunctions, it throws error. This is because it doesn't reset currentFunction to null.

Reviewed By: jjs0

Differential Revision: D3209237

fb-gh-sync-id: 5b6e2d967fc3c0986320d23b8d61eb1bfbff8940
fbshipit-source-id: 5b6e2d967fc3c0986320d23b8d61eb1bfbff8940

Summary: Closes https://github.com/facebook/folly/pull/401

Reviewed By: yfeldblum

Differential Revision: D3207682

Pulled By: snarkmaster

fb-gh-sync-id: 617aeec0e6fe1f46d2464df4b72a3e91c953dc12
fbshipit-source-id: 617aeec0e6fe1f46d2464df4b72a3e91c953dc12

Summary: Add more compatibility for missing gflags

Reviewed By: yfeldblum

Differential Revision: D3202560

fb-gh-sync-id: d25e4abfe8ceee9fb329c9ba12d259d1d03d4974
fbshipit-source-id: d25e4abfe8ceee9fb329c9ba12d259d1d03d4974

Summary: these macros are generally useful for other higher-order macros

Reviewed By: yfeldblum

Differential Revision: D3194777

fb-gh-sync-id: 667fc51c681786ad422309ee463881dc22c972f7
fbshipit-source-id: 667fc51c681786ad422309ee463881dc22c972f7

Summary:Clean up a deprecation warning for JSONSchema's use of
Singleton. This is in experimental, so the interface change should be
reasonable..

Reviewed By: agoder

Differential Revision: D3203348

fb-gh-sync-id: 3283c7d9c507a545f3217eb5afc3734eb047b833
fbshipit-source-id: 3283c7d9c507a545f3217eb5afc3734eb047b833

Summary: find replace 's/{([0-9, a-z"-]+)}/dynamic::array(\1)/g'

Reviewed By: agoder

Differential Revision: D3203454

fb-gh-sync-id: 064bb2bdd0e19a80da32e8f4eb730fc4268d7cad
fbshipit-source-id: 064bb2bdd0e19a80da32e8f4eb730fc4268d7cad

Summary:There're currently two ways to set RequestContext
- RequestContext::create() - creates new context and sets it
- RequestContext::setContext(context) - sets context previously captured by saveContext
In most cases, the RequestContext is set back after the request is processed but sometimes it's not (especially with RequestContext::create). We want to measure cpu time for a request by measuring the total cpu time when a RequestContext is set, so we need to make sure that it's properly reset after the thread is done with the request. Scope guards can help us with that.

Reviewed By: haijunz

Differential Revision: D3156698

fb-gh-sync-id: 7c3eb06c1cc27849071625011bf64c5ad36c0612
fbshipit-source-id: 7c3eb06c1cc27849071625011bf64c5ad36c0612

Summary: Before this fix, the callback would silently ignore `ret == -1` if the error isn't `EAGAIN`.

Reviewed By: spacedentist

Differential Revision: D3193845

fb-gh-sync-id: e4a7aa37de7dab8ebe0633dd9888d8adc11dd1c2
fbshipit-source-id: e4a7aa37de7dab8ebe0633dd9888d8adc11dd1c2

Summary: `__attribute__((no_sanitize("address")))` is not valid in clang 3.6 and earlier

Reviewed By: skotchvail

Differential Revision: D3197412

fb-gh-sync-id: bd555b030fe48268988299dd88b9b7aea54c1a73
fbshipit-source-id: bd555b030fe48268988299dd88b9b7aea54c1a73

Summary: ^^^ this is a stack overflow in the test, and a possible stack or heap overflow.

Reviewed By: dcolascione

Differential Revision: D3151717

fb-gh-sync-id: b4f0660ebbb89139dff003870e132c312068d9a8
fbshipit-source-id: b4f0660ebbb89139dff003870e132c312068d9a8

Summary: This function is being proposed in WG21, the C++ standards body for inclusion in the STL via the Library Fundamentals v2 TS. Using the normal constructor for a std::array with an initializer list introduces a source of coupling between the # of elements you put in the initializer list and the size of the array you specify as a template argument. Worse still, if you put less things in the initializer list than the template argument specifies, it doesn't warn you that you've probably made a pretty devious and subtle error. With this function your array size will always be the same as the # of things you actually put in it. What's more, in some cases this can deduce the type of the elements as well.

Reviewed By: yfeldblum

Differential Revision: D3164432

fb-gh-sync-id: beceaae2ee01cd5f93dec86cf36efdb78a28b4a3
fbshipit-source-id: beceaae2ee01cd5f93dec86cf36efdb78a28b4a3

Summary:There're currently two ways to set RequestContext
- RequestContext::create() - creates new context and sets it
- RequestContext::setContext(context) - sets context previously captured by saveContext
In most cases, the RequestContext is set back after the request is processed but sometimes it's not (especially with RequestContext::create). We want to measure cpu time for a request by measuring the total cpu time when a RequestContext is set, so we need to make sure that it's properly reset after the thread is done with the request. Scope guards can help us with that.

Reviewed By: haijunz

Differential Revision: D3156698

fb-gh-sync-id: cfb678531810e8be5faaf02cb7803bd247557e42
fbshipit-source-id: cfb678531810e8be5faaf02cb7803bd247557e42

Summary: Add some logging to figure out the state of the Qeueu when the write error happens.

Differential Revision: D3190882

fb-gh-sync-id: 6515d77df8aa3086922cb4053f2e437f3e527a36
fbshipit-source-id: 6515d77df8aa3086922cb4053f2e437f3e527a36

Summary:folly::fibers does not use folly::MoveWrapper anymore, so no need to
include that header file.

Reviewed By: yfeldblum

Differential Revision: D3169374

fb-gh-sync-id: 2409b46156843fb0a1454b560c42186f1c412988
fbshipit-source-id: 2409b46156843fb0a1454b560c42186f1c412988

Summary:This is the last place in folly that uses MoveWrapper (other than
the MoveWrapper implementation itself and its tests, of course).

Instead of using a MoveWrapper, the object in question is moved
into the lambda using C++14 syntax, and the lambda is moved in a
call to EventBase::runInEventBaseThread which is possible now
that the EventBase methods accept non-copyable callbacks.

Reviewed By: yfeldblum

Differential Revision: D3169316

fb-gh-sync-id: 2dcb1a523ac417f4619c607898e58b572648e3da
fbshipit-source-id: 2dcb1a523ac417f4619c607898e58b572648e3da

Summary:Renamed AtomicLinkedList to AtomicIntrusiveLinkedList.
AtomicLinkedList is a simple AtomicIntrusiveLinkedList wrapper, which handles intrusive list hook.

Reviewed By: yfeldblum

Differential Revision: D3188171

fb-gh-sync-id: 0823b04a48336d65e0a6a8cd412c75f52afe02b9
fbshipit-source-id: 0823b04a48336d65e0a6a8cd412c75f52afe02b9

Summary:9ab69bc7 removed `__APPLE__` around the strndup definition
because it is defined on modern OSX.  But there was another reference
in String.cpp. Fixing that.

Reviewed By: yfeldblum

Differential Revision: D3186360

fb-gh-sync-id: 709c3b93cd22945e2237412637929df1979526c1
fbshipit-source-id: 709c3b93cd22945e2237412637929df1979526c1

Summary:Although, according to the manpage, these functions are defined in `strings.h`, but they are also defined in `string.h`. We never actually use these functions via `strings.h`, and instead only ever reference them via `string.h`.
To keep things sane, lets just move the functions into `string.h` and kill `strings.h`.

Reviewed By: yfeldblum

Differential Revision: D3181596

fb-gh-sync-id: 8a474df510ddafc4c595b08b809a7c33e3256177
fbshipit-source-id: 8a474df510ddafc4c595b08b809a7c33e3256177

Summary:Fix a bug in folly where it can't infer any RNG type except the
default-supplied parameter.

Differential Revision: D3163421

fb-gh-sync-id: 23d3963ba19dac93fa3407f3a2dfd1d9aa39ea44
fbshipit-source-id: 23d3963ba19dac93fa3407f3a2dfd1d9aa39ea44

Summary: unique_ptr doesn't cast to void*

Reviewed By: andriigrynenko

Differential Revision: D3181346

fb-gh-sync-id: 5b912d2b5d46f3c9953b44d5ced7a8e1b4320678
fbshipit-source-id: 5b912d2b5d46f3c9953b44d5ced7a8e1b4320678

Summary: This fixes folly::ThreadLocal perf after several refactorings which touched the code.

Reviewed By: ericniebler

Differential Revision: D3170761

fb-gh-sync-id: d44198f19aebc9f9f2588a65950efba0694e2a11
fbshipit-source-id: d44198f19aebc9f9f2588a65950efba0694e2a11

Summary:Currently GuargPageAllocator mmap's a memory block enough for 100 fiber stacks and then protects a bottom page for each stack. If FiberManager is used to process a single task, protecting 100 stacks doesn't make much sense, but is costly.

This change makes sure we protect a bottom page of every stack the first time given stack is requested.

Reviewed By: alikhtarov

Differential Revision: D3139944

fb-gh-sync-id: d9d724eaa0e65a227eac1d09a33018e6cb098aae
fbshipit-source-id: d9d724eaa0e65a227eac1d09a33018e6cb098aae

Reviewed By: yfeldblum

Differential Revision: D3174112

fb-gh-sync-id: 00a01f64fb43d2333818097bb2212e26e4dd5775
fbshipit-source-id: 00a01f64fb43d2333818097bb2212e26e4dd5775

Summary:We use `size_t` but didn't include `<stdlib.h>`.
Fix #385

Reviewed By: markisaa

Differential Revision: D3171643

fb-gh-sync-id: 1f915f9602c4be59a21cdf77b31fe18816f35f81
fbshipit-source-id: 1f915f9602c4be59a21cdf77b31fe18816f35f81

Summary: Have the AsyncSocket keep track of the timeout used for connecting and add a getter to retrieve it.

Reviewed By: hiteshk

Differential Revision: D3170625

fb-gh-sync-id: 61d0ecd8d975c49978a1cf222671aa16a2160499
fbshipit-source-id: 61d0ecd8d975c49978a1cf222671aa16a2160499

Summary: Add it to the Makefile.am

Reviewed By: Orvid

Differential Revision: D3168833

fb-gh-sync-id: 7184acc565ffebde0f93bc8bdce4d38ba1a79923
fbshipit-source-id: 7184acc565ffebde0f93bc8bdce4d38ba1a79923

Summary:Change the order of EXPECT_EQ parameters to
EXPECT_EQ(expected, actual). It will make gtest print
the correct error message if a test fails.

Reviewed By: yfeldblum

Differential Revision: D3161878

fb-gh-sync-id: 69e4536c6f396858d189a9d25904ef4df639ad49
fbshipit-source-id: 69e4536c6f396858d189a9d25904ef4df639ad49

Summary:[Folly] Some cleanups to `folly::EventBase` after converting to `folly::Function`.

* Fix up some comments referring to `std::function`.
* Remove the `SmallFunctor` bits - `folly::Function` takes over for that.
* Remove `runFunctionPtr` - it's unused.

Reviewed By: spacedentist

Differential Revision: D3155511

fb-gh-sync-id: 38c75d1254993f59c8eaa7826dc8d9facb50a3a1
fbshipit-source-id: 38c75d1254993f59c8eaa7826dc8d9facb50a3a1

Summary: This header is necessary for the placement new operator used in the construct method (line 265)

Reviewed By: yfeldblum

Differential Revision: D3156741

fb-gh-sync-id: 84a64821553b42d46fb70b5ee267a401028c94f2
fbshipit-source-id: 84a64821553b42d46fb70b5ee267a401028c94f2

Summary: Primarily to support slightly more flexible implementations of `split()`;

Reviewed By: ot

Differential Revision: D3116763

fb-gh-sync-id: 69023c0f26058516f25b9c1f9824055efc7021f9
fbshipit-source-id: 69023c0f26058516f25b9c1f9824055efc7021f9

Summary:We have a bunch of code that manually parses `folly::dynamic`s into program structures. I can be quite hard to get this parsing to be good, user-friendly, and concise. This diff was primarily motivated by the mass of JSON-parsing done by Bistro, but this pattern recurs in other pieces of internal code that parse dynamics.

This diff **not** meant to replace using Thrift structs with Thrift's JSON serialization / deserialization. When all you have to deal with is correct, structured plain-old-data objects produced by another program -- **not** manually entered user input -- Thrift + JSON is perfect. Go use that.

However, sometimes you need to parse human-edited configuration. The input JSON might have complex semantics, and require validation beyond type-checking. The UI for editing your configs can easily enforce correct JSON syntax. Perhaps, you can use `folly/experimental/JSONSchema.h` to have your edit UI provide type correctness. Despite all this, people can still make semantic errors, and those can be impossible to detect until you interpret the config at runtime. Also, as your system evolves, sometimes you need to break semantic backwards-compatibility for the sake of moving forward ? thus making previously valid configurations invalid, and requiring them to be fixed up manually.

So, people end up needing to write manual parsers for `dynamic`s. These all have very similar recurring issues:

 - Verbose: to get an int field out of an object, typical code: (i) tests if the field is present, (ii) checks if the field is an integer, (iii) extracts the integer. Sometimes, you also want to handle exceptions, and compose helpful error messages. This makes the code far longer than its intent, and encourages people to write bad parsers.

 - Unsystematic: sometimes, we use `if (const auto* p = dyn_obj.get_ptr("key")) { ... }`, other times we use `dyn_obj.getDefault()` or `if (dyn_obj.count())`, and so on. The patterns differ subtly in meaning. Exceptions sometimes get thrown, leading to error messages that cannot be understood by the user.

 - Imperative parses: a typical parse proceeds step by step, and throws at the earliest error. This is bad because (i) errors have to be fixed one-by-one, instead of getting a full list upfront, (ii) even if 99% of the config is parseable, the imperative code has no way of recording the information it would have parsed after the first error.

 `DynamicParser` fixes all of the above, and makes your parsing so clean that you might not even bother with `JSONSchema` as your first line of defense -- type-coercing, type-enforcing, friendly-error-generating C++ ends up being more concise. Besides all the sweet syntax sugar, `DynamicParser` lets you parse **all** the valid data in your config, while recording  *all* the errors in a way that does not lose the original, buggy config. This means your code can parse a config that has errors, and still be able to meaningfully export it back to JSON. As a result, stateless clients (think REST APIs) can provide a far better user experience than just discarding the user?s input, and returning a cryptic error message.

For the details, read the docs (and see the example) in `DynamicParser.h`. Here are the principles of `DynamicParser::RECORD` mode in a nutshell:
 - Pre-populate your program struct with meaningful defaults **before** you parse.
 - Any config part that fails to parse will keep the default.
 - Any config part that parses successfully will get to update the program struct.
 - Any errors will be recorded with a helpful error message, the portion of the dynamic that caused the error, and the path through the dynamic to that portion.

 I ported Bistro to use this in D3136954. I looked at using this for JSONSchema's parsing of schemas, but it seemed like too much trouble for the gain, since it would require major surgery on the code.

Reviewed By: yfeldblum

Differential Revision: D2906819

fb-gh-sync-id: aa997b0399b17725f38712111715191ffe7f27aa
fbshipit-source-id: aa997b0399b17725f38712111715191ffe7f27aa

Summary:[Folly] Use `folly::Function` in `folly::EventBase`.

`folly::Function` is moveable but noncopyable and therefore supports wrapping moveable but noncopyable lambdas - like the kind that arises when move-capturing a `std::unique_ptr`.

`std::function` is copyable - therefore it does not support wrapping such noncopyable lambdas.

Switching `folly::EventBase` to use it will allow callers to pass such noncopyable lambdas, allowing, e.g.:

```
auto numptr = folly::make_unique<int>(7); // unique_ptr is noncopyable
folly::EventBase eb;
eb.runInLoop([numptr = std::move(numptr)] { // therefore lambda is noncopyable
  int num = *numptr;
});
eb.loop();
```

This allows us to move away from the `folly::MoveWrapper` hack, which worked like:

```
auto numptr = folly::make_unique<int>(7); // unique_ptr is noncopyable
auto numptrw = folly::makeMoveWrapper(std::move(numptr)); // MoveWrapper is "copyable" - hacky
folly::EventBase eb;
eb.runInLoop([numptrw] { // therefore lambda is "copyable" - hacky
  int num = **numptrw;
});
```

We needed to do that hack while:

But neither condition is true anymore.

Reviewed By: spacedentist

Differential Revision: D3143931

fb-gh-sync-id: 4fbdf5fb77eb5848ed1c6de942b022382141577f
fbshipit-source-id: 4fbdf5fb77eb5848ed1c6de942b022382141577f

Reviewed By: luciang

Differential Revision: D3145033

fb-gh-sync-id: f37d0a2c6e22c1866134159b78722ff43d70918b
fbshipit-source-id: f37d0a2c6e22c1866134159b78722ff43d70918b

Summary: Use malloc/malloc.h there instead

Reviewed By: Orvid

Differential Revision: D3143768

fb-gh-sync-id: 3258b68df49cf7fbff28a3853663d39c147aee8b
fbshipit-source-id: 3258b68df49cf7fbff28a3853663d39c147aee8b

Summary: Sometimes variable shadowing is fine, sometimes it can cause subtle mistakes.

Reviewed By: yfeldblum

Differential Revision: D3140450

fb-gh-sync-id: acf7195ad65614d4f012bef8ce7dccb3a3038456
fbshipit-source-id: acf7195ad65614d4f012bef8ce7dccb3a3038456

Summary:We are jumping through some ugly hoops in the implementation of
fibers to allow for non-copyable functors/lambdas. We can get rid of
those by using folly::Function instead of std::function to store
functions in folly::fibers::Fiber.

This involves one observable interface change: the virtual function
folly::fibers::InlineFunctionRunner::run must take a
folly::Function<void()> argument instead of a std::function<void()>.

Reviewed By: andriigrynenko

Differential Revision: D3102711

fb-gh-sync-id: 56705b972dc24cc0da551109ed44732b97cb6e13
fbshipit-source-id: 56705b972dc24cc0da551109ed44732b97cb6e13

Summary: For exceptions aggregation conveniece

Reviewed By: philippv

Differential Revision: D3128132

fb-gh-sync-id: 48c72df364228c1d2c8f29161c2b85c131b4fea8
fbshipit-source-id: 48c72df364228c1d2c8f29161c2b85c131b4fea8